Twin chorionicity and the risk of adverse perinatal outcome

Perinatal outcomes following fetoscopic laser surgery for early twin-to-twin transfusion syndrome: Systematic review and meta-analysis

INTRODUCTION

Our objective was to investigate outcomes in twin-to-twin transfusion syndrome (TTTS) treated with fetoscopic laser surgery (FLS) at <18 weeks vs ≥18 weeks, and to conduct subgroup analysis of TTTS with FLS at <16 weeks vs 16-18 weeks.

MATERIAL AND METHODS

PubMed, Scopus and Web of Science were searched systematically from inception until May 2023. Primary outcome was survival, and secondary outcomes included preterm premature rupture of membranes (PPROM), preterm birth and gestational age (GA) at delivery.

RESULTS

Nine studies encompassing 1691 TTTS pregnancies were included. TTTS stage III was significantly more common in TTTS pregnancies treated with FLS at <18 weeks (odds ratio [OR] 2.84, 95% confidence interval [CI] 1.24-6.54), and procedure duration was shorter at <18 weeks (MD -5.27 minutes, 95% CI -9.19 to -1.34). GA at delivery was significantly earlier in TTTS pregnancies treated with FLS at <18 weeks (MD -3.12 weeks, 95% CI -6.11 to -0.13). There were no significant differences in outcomes, including PPROM, PPROM at <7 days post-FLS, preterm birth at <28 and <32 weeks, delivery at <7 days post-FLS, and survival outcomes, including fetal demise, live birth and neonatal survival. Similarly, TTTS stage III was more common in TTTS with FLS at <16 weeks than at 16-18 weeks (OR 2.95, 95% CI 1.62-5.35), with no significant differences in the aforementioned outcomes.

CONCLUSIONS

In early TTTS treated with FLS, outcomes were comparable between those treated at <18 weeks compared with ≥18 weeks except for GA at delivery, which was 3 weeks earlier. In the subset treated at <16 weeks vs 16-18 weeks, the procedure was feasible without an increased risk of very early preterm birth or perinatal mortality.

The prognostic role of CRL discordance in first trimester ultrasound

OBJECTIVES

In the first trimester, intertwin crown-rump length (CRL) discordance has emerged as a notable factor linked to adverse perinatal health effects. It is frequently employed as a basis for counseling parents regarding potential adverse pregnancy outcomes. Despite its established association with adverse outcomes, the significance of CRL discordance in substantially predicting pregnancy problems and its efficacy in pregnancy screening remain subjects of ongoing discussion. The aim of this manuscript is to present current knowledge on CRL discordance.

METHODS

PubMed was searched for related articles with terms "Crown-Rump length", "Prenatal Screening", "Twin pregnancy", "Discordance".

RESULTS

Twenty-two studies were included in our study with six reporting data on monochorionic and 16 assessing the correlation between CRL discordance and adverse pregnancy outcomes. Fetal loss at the 20th and 24th week of the pregnancy, SGA neonates, pre-term delivery (32 weeks), perinatal death (24 weeks) are all reported adverse outcomes associated with CRL discordance. The reported cut-off for increased risk of adverse perinatal outcomes is a discordance of at least 10% or more.

CONCLUSIONS

Increased CRL (>10 %) discordance is linked to a higher risk of sFGR in both monochorionic and dichorionic pregnancies, fetal loss, and preterm delivery.

Pregnancy and obstetric outcomes of dichorionic triamniotic triplet pregnancies with selective foetal reduction after assisted reproductive technology

BACKGROUND

It is generally beneficial and recommended that dichorionic triamniotic (DCTA) triplet pregnancies be reduced to monochorionic (MC) twin or singleton pregnancies after assisted reproductive technology (ART). However, some infertile couples still have a firm desire to retain twins. For this reason, the best foetal reduction strategies need to be available for infertile couples and clinicians. Given that data on the elective reduction of DCTA triplet pregnancies to twin pregnancies are scarce, we investigated the outcomes of elective reduction of DCTA triplet pregnancies through the retrospective analysis of previous data.

METHOD

Patients with DCTA triplet pregnancies who underwent elective foetal reduction between January 2012 and June 2020 were recruited. A total of 67 eligible patients with DCTA triplet pregnancies were divided into two groups: a DCTA-to-dichorionic diamniotic (DCDA) twin group (n = 38) and a DCTA-to-monochorionic diamniotic (MCDA) twin group (n = 29); the basic clinical data of the two groups were collected for comparison.

RESULTS

Compared with the DCDA-to-MCDA twin group, the DCTA-to-DCDA twin group had lower rates of complete miscarriage (7.89% versus 31.03%, p = 0.014), early complete miscarriage (5.26% versus 24.14%, p = 0.034), late preterm birth (25.71% versus 65.00%, p = 0.009) and very low birth weight (0 versus 11.11%, p = 0.025). In addition, the DCTA-to-DCDA twin group had higher rates of full-term delivery (65.71% versus 25.00%, p = 0.005), survival (92.11% versus 68.97%, p = 0.023), and taking the babies home (92.11% versus 68.97%, p = 0.023) than did the DCTA-to-MCDA twin group. In terms of neonatal outcomes, a significantly greater gestational age (38.06 ± 2.39 versus 36.28 ± 2.30, p = 0.009), average birth weight (3020.77 ± 497.33 versus 2401.39 ± 570.48, p < 0.001), weight of twins (2746.47 ± 339.64 versus 2251.56 ± 391.26, p < 0.001), weight of the larger neonate (2832.94 ± 320.58 versus 2376.25 ± 349.95, p < 0.001) and weight of the smaller neonate (2660.00 ± 345.34 versus 2126.88 ± 400.93, p < 0.001) was observed in the DCTA-to-DCDA twin group compared to the DCTA-to-MCDA twin group.

CONCLUSION

The DCTA-to-DCDA twin group had better pregnancy and neonatal outcomes than the DCTA-to-MCDA twin group. This reduction approach may be beneficial for patients with dichorionic triamniotic triplet pregnancies who have a strong desire to have DCDA twins.

Selective fetal growth restriction in dichorionic diamniotic twin pregnancy: systematic review and meta-analysis of pregnancy and perinatal outcomes

OBJECTIVE

Most of the published literature on selective fetal growth restriction (sFGR) has focused on monochorionic twin pregnancies. The aim of this systematic review was to report on the outcome of dichorionic diamniotic (DCDA) twin pregnancies complicated by sFGR.

METHODS

MEDLINE, EMBASE and The Cochrane Library databases were searched. The inclusion criteria were DCDA twin pregnancies complicated by sFGR. The outcomes explored were intrauterine death (IUD), neonatal death and perinatal death (PND), survival of at least one and both twins, preterm birth (PTB) (either spontaneous or iatrogenic) prior to 37, 34, 32 and 28 weeks' gestation, pre-eclampsia (PE) or gestational hypertension, neurological, respiratory and infectious morbidity, Apgar score < 7 at 5 min, necrotizing enterocolitis, retinopathy of prematurity and admission to the neonatal intensive care unit (NICU). A composite outcome of neonatal morbidity, defined as the occurrence of respiratory, neurological or infectious morbidity, was also evaluated. Random-effects meta-analysis was used to analyze the data, and results are reported as pooled proportion or odds ratio (OR) with 95% CI.

RESULTS

Thirteen studies reporting on 1339 pregnancies with sFGR and 6316 pregnancies without sFGR were included. IUD occurred in 2.6% (95% CI, 1.1-4.7%) of fetuses from DCDA pregnancies with sFGR and 0.6% (95% CI, 0.3-9.7%) of those from DCDA pregnancies without sFGR, while the respective values for PND were 5.2% (95% CI, 3.5-7.3%) and 1.7% (95% CI, 0.1-5.7%). Spontaneous or iatrogenic PTB before 37 weeks complicated 84.1% (95% CI, 55.6-99.2%) of pregnancies with sFGR and 69.1% (95% CI, 45.4-88.4%) of those without sFGR. The respective values for PTB before 34, 32 and 28 weeks were 18.4% (95% CI, 4.4-38.9%), 13.0% (95% CI, 9.5-17.1%) and 1.5% (95% CI, 0.6-2.3%) in pregnancies with sFGR and 10.2% (95% CI, 3.1-20.7%), 7.8% (95% CI, 6.8-9.0%) and 1.8% (95% CI, 1.3-2.4%) in those without sFGR. PE or gestational hypertension complicated 19.9% (95% CI, 12.4-28.6%) of pregnancies with sFGR and 12.8% (95% CI, 10.4-15.4%) of those without sFGR. Composite morbidity occurred in 28.2% (95% CI, 7.8-55.1%) of fetuses from pregnancies with sFGR and 13.9% (95% CI, 6.5-23.5%) of those from pregnancies without sFGR. When stratified according to the sFGR status within a twin pair, composite morbidity occurred in 39.0% (95% CI, 11.1-71.5%) of growth-restricted fetuses and 29.9% (95% CI, 3.5-65.0%) of appropriately grown fetuses (OR, 1.9 (95% CI, 1.7-3.1)), while the respective values for PND were 3.0% (95% CI, 1.8-4.5%) and 1.6% (95% CI, 0.9-2.6%) (OR, 2.1 (95% CI, 1.0-4.1)). On risk analysis, DCDA pregnancies complicated by sFGR had a significantly higher risk of IUD (OR, 5.2 (95% CI, 3.2-8.6)) and composite morbidity or admission to the NICU (OR, 3.2 (95% CI, 1.9-5.6)) compared to those without sFGR, while there was no difference in the risk of PTB before 34 weeks (P = 0.220) or PE/gestational hypertension (P = 0.210).

CONCLUSIONS

DCDA twin pregnancies complicated by sFGR are at high risk of perinatal morbidity and mortality. The findings of this systematic review are relevant for counseling and management of complicated DCDA twin pregnancies, in which twin-specific, rather than singleton, outcome data should be used. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Clinical outcomes of fetal selective reduction in dichorionic triplet pregnancies

BACKGROUND

It is recommended to reduce triplet pregnancy containing monochorionic (MC) twins to singleton. Given that some couples with infertility are eager to retain twins, better strategy is needed to avoid obstetrical risks and satisfy their strong wish. This retrospective observational study aimed to investigate the outcomes of triplet pregnancy reduction.

METHODS

Subjects with triplet pregnancies who underwent selective reduction between 2016 and 2019 at our hospital were enrolled. A total of 66 subjects with dichorionic triplet (DCT) with MC twins and an MC singleton were divided into two groups: group A (N = 38), reduced to dichorionic diamniotic (DCDA) twins; group B (N = 28), reduced to MC diamniotic (MCDA) twins. Obstetrical and perinatal outcomes were compared between groups.

RESULTS

Group A had significantly lower rates of early miscarriage (0% vs 14.3%, p = 0.028), cesarean section (81.6% vs 100%, p = 0.041), and late premature delivery (21.1% vs 45.4%, p = 0.047) than group B. Significantly higher rates of full-term delivery (71% vs 36.4%, p = 0.009) and take-home baby (100% vs 78.6%, p = 0.004), and higher gestational age at delivery (median: 38 [36.9, 39.0] vs 35.8 [34.4, 37.0] weeks, p < 0.001), total neonatal weight (2899.7 ± 647.6 vs 2354.4 ± 651.8 g, p < 0.001), weight of twins (2550 vs 2350 g, p = 0.039), and weight of larger neonate in twins (2790 vs 2500 g, p = 0.045) were observed in group A compared to group B.

CONCLUSION

DCT reduced to DCDA twins confers better pregnancy outcomes than into MCDA twins. This might benefit for triplet pregnancy subjects who strongly want to retain fraternal twins.

The impact of placental anastomoses and umbilical cord insertions' sites on monochorionic twin pregnancy outcomes: Evidence from color-dye injection studies

INTRODUCTION

Our knowledge of monochorionic pregnancies' complications is largely based on the extensive ongoing research on monochorionic placental structure. Previous studies on the concordance of umbilical cord insertions are limited. This study aimed to evaluate placental anastomoses and cord insertions as independent risk factors for neonatal adverse outcomes.

METHODS

This was a prospective study conducted at Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Rome, Italy from April 2021 to December 2022. Seventy-six women with a monochorionic pregnancy were enrolled at their first-trimester scan. After delivery, all placentas that were confirmed to be monochorionic were analyzed according to standard protocols, including those of complicated monochorionic twin pregnancies. The primary outcomes were a Composite Monochorionic Pregnancy Outcome (CMPO) and a Composite Neonatal Adverse Outcome (CNAO). The secondary outcome was the birth weight discordance between the neonates.

RESULTS

The CMPO occurred in 15.8 % pregnancies, and the CNAO occurred in 67.1 % pregnancies. The analysis confirmed a significant association between velamentous cord insertions and neonatal adverse events (p = 0.003). Also, a significant positive association (p = 0.0326) between twin birth weight discordance and discordance in twins umbilical cord insertions' sites was found. No significant association between the number and type of the anastomoses and both the CMPO or CNAO was detected.

DISCUSSION

Our data suggest that the routine sonographic assessment of umbilical cords' insertion sites during the first trimester could be helpful in predicting fetal and neonatal adverse events. We believe that this sonographic assessment should start to be implemented in our routine care of monochorionic pregnancies.

The High-Risk Profile of Selective Growth Restriction in Monochorionic Twin Pregnancies

The present review aims to provide a critical appraisal of the sonographic diagnosis and follow-up and to evaluate the optimal clinical management of monochorionic twin pregnancies where one of the twins is complicated by selective fetal growth restriction (sFGR). The classification is based on the umbilical artery (UA) diastolic flow reflecting the outcome. If the sFGR twin has positive diastolic flow (Type I) then the prognosis is good, and it does not require close surveillance. Biweekly or weekly sonographic and Doppler surveillance and fetal monitoring are recommended strategies to detect unpredictable complications in type II and type III forms, which are defined by persistently absent/reverse end-diastolic flow (AREDF) or cyclically intermittent absent/reverse end-diastolic flow (iAREDF) in the umbilical waveforms, respectively. The latest forms are associated with an increased risk of unexpected fetal demise of the smaller twin and 10-20% risk of neurological injury in the larger twin in addition to the overall risk of prematurity. The clinical course can be affected by elective fetal therapy ('dichorinization' of the placenta with laser or selective fetal reduction) or elective delivery in the presence of severe fetal deterioration. The prediction of the clinical outcome in complicated cases of type II and III sFGR cases remains elusive. Novel routines in fetal and placental scans in order to predict neurological impairments and unexpected fetal death to optimize the delivery time-point are needed.

[Monochorionic biamniotic twin pregnancies outcomes in Reunion Island with indication of in utero transfert]

OBJECTIVE

Complicated monochorionic biamniotic (MCBA) twin pregnancies may require treatment with fetoscopic laser photocoagulation, in case of Twin Oligo-Polyhydramnios Sequence or need of a selective termination of pregnancy. Patients requiring these treatments would need medical transfer to Metropolitan France because these are unavailable in Réunion Island. We evaluated the outcomes of MCBA pregnancies in Reunion Island with indications for fetoscopy, with a view to discussing the interest of training doctors on the Reunion Island, to practice fetoscopy on site.

MATERIALS AND METHODS

Retrospective hospital study running from 2015 to 2018. We included all MCBA pregnancies between 15 and 25 weeks of gestation, with indications for in utero transfer. Our objective was to examine whether and why they were transferred and pregnancy outcomes.

RESULTS

Of the 23 patients, 17 (73.9%) benefited from sanitary transfers. The survival rate of the fetuses in 15 pregnancies with Twin Oligo-Polyhydramnios Sequence (TOPS) was 73.3% for one twin and 53.3% for both twins. For the eight cases of Selective Termination of the pregnancy (ST), the survival rate of the twin was better with a transfer (n=5/6, 83.3%) than without a transfer (n=1/2 or 50%). The rate of premature rupture of the membranes after sanitary transfer among patients with TOPS was 63.6%.

CONCLUSION

The sanitary transfer allows the management in expert center of complicated MCBA twin pregnancies, but is not always feasible and is accompanied by a high rate of premature ruptures of membranes.

Abnormal umbilical cord insertion and birth weight discordancy in monochorionic diamniotic twins: A retrospective study

To investigate the relationship between abnormal umbilical cord insertion and birthweight discordance in monochorionic diamnionic (MCDA) twins. A total of 137 pairs of MCDAs were retrospectively analyzed who delivered and survived in Hangzhou Women's Hospital from January 2016 to December 2021. According to different insertion methods, they were divided into normal cord insertion group (n = 57), marginal cord insertion (MCI) group (n = 34) and velamentous cord insertion (VCI) group (n = 46). The correlation was analyzed between different insertion methods of umbilical cord and the discordant birth weight of MCDAs. The gestational age of delivery with velamentous cord insertion was significantly earlier than those with normal and marginal insertion (P < .05). There were significant differences in birthweight between large fetus (F1) and small fetus (F2) with different umbilical insertion methods (P < .05). The birthweight of F1 and F2 in normal insertion group was significantly higher than those in MCI and VCI group (P < .05). Logistic regression analysis showed that VCI was significantly associated with birth weight in F1/F2, birthweight discordance ≥ 20%, and birthweight discordance ≥ 25%, however MCI and VCI were not an independent factor for discordance in birthweight of MCDAs (P > .05). Umbilical cord insertion method can lead to inconsistency in birthweight of MCDA twins, however they were not an independent factor for discordance in birthweight.

Acute Twin-to-Twin Transfusion Syndrome Resulting in Fetal Bradycardia and Neonatal Death: A Case Report

In monochorionic twins with no evidence of chronic twin-to-twin transfusion syndrome or twin anemia-polycythemia sequence, a sudden onset of fetal transfusion syndrome after the second trimester of pregnancy is defined as acute twin-to-twin transfusion syndrome. Labor pain, change in the fetal position, and birth order are known risk factors for this condition, and the hemoglobin level of the donor twin is usually reported to be <12 g/dL. We report a recent case of acute twin-to-twin transfusion syndrome without effective labor pain causing cervical changes, resulting in fetal bradycardia and neonatal death after birth; however, the anemia of the donor twin was not as severe as has been reported previously in twin-to-twin transfusion syndrome cases.

Premature monochorionic monoamniotic twins have lower lung compliance at birth than matched dichorionic diamniotic twins

BACKGROUND: Premature infants are born with immature lungs that demonstrate abnormal pulmonary function with differences in passive respiratory system compliance and resistance, and functional residual capacity. To our knowledge, no studies have evaluated differences in neonatal pulmonary function based on the type of twin gestation, or chorionicity. Given the effect of chorionicity on outcomes, we aimed to study the effect of twin type, monochorionic monoamniotic (MCMA) vs dichorionic diamniotic (DCDA), on neonatal early pulmonary function tests. METHODS: In this prospective cohort study, 5 sets of DCDA twins were matched to 5 sets of MCMA twins on gestational age at delivery, latency from antenatal corticosteroid exposure, birthweight, race and gender. Mean values were compared for passive respiratory system compliance and resistance, functional residual capacity, and tidal volume. RESULTS: MCMA infants had a significantly lower compliance (0.64 vs 1.25 mL/cm H2O /kg; p = 0.0001) and significantly higher resistance (0.130 vs 0.087 cm H2O /mL/sec; p = 0.0003) than DCDA infants. Functional residual capacity was lower for MCMA than DCDA infants (17.5 vs 23.4 mL/kg; p = 0.17). Further, 80% of MCMA infants required intubation for surfactant administration compared to 20% of DCDA infants, indicating the clinical significance of these objective measures. CONCLUSIONS: Due to the matched case-control design, causality cannot be established. However, we speculate that these differences in lung function may derive from differential exposure to preterm labor and endogenous maternal corticosteroid exposure. Further study is necessary to establish the true causal relationship.

Diagnosis-Related Group Weight and Derived Case Mix Index to Assess the Complexity among Twins

OBJECTIVE

Diagnosis-related groups (DRGs) are used to summarize hospital morbidity and mortality. Each DRG has a weight which is important in calculating the case mix index (CMI), a numeric summary of disease complexity in a population of patients. We utilized DRG weight and resultant CMI to compare postnatal outcomes among singletons versus monochorionic and monoamniotic, monochorionic diamniotic, and dichorionic diamniotic twins.

STUDY DESIGN

This single-center and retrospective cohort study evaluated DRGs assigned by the investigators, birth weight, gestational age, length of stay (LOS), NICU admission rate, and mortality in twin births between 2014 and 2016. Twins were analyzed depending on chorionicity and amnionicity. Overall, 3 months of singleton births served as the control. The CMI derived from DRG weights were compared across groups.

RESULTS

Twins (n = 288) had lower gestational ages and birth weights and higher mortality, LOS, NICU admission rates and DRG weights/CMI compared with singletons (n = 327; p < 0.001 for each). The LOS was no different between twin subtypes; monochorionic monoamniotic twins had the highest mortality and DRG weight (p < 0.001).

CONCLUSION

DRG weight and CMI values summarize in-hospital complexity and can be a useful tool to evaluate differences in care complexity among groups of patients.

KEY POINTS

· Using diagnosis-related group and case mix index to assess morbidities.. · Morbidities of twins are monochorionic-monoamniotic versus monochorionic-diamniotic versus dichorionic-diamniotic twins.. · Only seven diagnosis-related group in neonatology make it a valuable tool for clinicians..

Are there differences between monochorionic twin placentas after spontaneous and assisted conception?

INTRODUCTION

No data are available on the placental characteristics of monochorionic twin pregnancies conceived by in vitro fertilization (IVF). This study investigates the differences between placentas from monochorionic diamniotic (MCDA) twin pregnancies conceived spontaneously and those conceived after IVF.

METHODS

This is a retrospective analysis of placental data from a consecutive series of MCDA twin pregnancies followed from the first trimester. The following placental characteristics were compared between IVF versus spontaneous MCDA pregnancies: placental sharing and birth weight discordance relative to placental sharing, the placental angioarchitecture (number, type, and size of anastomoses), and the umbilical cord insertion types.

RESULTS

Of the 256 MCDA placentas included in this analysis, 32 (12%) were conceived through IVF and 224 (88%) spontaneously. MCDA twin placentas after IVF did not differ significantly from MCDA twin placentas after spontaneous conception regarding placental sharing, birthweight discordance relative to sharing discordance, and angioarchitecture. There was a trend toward more discordant cord insertions (combination eccentric and velamentous) in IVF (25%) than in spontaneously conceived placentas (12%) (P = 0.05).

DISCUSSION

No differences could be demonstrated between MCDA placentation after spontaneous conception and IVF. Any differences in pregnancy outcome between spontaneous and IVF conceived MCDA twins may not be related to differences in placental sharing, angioarchitecture and cord insertion type.

Selective Fetal Growth Restriction Type III: Application of a Recent Expert Consensus Definition

OBJECTIVES

Per a recent expert definition, diagnosis of selective fetal growth restriction (sFGR) in monochorionic diamniotic twins is based on an estimated fetal weight (EFW) <3% as sole criterion and/or combinations of 4 contributory criteria (1 twin EFW <10%; 1 twin abdominal circumference <10%; EFW discordance ≥25%; and smaller twin umbilical artery [UA] pulsatility index >95th percentile). We assessed these criteria in sFGR Type III (intermittent absent or reversed end-diastolic flow of the UA [iAREDF]) patients to test whether meeting the more stringent parameters of the consensus definition had worse outcomes, that is, progression to sFGR Type II (persistent AREDF) or twin-twin transfusion syndrome; or secondarily, decreased dual survivorship.

METHODS

This was a retrospective study of referred sFGR Type III patients (2006-2017). Patients were retrospectively categorized using consensus criteria for 2 comparisons: 1) EFW <3% versus remaining cohort; 2) EFW <3% or met all 4 contributory criteria versus remaining cohort.

RESULTS

Forty-eight patients were studied. Comparison 1: EFW <3% patients (58.3%) were not more likely to demonstrate disease progression (46.4% versus 65.0%, P = .2489) or worse dual survivorship (78.6% versus 85.0%, P = .7161). Comparison 2: EFW <3% or met all 4 contributory criteria (75.0%) patients were not more likely than the others to demonstrate progression (44.4% versus 83.3%, P = .0235) or worse dual survivorship (80.6% versus 83.3%, P = 1.0000).

CONCLUSIONS

In a referred cohort of sFGR Type III patients, there was no evidence that meeting more stringent parameters of the consensus definition was associated with disease progression or dual survivorship.

Incidence of small-for-gestational-age infant birthweight following early intertwin fetal growth discordance in dichorionic and monochorionic twin pregnancies

BACKGROUND

Serial growth scans are routinely recommended for twin pregnancies to identify fetal growth restriction (defined as an estimated fetal weight of <10th percentile), which can result in increased perinatal morbidity and mortality. However, the clinical significance of early intertwin growth discordance in the absence of fetal growth restriction remains unclear.

OBJECTIVE

This study aimed to compare the rates of small-for-gestational-age infants among twin pregnancies with intertwin growth discordance in the absence of fetal growth restriction with that among twin pregnancies with concordant, normal growth identified by ultrasound between 24 0/7 and 31 6/7 weeks' gestation.

STUDY DESIGN

This was a retrospective cohort study of twin deliveries at a single hospital from 2010 to 2019. Pregnancies without fetal growth restriction were categorized as discordant or concordant using the earliest prenatal growth ultrasound between 24 0/7 and 31 6/7 weeks' gestation. Discordance was defined as an estimated fetal weight difference of ≥18% between twins. Pregnancies with major fetal anomalies, no growth ultrasound between 24 0/7 and 31 6/7 weeks' gestation, or twin-twin transfusion syndrome were excluded. The cohort was stratified by chorionicity. Our primary outcome was small-for-gestational-age defined as <10th percentile per the Fenton growth curve at delivery. Secondary outcomes included gestational age at delivery, mode of delivery, neonatal intensive care unit admission, length of stay, and neonatal complications and placental pathology.

RESULTS

Of the 707 twin pregnancies that met the inclusion criteria, 558 (79%) were dichorionic and 149 (21%) were monochorionic. Most pregnancies were concordant on ultrasound between 24 0/7 and 31 6/7 weeks' gestation (dichorionic, 93%; monochorionic, 87%). Regardless of chorionicity, twin pregnancies with discordance at ultrasound, were more likely to have a small-for-gestational-age infant than concordant twin pregnancies (dichorionic: 51% vs 29%; P=.002; monochorionic: 65% vs 24%; P<.001). Furthermore, women with twin pregnancies with discordance were delivered at an earlier gestational age (dichorionic: 36 weeks [interquartile range, 33-36] vs 34 weeks [interquartile range, 34-38]; P<.001; monochorionic: 34 weeks [interquartile range, 32-34] vs 36 weeks [interquartile range, 34-37]; P=.003). Pregnancies with growth discordance were more likely to be delivered by cesarean delivery (dichorionic: 90% vs 72%; P=.01; monochorionic: 65% vs 60%; P=.70), although this was only statistically significant for dichorionic twin pregnancies. Neonates of pregnancies with growth discordance had a higher incidence of respiratory distress syndrome (dichorionic: 54% vs 37%; P=.04; monochorionic: 70% vs 45%; P=.04) and neonatal intensive care unit admission (dichorionic: 71% vs 50%; P=.01; monochorionic: 90% vs 65%; P=.03). Furthermore, dichorionic infants had longer neonatal intensive care unit stays (30 [interquartile range, 18-61] vs 18 [interquartile range, 10-35] days; P=.02).

CONCLUSION

Regardless of chorionicity, twin pregnancies with discordance without fetal growth restriction identified on growth ultrasound between 24 0/7 and 31 6/7 weeks' gestation were nearly twice as likely to develop small-for-gestational-age neonates, deliver earlier in gestation, and experience greater neonatal morbidity than twin pregnancies without discordance. Patients with pregnancies complicated by isolated intertwin discordance between 24 0/7 and 31 6/7 weeks' gestation will need counseling regarding adverse perinatal outcomes.

Growth patterns of monochorionic twin pregnancy complicated by Type-III selective fetal growth restriction

OBJECTIVES

Little is known regarding fetal growth patterns in monochorionic twin pregnancy complicated by Type-III selective fetal growth restriction (sFGR). We aimed to assess fetal growth and umbilical artery Doppler pattern in Type-III sFGR across gestation and evaluate the effect of changing Doppler flow pattern on growth and intertwin growth discordance.

METHODS

This was a retrospective cohort study of all Type-III sFGR pregnancies managed at nine fetal centers over a 12-year time period. Higher-order multiple pregnancy and cases with major fetal anomaly or other monochorionicity-related complications at presentation were excluded. Estimated fetal weight (EFW) was assessed on ultrasound for each twin pair at five timepoints (16-20, 21-24, 25-28, 29-32 and > 32 weeks' gestation) and compared with singleton and uncomplicated monochorionic twin EFW. EFW and intertwin EFW discordance were compared between pregnancies with normalization of umbilical artery Doppler of the smaller twin later in pregnancy and those with persistently abnormal Doppler.

RESULTS

Overall, 328 pregnancies (656 fetuses) met the study criteria. In Type-III sFGR, the smaller twin had a lower EFW than an average singleton fetus (EFW Z-score ranging from -1.52 at 16 weeks to -2.69 at 36 weeks) and an average monochorionic twin in uncomplicated pregnancy (Z-score ranging from -1.73 at 16 weeks to -1.49 at 36 weeks) throughout the entire gestation, while the larger twin had a higher EFW than an average singleton fetus until 22 weeks' gestation and was similar in EFW to an average uncomplicated monochorionic twin throughout gestation. As pregnancy advanced, growth velocity of both twins decreased, with the larger twin remaining appropriately grown and the smaller twin becoming more growth restricted. Intertwin EFW discordance remained stable throughout gestation. On multivariable longitudinal modeling, normalization of fetal umbilical artery Doppler was associated with better growth of the smaller twin (P = 0.002) but not the larger twin (P = 0.1), without affecting the intertwin growth discordance (P = 0.09).

CONCLUSIONS

Abnormal fetal growth of the smaller twin in Type-III sFGR was evident early in pregnancy, while EFW of the larger twin remained normal throughout gestation. Normalization of umbilical artery Doppler was associated with improved fetal growth of the smaller twin. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Twin-twin transfusion syndrome and the definition of recipient polyhydramnios

BACKGROUND

Controversy exists regarding the threshold of recipient twin polyhydramnios required to diagnose twin-twin transfusion syndrome at a gestational age of ≥20 weeks. One criterion set (Quintero staging) requires the amniotic fluid maximum vertical pocket for the recipient twin to measure ≥8 cm, whereas another (European) system uses a maximum vertical pocket for the recipient twin of ≥10 cm.

OBJECTIVE

This study aimed to characterize the patients with twin-twin transfusion syndrome who were treated with laser surgery and would be excluded from laser surgery according to the European criteria.

STUDY DESIGN

A total of 366 monochorionic diamniotic twins diagnosed with twin-twin transfusion syndrome from 20 to 26 weeks' gestation who underwent laser surgery at our center were studied. A maximum vertical pocket for the recipient twin of ≥8 cm was used to diagnose twin-twin transfusion syndrome. Patients were retrospectively divided into the following 2 groups: group A with a maximum vertical pocket for the recipient twin of ≥8 cm and <10 cm and group B with a maximum vertical pocket for the recipient twin of ≥10 cm. The association of each of the groups with the survivorship outcomes was tested. Bivariate associations between the patient characteristics and the 30-day donor twin and dual survivorship outcomes were evaluated. Tests used in the analysis were chi-square or Fisher exact tests as appropriate for categorical variables and Kruskal-Wallis tests for continuous variables. Multiple logistic regression models for each of the survivorship outcomes were then assessed. The results are reported as mean±standard deviation.

RESULTS

Of the 366 studied patients, 53 (14.5%) had a maximum vertical pocket for the recipient twin of ≥8 and <10 cm (group A) and 313 (85.5%) had a maximum vertical pocket for the recipient twin of ≥10 cm (group B). Groups A and B did not differ in the Quintero stage. Notably, 60.4% (32 of 53) of group A patients were stage III or IV. When compared with group B, group A was diagnosed with twin-twin transfusion syndrome at an earlier gestational age (21.7±1.6 vs 22.3±1.6 weeks; P=.0037) and had a higher prevalence of donor growth restriction (81.1% [43 of 53] vs 65.5% [205 of 313]; P=.0260). Rates of at least 1 twin and dual twin survival between group A and B were similar (98.1% [52 of 53] vs 95.8% [300 of 313]; P=.7023, and 79.2% [42 of 53] vs 83.4% [261 of 313]; P=.4369, respectively). Logistic regression models adjusted for perioperative characteristics showed no difference in the outcomes between the groups (group B as reference) (donor twin survival odds ratio, 0.64; 95% confidence interval, 0.29-1.42; P=.2753; and dual survivor odds ratio, 0.90; 95% confidence interval, 0.42-1.91; P=.7757).

CONCLUSION

Restriction of the definition of twin-twin transfusion syndrome to a maximum vertical pocket for the recipient of ≥10 cm beyond 20 weeks gestational age would potentially exclude 14.5% of patients from laser surgery, the majority of whom had advanced stage twin-twin transfusion syndrome. A unifying criterion of a maximum vertical pocket for the recipient of ≥8 cm regardless of gestational age would allow inclusion of these patients and access to surgical management.

Dual demise following laser surgery for twin-twin transfusion syndrome: Analysis of 52 cases at a single fetal surgery center

OBJECTIVE

To evaluate all individual cases of dual twin demise following laser surgery for twin-twin transfusion syndrome (TTTS).

METHOD

This is an analysis of all monochorionic diamniotic twin gestations with TTTS complicated by dual demise following laser surgery from 2006 to 2019. Cases were reviewed by (1) a fetal surgeon researcher and (2) a panel of independent experienced maternal-fetal medicine specialists to code an etiology of demise for the donor and recipient, and to assess for possible preventability.

RESULTS

Of 753 twins that underwent laser surgery for TTTS, 52 (6.9%) had postoperative dual demise. In this subgroup, gestational age at surgery was 19.5 (16.1-24.9) weeks, and 36 (69.2%) patients were Quintero stage III and IV. The most common etiology was the spectrum of disorders leading to preterm delivery, which included cervical insufficiency, preterm premature rupture of membranes, and preterm labor (44.2% and 48.1%, donor and recipient, respectively). Some degree of preventability was estimated for 23.1% of dual demises.

CONCLUSIONS

The most common cause of dual demise post laser surgery for TTTS was preterm birth, reinforcing the need for studies regarding the etiology and prevention of post-fetoscopy prematurity. Nearly one-quarter of dual demise cases were deemed potentially preventable.

Outcomes of Monochorionic, Diamniotic Twin Pregnancies with Prenatally Diagnosed Intertwin Weight Discordance

OBJECTIVE

Monochorionic, diamniotic (MCDA) twin pairs are predisposed to various pregnancy complications due to the unique placental angioarchitecture of monochorionicity. Few studies have evaluated the outcomes of weight-discordant MCDA pairs without selective fetal growth restriction (SFGR) or the risk factors for development of SFGR. This study aims to describe the natural history of expectant, noninvasive management of weight-discordant MCDA twins and to evaluate risk factors associated with progression to SFGR.

STUDY DESIGN

This was a retrospective cohort study at a single, tertiary care center in the United States. All MCDA twins with isolated intertwin weight discordance (ITWD) ≥ 20% diagnosed before 26 weeks' gestational age (GA) were included. The primary outcome of descriptive analyses was overall pregnancy outcome, incorporating both survival to delivery and GA at delivery, as defined by the North American Fetal Therapy Network. The secondary outcome was SFGR in one twin (defined as estimated fetal weight < 10% for GA) and factors associated with this progression. Only those with fetal ultrasound (US) within 4 weeks of delivery were included in this secondary analysis.

RESULTS

Among 73 MCDA pairs with ITWD, 73% had a good pregnancy outcome, with dual live delivery at a median GA of 33 weeks. Among the 34 pairs with adequate US follow-up, 56% developed SFGR. There were no differences in GA at delivery or discordance at birth between those who did and those who did not develop SFGR. There was a nonsignificant association between increasing ITWD at diagnosis and subsequent development of SFGR.

CONCLUSION

Expectant, noninvasive management can be considered in MCDA twin pregnancies with ITWD ≥ 20% diagnosed before 26 weeks. This approach is associated with a good pregnancy outcome in the majority of cases, even after the development of SFGR in the smaller twin.

KEY POINTS

· Nearly 75% of weight-discordant mo/di twins have a good pregnancy outcome.. · Weight-discordant mo/di twins deliver at a mean gestational age of 33 weeks without invasive therapy.. · Noninvasive management should be considered for weight-discordant mo/di twins..

Why Pregnancy Weight Gain Guidelines Need to Differ for Multiple Versus Single Pregnancies

PURPOSE OF THE REVIEW

The purpose of this review was to compare physiological and metabolic changes in singleton and twin gestations and to review pregnancy outcomes with respect to current weight gain guidelines.

RECENT FINDINGS

Reviews in singleton gestations show that weight gain below the recommended guidelines has been associated with small for gestational age infants (less than the 10th percentile) which place these infants at increased risk for neonatal morbidities. Observational studies have shown that adequate and excessive gestational weight gain in twin gestations has been associated with longer gestations and less preterm birth along with increased birth weight at delivery. Weight gain in pregnancy has been identified as a factor that affects both maternal and infant health outcomes in singleton and twin gestations. There is a larger body of research examining these effects in singleton gestations than twin gestations; however, in both groups, the data remain mostly observational and retrospective. Thus far, the research supports the Institute of Medicine recommended weight gain guidelines in singleton and twin gestations for women with normal BMI, but future research should be directed toward underweight and overweight women and the long-term outcomes in all mothers and their offspring.

Feasibility of fetal left modified myocardial performance index in twin anemia polycythemia sequence and perinatal outcomes after antenatal intervention

OBJECTIVE

To evaluate the feasibility and clinical value of fetal left modified myocardial performance index (Mod-MPI) in assessment and management of prenatal twin anemia polycythemia sequence (TAPS).

METHODS

We retrospectively reviewed fetuses with TAPS diagnosed prenatally between 2015 and 2019 at Asan Medical Center. Doppler ultrasound evaluation including the peak systolic velocity (PSV) of the middle cerebral artery (MCA) and fetal echocardiography including left Mod-MPI were evaluated and followed up after antenatal management.

RESULTS

Among 10 cases of fetal twin pregnancies with prenatal TAPS, six were spontaneous and four were post-laser TAPS. Left Mod-MPI was abnormal in one or both twins of nine cases (90%) including all post-laser TAPS (n = 4) and 83.3% of spontaneous TAPS (n = 5). Three recipients, one donor and three former recipients/new donors had elevated left Mod-MPI values, and one donor, one recipient, two former donors/new recipients had decreased values. Antenatal intervention was performed in eight cases with intrauterine transfusion (n = 4), fetoscopic laser surgery (n = 2), radiofrequency ablation (n = 1), and intrauterine transfusion followed by radiofrequency ablation (n = 1). The remaining two cases were either delivered or managed expectantly. MCA-PSV and left Mod-MPI became normal on the follow-up scans in all cases except the delivered case. There were four fetal deaths: two occurred spontaneously and two were selectively terminated by radiofrequency ablation. Overall perinatal survival per fetus was 80% (16/20) and the median gestational age at delivery was 34.4 (range, 29.2-37.4) weeks. Neither postnatal death nor neurodevelopmental delay occurred during a median follow-up of 13 months (range, 0.25-60 months).

CONCLUSION

Fetal left Mod-MPI was useful for assessment of compromised fetal cardiac function in cases with prenatal TAPS. Application of fetal left Mod-MPI in prenatal staging of TAPS might help evaluate the severity of TAPS and decide timely antenatal intervention.

Neonatal outcomes of extremely preterm twins by sex pairing: an international cohort study

OBJECTIVE

Infant boys have worse outcomes than girls. In twins, the 'male disadvantage' has been reported to extend to female co-twins via a 'masculinising' effect. We studied the association between sex pairing and neonatal outcomes in extremely preterm twins.

DESIGN

Retrospective cohort study SETTING: Eleven countries participating in the International Network for Evaluating Outcomes of Neonates.

PATIENTS

Liveborn twins admitted at 23-29 weeks' gestation in 2007-2015.

MAIN OUTCOME MEASURES

We examined in-hospital mortality, grades 3/4 intraventricular haemorrhage or cystic periventricular leukomalacia (IVH/PVL), bronchopulmonary dysplasia (BPD), retinopathy of prematurity requiring treatment and a composite outcome (mortality or any of the outcomes above).

RESULTS

Among 20 924 twins, 38% were from male-male pairs, 32% were from female-female pairs and 30% were sex discordant. We had no information on chorionicity. Girls with a male co-twin had lower odds of mortality, IVH/PVL and the composite outcome than girl-girl pairs (reference group): adjusted OR (aOR) (95% CI) 0.79 (0.68 to 0.92), 0.83 (0.72 to 0.96) and 0.88 (0.79 to 0.98), respectively. Boys with a female co-twin also had lower odds of mortality: aOR 0.86 (0.74 to 0.99). Boys from male-male pairs had highest odds of BPD and composite outcome: aOR 1.38 (1.24 to 1.52) and 1.27 (1.16 to 1.39), respectively.

CONCLUSIONS

Sex-related disparities in outcomes exist in extremely preterm twins, with girls having lower risks than boys and opposite-sex pairs having lower risks than same-sex pairs. Our results may help clinicians in assessing risk in this large segment of extremely preterm infants.

Prenatal and perinatal outcomes of twin pregnancy discordant for one fetus with nuchal translucency above the 95th percentile

OBJECTIVE

To compare prenatal and perinatal outcomes of twin pregnancies in which one twin the nuchal translucency (NT) was above the 95th percentile in dichorionic twins (DCT) and monochorionic twins (MCT).

METHOD

In this retrospective study, 93 twin pregnancies (186 fetuses) in which one twin the NT was above the 95th percentile and the co-twin had normal NT were analyzed. Results of of G-banding and Chromosomal microarray (CMA), ultrasound findings and pregnancy outcomes were reviewed.

RESULTS

Totally, 57 pregnancies (114 fetuses) were DCT and 36 pregnancies (72 fetuses) were MCT. Karyotyping and CMA results shown that clinically significant chromosomal abnormalities were found in 16 fetuses, including 13 aneuploidies, 2 chromosomal mosaic and 1 pathological Copy number variations (CNVs) (14 were DCT and 2 were MCT). Overall, the incidence of fetal chromosomal abnormalities was 12.3% (14/114) in DCT and 2.8%(2/72) in MCT (χ² = 3.932, p = 0.047). Among the cases with normal prenatal diagnosis result, structural abnormalities were found in four fetuses (4.0%, 4/100) in DCT and two fetuses (2.9%, 2/70) in MCT (p > 0.999). There were one intrauterine fetal demises (IUFD) and two miscarry in DCT. One IUFD, three subsequently developed Twin-to-Twin Transfusion Syndrome (TTTS) and four developed selective intrauterine growth restriction (sIUGR) in MCT. Totally, the overall fetal survival rate was 85.1% (97/114) in DCT and 80.6% (58/72) in MCT (χ² = 0.653, p = 0.419).

CONCLUSION

Compared to MCT, the incidence of chromosomal abnormalities in DCT discordant for one fetus with NT above the 95th percentile was higher. The risk of structural abnormalities and the rate of fetal survival for both MCT and DCT was similar.

Renal artery Doppler studies in the assessment of monochorionic, diamniotic twin pregnancies with and without twin-twin transfusion syndrome

BACKGROUND

In monochorionic, diamniotic twin pregnancies complicated by twin-twin transfusion syndrome, imbalanced fetofetal blood shunting and discordant activation of the renin-angiotensin system result in a hypovolemic, oliguric donor twin and a hypervolemic, polyuric recipient twin. Renal artery Doppler assessments have been reported to predict oligohydramnios in singleton pregnancies; however, their value in assessing monochorionic, diamniotic twin gestations, including pregnancies complicated by twin-twin transfusion syndrome, remains unstudied.

OBJECTIVE

This investigation evaluated whether renal artery Doppler parameters are different between sets of monochorionic, diamniotic twins with and without twin-twin transfusion syndrome.

STUDY DESIGN

We conducted a prospective study of women with monochorionic, diamniotic twin pregnancies complicated by twin-twin transfusion syndrome and women with gestational-age matched monochorionic, diamniotic twin control pregnancies without twin-twin transfusion syndrome. For each twin, renal artery Doppler assessment was performed from a coronal view of the fetus, and pulsatility index, resistive index, and peak systolic velocity were measured. In twin pairs complicated by twin-twin transfusion syndrome, renal artery Doppler pulsatility index, resistive index, and peak systolic velocity intertwin ratios were calculated by comparing paired recipient-to-donor values. Similar ratios were calculated for control twin pairs. We compared each measurement between donors and controls and between recipients and controls. Intertwin ratios were compared between twin-twin transfusion syndrome cases and monochorionic, diamniotic controls. Our primary outcome was a comparison of renal artery Doppler pulsatility index measurement between donor fetuses in twin-twin transfusion syndrome cases and matched control twins. Secondary outcomes included comparisons of other renal artery Doppler parameters between twin-twin transfusion syndrome donor twins and controls and between twin-twin transfusion syndrome recipients and controls and comparisons of the renal artery Doppler parameter ratios between twin-twin transfusion syndrome and non-twin-twin transfusion syndrome twin pair groups. Finally, we performed a subgroup analysis involving pregnancies with twin-twin transfusion syndrome that underwent fetoscopic laser therapy and resulted in twin survivors to evaluate if laser therapy influenced renal artery Doppler findings.

RESULTS

We recruited 12 donors and 12 controls. Renal artery Doppler pulsatility index and resistive index did not differ between donors and controls. However, donor renal artery Doppler peak systolic velocity (median, 14.24 [11.51-15.36]) was significantly lower than that of controls (median, 24.79 [22.46-27.03]; P<.0004). When recipient twins were compared with controls, there was no difference in renal artery Doppler pulsatility index, renal artery Doppler resistive index, or renal artery Doppler peak systolic velocity. Renal artery Doppler peak systolic velocity ratios were significantly higher among cases with twin-twin transfusion syndrome (median, 1.70 [1.53-2.02]) than controls (median, 1.06 [1.03-1.15]; P=.002). Applying a renal artery Doppler peak systolic velocity ratio cutoff of >1.35 for the diagnosis of twin-twin transfusion syndrome correctly classified 11 of 12 cases with twin-twin transfusion syndrome and all 12 controls without twin-twin transfusion syndrome (92% sensitivity and 100% specificity). Among donors with twin-twin transfusion syndrome with double survivors after undergoing laser therapy (n=4), prelaser renal artery Doppler peak systolic velocity ratios (mean, 1.46; standard deviation, 0.37) were significantly higher than postlaser renal artery Doppler peak systolic velocity ratios (mean, 0.87; standard deviation=0.37; P=.02). Postlaser intertwin renal artery Doppler peak systolic velocity ratios did not differ from control twin pairs (P=.125).

CONCLUSION

Renal artery Doppler peak systolic velocity ratios differ between monochorionic, diamniotic twins with twin-twin transfusion syndrome and those without twin-twin transfusion syndrome. This effect seems to be driven by altered donor twin renal artery Doppler peak systolic velocity. Laser therapy may normalize renal artery Doppler peak systolic velocity ratios and donor twin renal artery Doppler values to those observed in monochorionic, diamniotic twins without twin-twin transfusion syndrome. Further study is warranted to explore whether renal artery Doppler peak systolic velocity has utility as a tool for twin-twin transfusion syndrome prediction, diagnosis, or staging, and fetal response to laser therapy.

Magnetic resonance imaging of the fetal brain in monochorionic diamniotic twin gestation: correlation of cerebral injury with ultrasound staging and survival outcomes

BACKGROUND

The current staging system of twin-twin transfusion syndrome (TTTS) is based on the ultrasound criteria and does not consider the cerebral injury.

OBJECTIVE

To assess the incidence of cerebral damage on fetal MRI and correlate abnormal cerebral diffusion-weighted imaging (DWI) findings with survival outcome and the ultrasound staging of TTTS.

MATERIALS AND METHODS

We conducted a retrospective review of MRI/DWI of fetal brains and the electronic medical records in monochorionic diamniotic twin gestations. Axial DWI of each fetal brain was performed on 1.5-tesla (T) clinical magnet with b values of 0 s/mm² and 700 s/mm². We correlated MRI/DWI abnormalities with the Quintero staging system and survival outcomes of the fetuses.

RESULTS

Thirty-four pregnancies (68 fetuses) with 42 fetal cerebral abnormalities were identified by MRI/DWI alone. Of these 42 fetal cerebral abnormalities, 33 fetal brain lesions were visible only on DWI (n=25 donor, n=8 recipients; n=30 unilateral, n=3 bilateral; n=26 diffuse, n=7 focal). Quintero staging in these 34 pregnancies was as follows: 9 Stage I, 7 Stage II, 13 Stage III, 4 Stage IV, 1 Stage V. There was no significant correlation between the presence of cerebral infarction or hemorrhage using MRI/DWI and ultrasound staging (P=0.138). The overall survival rate was 63.2% (43/68). There was a significant correlation between the presence of cerebral infarction or hemorrhage on MRI/DWI and delivery status (P=0.009).

CONCLUSION

Abnormal cerebral imaging findings on MRI/DWI from hypoxic-ischemic injury or hemorrhage can be seen at the beginning of the second trimester and do not correlate with the current ultrasound staging system; however, they do correlate with decreased survival. Fetal cerebral abnormalities could be incorporated into the TTTS staging system as an independent risk factor.

Combination of "Markers" and the Consequent Importance of Fetal Abdominal Circumference in the First Trimester for Predicting Complications Specific to Monochorionic Twin Pregnancies

BACKGROUND

Multifetal pregnancies are considered high-risk pregnancies compared to singleton pregnancies. Monochorionic diamniotic (MCDA) twin pregnancies tend to have a more complicated intrauterine course than their dichorionic counterparts. The most common complications are twin-to-twin transfusion syndrome (TTTS), selective fetal growth restriction (sFGR), and unexplained intrauterine fetal demise (IUFD). Early recognition of pregnancies at risk of developing complications will be helpful for counselling the parents and preparing them for necessary interventions in case a complication arises.

OBJECTIVES

The aim of our study was to assess the role of discordant crown-rump length (dCRL), discordant nuchal translucency (dNT), and discordant abdominal circumference (dAC) measurements in isolation and in combination at the 11-13+6 weeks' scan in predicting the development of TTTS, sFGR, and IUFD.

METHODS

All MCDA twin pregnancies with structurally normal, both live fetuses at the 11-13+6 weeks' scan were followed up by FMF (Fetal Medicine Foundation)-certified operators for development of TTTS, sFGR, and single/double IUFD until delivery. Discordance of CRL, NT, and AC of more than or equal to 10% was considered a "marker," and its presence was correlated with the occurrence of specific antenatal complications, i.e., TTTS, sFGR, and single or double IUFD.

RESULTS

Combination of two markers predicted MCDA-related complications in the majority of cases (70.8% positive predictive value). Combination of dNT and dAC was the strongest predictor (80% positive predictive value).

CONCLUSIONS

In our population of MC twin pregnancies, dCRL, dNT, and dAC at the 11+0-13+6 weeks' scan, in isolation, had a low predictive value for antenatal complications, i.e., TTTS, sFGR, and single/double IUFD. However, the presence of at least two markers in the first trimester could predict complications in the majority of these pregnancies. The combination of dNT and dAC appears to be the best.

Changes in the perinatal outcomes of twin pregnancies delivered at a tertiary referral center in Korea during a 24-year period from 1995 to 2018

Objective

To analyze the changes in the clinical characteristics and perinatal outcomes of twin pregnancies delivered at a tertiary referral center in Korea during a 24-year period.

Methods

This was a retrospective cohort study of twin pregnancies delivered at 24–40 weeks of gestation, from 1995 to 2018. The subjects were divided into 4 groups according to the year of delivery: 1995–2000, 2001–2006, 2007–2012, and 2013–2018. The trends in the changes in the twin birth rate, maternal age, assisted reproductive technology (ART) pregnancy rate, chorionicity, obstetric complications, delivery outcomes, and neonatal outcomes over the periods were analyzed.

Results

A total of 2,133 twin pregnancies were included in the study. The twin birth rate increased from 16.7/1,000 in 1995–2000 to 42.2/1,000 in 2001–2006, 49.5/1,000 in 2007–2012, and 61.8/1,000 in 2013–2018. The maternal age and ART pregnancy and dichorionic twin rates increased, while the monochorionic twin rate decreased over the periods. The incidence of fetal congenital anomalies, cervical incompetence, gestational diabetes mellitus, preeclampsia, and placental abruption increased over the periods. The preterm birth (PTB) rate significantly decreased owing to the decreasing elective late-PTB rate; however, the early-PTB rate significantly increased.

Conclusion

This study found that twin pregnancies increased steadily over the last 24 years and that the increase was related to increased maternal age and ART pregnancy rate. The incidence of obstetric complications increased over the periods; however, the neonatal intensive care unit admission rate decreased, along with decreases in the elective late-PTB rate.

The impact of chorionicity on pregnancy outcome and neurodevelopment at 2 years old among twins born preterm: the EPIPAGE-2 cohort study

OBJECTIVE

To compare the short- and mid-term outcomes of preterm twins by chorionicity of pregnancy.

DESIGN

Prospective nationwide population-based EPIPAGE-2 cohort study.

SETTING

546 maternity units in France, between March and December 2011.

POPULATION

A total of 1700 twin neonates born between 24 and 34 weeks of gestation.

METHODS

The association of chorionicity with outcomes was analysed using multivariate regression models.

MAIN OUTCOME MEASURES

First, survival at 2-year corrected age with or without neurosensory impairment, and second, perinatal, short-, and mid-term outcomes (survival at discharge, survival at discharge without severe morbidity) were described and compared by chorionicity.

RESULTS

In the EPIPAGE 2 cohort, 1700 preterm births were included (850 twin pregnancies). In all, 1220 (71.8%) were from dichorionic (DC) pregnancies and 480 from monochorionic (MC) pregnancies. MC pregnancies had three times more medical terminations than DC pregnancies (1.67 versus 0.51%, P < 0.001), whereas there were three times more stillbirths in MC than in DC pregnancies (10.09 versus 3.78%, P < 0.001). Both twins were alive at birth in 86.6% of DC pregnancies compared with 80.0% among MC pregnancies (P = 0.008). No significant difference according to chorionicity was found regarding neonatal deaths and morbidities. Likewise, for children born earlier than 32 weeks, the 2-year follow-up neurodevelopmental results were not significantly different between DC and MC twins.

CONCLUSIONS

This study confirms that MC pregnancies have a higher risk of adverse outcomes. However, the outcomes among preterm twins admitted to neonatal intensive care units are similar irrespective of chorionicity.

TWEETABLE ABSTRACT

Monochorionicity is associated with adverse perinatal outcomes, but outcomes for preterm twins are comparable irrespective of their chorionicity.

Characteristics of vascular anastomoses in monochorionic twin 587 placentas with selective intrauterine growth restriction via 89 three-dimensional computed tomography angiography

OBJECTIVE

To determine the characteristics of the choriovascular anatomy, especially the potential role of arteriovenous perfusion imbalance in the pathogenesis of selective intrauterine growth restriction (sIUGR) using three-dimensional computed tomography angiography (3D-CTA).

METHOD

Computed tomography angiography of the placental choriovascular tree from 15 twins with sIUGR and 15 twins without sIUGR were analyzed, and inter-twin vascular anastomoses were compared between the placentas from these two groups. The parameters evaluated were the presence and measures of artery-to-artery anastomoses (AAA), vein-to-vein anastomoses (VVA) or artery-to-vein anastomoses (AVA).

RESULTS

The frequency of AAA, VVA, and AVA did not differ significantly between sIUGR and without sIUGR-pairs. The area of the vein draining to the AVA in the larger twin's placenta was significantly greater in sIUGR compared to when no sIUGR was present. Based on the net cross-sectional area difference we speculate that in sIUGR there is net flow from the smaller to the larger twin.

CONCLUSION

We used 3D-CTA to display the vascular anastomoses in sIUGR twin pairs, demonstrating a difference in cross-sectional diameter of the vein draining to the AVA.

Percent Absent End-Diastolic Velocity in the Umbilical Artery and Donor Twin Demise after Laser Surgery for Twin-Twin Transfusion Syndrome

INTRODUCTION

To examine the association of preoperative absent end-diastolic velocity (AEDV) and percent AEDV (%AEDV) in the umbilical artery (UA) with donor twin intrauterine fetal demise (IUFD) after laser surgery for twin-twin transfusion syndrome (TTTS).

METHODS

We performed a retrospective study of stage III/IV TTTS patients who underwent laser surgery from 2006 to 2016. Donors were classified as having preoperative persistent AEDV (yes/no). %AEDV was calculated for those with AEDV as 100× the proportion of the total cardiac cycle in AEDV. Using multiple logistic regression, we tested for an association between the outcome donor IUFD and AEDV risk factors (part 1) and %AEDV (part 2). We stratified these analyses by estimated fetal weight (EFW) discordance ≥20 versus <20%.

RESULTS

Of 344 cases, 153 (44.5%) donors had AEDV. Part 1 did not confirm an independent association between AEDV and donor IUFD. In the part 2 analysis of the 153 patients with AEDV, %AEDV was a positive risk factor for donor IUFD only in those with discordance (n = 129) (OR 1.04, 95% CI 1.01-1.08, p = 0.0278) when adjusting for %EFW discordance, presence of arterioarterial anastomoses, and multiparity.

DISCUSSION

Among stage III/IV TTTS patients with AEDV, %AEDV was a risk factor for donor IUFD only in the presence of EFW discordance.

Impact of first trimester determination of abnormal cord insertion on twin-to-twin transfusion syndrome and other adverse outcomes in monochorionic diamniotic twins: A retrospective cohort study

OBJECTIVE

To assess the influence of abnormal cord insertion (CI) detected by first trimester ultrasonography on the development of twin-to-twin transfusion syndrome (TTTS) in monochorionic diamniotic (MCDA) twins.

METHOD

In this retrospective cohort study, consecutive patients with MCDA twins who underwent fetal ultrasound screening in the first trimester between January 2011 and January 2017 were enrolled. The CI sites were evaluated between 11 + 0 and 13 + 6 weeks' gestation. All twin pairs were assigned to the abnormal CI group (twin pair with velamentous cord insertion (VCI) and/or marginal cord insertion (MCI) in one or both twins) or the normal CI group (twin pair with both normal CI). The relationships of adverse outcomes in two groups were analyzed.

RESULTS

A total of 109 MCDA twin pairs were examined; 15 cases were classified into the abnormal CI group and 94 cases into the normal CI group. The incidence of TTTS was significantly higher in the abnormal than in the normal CI group (26.7% vs 7.45%, P = .04). In patients who developed TTTS, all donors had VCI.

CONCLUSION

Ultrasound evaluation of abnormal CI at 11 + 0 to 13 + 6 weeks' gestation in MCDA twins is valuable in the assessment of the risk for TTTS.

Placental MRI and its application to fetal intervention

OBJECTIVE

Magnetic resonance imaging (MRI) of placental invasion has been part of clinical practice for many years. The possibility of being better able to assess placental vascularization and function using MRI has multiple potential applications. This review summarises up-to-date research on placental function using different MRI modalities.

METHOD

We discuss how combinations of these MRI techniques have much to contribute to fetal conditions amenable for therapy such as singletons at high risk for fetal growth restriction (FGR) and monochorionic twin pregnancies for planning surgery and counselling for selective growth restriction and transfusion conditions.

RESULTS

The whole placenta can easily be visualized on MRI, with a clear boundary against the amniotic fluid, and a less clear placental-uterine boundary. Contrasts such as diffusion weighted imaging, relaxometry, blood oxygenation level dependent MRI and flow and metabolite measurement by dynamic contrast enhanced MRI, arterial spin labeling, or spectroscopic techniques are contributing to our wider understanding of placental function.

CONCLUSION

The future of placental MRI is exciting, with the increasing availability of multiple contrasts and new models that will boost the capability of MRI to measure oxygen saturation and placental exchange, enabling examination of placental function in complicated pregnancies.

Early-onset twin-twin transfusion syndrome: Case series and systematic review

Introduction

Data on the outcomes of early-onset twin-twin transfusion syndrome (TTTS), diagnosed before 18 weeks gestational age (GA), are sparse. We aimed to review the diagnosis, management and outcomes of early-onset TTTS.

Material and methods

Pregnancy records at a single referral unit 2010-6 were reviewed. In early-onset TTTS cases, data for pregnancy characteristics, interventions and outcomes were collected. PubMed and Scopus databases were searched for studies including pregnant women with early-onset TTTS. The primary outcome measure was livebirths.

Results

Case series: 58 cases of early-onset TTTS 2010-6, with full outcome data in 44. Diagnostic criteria were variable. Median GA at intervention was 17⁺⁴ (range 15⁺⁰-28⁺¹); 67% of patients had laser therapy (39/58). Overall survival: 60% (53/88). At least one livebirth: 86% (38/44), Two livebirths: 34% (15/44); No survivors: 14% (6/44). GA at delivery was 32^+1.5 (range 16⁺²-37⁺⁴). Systematic review: 16 studies included (n = 171 pregnancies). Diagnostic criteria varied widely: 79% of studies used Quintero staging. Most offered laser (89%) at median 17⁺⁰ weeks (range 16⁺⁰-21⁺⁶). GA at delivery was 23⁺⁰-39⁺⁵ weeks. Overall survival: 69% (129/186). At least one livebirth: 74% (127/171). Two livebirths: 59% (55/93). No survivors: 26% (44/171).

Conclusions

In comparison with the commonly accepted overall survival for TTTS treated after 18 weeks of 60-90%, outcomes in early-onset TTTS were at the lower bound of this range. Gestational age at intervention is similar to that of later onset TTTS, indicating a lack of therapeutic options when a diagnosis is made before 18 weeks.

Influence of maternal obesity and metabolic and vascular mediators in twin-twin transfusion syndrome

Obesity is a risk factor for complications in singleton and twin pregnancies; however, there are limited data regarding maternal body mass index (BMI) in the setting of twin-twin transfusion syndrome (TTTS). We hypothesized that increased BMI in TTTS is associated with adverse perinatal outcomes and vascular pathology. A retrospective study of twin reversed arterial perfusion (n = 4), selective intrauterine growth restriction (n = 10) and TTTS (n = 33) was conducted. Treatment included fetoscopic laser photocoagulation (FLP) (n = 35) or Solomon technique (n = 12). Ex vivo placental intravascular injections, immunohistochemistry, and perinatal outcomes were compared by maternal BMI. In pregnancy complicated by TTTS, 16/33 women were obese (BMI > 30 kg/m²) and 11/33 were overweight (BMI 25-29.9 kg/m²). Women who were overweight or obese had an increased rate of premature rupture of membranes (PPROM), cesarean delivery, and/or concomitant co-morbidities when compared to the normal weight group. Duration of neonatal intensive care unit (NICU) admission was longer in neonates of overweight/obese women versus normal weight. Placental examination of FLP sites in the obese group showed larger infarcts, increased adipose triglyceride lipase, and a proangiogenic phenotype. Increased BMI is common in our TTTS cohort and it is associated with higher rate of co-morbidity, PPROM, prolonged NICU stay, and an imbalance of placental metabolic and vascular mediators.

Stage I Twin-Twin Transfusion Syndrome: Outcomes of Expectant Management and Prognostic Features

OBJECTIVE

This article describes the natural history of stage I twin-twin transfusion syndrome (TTTS) including risk of progression to higher stage TTTS and pregnancy outcomes, and to identify risk factors for progression.

STUDY DESIGN

Retrospective cohort study of monochorionic diamniotic (MCDA) twin pregnancies from 2006 to 2016 with expectantly managed Quintero stage I TTTS.

RESULTS

A total of 30 MCDA twin pregnancies with expectantly managed stage I TTTS were identified. Of these, eight (26.7%) progressed to higher stage TTTS. Median gestational age (GA) at diagnosis for those that progressed was 18.9 ± 2.9 weeks versus 21.4 ± 3.4 weeks in those that remained stable (p = 0.06). Presence of an arterioarterial (A-A) anastomosis was assessed for 20/30 patients, and eight A-A were identified. Of those, 7/8 (87.5%) remained stable. In the complete cohort, a tiny or transiently visible bladder was noted in seven donor twins. Of these, 4/7 (57.1%) progressed. Excluding one termination, 47/58 (81.0%) fetuses survived.

CONCLUSION

With expectant management of stage I TTTS, nearly three-fourths of pregnancies remain stable and most have survival of ≥ 1 twin. A-A anastomoses were not associated with progression to higher stage TTTS, whereas earlier GA at diagnosis or a small or intermittently visible donor bladder may herald greater risk of progression.

The incidence of unexpected critical complications in monochorionic diamniotic twin pregnancies according to the interval period between ultrasonographic evaluations

AIM

This study aimed to evaluate the incidence of unexpected critical complications (UCC) in monochorionic diamniotic (MCDA) twin pregnancies according to ultrasonographic scan interval.

METHODS

This retrospective single-center cohort study, conducted between January 2005 and April 2015, investigated the incidence of UCC in patients with MCDA twin pregnancies undergoing weekly ultrasound (Group A) and those undergoing biweekly ultrasound (Group B). We also examined the incidence of predictable critical complications according to ultrasound interval.

RESULTS

Of all 385 cases, the total incidence of UCC was 20 (5.2%), including 14 cases of twin-twin transfusion syndrome and 6 cases of intrauterine fetal death. The incidence of UCC was 3.9% in Group A and 9.0% in Group B (P = 0.046). In contrast, the incidence of predictable critical complications was 6.7% in Group A and 9.0% in Group B (P = 0.440).

CONCLUSION

The incidence of UCC in patients with MCDA twin pregnancies was significantly lower in patients undergoing weekly ultrasound. Our results suggest that weekly ultrasound evaluation for patients with MCDA pregnancy is more effective for early detection of UCC such as intrauterine fetal death and twin-twin transfusion syndrome ; however, further investigations are needed to determine whether weekly ultrasound evaluation can improve clinical outcomes.

Does site of cord insertion increase risk of adverse outcome, twin-to-twin transfusion syndrome and discordant growth in monochorionic twin pregnancy?

OBJECTIVES

It is not currently well known to what extent the sites of cord insertion influence the risk of complicated outcome in monochorionic twin pregnancy. The objectives of this study were to examine whether the sites of cord insertion, as determined on prenatal ultrasound examination, affect the risks of adverse outcome, twin-to-twin transfusion syndrome (TTTS) and discordant growth, and whether discordance in insertion sites or velamentous insertion in one or both twins best predicts risk.

METHODS

This was a retrospective cohort study of monochorionic diamniotic twin pregnancies followed from the first trimester. The cohort was divided into three groups of increasing discordance in cord insertion sites: concordant (normal-normal; marginal-marginal; velamentous-velamentous), intermediate (normal-marginal; marginal-velamentous) and discordant (normal-velamentous). Adverse outcome was defined as fetal or neonatal loss or birth prior to 32 weeks. The associations of adverse outcome, TTTS and discordant growth were assessed using logistic regression analysis with the following predictors: the three groups of insertion sites and velamentous insertion in one or both twins.

RESULTS

Included in the analysis were 518 pregnancies. On univariate analysis, both discordant and velamentous insertions in one twin increased the risk of adverse outcome, TTTS and discordant growth. Intermediate insertion only increased the risk of discordant growth. Velamentous insertion in both twins increased the risk of adverse outcome and TTTS, but not of discordant growth. Multivariate logistic regression analysis showed velamentous insertion in one or both twins to independently predict adverse outcome and TTTS. For discordant growth, both intermediate/discordant and velamentous cord insertion in one twin were independent predictors.

CONCLUSIONS

Velamentous cord insertion in one or both twins increases the risk of adverse outcome and TTTS, irrespective of discordance in the insertion sites, whereas the risk of discordant growth is determined by both discordance in insertion sites and velamentous cord insertion in one twin. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Weight discordance and perinatal mortality in twin pregnancy: systematic review and meta-analysis

OBJECTIVES

The primary aim of this systematic review was to explore the strength of association between birth-weight (BW) discordance and perinatal mortality in twin pregnancy. The secondary aim was to ascertain the contribution of gestational age and growth restriction in predicting mortality in growth-discordant twins.

METHODS

MEDLINE, EMBASE, CINAHL and ClinicalTrials.gov databases were searched. Only studies reporting on the risk of mortality in twin pregnancies affected compared with those not affected by BW discordance were included. The primary outcomes explored were incidence of intrauterine death (IUD), neonatal death (NND) and perinatal death. Outcome was assessed separately for monochorionic (MC) and dichorionic (DC) twin pregnancies. Analyses were stratified according to BW discordance cut-off (≥ 15%, ≥ 20%, ≥ 25% and ≥ 30%) and selected gestational characteristics, including incidence of IUD or NND before and after 34 weeks' gestation, presence of at least one small-for-gestational age (SGA) fetus in the twin pair and both twins being appropriate-for-gestational age. Risk of mortality in the larger vs smaller twin was also assessed. Meta-analyses using individual data random-effects logistic regression and meta-analyses of proportion were used to analyze the data.

RESULTS

Twenty-two studies (10 877 twin pregnancies) were included in the analysis. In DC pregnancies, a higher risk of IUD, but not of NND, was observed in twins with BW discordance ≥ 15% (odds ratio (OR) 9.8, 95% CI, 3.9-29.4), ≥ 20% (OR 7.0, 95% CI, 4.15-11.8), ≥ 25% (OR 17.4, 95% CI, 8.3-36.7) and ≥ 30% (OR 22.9, 95% CI, 10.2-51.6) compared with those without weight discordance. For each cut-off of BW discordance explored in DC pregnancies, the smaller twin was at higher risk of mortality compared with the larger one. In MC twin pregnancies, excluding cases affected by twin-twin transfusion syndrome, twins with BW discordance ≥ 20% (OR 2.8, 95% CI, 1.3-5.8) or ≥ 25% (OR 3.2, 95% CI, 1.5-6.7) were at higher risk of IUD, compared with controls. MC pregnancies with ≥ 25% weight discordance were also at increased risk of NND (OR 4.66, 95% CI, 1.8-12.4) compared with those with concordant weight. The risk of IUD was higher when considering discordant pregnancies involving at least one SGA fetus. The overall risk of mortality in MC pregnancies was similar between the smaller and larger twin, except in those with BW discordance ≥ 20%.

CONCLUSION

DC and MC twin pregnancies discordant for fetal growth are at higher risk of IUD but not of NND compared with pregnancies with concordant BW. The risk of IUD in BW-discordant DC and MC twins is higher when at least one fetus is SGA. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Polyhydramnios Affecting a Recipient-like Twin: Risk of Progression to Twin-Twin Transfusion Syndrome and Outcomes

OBJECTIVE

The significance of polyhydramnios of one twin in the absence of oligohydramnios of the cotwin in monochorionic diamniotic (MCDA) twin pregnancies (polyhydramnios affecting a recipient-like twin [PART]) is unknown. Our aim is to assess the risk of progression to twin-twin transfusion syndrome (TTTS) with PART, progression to ≥ stage II TTTS, and neonatal survival.

STUDY DESIGN

This study was a retrospective cohort study of MCDA twin pregnancies with PART evaluated at a referral center from 2008 to 2015.

RESULTS

Sixty-four MCDA twin pregnancies with PART were identified. Fifteen (23.4%) progressed to TTTS, including 10 (15.6%) who progressed to ≥ stage II TTTS. Three pregnancies were terminated and one underwent selective reduction by radiofrequency ablation. Overall survival was 113 out of 128 (88.3%). Of those who remained stable, 91.8% (N = 45) had survival of both neonates. In multivariate analysis, the presence of arterioarterial (A-A) anastomosis by in utero Doppler ultrasound was associated with decreased risk of progression to TTTS (odds ratio: 0.12, p = 0.03, 95% confidence interval: 0.02-0.78).

CONCLUSION

Most MCDA twin pregnancies with PART do not progress to TTTS and have a favorable prognosis. Progression rates are higher than observed in uncomplicated MCDA twins; however, so close surveillance is warranted. The presence of an A-A anastomosis appears to confer decreased risk of progression to TTTS.

Impact of laser therapy for twin-to-twin transfusion syndrome on subsequent pregnancy

OBJECTIVES

The objective of our study was to determine the impact of laser therapy for twin-to-twin transfusion syndrome (TTTs) on subsequent pregnancies.

METHODS

This was a monocentric retrospective observational study. Women treated by laser fetoscopy for TTTs were asked to answer a postal questionnaire about subsequent pregnancies. The primary outcome was fecundity (number of pregnancies and time to pregnancy). We also assessed pregnancy complications, birth weight, and gestational age at delivery. Pregnancy complications included the following: threatened preterm labor, preeclampsia, placenta accreta, postpartum hemorrhage, and psychological disorders. Our study population was compared with an external control group made up of mothers of monochorionic twins without TTTs.

RESULTS

We included 122 cases managed at the Necker Hospital between 2008 and 2012 and 39 controls. The median conception time was longer in the TTTs group (6.4 ± 11.1 versus 2 ± 1.6 months, P = .03). The numbers of live childbirths at the end of those pregnancies were equivalent (77.6% versus 66.7%, P = .56). Birth weight (3317 ± 726 versus 3240 ± 382 g, P = .81) and gestational age at delivery (38.2 ± 6.8 WG versus 39.5 ± 1.2 WG, P = .64) were similar, with no increase of obstetrical complications compared with the control group.

DISCUSSION

Twin-to-twin transfusion syndrome and its treatment do not seem to impact subsequent pregnancies.

Neurodevelopmental Outcomes of Twins Compared With Singleton Children: A Systematic Review

More than 200 million children aged <5 years fail to reach their full cognitive potential, and children born as twins are particularly at risk. In this article, we review studies that examined differences in the neurodevelopmental outcomes of twins compared to singletons. We searched the Medline database for articles on twins, singletons, neuro, and cognitive development. We also inspected bibliographies of relevant publications to identify related articles from 2011 to 2017. Our search criteria yielded 162 studies, 8 of which met the inclusion criteria. Of the eight studies examined, four were prospective follow-up studies, three were cross-sectional studies, and one was a randomized controlled trial. Five of these studies were carried out in developed countries, and they found no statistically significant difference in neurodevelopmental outcomes among twins and singletons. However, two of the three studies carried out in developing countries found a difference with singletons having significantly higher academic ratings than twins. Studies in which neurodevelopmental outcomes were measured early in life (1-5 years) showed no significant twin-singleton differences, while those in which it was measured later in life showed mixed twin-singleton differences. Overall, these studies may have been underpowered and may not have been optimally designed and implemented. There is need for studies with adequate sample sizes, good design, and optimal measurement of all relevant covariates in order to resolve the conflicting reports in the literature.

Twins and neurodevelopmental outcomes: the effect of IVF, fetal growth restriction, and preterm birth

This invited review aimed at presenting the evidence concerning neurodevelopmental outcomes, particularly cerebral palsy (CP), motor disability, cognitive impairment, mental retardation, any major disability, blindness and deafness in cases of twins, conceived after in vitro fertilization, presenting fetal/intrauterine growth restriction (FGR/IUGR) or being prematurely born. FGR/IUGR, prematurity and zygosity affect neurodevelopmental outcome; CP is higher in term infants, those presenting with FGR/IUGR, as well as in survivors of intrauterine co-twin death; cognitive ability of twins versus singletons mainly relates to confounding factors, as FGR/IUGR and prematurity, while evidence for differences in behavioral and psychiatric disorders between twins and singletons is limited. The impact of IVF per se has not been documented. Nevertheless, available literature, usually of heterogeneous and retrospective nature, diverges in the criteria for neurodevelopmental delay. Furthermore, differences in selection/exclusion criteria and small mixed cohorts, including the full range of complications, make comparison of the existing studies difficult. Future studies should focus in confirming the lack of IVF impact on twins' neurodevelopment and general health, in comparing long-term outcome of naturally conceived twins with those conceived following assisted reproduction techniques and in including evaluation of individual, longitudinal trajectories of growth, and development. In this respect, worldwide population-based registries will enable more precise description of neurodevelopmental outcomes among twins.

Comparison of conventional 2D ultrasound to magnetic resonance imaging for prenatal estimation of birthweight in twin pregnancy

BACKGROUND

During prenatal follow-up of twin pregnancies, accurate identification of birthweight and birthweight discordance is important to identify the high-risk group and plan perinatal care. Unfortunately, prenatal evaluation of birthweight discordance by 2-dimensional ultrasound has been far from optimal.

OBJECTIVE

The objective of the study was to prospectively compare estimates of fetal weight based on 2-dimensional ultrasound (ultrasound-estimated fetal weight) and magnetic resonance imaging (magnetic resonance-estimated fetal weight) with actual birthweight in women carrying twin pregnancies.

STUDY DESIGN

Written informed consent was obtained for this ethics committee-approved study. Between September 2011 and December 2015 and within 48 hours before delivery, ultrasound-estimated fetal weight and magnetic resonance-estimated fetal weight were conducted in 66 fetuses deriving from twin pregnancies at 34.3-39.0 weeks; gestation. Magnetic resonance-estimated fetal weight derived from manual measurement of fetal body volume. Comparison of magnetic resonance-estimated fetal weight and ultrasound-estimated fetal weight measurements vs birthweight was performed by calculating parameters as described by Bland and Altman. Receiver-operating characteristic curves were constructed for the prediction of small-for-gestational-age neonates using magnetic resonance-estimated fetal weight and ultrasound-estimated fetal weight. For twins 1 and 2 separately, the relative error or percentage error was calculated as follows: (birthweight - ultrasound-estimated fetal weight (or magnetic resonance-estimated fetal weight)/birthweight) × 100 (percentage). Furthermore, ultrasound-estimated fetal weight, magnetic resonance-estimated fetal weight, and birthweight discordance were calculated as 100 × (larger estimated fetal weight-smaller estimated fetal weight)/larger estimated fetal weight. The ultrasound-estimated fetal weight discordance and the birthweight discordance were correlated using linear regression analysis and Pearson's correlation coefficient. The same was done between the magnetic resonance-estimated fetal weight and birthweight discordance. To compare data, the χ², McNemar test, Student t test, and Wilcoxon signed rank test were used as appropriate. We used the Fisher r-to-z transformation to compare correlation coefficients.

RESULTS

The bias and the 95% limits of agreement of ultrasound-estimated fetal weight are 2.99 (-19.17% to 25.15%) and magnetic resonance-estimated fetal weight 0.63 (-9.41% to 10.67%). Limits of agreement were better between magnetic resonance-estimated fetal weight and actual birthweight as compared with the ultrasound-estimated fetal weight. Of the 66 newborns, 27 (40.9%) were of weight of the 10th centile or less and 21 (31.8%) of the fifth centile or less. The area under the receiver-operating characteristic curve for prediction of birthweight the 10th centile or less by prenatal ultrasound was 0.895 (P < .001; SE, 0.049), and by magnetic resonance imaging it was 0.946 (P < .001; SE, 0.024). Pairwise comparison of receiver-operating characteristic curves showed a significant difference between the areas under the receiver-operating characteristic curves (difference, 0.087, P = .049; SE, 0.044). The relative error for ultrasound-estimated fetal weight was 6.8% and by magnetic resonance-estimated fetal weight, 3.2% (P < .001). When using ultrasound-estimated fetal weight, 37.9% of fetuses (25 of 66) were estimated outside the range of ±10% of the actual birthweight, whereas this dropped to 6.1% (4 of 66) with magnetic resonance-estimated fetal weight (P < .001). The ultrasound-estimated fetal weight discordance and the birthweight discordance correlated significantly following the linear equation: ultrasound-estimated fetal weight discordance = 0.03 + 0.91 × birthweight (r = 0.75; P < .001); however, the correlation was better with magnetic resonance imaging: magnetic resonance-estimated fetal weight discordance = 0.02 + 0.81 × birthweight (r = 0.87; P < .001).

CONCLUSION

In twin pregnancies, magnetic resonance-estimated fetal weight performed immediately prior to delivery is more accurate and predicts small-for-gestational-age neonates significantly better than ultrasound-estimated fetal weight. Prediction of birthweight discordance is better with magnetic resonance imaging as compared with ultrasound.

Risk factors for fetomaternal bleeding after laser therapy for twin-twin transfusion syndrome

OBJECTIVE

To quantify and assess potential risk factors for transplacental passage of fetal red blood cells (RBCs) into the maternal circulation (fetomaternal bleeding, FMB) after laser surgery for twin-twin transfusion syndrome (TTTS).

STUDY DESIGN

A retrospective study of Rhesus-D negative patients that underwent laser surgery for TTTS. Patients with and without postoperative detectable fetal RBCs on Kleihauer-Betke (KB) testing were compared to determine risk factors for FMB. Patients were further sub-classified into those with a FMB < 20% and ≥20% of estimated fetoplacental blood volume.

RESULTS

Of 60 studied patients, 26/60 (43%) had a positive postoperative KB test. The median fetal:adult RBC ratio was 0.00125, estimated to be a FMB volume of 6.25 mL. There were 17/26 (65%) of patients with FMB < 20% and 9/26 (35%) patients with ≥20% of the fetoplacental blood volume. Stage III-Recipient and III-Recipient/Donor patients were more likely to have a positive KB test (14/21 [66.7%] vs 12/39 [30.8%], OR = 4.50 [1.27-16.54], P = 0.0162). No other risk factors for FMB were apparent.

CONCLUSIONS

Fetomaternal bleed appears to be a common finding after laser surgery for TTTS. TTTS Stage, particularly stage III-Recipient and III-Recipient/Donor, appears to be a risk factor for FMB.

Transient amniotic fluid leakage after fetoscopic laser photocoagulation for twin-twin transfusion syndrome

AIM

Iatrogenic premature rupture of membrane (PROM) is one of the major complications related to fetoscopic laser photocoagulation (FLP) for twin-twin transfusion syndrome (TTTS). However, amniotic fluid leakage (AFL) sometimes spontaneously disappears. This study evaluated the incidence and clinical characteristics of transient AFL after FLP.

METHODS

We retrospectively reviewed pregnancies that underwent FLP for TTTS at a single center. Patients with apparent AFL within 2 weeks after FLP were divided into two groups: transient AFL, defined by the disappearance of fluid leakage within a week; and PROM, if AFL persisted continuously for more than a week or premature birth occurred, including miscarriage, within a week of the first symptom of AFL.

RESULTS

Among 201 monochorionic twin pregnancies that underwent FLP during the study period, nine patients (4.5%) were diagnosed with AFL within a week after FLP. Four patients (2.0%) were classified as transient AFL and five as PROM. Median gestational age at FLP was not significantly different between the groups; operative time in the PROM group was significantly longer (P = 0.01). The surgery to delivery interval and median gestational age at delivery were greater in the transient AFL group (87.8 vs 17.6 days, P = 0.01; 32.5 vs 23.6 weeks, P = 0.01, respectively).

CONCLUSIONS

The incidence of transient AFL after FLP was 2%. Perinatal outcomes of transient AFL might be better than that of PROM.