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.

Outcome of monochorionic diamniotic twin pregnancy with selective intrauterine growth restriction, a single center study in China

INTRODUCTION

This retrospective study aimed to evaluate clinical outcomes of monochorionic diamniotic (MCDA) twins with selective intrauterine growth restriction (sIUGR).

MATERIALS AND METHODS

MCDA twins, either sIUGR and non-sIUGR, underwent expectant management from 2016 to 2019 in our hospital were included. sIUGR fetuses were classified into three types according to umbilical artery Doppler assessment. Non-sIUGR were considered as the control group. Outcomes were pregnancy outcomes and maternal complications.

RESULTS

Forty-three sIUGR (type I: 23; type II: 14, and type III: 6) and 282 non-sIUGR fetuses were included. The sIUGR group had a significantly earlier birth, lower birth weight of the twins, larger inter-twin weight difference, lower Apgar score of the twins, and higher intrauterine fetal death (IUFD) than the non-sIUGR group (all p < 0.001). The same trend was found in the sIUGR type II group compared to type I and III groups. A significantly lower gestational diabetes rate (p = 0.01) and placenta weight (p < 0.001), and higher proportions of abnormal placental umbilical cord insertion (p < 0.001), and ultrasound Doppler monitoring indicators (p = 0.006) were found in the sIUGR group than the non-sIUGR group.

CONCLUSIONS

The MCDA twins with sIUGR showed poorer outcomes than the non-sIUGR group. Doppler interrogation was a useful clinical marker for fetal outcome.

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.

Neurological morbidity in monochorionic twins with selective fetal growth restriction

The increased risks of various obstetric, maternal and fetal comorbidities of monochorionic twin pregnancies are widely known. However, despite its high prevalence and significance, the assessment of neurological morbidity as more commonly in selective fetal growth restriction (sFGR) is concerned with more health care. This literature review aims to provide more information about such an assessment. To this end, retrospective cases of sFGR were studied in monochorionic twins, already diagnosed, classified and who had the recommended management, published between 2001 and 2018 in 17 scientific articles. In the assessment of fetal mortality, the highest risk of death of the restricted fetus was found in type 3 of sFGR, while type 2 sFGR was responsible for the highest death rates of both fetuses and also the lowest mean gestational age at delivery, 30.9 weeks. Regarding neurological morbidity, however, studies have shown a higher risk of brain damage in the habitually growing twin compared to the restricted one in the case of sFGR. This may be due to prematurity or intermittent diastolic flow on Doppler in type 2 and 3 of sFGR, however, statements about its pathophysiology still lack further studies.

First-trimester biomarkers and ultrasound biometries in relation to growth discordance in monochorionic diamniotic twins

Objective: The aim of this study was to investigate the association and predictive value between intertwin discordance in first trimester biometries crown-rump length (CRL) and nuchal translucency (NT), and the first trimester biochemical markers PAPP-A and free β-hCG in relation to birth weight discordance (BWD) ≥25% in monochorionic diamniotic (MCDA) twin pregnancies.Methods: First trimester screening information and pregnancy outcome data on MCDA twin pregnancies with delivery from July 2008 to July 2017 were retrieved from the Danish Fetal Medicine Database. CRL discordance was divided into: <10% (reference group) and ≥10%. NT discordance was divided into: <20% (reference group) and ≥20%. The twin pregnancies were classified according to BWD into the following groups: <10% (reference group), 10-24.9%, and ≥25% including cases undergoing umbilical cord occlusion due to selective fetal growth restriction (sFGR). The twin pregnancies with the most severe BWD (BWD ≥25%) were subdivided into three groups including cases with only one growth-restricted (<10th centile) infant defined as sFGR, and cases where both twins were <10th centile. Median multiples of the median (MoM) values of PAPP-A and free ß-hCG were compared with the group with BWD <10% using the Wilcoxon two-sample test. The ability of CRL discordance and NT discordance to predict BWD ≥25% was examined by the area under the receiver operator characteristic (ROC) curve.Results: A total of 762 MCDA pregnancies were included. The proportion of pregnancies with CRL discordance ≥10% and NT discordance ≥20% was significantly higher in the group with severe BWD discordance (27.0% vs. 4.7% (p < 0.001) and 40.9% vs. 23.9% (p = 0.001), respectively). When examining the three subgroups of severe BWD, we found a significantly higher percentage of pregnancies with CRL discordance ≥10% in the group where umbilical cord occlusion was performed (52.6% vs. 4.7% in the group with BWD <10% (p < 0.001)) and in the group of BWD ≥25% with sFGR (21.7% vs. 4.7% (p < 0.001)). Additionally, a significantly higher percentage of pregnancies with NT discordance ≥20% was found in the group where umbilical cord occlusion was performed (52.6% vs. 23.9% (p = 0.005)) and in the group with both twins <10th centile (66.7% vs. 23.9% (p = 0.003)). No statistically significant differences were found when comparing levels of PAPP-A and free β-hCG MoMs with the group with BWD <10%. In ROC curves, CRL discordance yielded an AUC for prediction of BWD ≥25% of 0.70 (95% CI 0.63-0.76), and for NT discordance AUC was 0.59 (95% CI 0.52-0.66)). OR for any BWD ≥ 25% was 6.7 (95% CI 3.8-12.0) for pregnancies with a CRL discordance ≥10% compared to pregnancies with a CRL discordance <10%.Conclusions: This study shows that a discordance in CRL and NT in MCDA twins are both significantly associated with development of BWD. The most important predictor remains CRL discordance ≥10%, thereby suggesting the unequal growth pattern in many cases with BWD is evident already in the first trimester of the pregnancy. No association was found between first trimester biochemical markers and severe BWD.

Fetal Doppler in monochorionic pregnancies complicated by twin-to-twin transfusion syndrome and selective in utero growth restriction

BACKGROUND

Monochorionic (MC) twin pregnancies may be complicated by placental pathologies that impact fetal cardiac function, such as twin-twin transfusion syndrome (TTTS) and selective intrauterine growth-restriction (sIUGR). In the TTTS, the unbalanced blood flow through placental anastomoses lead a recipient volume overload, hypertension and hypertrophic cardiomyopathy and the donor twin experiences hypovolemia and hypertension due to increased placental resistance and poor renal perfusion. When MC pregnancies were complicated by sIUGR, the increase of placental resistances lead to complex fetal compensatory mechanisms with redistribution of cardiac output to vital organs. Increased placental vascular resistances, hypoxia and hemodynamic compensation mechanisms lead to higher pre and/or afterload for both ventricles, right cardiac failure and eventually left cardiac failure observed just before fetal death.

OBJECTIVES

The purpose of this study was to describe the anomalies of umbilical, ductal and aortic isthmic Doppler as well as left and right myocardial performance index (MPI) across various clinical phenotypes of MC twin pregnancies, uncomplicated or complicated by TTTS or sIUGR, in order to help differentiating these conditions and to improve the understanding of TTTS and sIUGR pathophysiology.

STUDY DESIGN

Aortic isthmic systolic index (ISI), umbilical artery pulsatility index (UAPI), ductus venosus pulsatility index (DVPI), and MPI were studied in uncomplicated MC twins (control group) and cases of sIUGR or TTTS.

RESULTS

The measurements were obtained in 113 pregnancies (24 uncomplicated, 22 sIUGR, 51 TTTS). In comparison with controls, the sIUGR smaller twin sets had lower ISI and higher UAPI, and the larger twin had higher ISI. The TTTS donor and recipient had lower ISI, higher UAPI and DVPI. Compared to the co-twin, the ISI values were lower in the sIUGR smaller twin and the TTTS donor had lower ISI and MPI. Comparing TTTS and sIUGR, the recipient had higher DVPI and MPI than the sIUGR larger twin.

CONCLUSIONS

The Doppler anomalies observed in the smaller twin reflected increased placental blood flow resistance, presumably due to abnormal feto-fetal transfusion in TTTS and to unequal placental sharing in sIUGR. Early hemodynamic changes suggestive of cardiac overload in the recipient twin may help to differentiate TTTS and sIUGR.

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.

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.

Perinatal outcomes in twin late preterm pregnancies: results from an Italian area-based, prospective cohort study

BACKGROUND

Multiple gestations represent a considerable proportion of pregnancies delivering in the late preterm (LP) period. Only 30% of LP twins are due to spontaneous preterm labor and 70% are medically indicated; among this literature described that 16-50% of indicated LP twin deliveries are non-evidence based. As non-evidence-based delivery indications account for iatrogenic morbidity that could be prevented, the objective of our observational study is to investigate first neonatal outcomes of LP twin pregnancies according to gestational age at delivery, chorionicity and delivery indication, then non evidence-based delivery indications.

METHODS

Prospective cohort study among twins infants born between 34 + 0 and 36 + 6 weeks, in Emilia Romagna, Italy, during 2013-2015. The primary outcome was a composite of adverse perinatal outcomes.

RESULTS

Among 346 LP twins, 84 (23.4%) were monochorionic and 262 (75.7%) were dichorionic; spontaneous preterm labor accounted for 85 (24.6%) deliveries, preterm prelabor rupture of membranes for 66 (19.1%), evidence based indicated deliveries were 117 (33.8%), while non-evidence-based indications were 78 (22.5%). When compared to spontaneous preterm labor or preterm prelabor rupture of membranes, pregnancies delivered due to maternal and/or fetal indications were associated with higher maternal age (p <  0.01), higher gestational age at delivery (p <  0.01), Caucasian race (p 0.04), ART use (p <  0.01), gestational diabetes (p <  0.01), vaginal bleeding (p <  0.01), antenatal corticosteroids (p <  0.01), diagnosis of fetal growth restriction (FGR) (p <  0.01), and monochorionic (p <  0.01). Two hundred twenty-six pregnancies (65.3%) had at least one fetus experiencing one composite of adverse perinatal outcome. Multivariate analysis confirmed that delivery indication did not affect the composite of adverse perinatal outcomes; the only characteristic that affect the outcome after controlling for confounding was gestational age at delivery (p <  0.01). Moreover, there was at least one adverse neonatal outcome for 94% of babies born at 34 weeks, for 73% of those born at 35 weeks and for 46% of those born at 36 weeks (p <  0.01).

CONCLUSION

Our study suggests that the decision to deliver or not twins in LP period should consider gestational age at delivery as the main determinant infants' prognosis. Delivery indications should be accurately considered, to avoid iatrogenic early birth responsible of preventable complications.

Correlation analysis of adverse outcomes for the selective reduction of twin pregnancies

BACKGROUND

Due to the extensive development of assisted reproductive technology, the number of twin pregnancies has increased significantly over recent decades. Twin pregnancy is the most representative type of multiple pregnancies and is associated with high infant morbidity and mortality. Perinatal complications of twin pregnancy are also markedly increased compared with those of single pregnancy. Transabdominal selective reduction (SR) is a remedial intervention. This study aimed to research the adverse outcomes of transabdominal selective reduction of twin pregnancy and the correlation between the reduction week and pregnancy outcomes.

OBJECTIVE

The purpose of this study was to examine the adverse outcomes of the transabdominal selective reduction of twin pregnancy and the correlation between the reduction week and pregnancy outcomes.

METHODS

A retrospective cohort study of the transabdominal reduction of twin pregnancy was conducted in a single prenatal diagnosis medical centre from September 2012 to October 2020. According to chorionicity, women with twin pregnancies were divided into 2 groups: dichorionic (DC) twin pregnancies and monochorionic (MC) twin pregnancies. Women with DC twin pregnancies underwent potassium chloride reduction, and those with MC twin pregnancies underwent radiofrequency ablation (RFA). The reduction indications included pregnancy complications, foetal abnormalities, and maternal factors. The perinatal outcomes of different chorionic twins after reduction were analysed. Each foetus with an adverse outcome was included. The relative relationship between the reduction weeks and delivery weeks of twins was examined by correlation analysis.

RESULTS

A total of 161 women were included in this study. A total of 112 women had DC twin pregnancies, and 49 women had MC twin pregnancies. Preterm delivery rates were significantly higher in the MC twin reduction group than in the DC twin reduction group prior to 37 weeks (53.1% vs. 29.5%, P = 0.004). The mean gestational age at delivery of the foetuses in the DC twin group that underwent SR was significantly older than that of those in the MC twin group that underwent SR (36.9 ± 4.0 vs. 33.5 ± 6.6 weeks, P = 0.001). The number of DC twins that underwent SR and were delivered after 37 weeks was obviously greater than that of the MC twins that underwent SR (70.5% vs. 46.9%, P = 0.004). The foetal survival rate was 95.5% in the DC twin reduction group and 77.6% in the MC twin reduction group. If the indication of TTTS was not included, there was no significant difference in the foetal survival rate of the DC and MC twin reduction groups (95.5% vs. 86.2%, P = 0.160). Cotwin death 1 week after reduction was greater in the MC group (6.1% vs. 0%, P = 0.027). Compared to other indications, this finding indicated that a significantly lower proportion of women remained undelivered after selective reduction with the indication of TTTS. There was a significant negative correlation between the reduction weeks and delivery weeks of the two groups (P < 0.01), and the best opportunity for reduction was before 22 weeks of gestation.

CONCLUSION

These findings highlighted an obviously negative correlation between the reduction week and delivery week. The transabdominal selective reduction of twin pregnancy should be considered for a lower rate of miscarriage or premature delivery if the reduction week takes place earlier in pregnancy. The rate of preterm delivery was the lowest when transabdominal selective reduction was completed before 22 weeks of gestation. Compared with other RFA indications, a higher rate of premature delivery was shown for MC twins with a reduction indication of TTTS. TTTS with sIUGR might be one of the reasons for the adverse outcomes of reduction for MC twin pregnancy.

Impact of Preoperative Cervical Length on Pregnancy Outcome in Twin-Twin Transfusion Syndrome

OBJECTIVE

To evaluate the impact of preoperative cervical length on pregnancy outcome in monochorionic diamniotic twin pregnancies complicated by twin-twin transfusion syndrome that underwent laser surgery or cord occlusion.

MATERIALS AND METHODS

Retrospective study of 330 patients stratified by preoperative cervical length (≥25 mm, 16-24 mm,≤15 mm). Maternal characteristics, operative data, and pregnancy outcomes were compared between the cervical length groups as well as between the subgroups of patients with a cervical length≤15 mm according to management (expectant vs. cerclage).

RESULTS

A preoperative cervical length≥25 mm was observed in 82% (n=271) of cases, 16-24 mm in 9% (n=29), and≤15 mm in 9% (n=30). Patients with a preoperative cervical length≤15 mm showed shorter median procedure-to-delivery interval (5.5 weeks vs. 11.6 (16-24 mm) vs. 13.0 (≥25 mm); p<0.001); lower median gestational age at delivery (29.5 weeks vs. 34.3 (16-24 mm) vs. 33.4 (≥25 mm); p<0.001); higher rate of preterm delivery<32 weeks (78 vs. 20% (16-24 mm) vs. 31% (≥25 mm); p<0.001); and lower neonatal survival rate of at least one twin (70 vs. 88% (16-24 mm) vs. 93% (≥25 mm); p<0.001). Outcome of patients with a preoperative cervical length≤15 mm was similar regardless of management.

CONCLUSION

Monochorionic diamniotic twin pregnancies complicated by twin-twin transfusion syndrome with a preoperative cervical length≤15 mm showed a higher rate of preterm delivery<32 weeks and lower neonatal survival. The role of a cervical cerclage remains unclear.

Fetoscopic Laser Ablation for the Selective Fetal Reduction in Twin-Twin Transfusion Syndrome Stage II-IV: The Experience of a New Fetal Medicine Center

Objective

To evaluate the surgery outcomes of fetoscopic laser ablation (FLA) for selective umbilical cord in treating twin-twin transfusion syndrome (TTTS) with special conditions and neonatal outcomes post-operation.

Methods

A prospective study, 21 monochorionic diamniotic (MCDA) twins diagnosed with TTTS stage II–IV according to Quintero classification from 16 to 26 weeks of gestation, among that, 12 cases of TTTS stage II with selective intrauterine growth restriction (sIUGR), 6 cases of TTTS stage II with proximate cord insertions, 3 cases of TTTS stage IV underwent fetoscopic laser ablation for the selective fetal reduction at Hanoi Obstetrics and Gynecology Hospital from September 2019 to July 2021. Complications and surgical outcomes were noted. Prenatal care was carried out every 2 weeks post operation until birth. Newborn neurologic complications were assessed at birth, three months, and six months after birth using Denver II test and magnetic resonance imaging (MRI).

Results

The mean gestational age at operation was 20.30 weeks. The average operation duration was 39.52 minutes. No complications of operation, such as bleeding or infection, were recorded. The mean gestational age at birth was 34.70 ± 4.33 weeks, with a mean duration of 12.97 ± 6.87 weeks between intervention and delivery. The survival rate of newborns after the operation was 90.48%. There were two stillbirths (9.52%) within seven days after the operation. No short-term neurological complications have been reported with follow-up of the newborn to 6 months after birth.

Conclusion

Our study showed that fetoscopic laser ablation of selected fetal reduction surgery for treatment of special conditions of TTTS had no complications of operation, high neonatal survival result (90.48%), no short-term neurological complications. This should be considered for TTTS in cases of indication.

Management of atypical cases of twin-to-twin transfusion syndrome

Up to 20% of monochorionic diamniotic twin pregnancies can be complicated with twin-to-twin transfusion syndrome (TTTS). This complication is diagnosed by ultrasound demonstrating amniotic fluid discordance between both amniotic sacs, with polyhydramnios in the recipient's sac and oligohydramnios in the donor's, secondary to an imbalance in blood volume exchange between twins. Ultrasound evaluation of the amniotic fluid volume, bladder filling, and assessment of fetal Doppler parameters provide the basis for classification of TTTS, allowing severity assessment. The Quintero's staging system provides a standardized prenatal estimate on the risk of intrauterine fetal demise of one or both twins and the need for fetoscopic laser coagulation of placental vascular anastomoses or delivery depending on the gestational age. However, a proportion of TTTS cases may present without a linear progressive deterioration and no ultrasound signs of preceding staging, in rare situations, they arise even without amniotic fluid discordance. Thus, these unusual clinical presentations of TTTS have long been grouped into the category of atypical TTTS. In this review, we show the clues for diagnosis and management of different atypical cases of TTTS highlighting their underlying mechanism to improve the clinical understanding of such atypical situations, avoid misdiagnosis of TTTS, and allow a timely referral to a fetoscopic center.

The heart after surviving twin-to-twin transfusion syndrome

BACKGROUND

The persistent changes in cardiac structure and function in children who survived twin-to-twin transfusion syndrome remain a matter of concern and controversy. Current fetal echocardiographic parameters and their postnatal evolution can help improve our understanding of the subject.

OBJECTIVE

To describe the echocardiographic changes of monochorionic fetuses affected by twin-to-twin transfusion syndrome, the recipient and the donor, before and after laser photocoagulation and to determine their evolution in the third trimester and during their first year of life.

STUDY DESIGN

An observational study was conducted including 55 uncomplicated monochorionic diamniotic twins and 78 pairs with twin-to-twin transfusion syndrome, 44 stage I-II and 34 stage III-IV, prospectively enrolled from 2015 until 2018. Comprehensive echocardiography was performed at 4 time periods: before laser photocoagulation, at 24 to 72 hours after surgery, at 28 to 30 weeks of gestation, and at 6 to 12 months after birth. Echocardiographic parameters were transformed to z-scores or indexed for heart area, estimated fetal weight, or body mass surface.

RESULTS

At diagnosis, recipients in all stages presented larger hearts (cardiothoracic ratio z-score: 2.77 [0.8] vs controls: -0.03 [0.5]; P<.001) and signs of ventricular hypertrophy (left end-diastolic ventricle wall thickness: 2.68 [0.7] vs controls -0.03 [0.7]; P<.001), along with systolic (cardiac index recipients: 317 [114] mL/min/kg vs controls: 400 [120] mL/min/kg, P<.001) and diastolic impairment (isovolumetric relaxation time z-score: 2.76 [0.6] vs controls: 0.05 [0.6]; P<.001). Donors presented smaller ventricular areas and diameters when compared with controls (left end-diastolic ventricle area z-score: -1.48 [1] vs 0.03 [0.9]; P<.001), along with decreased longitudinal motion (tricuspid annular plane systolic excursion z-score: -0.9 [1] vs controls -0.04 [1]; P<.001) and shorter ejection time z-score (-1.5 [0.7] vs controls: 0.0 [0.7]; P<.001). After surgery, an improvement in functional parameters was observed in both fetuses, whereas most morphometric changes prevailed in donors and recipients in the prenatal period. Postnatally, cardiac remodeling persisted in recipients (left relative wall thickness: 0.34 [0.02] vs controls: 0.30 [0.02]; P<.001), whereas donors mainly presented a decreased longitudinal motion in infancy (tricuspid annular plane systolic excursion z-score: -0.72 [0.7] vs controls: 0.23 [0.9]; P<.05).

CONCLUSION

Cardiac remodeling is present in both fetuses at the twin-to-twin transfusion syndrome diagnosis, whereas diastolic dysfunction is only significant in the recipient. Fetal therapy improves most echocardiographic parameters, although postnatally, the echocardiographic changes persist in both fetuses.

Comparison of outcomes of monochorionic twin pregnancies conceived by assisted reproductive technology vs. spontaneous conceptions: A systematic review and meta-analysis

BACKGROUND

This review aimed to assess if monochorionic twin pregnancies conceived by assisted conception have worse maternal and neonatal outcomes as compared to those conceived naturally.

METHODS

Datasets of PubMed, ScienceDirect, CENTRAL, Embase, and Google Scholar were searched for studies comparing maternal and neonatal outcomes of monochorionic twin pregnancies conceived by assisted vs. spontaneous methods.

RESULTS

Eight studies comparing 337 assisted with 2,711 spontaneously conceived monochorionic twin pregnancies were included. Meta-analysis revealed that the mode of conception of monochorionic twin pregnancies had no impact on the risk of hypertensive disorders of pregnancy (HDP) (OR: 1.36 95% CI, 0.73, 2.54 I ² = 9% p = 0.03), twin-twin transfusion syndrome (TTTS) (OR: 0.83 95% CI, 0.52, 1.31 I ² = 0% p = 0.42), and very preterm delivery (OR: 1.18 95% CI, 0.74, 1.88 I ² = 41% p = 0.49). We noted no statistically significant difference in the mean birth weights (MD: -17.66 95% CI, -157.23, 121.91 I ² = 82% p = 0.80), risk of intra-uterine death (OR: 0.90 95% CI, 0.51, 1.60 I ² = 36% p = 0.73) and small for gestational age between the two groups (OR: 0.92 95% CI, 0.67, 1.26 I ² = 0% p = 0.59). There was an increased risk of caesarean sections (OR: 1.34 95% CI, 1.00, 1.80 I ² = 0% p = 0.05) and neonatal death with assisted conceptions as compared to spontaneous conceptions (OR: 2.35 95% CI, 1.11, 5.01 I ² = 37% p = 0.03).

CONCLUSION

Monochorionic twin pregnancies conceived via assisted reproductive technology have a heightened risk of cesarean section and neonatal deaths. However, there is a need for further studies to supplement current evidence.Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=325133, identifier: CRD42022325133.

Left myocardial performance index in monochorionic diamniotic twin pairs complicated by selective fetal growth restriction with abnormal umbilical artery Doppler

OBJECTIVE

To evaluate left myocardial performance index (MPI) and its time intervals in monochorionic diamniotic (MCDA) twin pairs complicated by selective fetal growth restriction (sFGR) with abnormal (persistent -type II- or intermittent -type III- absent or reversed end-diastolic flow) umbilical artery Doppler.

METHODS

Retrospective study including 16 MCDA twin pairs with sFGR type II, 26 MCDA twin pairs with sFGR type III and 42 gestational age-matched uncomplicated MCDA twin pairs in a single tertiary center. Left isovolumetric contraction time (ICT), ejection time (ET), and isovolumetric relaxation time (IRT) were measured and MPI calculated by conventional Doppler at diagnosis of sFGR.

RESULTS

In sFGR type II, the smaller twin had shorter ET and prolonged IRT and MPI, while the larger twin showed prolonged ICT and MPI as compared to uncomplicated MCDA twins. In sFGR type III, the smaller twin had shorter ICT and ET, while the larger twin showed prolonged ICT, IRT, and MPI in comparison to controls.

CONCLUSION

A differential pattern of MPI time intervals could be observed in MCDA twins with sFGR type II and III. All twins had echocardiographic signs of pressure/volume overload, except the smaller twin type III with shorter systolic times probably reflecting reduced volume load.

Prescriptive standards of echocardiographic morphometric and functional parameters in uncomplicated monochorionic diamniotic fetuses

OBJECTIVE

To create prescriptive standards of cardiac morphometric and functional parameters in a cohort of uncomplicated monochorionic diamniotic (MCDA) twins.

METHOD

Fetal echocardiography was performed in a cohort of uncomplicated monochorionic twin fetuses scanned longitudinally, including comprehensive morphometric and functional parameters, using 2-D imaging, M-mode and conventional Doppler. A multilevel polynomial hierarchical model adjusted by gestational age and estimated fetal weight was used to fit each cardiac parameter.

RESULTS

The global heart dimensions including the atrial and ventricular areas, the ventricles dimensions and myocardial wall thicknesses and most of the functional parameters, such as the longitudinal myocardial motion and the biventricular cardiac output showed a positive quadratic increment throughout pregnancy. On the other hand, the left ejection fraction, shortening fraction and right fractional area change decreased with gestational age. Scatterplots for the main structural and functional parameters and ratios by gestational age, with mean, 5th, 10th, 90th, and 95th percentiles are provided. Regression equations by estimated fetal weight are also created.

CONCLUSION

We provide specific comprehensive echocardiographic prescriptive standards for uncomplicated MCDA twin fetuses following current standardized methodology. The implementation of these charts will potentially help to better identify abnormal cardiovascular parameters associated to monochorionic complications.

Perinatal Outcome of Selective Intrauterine Growth Restriction in Monochorionic Twins: Evaluation of a Retrospective Cohort in a Developing Country

Selective intrauterine growth restriction (sIUGR) in monochorionic twin pregnancies is associated with greater morbidity and mortality for both fetuses when compared to singleton and dichorionic pregnancies. This retrospective cohort study aimed to assess the perinatal outcomes of monochorionic twin pregnancies affected by this disorder and conducted expectantly, by analyzing the results according to the end-diastolic flow in the umbilical artery Doppler of the smaller twin (type I: persistently forward/type II: persistently absent or reversed/type III: intermittently absent or reversed). Seventy-five monochorionic diamniotic twin pregnancies with sIUGR were included in this study. sIUGR was defined by estimated fetal weight below the 3rd centile for gestational age, or below the 10th centile, when associated with at least one of the following three criteria: abdominal circumference below the 10th percentile, umbilical artery pulsatility index of the smaller twin above the 95th percentile, or estimated fetal weight discordance of 25% or more. Perinatal outcomes were analyzed from the prenatal period to hospital discharge and included perinatal death, neurological injury, retinopathy of prematurity (ROP), bronchopulmonary dysplasia (BPD), necrotizing enterocolitis (NEC), and sepsis. The mortality rate was 1.33% in this cohort. The overall morbidity rate was lower in type I twin pregnancies. In conclusion, this study shows that sIUGR type I has lower morbidity than types II and III in expectant management.

Prediction of adverse perinatal outcome and the mean time until delivery in twin pregnancies with suspected pre-eclampsia using sFlt-1/PIGF ratio

PURPOSE

An elevated soluble fms-like tyrosine kinase-1 (sFlt-1) / placental growth factor (PlGF) ratio is associated with adverse perinatal outcome (APO) and the mean time until delivery (MTUD) in singleton pregnancies complicated by pre-eclampsia (PE). Data on APO and MTUD prediction in twin pregnancies using sFlt-1/PlGF ratio are scarce. We evaluated the predictive value of the sFlt-1/PIGF ratio regarding APO and MTUD in twin pregnancies with suspected PE and/or HELLP syndrome.

METHODS

This is a single center retrospective cohort study. All twin pregnancies with suspected PE/HELLP and determined sFlt-1/PIGF were included. Composite APO (CAPO) was defined as the presence of at least one of the following outcomes: respiratory distress syndrome (RDS), intubation, admission to neonatal intensive care unit (NICU) and arterial umbilical cord pH value < 7.10. Selective fetal growth restriction (s-FGR) was analyzed separately.

RESULTS

For final analysis, 49 twin pregnancies were included. Median sFlt-1/PIGF ratio was not significantly different in patients with CAPO compared to those without (89.45 vs. 62.00, p = 0.669). MTUD was significantly negative correlated with sFlt-1/PIGF ratio (r = -0.409, p < 0.001). For the whole study cohort, ROC analysis revealed no predictive value for sFlt-1/PIGF and CAPO (AUC = 0.618, 95% CI: 0.387-0.849, p = 0.254). However, sFlt-1/PIGF ratio showed a predictive value for s-FGR (AUC = 0.755, 95% CI: 0.545-0.965, p = 0.032).

CONCLUSION

In twin pregnancies with PE and/or HELLP, sFlt-1/PIGF ratio may be helpful for s-FGR prediction and decision-making regarding close monitoring of high-risk patients. However, further prospective studies are warranted to define the role of sFlt-1/PlGF ratio as outcome predictor in twin pregnancies.

Influence of indications on perinatal outcomes after radio frequency ablation in complicated monochorionic pregnancies: a retrospective cohort study

Background

Radiofrequency ablation (RFA) is recommended to prevent potential neurological injury or intrauterine foetal death (IUFD) of the co-twin(s) in complicated monochorionic (MC) pregnancies. However, the impacts of various indications on the pregnancy outcome following RFA remain unclear. This study aimed to determine how the indications influence the perinatal outcomes in complicated MC pregnancies undergoing radiofrequency ablation.

Methods

This was a retrospective cohort study performed in a single centre. All consecutive MC pregnancies treated with RFA between July 2011 and July 2019 were included. The adverse perinatal outcomes and the survival rate were analysed based on various indications. The continuous variables with and without normal distribution were compared between the groups using Student’s t-test and Mann–Whitney U test, respectively, and for categorical variables, Chi-square and Fisher’s exact tests were used. P < 0.05 indicated a significant difference.

Results

We performed 272 RFA procedures in 268 complicated MC pregnancies, including 60 selective intrauterine growth restriction (sIUGR), 64 twin–twin transfusion syndrome (TTTS), 12 twin reversed arterial perfusion sequence (TRAPs), 66 foetal anomaly and 66 elective foetal reduction (EFR) cases. The overall survival rate of the co-twin was 201/272 (73.9%). The overall technical successful rate was determined at 201/263 (76.7%). The IUFD rate in the co-twin was 20/272 (7.4%). The TTTS group had recorded the lowest survival rate (37/64, 57. 8%), and the survival rate was significantly correlated with Quintero stages (P = 0.029). Moreover, the sIUGR III subgroup had a lower survival rate compared with sIUGR II (55.6%, versus 84.3%). The subgroup of foetal anomaly of gastroschisis or exomphalos had the highest IUFD rate (4/10, 40%), followed by sIUGR III (2/9, 22.2%) and dichorionic triamniotic (DCTA) subgroup (8/46, 17.9%). In EFR group, eight IUFD cases were all coming from the DCTA subgroup and received RFA before 17 weeks.

Conclusions

The perinatal outcome of RFA was correlated with the indications, with the lowest survival rate in TTTS IV and the highest IUFD incidence in abdominal wall defect followed by sIUGR III. Elective RFA after 17 weeks may prevent IUFD in DCTA pregnancies.

Monochorionic twins with selective fetal growth restriction: insight from placental whole-transcriptome analysis

BACKGROUND

The underlying pathomechanism in placenta-related selective fetal growth restriction in monochorionic diamniotic twin pregnancy is not known.

OBJECTIVE

This study aimed to investigate any differences in placental transcriptomic profile between the selectively growth-restricted twins and the normally grown cotwins in monochorionic diamniotic twin pregnancies.

STUDY DESIGN

This was a prospective study of monochorionic diamniotic twin pregnancies complicated by selective fetal growth restriction. Placental biopsy specimens were obtained from the subjects in the delivery suite. The placental transcriptome of the selectively growth-restricted twin was compared with that of the normally grown cotwin. This study was divided into 2 stages: (1) gene discovery phase in which placental tissues from 5 monochorionic diamniotic twin pregnancies complicated by selective fetal growth restriction plus 2 control twin pregnancies underwent transcriptome profiling, and transcriptome profiling was carried out using whole-genome RNA sequencing; and (2) validation phase in which placental tissues from 13 monochorionic diamniotic twin pregnancies with selective fetal growth restriction underwent RNA and protein validation. RNA and protein expression levels of candidate genes were determined using quantitative real-time polymerase chain reaction and immunohistochemistry staining.

RESULTS

A total of 1429 transcripts were differentially expressed in the placentae of selectively growth-restricted twin pairs, where 610 were up-regulated and 819 were down-regulated. Endoplasmic reticulum lectin and mannose 6-phosphate receptor were consistently differentially up-regulated in all placentae of selectively growth-restricted twins. Quantitative real-time polymerase chain reaction and immunohistochemistry staining were used to validate the results (P<.05).

CONCLUSION

The expression of endoplasmic reticulum lectin and mannose 6-phosphate receptor, which are important for angiogenesis and fetal growth, was significantly increased in the placentae of selectively growth-restricted twin of a monochorionic twin pair.

Selective fetal reduction in complicated monochorionic twin pregnancies: A comparison of techniques

OBJECTIVE

To compare perinatal outcomes associated with three methods of selective reduction in complicated monochorionic (MC) twin pregnancies: bipolar cord coagulation (BC), fetoscopic or ultrasound guided laser cord occlusion and radiofrequency ablation (RFA).

METHODS

Retrospective cohort study of complicated MC twin pregnancies undergoing selective fetal reduction at a tertiary fetal center over a 20-year period. Obstetric and perinatal outcomes were compared.

RESULTS

105 procedures met inclusion criteria: 74 RFAs, 17 lasers and 14 BCs. Procedure duration was significantly shorter for RFA (27.4 ± 15.8 minutes) compared to BC (91.7 ± 38.7 minutes) and laser (83.4 ± 40.4 minutes), P < .0001). The incidence of preterm prelabor rupture of membranes (PPROM) and co-twin demise did not differ between groups, however preterm delivery <34 weeks occurred less frequently following RFA (29.7%), compared to laser (64.7%) or BC (42.9%) (P = .02); delivery <37 weeks was also less frequent following RFA (45.9%), compared to laser (76.5%) or BC (78.6%)(P = .01). The difference in preterm birth<34 weeks between RFA and laser was maintained after adjusting for cord occlusion indication and amnionicity (OR 3.96, 95% CI 1.27-12.31).

CONCLUSIONS

In our experience, RFA procedures were simpler, faster and associated with a lower risk of preterm delivery <34 and <37 weeks, compared to laser or BC.

Microwave ablation versus radiofrequency ablation for the treatment of severe complicated monochorionic pregnancies in China：protocol for a pilot randomised controlled trial

INTRODUCTION

Complicated monochorionic twin pregnancies are often associated with high perinatal morbidity and mortality, some of which are severe enough to require a gestational reduction surgery to improve fetal survival and reduce disabilities. While radiofrequency ablation is currently the most commonly used procedure with higher fetal survival and fewer maternal and fetal complications compared with other surgical methods, the therapeutic effect of microwave ablation (MWA) is reported to be better, presumably due to the higher thermal effect and fewer restrictions. Currently there is limited evidence to prove the feasibility of MWA for selective reduction. The aim of this pilot study is to explore the feasibility, efficacy and safety of MWA reduction for severe complicated monochorionic pregnancies and may provide evidence for using the MWA in intrauterine surgeries extensively.

METHODS AND ANALYSIS

This is a study protocol for a parallel-design pilot randomised controlled trial. 60 eligible patients with severe complicated monochorionic pregnancies will be randomised in a ratio of 1:1 to MWA group and radiofrequency group. Patients will be followed up until 6 months of age of the retained fetal. The primary analysis will compare the rates of neonatal survival at 28 days to evaluate the effect of MWA. The study will also evaluate the safety profile of MWA including the occurrence of postoperative adverse events and maternal and fetal complications. Additional secondary outcomes to be explored include the condition of neonatal asphyxia and the growth of surviving fetus at 6 months. Outcomes will be analysed by both a frequentist and the Bayesian statistical approach.

ETHICS AND DISSEMINATION

This study was approved by the ethical review committee of the Peking University Third Hospital (Beijing, China). The results of this study will be published in peer-reviewed scientific journals and presented at relevant academic conferences.

TRIAL REGISTRATION NUMBER

NCT04014452; Pre-results.

Growth patterns and associated risk factors of congenital malformations in twins

BACKGROUND

The rate of twinning continues to increase due to the combined effect of a rise in parental age and increased use of assisted reproductive technology. The risk of congenital anomalies in twins is higher than in singletons, but it is less well reported in relation to growth patterns. We focused to the auxological outcome of twin pregnancies when one or both of twins are affected by one or more malformations.

METHODS

We conducted a retrospective observational study reviewing the clinical charts of twins admitted in the period between January 2003 and December 2018 at the University Hospital of Palermo. The associations between malformations and anthropometric variables at birth were analyzed by comparison within each twin pair and regarding each variable as ordered difference between the two twins.

RESULTS

We studied data of 488 neonates (52% females) from 244 pregnancies. The rate of major congenital anomalies was 11%, affecting significantly the smaller twin (p = .00018; Odds ratio 3.21; 95% CI 1.65 6.59). Malformation class distribution was as following: genitourinary (24%), gastrointestinal (20%), cardiovascular (18.5%), musculoskeletal (11%), central nervous system (9%), syndromic (9%), ocular (5.5%) and diaphragmatic hernia (2%). The most predictive value, the Birthweight (BW) difference mean ratio in malformed versus not malformed neonates (- 0.31 vs 0.02; p = .0016) was distributed equally lower than zero in all malformed twins, except for those with congenital heart defects (p = .0000083). Microcephaly (head circumference < 2 standard deviation, SD) was present in 3% of symmetrically smaller twin, and severe microcephaly (< 3 SD) was present in 0.6%. We found that an intertwin BW discordance of 18% or greater identified 50% of neonates with microcephaly, but only 11% of malformed twins.

CONCLUSIONS

In case of one twin with a BW < 10th centile, a concomitant intertwin BW discordance ≥18% could reveal an increased risk for microcephaly but not for malformation. Lower values of BW, Ponderal index, Body mass index but above all negative value of BW difference mean ratio are associated with malformations in twin pairs.

Pregnancy outcomes associated with chorioamnion membrane separation severity following fetoscopic laser surgery for twin-twin transfusion syndrome

OBJECTIVE

We tested the hypothesis that increasing severity of chorioamnion membrane separation (CAS) after fetoscopic laser surgery (FLS) for twin-twin transfusion syndrome (TTTS) is associated with worse pregnancy outcomes.

METHODS

Prospective cohort of patients undergoing FLS for TTTS between 2011 and 2018. CAS was defined as separation of fetal membranes from the uterine wall on post-operative ultrasound. Patient groups were defined: Group 1: No CAS; Group 2: CAS lower than 50th centile; Group 3: CAS upper than 50th centile or complete CAS. Comparative analysis was performed.

RESULTS

Of 387 patients meeting inclusion criteria, 29 (7.5%) had CAS (median 9.8 mm [4.9-30.8 mm]). Group 1 patients were more likely to undergo FLS at later gestational age, had increased recipient maximum vertical pocket, and higher amnioreduction volume than Group 3. Group 3 had higher rates of preterm premature rupture of membrane, delivered earlier and were more likely to terminate than Group 1. Group 2 had fewer neonatal survivors than Group 1. Survival analysis for gestational age at delivery and Cox proportional hazards model indicated increased risk for early delivery in Groups 2 and 3 compared with Group 1.

CONCLUSIONS

Patients with CAS ≥9.8 mm or complete CAS after FLS for TTTS had worse obstetric and neonatal outcomes.

Twin-to-twin transfusion syndrome as a cause of neonatal acute liver failure

Background

Acute liver failure (ALF) is a rare condition during neonatal period.

Objective

To report a case of recipient twin with fulminant ALF secondary to hydrops fetalis caused by twin-to-twin transfusion syndrome (TTTS).

Method

The patient was admitted to the neonatal intensive care unit (NICU) for respiratory failure requiring mechanical ventilation and fulminant ALF with prolonged international normalized ratio (INR) and elevated liver enzymes with highest aspartate aminotransferase of 4,580 U/L.

Results

Laboratory investigation for secondary causes of liver failure was not revealing. Her liver enzymes and coagulation levels were dramatically normalized as the clinical symptoms of hypervolemia improved within 1 week.

Conclusion

TTTS can be a possible cause of neonatal ALF. Early detection with proper management of TTTS is important to avoid adverse outcomes. However, pathogenesis of hepatic dysfunction in TTTS is rarely described, and further studies are needed to help understanding the correlation between liver diseases and TTTS.

Twin-twin transfusion syndrome in the era of fetoscopic laser surgery: antenatal management, neonatal outcome and beyond

Introduction: Twin-twin transfusion syndrome (TTTS) is a devastating complication of monochorionic twin pregnancy and remains a major challenge for worldwide fetal medicine specialists. In TTTS, intertwin transfusion through vascular anastomoses in the shared placenta leads to severe hemodynamic imbalance. This review summarizes the current knowledge of TTTS.Areas covered: The most recent insights concerning the management of TTTS, as well as fetal and neonatal complications are described. Relevant articles were selected based on a Pubmed search using the keywords below. Understanding of the underlying pathophysiology has improved greatly as a result of placental injection studies. Advancements in antenatal management have led to increased perinatal survival and a decreased incidence of neonatal complications, including brain injury and neurodevelopmental impairment.Expert opinion: Further opportunities for improvement comprise technological innovations in laser procedures and the prevention of preterm rupture of membranes with subsequent prematurity. A noninvasive treatment such as high-intensity focused ultrasound (HIFU) seems to hold promise for the future treatment of TTTS. Fetal MRI studies are important to improve our understanding of fetal brain injury and should relate their findings to long-term neurodevelopment. International collaboration and centralization of care are of paramount importance to ensure the best care for our patients.

Management and perinatal outcome of selective intrauterine growth restriction in monochorionic pregnancies

Introduction: Selective intrauterine growth restriction (sIUGR) is a complication observed in about 10-15% of all monochorionic (MC) pregnancies, causing a significant increase in perinatal mortality and morbidity.Objective: To evaluate clinical management options and perinatal outcomes of sIUGR in MC pregnancies monitored in a single tertiary center.Methods: A retrospective study was performed on 55-MC pregnancies with sIUGR between January 2012 and May 2018 at the Fetal Medicine Unit of La Paz Hospital. Cases were classified according to the umbilical artery (UA) Doppler pattern as type I (positive end-diastolic flow; n = 25), type II [persistently absent or reversed end-diastolic flow (AREDF); n = 5] and type III [intermittently absent or reversed end-diastolic flow (iAREDF); n = 25]. Types II and III were then merged together as severe sIUGR cases. Subsequently, two possible approaches were considered: expectant management (EM) with elective preterm delivery in case of fetal deterioration, or in-utero therapy via fetoscopic laser photocoagulation (FLP) of intertwin anastomosis or selective umbilical cord occlusion (CO) of the growth-restricted fetus.Results: Gestational age (GA) at diagnosis was progressively lower with each type. Severe sIUGR cases delivered significantly earlier than type I, showing lower birth weights and higher intertwin biometric discordance. Unintended fetal demise occurred in 14% (6/25) of severe sIUGR pregnancies as opposed to 0% (0/19) in type I, p = .028. A significantly higher proportion of twins was admitted in NICU in severe cases when compared to type I [87% (33/38) versus 47% (18/38), p < .001]. In addition, brain damage at birth was also found to be more prevalent in this group [21% (8/38) versus 11% (4/38), p = .346], especially in the larger twin, when comparing any short-term neurological sequel [30% (7/23) versus 0% (0/19), p = .011] or specifically periventricular leukomalacia [PVL; 22% (5/23) versus 0% (0/19), p = .053]. Although the overall mortality rate was significantly higher in severe sIUGR that underwent CO instead of EM [58% (7/12) versus 11% (4/36), p = .002], NICU admissions were higher in the latter [94% (17/18) versus 40% (2/5), p = .021]. Neurological sequels at birth were similar in both groups [39% (7/18) versus 40% (2/5), p = 1.000], similarly when considering only the larger twin for any brain lesion [28% (5/18) versus 40% (2/5), p = .621] or just PVL [22% (4/18) versus 20% (1/5), p = 1.000].Conclusion: Given the good prognosis of type I sIUGR, expectant management is the first approach to consider. However, due to the poorer clinical evolution of types II and III sIUGR, the decision-making is challenging and needs to be individualized depending on the UA Doppler pattern, GA at diagnosis, severity of growth restriction and biometric discordance, technical issues and parents' preferences.

Distance Traveled to a Fetal Center and Pregnancy Outcomes in Twin-Twin Transfusion Syndrome

BACKGROUND

Fetoscopic laser photocoagulation (FLP) is the definitive treatment for twin-twin transfusion syndrome (TTTS). Due to variability in geographic proximity to high-volume fetal centers, many patients travel great distances to receive experienced care. We sought to determine whether distance traveled (DT) is associated with gestational age (GA) at delivery and neonatal survival.

METHODS

A prospective cohort study of patients within the continental United States referred to our center between September 23, 2011 and July 25, 2018 undergoing planned FLP for TTTS (n = 393; GA 20.6 ± 2.5 weeks; stage I: n = 50; stage II: n = 118; stage III: n = 208; stage IV: n = 17) was performed. The great-circle distance to our center was calculated using patients' home zip codes. DT was stratified into groups containing equal patient numbers and pregnancy outcomes assessed.

RESULTS

A total of 393 patients met the inclusion criteria. The threshold distance from our center was <250 miles (n = 181), 250-499 miles (n= 119), and ≥500 miles (n = 93). There was no significant difference between any of the preoperative variables among the three groups, with the exception of race and rural status. Furthermore, there was no significant association between DT and GA at delivery (p = 0.34), time interval from procedure to delivery (p = 0.37), and the number of neonatal survivors (p= 0.21). Preterm premature rupture of membranes (PPROM) at <34 weeks was highest (47.9%, p = 0.04) in the group traveling 250-499 miles.

CONCLUSION

To our knowledge, this is the largest study to show that in TTTS, DT is not associated with GA at delivery, time interval from procedure to delivery, or neonatal survival. Although PPROM at <34 weeks was higher in the group traveling 250-499 miles, there was no significant difference in GA at delivery. While patients with advanced disease may choose to seek treatment based on proximity, traveling long distances does not adversely affect pregnancy outcomes.

Neurological complications after therapy for fetal-fetal transfusion syndrome: a systematic review of the outcomes at 24 months

OBJECTIVE

The main objective of this study was to review the available scientific evidence about mid-term neurological outcomes in twins after laser therapy for twin-to-twin transfusion syndrome (TTTS).

METHODS

A systematic review of studies on neurodevelopmental outcomes (cognition, motor development, communication skills and cerebral palsy) of twins after laser therapy for TTTS was conducted. Outcomes at 24 months of age and the use of validated scales for assessment were the selected criteria. Electronic and manual research identified 25 studies, and nine of them were eligible for the review.

RESULTS

The global mean rate of neurological injury in twins treated with laser was 14.07%. The mean rate of cognitive impairment was 8.41%, 11.14% for motor delay, 16.5% for communication delay and 5.73% for cerebral palsy. These rates were higher than the results found in dichorionic twins, but lower than the results found in twins treated with amnio-reductions or conservative management.

CONCLUSION

Laser therapy is associated with a lower rate of neurological injury at 24 months of age compared to other therapeutic techniques. This tendency was also observed with specific incidences regarding cognition, motor skills and cerebral palsy.

Major Discordant Structural Anomalies in Monochorionic Twins: Spectrum and Outcomes

Monochorionic twins, resulting from a single fertilized egg giving rise to two separate embryos, are monozygotic and considered genetically identical. However, discordant phenotypes have been reported in monozygotic twins. We analyzed a retrospective cohort of 155 monochorionic pregnancies (312 twins) with major discordant structural anomalies coded by the ICD-10 system in order to describe the spectrum of anomalies, the management of the pregnancies, and the perinatal outcome. Treatment options included conservative management, selective feticide with bipolar cord coagulation, or complete termination. All survivors underwent at least 24 months of postnatal follow-up. Discordancy was complicated by twin-to-twin transfusion syndrome in eight pregnancies (5%) and by selective intrauterine growth restriction in 41 (26%). Major structural anomalies affected one system in 139 cases (90%) and multiple systems in 16 (10%). Median gestational age at diagnosis was 19.1 weeks (IQR 16.4-21.3). The most frequent single-system anomalies involved the nervous and circulatory systems. In total, 72 anomalous twins (46%) and 116 normal co-twins (74%) were delivered at a median gestational age of 34.6 weeks (IQR 31.0-36.3). Neonatal/infant death of the anomalous twin occurred in 22 cases (14%), with an overall survival rate of 32% (50/155). Surviving anomalous twins underwent major surgery in 22/50 cases (44%), four of whom (8%) now suffer from severe neurologic morbidity. This study shows that a wide spectrum of major discordant structural anomalies can be found in monochorionic pregnancies. The outcome for the anomalous twin is poor, while the survival rate for the normal co-twin was 71%, with a favorable overall prognosis.

Twin-to-Twin Transfusion Syndrome: A Case Report

PURPOSE

To present a case of twin-to-twin transfusion syndrome (TTTS), followed by discussion of the etiology, pathophysiology, prenatal diagnosis, management, complications, prognosis, and family considerations.

METHODS

A literature review was conducted using MEDLINE, PubMed, CINAHL, ProQuest, and Google Scholar. The search resulted in 593 articles; 25 relevant articles were chosen.

RESULTS

Approximately 1 of every 250 cases of monochorionic twins acquire TTTS. The progression of TTTS is unpredictable; nontreatment and early onset have been associated with >90 percent mortality of both twins. Neurodevelopmental impairment, preterm birth, renal hypoperfusion, growth restriction, cardiomyopathy, and hydrops fetalis have been associated with TTTS.

LIMITATIONS

A paucity of research and case reports exists, limiting recommendations for optimal diagnosis, management, and treatment regimens.

IMPLICATIONS FOR PRACTICE

TTTS is unpredictable in progression; earlier identification of chorionicity, diagnosis of TTTS, and improvement of treatment and management have the potential to improve the mortality and morbidity outcomes associated with TTTS.

Factors associated to early intrauterine fetal demise after laser for TTTS by preoperative fetal heart and Doppler ultrasound

OBJECTIVE

To determine the prognostic value of fetal Doppler and echocardiographic parameters for intrauterine fetal demise (IUFD) within 24 hours and within 1 week after laser coagulation in monochorionic pregnancies complicated by twin-twin transfusion syndrome.

METHOD

This retrospective study correlated the preoperative hemodynamic and echocardiography parameters to the outcome in fetuses with twin-twin transfusion syndrome undergoing laser therapy.

RESULTS

One hundred and twelve laser coagulations were performed between February 2006 and June 2015. The total (single and double) IUFD rate was 27.7%. Further, 59% of IUFD occurred within 24 hours and 74.4% occurred within 1 week after laser. The following were associated to IUFD within 24 hours: the middle cerebral arterial pulsatility index in the donor, abnormal umbilical artery (UA) end diastolic flow, increased middle cerebral artery peak systolic velocity, and right ventricular myocardial performance index (RV-MPI) z-score in the recipient. For IUFD within 1 week were the pulsatility index in the donor UA and the recipient abnormalities in UA, ductus venosus, middle cerebral artery-peak systolic velocity, and RV-MPI z-score.

CONCLUSION

Following laser was early IUFD that was associated with Doppler findings suggesting donor cerebroplacental redistribution, and recipient overload cardiomyopathy, such as abnormal ductus venosus and UA Dopplers as well as an increase of RV-MPI.

Differential Changes in Myocardial Performance Index and Its Time Intervals in Donors and Recipients of Twin-to-Twin Transfusion Syndrome before and after Laser Therapy

OBJECTIVE

To evaluate left myocardial performance index (MPI) and time intervals in fetuses with twin-to-twin transfusion syndrome (TTTS) before and after laser surgery.

METHODS

Fifty-one fetal pairs with TTTS and 47 uncomplicated monochorionic twin pairs were included. Left ventricular isovolumetric contraction time (ICT), ejection time (ET), and isovolumetric relaxation time (IRT) were measured using conventional Doppler.

RESULTS

Recipients showed prolonged ICT (46 ± 12 vs. 31 ± 8 vs. 30 ± 5 ms; p < 0.001) and IRT (51 ± 9 vs. 43 ± 8 vs. 43 ± 5 ms; p < 0.001) and higher MPI (0.57 ± 0.12 vs. 0.47 ± 0.09 vs. 0.44 ± 0.05; p < 0.001) than donors and controls. Donors showed shorter ET than recipients and controls (157 ± 12 vs. 169 ± 10 vs. 168 ± 10 ms; p < 0.001) and higher MPI than controls (0.47 ± 0.09 vs. 0.44 ± 0.05; p = 0.006). Preoperative MPI changes were observed in all TTTS stages. Time intervals partially improved after surgery.

CONCLUSION

Donor and recipient twins had higher MPI due to different changes in the time intervals, possibly reflecting the state of hypovolemia in the donor and hypervolemia and pressure overload in the recipient.

Fetoscopic laser photocoagulation in twin-to-twin transfusion syndrome: experience from a single institution

INTRODUCTION

Twin-to-twin transfusion syndrome (TTTS) is the most common serious complication of monochorionic (MC) twin pregnancies, with perinatal mortality rates of up to 90% if untreated. This study aimed to review the perinatal and perioperative outcomes of MC twin pregnancies treated for TTTS by fetoscopic laser photocoagulation (FLP) since its introduction at KK Women's and Children's Hospital (KKH), Singapore, in 2011.

METHODS

This was a retrospective review of five consecutive patients who underwent FLP of placental anastomoses for TTTS at KKH from June 2011 to March 2014. FLP was offered to patients who were diagnosed with TTTS of at least Quintero Stage II before 26 weeks of gestation. The main outcome measures were perioperative complications and perinatal survival rates.

RESULTS

Five sets of MC twin pregnancies underwent FLP during the study period - three pregnancies were diagnosed with Stage III TTTS and two pregnancies with Stage II TTTS. Median gestational ages at initial presentation, laser photocoagulation and delivery were 19 (range 17-20) weeks, 20 (range 19-23) weeks and 29 (range 28-34) weeks, respectively. One patient had bleeding into the amniotic cavity intraprocedurally. Overall, the perinatal survival rate, double-infant survival rate and survival rate for at least one twin were 60% (6/10 fetuses), 40% (2/5 twins) and 80% (4/5 twins), respectively.

CONCLUSION

FLP is a feasible treatment for TTTS, with minimal maternal complications. Perinatal survival rates of this patient group that was managed at our centre were comparable to those of international centres.

The Outcome of Monochorionic Diamniotic Twins Discordant at 11 to 13+6 Weeks' Gestation

BACKGROUND

Monochorionic diamniotic (MCDA) twin pregnancies are associated with adverse perinatal outcome. Intertwin discordances at the time of nuchal translucency (NT) screening may have a value in the prediction of fetal loss or twin-to-twin transfusion syndrome. We aimed to determine the ability of intertwin NT and crown rump length (CRL) discordances among MCDA twins to predict adverse outcomes.

MATERIAL AND METHODS

All MCDA twins with a documented routine ultrasound at 11 to 13+6 weeks' gestation, and known pregnancy outcome between August 2003 and August 2012 were included. Receiver operating characteristic curves were used to determine the ideal NT and CRL discordances cut-off points that maximized the ability to predict adverse outcome, which was defined as any of: death of one or both twins, twin-to-twin transfusion syndrome, or estimated fetal weight or birth weight discordances ≥25%.

RESULTS

Of the 89 cases, 20 (22.5%) had at least one adverse outcome. NT discordance was more discriminatory of adverse outcome than was CRL discordance. The optimal values for predicting any adverse outcomes for NT were >23.7% and for CRL >3.5%. The positive predictive values for NT (52.4%) and CRL (29.8%) screening were relatively low; however, the lack of either NT or CRL discordances was more reassuring, with negative predictive values of 86.8% and 86.4%, respectively.

CONCLUSIONS

NT discordance is more predictive for adverse fetal outcome in MCDA twins than CRL discordance. Neither NT nor CRL discordance are likely to modify the intensive monitoring required for these very high-risk pregnancies.

Chorioamniotic membrane separation after fetoscopy in monochorionic twin pregnancy: incidence and impact on perinatal outcome

OBJECTIVE

To evaluate the incidence of chorioamniotic membrane separation (CMS) after fetoscopy in monochorionic diamniotic (MCDA) twins and its impact on pregnancy outcome.

METHODS

The study group comprised a consecutive series of 338 women with an MCDA pregnancy complicated by twin-twin transfusion syndrome (TTTS) or selective intrauterine growth restriction (sIUGR) treated with selective laser photocoagulation of communicating vessels (SLPCV) or cord occlusion (CO). Data obtained included cervical length, gestational age at procedure, type and duration of surgery and placental location. The incidence of CMS, the rates of miscarriage and preterm prelabor rupture of membranes (PPROM), gestational age at delivery and neonatal survival were recorded.

RESULTS

Of the study population of MCDA pregnancies, 270 (79.9%) had TTTS and 68 (20.1%) had sIUGR. SLPCV was performed in 252 (74.6%) cases and CO in 86 (25.4%). Postoperative CMS was observed in 70 (20.7%) cases. Patients with CMS had higher rates of miscarriage (14.3% vs 7.1%; P = 0.049), PPROM before 32 weeks (43.3% vs 13.7%; P < 0.001) and preterm delivery before 32 weeks (53.3% vs 26.1%; P < 0.001) and a lower rate of neonatal survival of at least one twin (81.7% vs 93.6%; P = 0.003). Multivariate analysis showed that gestational age at surgery was the only independent predictor, with the highest proportion of CMS occurring in cases that underwent surgery before 18 weeks' gestation (odds ratio, 2.941 (95% CI, 1.640-5.275); P < 0.001). There was no influence of cervical length, placental location, duration of surgery or type of surgery on the risk of CMS.

CONCLUSIONS

CMS complicated one-fifth of all MCDA pregnancies that underwent fetoscopy. It appeared to be more common in those who underwent surgery before 18 weeks' gestation and was associated with poorer outcomes. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Guidelines for scanning twins and triplets with US and MRI

Multiple-fetus gestations have an increased risk of discordant anomalies, aneuploidy and growth restriction compared to singleton pregnancies. In addition, twins sharing the same placenta are at risk for developing specific conditions that are potentially amenable to surgical management. In those scenarios, patients might need to be evaluated not only with US but with fetal MRI as well. This paper outlines basic guidelines to consider when imaging complicated multiple-fetus gestations during the 2nd and 3rd trimesters.

Review of the correlation between blood flow velocity and polycythemia in the fetus, neonate and adult: appropriate diagnostic levels need to be determined for twin anemia-polycythemia sequence

Twin anemia-polycythemia sequence (TAPS) is recognized increasingly antenatally by the demonstration of an anemic twin and a polycythemic cotwin using the middle cerebral artery peak systolic velocity (MCA-PSV). While the MCA-PSV has been shown to correlate well with anemia in singleton fetuses, the evidence to support its use to diagnose fetal polycythemia appears to be less clear-cut. We aimed to evaluate fetal, neonatal and adult literature used to support the use of MCA-PSV for the diagnosis of polycythemia. Comprehensive literature searches were performed for ultrasound evidence of polycythemia in the human fetus, neonate and adult using key search terms. Only manuscripts in the English language with an abstract were considered for the review, performed in June 2014. Fifteen manuscripts were found for the human fetus, including 38 cases of TAPS. Nine of these defined fetal polycythemia as MCA-PSV < 0.8 multiples of the median (MoM), five used < 1.0 MoM and one used 0.8-1.0 MoM. Only two studies, involving a total of 15 cases, proposed a diagnostic level, acknowledging false-positive and -negative cases, though neither reported sensitivities or specificities. Six neonatal studies (96 neonates) demonstrated evidence of decreased cerebral velocities in polycythemia and a consequent increase with hemodilution. In the adult, five studies (57 polycythemic adults) demonstrated increased flow or velocity with hemodilution. Neither neonatal nor adult studies conclusively defined levels for screening for polycythemia. Despite widespread adoption of a cut-off of < 0.8 MoM in the published literature for the polycythemic fetus in TAPS, this is based upon minimal evidence, with unknown sensitivity and specificity. We recommend caution in excluding TAPS based purely upon the absence of a reduced MCA-PSV.

Monochorionic diamniotic in vitro fertilization twins have a decreased incidence of twin-to-twin transfusion syndrome

OBJECTIVE

To compare the incidence of twin-to-twin transfusion syndrome (TTTS) in spontaneous versus IVF-conceived twin pregnancies.

DESIGN

Retrospective multicenter study.

SETTING

University-affiliated tertiary medical centers.

PATIENT(S)

Women admitted for 11-14 week's scan between January 1997 and July 2013 who were diagnosed with monochorionic (MC) diamniotic twin pregnancies.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Mode of conception, TTTS.

RESULT(S)

The study cohort included 327 pregnant women with live MC diamniotic twins. Of them, 284 (86.9%) and 43 (13.1%) were spontaneous and IVF conceived, respectively. The mean maternal age was significantly higher in IVF compared with in spontaneously conceived pregnancies (33.8 ± 5.5 vs. 31.6 ± 5.4, respectively). Thirty-seven twins (11.3%) had TTTS, of whom 36/284 (12.7%) versus 1/43 (2.3%) were spontaneously and IVF conceived, respectively. The mean week of delivery was significantly lower in MC twins diagnosed with TTTS compared with those without TTTS (32.7 ± 3.3 vs. 35.5 ± 2.5, respectively). Furthermore, there was a significantly higher birthweight discordancy in twins diagnosed with TTTS compared with those without (20.6% vs. 11%, respectively).

CONCLUSION(S)

The significantly lower proportion of TTTS found in IVF-conceived twins may suggest a different embryological process that lies at the core of IVF conception of monozygotic twinning.

Anomalies of the placenta and umbilical cord in twin gestations

The frequency of twin gestations has increased over the last few decades, mainly due to maternal age at childbearing, and the use of assisted reproductive technologies. Twins are at higher risk of aneuploidy, structural anomalies, and placental abnormalities. Some of the placental and umbilical cord abnormalities found in twin gestations are nonspecific and can be found in singleton gestations (ie, placenta previa, placental abruption, single umbilical artery, velamentous cord insertion, vasa previa, etc). However, other anomalies are unique to twin gestations, and are mainly associated with monochorionic twins-these include intraplacental anastomosis and cord entanglement. Most of these conditions can be diagnosed with ultrasound. An accurate and early diagnosis is important in the management of twin gestations. Determination of chorionicity, amnionicity, and the identification of placental anomalies are key issues for the adequate management of twin pregnancies. Pathologic placental examination after delivery can help in assessing the presence of placental and umbilical cord abnormalities, as well as providing information about chorionicity and gaining insight into the potential mechanisms of disease affecting twin gestations.

Longitudinal annular displacement by M-mode (MAPSE and TAPSE) in twin-to-twin transfusion syndrome before and after laser surgery

OBJECTIVE

To evaluate mitral and tricuspid annular plane systolic excursion (MAPSE and TAPSE) in fetuses with twin-to-twin transfusion syndrome (TTTS) before and after laser therapy.

METHODS

A prospective study in 24 fetal pairs with TTTS evaluated 24 h before and within 48 h after fetoscopy and 13 gestational age-matched normal monochorionic fetal pairs. MAPSE and TAPSE were measured in an apical or basal four-chamber view by placing the M-mode cursor at the lateral valve ring.

RESULTS

Mean preoperative MAPSE (controls 3.6 ± 1.3 mm vs. donors 2.7 ± 0.8 mm vs. recipients 2.8 mm ± 0.9; P < 0.001) and TAPSE (controls 4.4 ± 1.5 mm vs. donors 3.3 ± 1 mm vs. recipients 3.6  ± 1.1 mm; P < 0.001) values were significantly reduced in both TTTS fetuses. When subdividing according to TTTS stages, changes were significant in both stage I-II and III-IV subgroups, although differences were more pronounced in the latter. All observations remained unchanged 48 h post-fetoscopy.

CONCLUSION

Both recipient and donor fetuses had decreased global longitudinal motion, even in early TTTS stages.

Cord Occlusion in Monochorionic Twins with Early Selective Intrauterine Growth Restriction and Abnormal Umbilical Artery Doppler: A Consecutive Series of 90 Cases

Objective: To describe perinatal outcomes achieved with cord occlusion (CO) in monochorionic twins with severe selective intrauterine growth restriction (sIUGR) and abnormal umbilical artery Doppler in the IUGR twin (types II and III). Methods: We studied a consecutive series of 90 cases of sIUGR with abnormal Doppler treated with CO of the IUGR fetus. Abnormal Doppler was defined as continuous (type II, n = 41) or intermittent (type III, n = 49) absent/reversed end-diastolic flow. All cases presented at least one of the following severity criteria: gestational age (GA) <22 weeks, inter-twin estimated weight discordance >35%, reversed end-diastolic umbilical artery flow or ductus venosus pulsatility index >95th centile. We prospectively recorded pregnancy course and perinatal outcome. Results: Median GA at surgery was 20.6 weeks and mean duration 22.4 min. Miscarriage (<24 weeks) occurred in 3.3% (3/90) and preterm delivery <32 weeks in 7.1% (6/84) of continuing pregnancies. GA at delivery was 36.4 weeks and neonatal survival of the larger twin was achieved in 93.3%. Conclusion: In a consecutive series studied by an experienced team, CO in monochorionic twins with severe sIUGR type II or III was associated with delivery >32 weeks in 92.9% and neonatal survival of the normal twin in 93.3% of pregnancies.