ISUOG Practice Guidelines: role of ultrasound in twin pregnancy

Evaluation of the new expert consensus-based definition of selective fetal growth restriction in monochorionic pregnancies

Objective: To compare the outcomes of a cohort of monochorionic pregnancies with selective fetal growth restriction (sFGR) diagnosed according to the International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) definition published in 2015 with a cohort considered as sFGR according to new expert consensus-based diagnostic parameters published in 2019.Methods: This was a retrospective study, conducted between January 1st 2010 and July 30th 2019. We reviewed the medical records of all the monochorionic pregnancies followed in our center including perinatal outcomes. Pregnancies complicated by fetal anomalies, infection, twin-twin transfusion syndrome, twin anaemia-polycythemia sequence and twin reversed arterial perfusion sequence were excluded. Patients were grouped according to the 2015 ISUOG definition into: normal (Group 1), sFGR (Group 2), and monochorionic pregnancies with abnormal growth that did not fulfill the full criteria for sFGR (Group 3). After the initial classifications were made, an additional group, was created, including all pregnancies reclassified as sFGR according to the 2019 expert consensus parameters (Group 4).Results: During the study period, 291 monochorionic pregnancies were followed in our center, 132 of whom were eligible for inclusion in the final analysis. The prevalence of sFGR increased from 17.4% to 26.5% after applying the expert consensus-based parameters to the study population. Compared to group 1, group 2 had higher rates of emergency cesarean, neonatal intensive care admissions, invasive and noninvasive ventilation, surfactant use, metabolic disorders and lower gestational ages at birth. In contrast, the neonatal outcomes of Groups 1 and 4 were not significantly different.Conclusion: When the 2019 consensus-based diagnostic parameters for sFGR were applied to our study population, the number of sFGR cases increased by over 50%, without any improvements in perinatal outcomes. Larger prospective studies are needed to examine the potential clinical implications of these new parameters for sFGR in monochorionic pregnancies.

Impact of different prenatal management strategies in short- and long-term outcomes in monochorionic twin pregnancies with selective intrauterine growth restriction and abnormal flow velocity waveforms in the umbilical artery Doppler: a retrospective observational study of 108 cases

OBJECTIVES

To review perinatal and neurodevelopmental outcome (NDO) following selective fetoscopic laser coagulation (SFLC), cord coagulation (CC) or expectant management of monochorionic diamniotic twin pregnancies complicated with selective intrauterine growth restriction (sIUGR) and absent or reverse end-diastolic flow (AREDF) in the umbilical arteries (UA).

DESIGN AND SETTING

Single-centre retrospective observational study.

POPULATION

108 cases of sIUGR diagnosed before 26⁺⁶  weeks' gestation with AREDF in the UA.

METHODS

Survival rate and potential risk factors were analysed. NDO was assessed using parental questionnaires.

MAIN OUTCOMES MEASURES

Survival, gestational age at delivery and NDO.

RESULTS

SFLC, CC and EM were performed in 13, 50 and 45 cases, respectively, with an overall survival of 23.1, 40 and 77.8% and intrauterine demise of the co-twin of 30.8, 10 and 6.7% respectively. Intrauterine demise of the sIUGR twin occurred in 76.9 and 17.8% following SFLC and EM, respectively. The discordance in EFW at diagnosis was higher and absent/negative a-wave in the ductus venosus (DV) was more prevalent in the surgical groups. NDO in survivors at follow up was abnormal in 0 and 18% in the smaller twin following SFLC and EM, respectively, and in 25, 24 and 21% in the larger twin following SFLC, CC and EM, respectively.

CONCLUSION

SFLC yielded a poor result. EM seems a valid option when EFW discordance is <30% and a-wave in DV is positive. Otherwise, CC should be considered to protect the AGA co-twin. The long-term outcome of both small and large twins seems unaffected by the choice in primary prenatal management strategy.

TWEETABLE ABSTRACT

In type II sIUGR in MC twins, long-term neurodevelopment is normal in over 80% of the survivors.

Post-Laser Twin Anemia Polycythemia Sequence: Diagnosis, Management, and Outcome in an International Cohort of 164 Cases

The aim of this study was to investigate the management and outcome in the post-laser twin anemia polycythemia sequence (TAPS). Data of the international TAPS Registry, collected between 2014 and 2019, were used for this study. The primary outcomes were perinatal mortality and severe neonatal morbidity. Secondary outcomes included a risk factor analysis for perinatal mortality and severe neonatal morbidity. A total of 164 post-laser TAPS pregnancies were included, of which 92% (151/164) were diagnosed antenatally and 8% (13/164) postnatally. The median number of days between laser for TTTS and detection of TAPS was 14 (IQR: 7-28, range: 1-119). Antenatal management included expectant management in 43% (62/151), intrauterine transfusion with or without partial exchange transfusion in 29% (44/151), repeated laser surgery in 15% (24/151), selective feticide in 7% (11/151), delivery in 6% (9/151), and termination of pregnancy in 1% (1/151). The median gestational age (GA) at birth was 31.7 weeks (IQR: 28.6-33.7; range: 19.0-41.3). The perinatal mortality rate was 25% (83/327) for the total group, 37% (61/164) for donors, and 14% (22/163) for recipients (p < 0.001). Severe neonatal morbidity was detected in 40% (105/263) of the cohort and was similar for donors (43%; 51/118) and recipients (37%; 54/145), p = 0.568. Independent risk factors for spontaneous perinatal mortality were antenatal TAPS Stage 4 (OR = 3.4, 95%CI 1.4-26.0, p = 0.015), TAPS donor status (OR = 4.2, 95%CI 2.1-8.3, p < 0.001), and GA at birth (OR = 0.8, 95%CI 0.7-0.9, p = 0.001). Severe neonatal morbidity was significantly associated with GA at birth (OR = 1.5, 95%CI 1.3-1.7, p < 0.001). In conclusion, post-laser TAPS most often occurs within one month after laser for TTTS, but may develop up to 17 weeks after initial surgery. Management is mostly expectant, but varies greatly, highlighting the lack of consensus on the optimal treatment and heterogeneity of the condition. Perinatal outcome is poor, particularly due to the high rate of perinatal mortality in donor twins.

Middle Cerebral Artery Doppler Velocimetry for the Diagnosis of Twin Anemia Polycythemia Sequence: A Systematic Review

Twin anemia polycythemia sequence (TAPS) is a rare complication of monochorionic diamniotic (MCDA) twins. Middle cerebral artery peak systolic velocity (MCA-PSV) measurements are used to screen for TAPS while fetal or neonatal hemoglobin levels are required for definitive diagnosis. We sought to perform a systematic review of the efficacy of MCA-PSV in diagnosing TAPS. Search criteria were developed using relevant terms to query the Pubmed, Embase, and SCOPUS electronic databases. Publications reporting diagnostic characteristics of MCA-PSV measurements (i.e., sensitivity, specificity or receiver operator curves) were included. Each article was assessed for bias using the Quality Assessment of Diagnostic Accuracy Studies II (QUADAS II) tool. Results were assessed for uniformity to determine whether meta-analysis was feasible. Data were presented in tabular form. Among publications, five met the inclusion criteria. QUADAS II analysis revealed that four of the publications were highly likely to have bias in multiple areas. Meta-analysis was precluded by non-uniformity between definitions of TAPS by MCA-PSV and neonatal or fetal hemoglobin levels. High-quality prospective studies with consistent definitions and ultrasound surveillance protocols are still required to determine the efficacy of MCA-PSV in diagnosing TAPS. Other ultrasound findings (e.g., placenta echogenicity discordance) may augment Doppler studies.

Selective Fetal Growth Restriction in Dichorionic Twin Pregnancies: Diagnosis, Natural History, and Perinatal Outcome

This study aims to evaluate the natural history, disease progression, and outcomes in dichorionic twins with selective fetal growth restriction (sFGR) according to different diagnostic criteria and time of onset. Dichorionic twins seen from the first trimester were included. sFGR was classified according to the Delphi consensus, and was compared to the outcomes of those classified by the International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) diagnostic criteria. Early sFGR occurred before 32-weeks, and late sFGR after 32-weeks. Disease progression, neonatal outcomes such as gestation at delivery, birthweight, neonatal unit (NNU) admission, and morbidities were compared. One-hundred twenty-three of 1053 dichorionic twins had sFGR, where 8.4% were classified as early sFGR, and 3.3% were late sFGR. Disease progression was seen in 36%, with a longer progression time (5 vs. 1 week) and higher progression rate (40% vs. 26%) in early sFGR. Perinatal death was significantly higher in the sFGR than the non-sFGR group (24 vs. 16 per 1000 births, p = 0.018), and those with early sFGR had more NNU admissions than late sFGR (p = 0.005). The ISUOG diagnostic criteria yielded a higher number of sFGR than the Delphi criteria, but similar outcomes. sFGR have worse perinatal outcomes, with early onset being more prevalent. Use of the Delphi diagnostic criteria can reduce over-diagnosis of sFGR and avoid unnecessary intervention.

Neonatal hair profiling reveals a metabolic phenotype of monochorionic twins with selective intrauterine growth restriction and abnormal umbilical artery flow

BACKGROUND

Selective intrauterine fetal growth restriction (sIUGR) in monochorionic diamniotic twins, especially types 2&3 with abnormal umbilical artery Doppler, results in increased risk of fetal/perinatal mortality and postnatal disability. We investigate whether the hair metabolome profiles of neonates were associated with the pathophysiological differences across the different clinical forms of sIUGR in twins.

METHODS

Hair samples were collected at delivery from 10 pairs of type 1 sIUGR twins, 8 pairs of types 2&3 sIUGR twins, and 11 pairs of twins without sIUGR. The hair metabolome was characterized using gas chromatography-mass spectrometry.

RESULTS

Our results demonstrated that the hair metabolite profiles of the different sIUGR subclinical forms were associated with the averaged fetal growth rate after 28 weeks of gestation but not with birthweight. The hair profiles were capable of discriminating type2&3 sIUGR twins from twins without sIUGR. In particular, the metabolites 2-aminobutyric acid, cysteine, alanine, and tyrosine all displayed areas under the receiver operating characteristic curve were above 0.9. The metabolic pathway analysis highlighted the associations of sIUGR twins with abnormal umbilical artery flow with increased metabolites from a nutrient depletion pathway, glutathione metabolism, and nerve development.

CONCLUSION

This study offers novel insight into the severity of intrauterine ischemia and hypoxia for T2&3 sIUGR twins, through evaluation of the neonatal hair metabolome.

Early- and late-onset selective fetal growth restriction in monochorionic diamniotic twin pregnancy: natural history and diagnostic criteria

OBJECTIVES

To evaluate the natural history and outcome of selective fetal growth restriction (sFGR) in monochorionic diamniotic (MCDA) twin pregnancy, according to gestational age at onset and various reported diagnostic criteria, and to quantify the risk of superimposed twin-to-twin transfusion syndrome (TTTS).

METHODS

This was a cohort study of MCDA twin pregnancies that had their routine antenatal care from the first trimester at St George's Hospital, London, UK. Pregnancies had ultrasound examinations every 2 weeks at 16-24 weeks and then every 2-3 weeks until delivery. The diagnostic criteria for sFGR were estimated fetal weight (EFW) of one twin < 10^th centile and intertwin EFW discordance ≥ 25%. We also applied other diagnostic criteria reported in a recent Delphi consensus. Pregnancies in which the diagnosis of TTTS was made before that of sFGR were not included in the analysis. Pregnancies that underwent fetal intervention for sFGR were excluded. The incidence of sFGR was compared between the different diagnostic criteria, overall and according to gestational age at onset. In all subsequent analyses, cases of sFGR included those diagnosed according to any of the criteria. The Gratacós classification of sFGR was applied (Type I, II or III). Pregnancy outcomes included miscarriage, intrauterine death, neonatal death and admission to the neonatal unit. Comparisons between groups were carried out using the Mann-Whitney U-test for continuous variables and the chi-square or Fisher's exact test for categorical variables.

RESULTS

The analysis included 287 MCDA twin pregnancies. According to the International Society of Ultrasound in Obstetrics and Gynecology diagnostic criteria, the incidence of early (< 24 weeks) sFGR was 4.9%, while that of late sFGR was 3.8%. When applying the various diagnostic criteria, the incidence of early sFGR varied from 1.7% to 9.1% and that of late sFGR varied from 1.1% to 5.9%. In early-onset cases, the incidence of Type I sFGR was 80.8%, that of Type II was 15.4% and that of Type III was 3.8%. The corresponding figures in late-onset cases were 94.4%, 5.6% and 0%. The incidence of superimposed TTTS was 26.9% in cases affected by early-onset sFGR and 5.6% in those affected by late-onset sFGR. The incidence of perinatal death was 8.0% in early-onset sFGR and 5.6% in late-onset sFGR (P = 0.661). Admission to the neonatal unit occurred in 61.0% and 52.9% of cases, respectively (P = 0.484).

CONCLUSIONS

In MCDA twin pregnancies, early-onset sFGR is slightly more common than is late-onset sFGR, although this difference was not significant, and is associated with worse perinatal outcome. The incidence of Types II and III sFGR is higher in early-onset sFGR. The incidence also varies according to the diagnostic criteria used, which supports the use of standardized international diagnostic criteria. Superimposed TTTS is more common in early- than in late-onset sFGR. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Cerebral oxygenation reflects fetal development in preterm monochorionic and dichorionic twins

BACKGROUND

Cerebral oxygenation (crSO₂) monitoring is increasingly used in high-risk infants. Monochorionic twins suffer from specific fetal pathologies that can affect cerebral hemodynamics. Limited data are available on crSO₂ and blood flow patterns in this population after birth.

OBJECTIVE

To evaluate crSO₂ changes in preterm monochorionic and dichorionic twins during the first 72 h of life.

METHODS

Near-infrared spectroscopy was used to measure crSO₂ in 62 infants from 31 twin pregnancies <32 weeks of gestation. The study group was divided into 4 subgroups: donor (1) and recipient (2) monochorionic twins (with twin-twin transfusion syndrome), fetal growth restriction (FGR) infants (3) and twins without fetal compromise (4).

RESULTS

There was significant difference in birth weight (p < 0.001) among 4 subgroups. We observed significant variation in crSO₂ among the subgroups using mixed model analysis (p < 0.001). The recipient twins exhibited the lowest crSO₂ (mean ± SE) throughout the study period (76 ± 0.3%), whereas the FGR and donor twins presented with the highest values (86 ± 0.3% and 83 ± 0.4% respectively). We found no statistically significant differences in neonatal mortality and morbidity among subgroups.

CONCLUSION

Our study revealed significant correlation between crSO₂ values postnatally and underlying fetal pathology in monochorionic and dichorionic preterm twins.

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.

The impact of assisted reproductive technology on prenatally diagnosed fetal growth restriction in dichorionic twin pregnancies

OBJECTIVE

Whether the use of assisted reproductive technologies (ART) affects the outcome of twin pregnancies is still a matter of debate. Previous studies have evaluated the association between birth weight and ART, without a clear distinction between fetal growth restriction (FGR), a condition at higher risk of adverse outcome, and constitutionally small for gestational age (SGA) fetuses. The aim of this study was to determine whether dichorionic (DC) twin pregnancies obtained by ART have a greater risk of developing FGR, defined by accurate ultrasound criteria, than those spontaneously conceived (SC), and to compare the severity of ultrasound features in the growth restricted fetuses.

METHODS

A retrospective study was conducted on DC twin pregnancies delivered between 2010 to 2018 at a tertiary hospital. Twin pregnancies conceived spontaneously were compared with those obtained via in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI), after exclusion of cases with major fetal or uterine malformations. The primary outcome was the incidence of FGR. Secondary outcome was the rate of SGA neonates, defined by a birth weight less than the 10th percentile. The ultrasound characteristics of the growth restricted fetuses in the two groups were also compared. The groups were compared using univariate and multivariate analyses.

RESULTS

Six hundred and seventy-eight DC twin pregnancies were identified. Of these, 367 (54.1%) conceived via IVF/ICSI and 311 (45.9%) conceived spontaneously. The incidence of FGR was not significantly different between the ART and the SC groups (7.9% vs 8.4% respectively, p = 0.76, adjusted OR 0.84, 95% CI 0.53-1.32). Growth restricted fetuses of the two groups showed similar occurrence of an estimated fetal weight less than the 3rd percentile, similar abnormalities in Doppler studies and similar gestational age at diagnosis. There was no difference in the incidence of delivery of an SGA neonate (p = 0.47) or in the rate of maternal complications and preterm delivery between the groups.

CONCLUSIONS

Twin pregnancies conceived by assisted reproductive technologies do not have a higher risk of ultrasound-diagnosed FGR than spontaneously conceived twin pregnancies, and fetuses diagnosed with growth restriction in the two groups show similar severity of the ultrasound findings.

Monochorionic diamniotic twins: What do I tell the prospective parents?

Monochorionic diamniotic twins occur in about 1 in 300 pregnancies. Compared with dichorionic twins, they face increased risks because of the shared circulation. In about 15%, an imbalance in blood exchange occurs, such as twin-twin transfusion syndrome and twin anemia polycythemia sequence. In this review, we summarize the latest evidence on the management of monochorionic diamniotic twin pregnancies and their specific complications, with a focus on information that is relevant for prospective parents.

Perinatal outcomes of twin pregnancies affected by early twin-twin transfusion syndrome: A systematic review and meta-analysis

INTRODUCTION

Twin-to-twin transfusion syndrome (TTTS) is associated with a high risk of perinatal mortality and morbidity if not treated. However, the optimal timing and management in case of early (occurring < 18 weeks) TTTS has not been established yet.

MATERIAL AND METHODS

This is a systematic review and meta-analysis aiming at evaluating the outcomes of monochorionic diamniotic twin pregnancies complicated by early (ie before 18 weeks) TTTS according to different management options (expectant, laser therapy, amnioreduction or cord occlusion). The primary outcome was mortality, including single and double intrauterine, neonatal and perinatal death. Secondary outcomes were: composite morbidity, neuromorbidity, respiratory distress syndrome, admission to neonatal intensive care unit, intact survival (defined as survival free from neurological complications) and preterm birth < 32 weeks of gestation. All outcomes were reviewed according to the different management options (expectant, laser therapy, amnioreduction or cord occlusion) and reported FOR the overall population of twins, and for the donor and recipient separately. Subgroup analysis for TTTS occurring before 16 weeks of gestation was performed. Random-effect meta-analyses of proportions were used to analyse the data.

RESULTS

Thirteen studies were included. Early TTTS occurred in 14.3% (95% confidence interval [CI] 11.9-17.0) of cases. The incidence of intrauterine death was 19.0% (95% CI 2.6-45.5) in twins managed expectantly, 32.4% (95% CI 16.5-50.7) in those who received laser treatment and 12.5% (95% CI 4.8-23.0) in those treated with amnioreduction. The incidence of neonatal death was 22.6% (95% CI 4.2-49.8) in twins managed expectantly, 24.7% (95% CI 0.5-80.3) in those who received laser and 20.2 (95% CI 5.8-43.4) in those who had amnioreduction; it was not possible to compute the incidence of these outcomes in twins undergoing cord occlusion because of insufficient sample and lack of reporting of most of the observed outcomes. Overall, the incidence of perinatal death was 43.9% (95% CI 5.9-87.7) in twins managed expectantly, 47.3% (95% CI 21.4-70.0) in those treated with laser and 28.5% in those who had amnioreduction.

CONCLUSIONS

Twin pregnancies affected by early TTTS are at substantial risk of perinatal mortality and morbidity; however, the data come from very small studies with a high risk of selection bias.

Association between impedance to blood flow in umbilical arteries and infant survival in twin-to-twin transfusion syndrome

OBJECTIVE

To evaluate infant survival according to the Doppler pattern of impedance to blood flow in the umbilical arteries (UAs) prior to laser surgery, in pregnancies with twin-to-twin transfusion syndrome (TTTS).

METHODS

This was a retrospective study of women with a monochorionic diamniotic twin pregnancy who underwent laser surgery for TTTS between January 2012 and May 2018 at a single institution. Absolute intertwin difference in UA pulsatility index (DUAPI) was measured within 48 h prior to laser surgery. Twins with intermittent or persistent absent/reversed end-diastolic flow (EDF) in the UA (UA-EDF) were analyzed separately. Survival of both or at least one infant at birth and at 30 days postpartum was compared between pregnancies with an intertwin DUAPI of ≥ 0.4 and those with an intertwin DUAPI of < 0.4, as well as between fetuses with intermittent and those with persistent absent/reversed UA-EDF. Parametric and non-parametric tests were used for analysis. Regression analysis was performed to determine if intertwin DUAPI and intermittent or persistent absent/reversed UA-EDF were associated independently with infant survival, while controlling for gestational age at delivery, Quintero stage and other important confounding variables.

RESULTS

Of 231 TTTS pregnancies that underwent laser surgery during the study period, UA Doppler information could be retrieved for 206 and delivery information was available for 184, which comprised the study population. Rates of double-twin survival at birth were significantly higher in pregnancies with an intertwin DUAPI of < 0.4 than in those with an intertwin DUAPI of ≥ 0.4 (83.9% (78/93) vs 50.0% (12/24); P < 0.001). Double-infant survival at birth was higher in pregnancies with intermittent compared to those with persistent absent/reversed UA-EDF (73.0% (27/37) vs 36.7% (11/30); P = 0.003). Regression analysis demonstrated that an intertwin DUAPI of < 0.4 was associated with increased survival of both twins at delivery (P < 0.001) and at 30 days postpartum (P = 0.002), as well as increased survival of at least one twin at delivery (P = 0.009). Similarly, intermittent absent/reversed UA-EDF was associated with increased survival of both twins at delivery (P = 0.007) and at 30 days after birth (P = 0.015).

CONCLUSIONS

Evaluation of intertwin differences in UA impedance to blood flow as well as identification of intermittent or persistent absent or reversed UA-EDF prior to laser surgery could help in the prediction of double-infant survival at birth and to 30 days in twin pregnancies with TTTS. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Short- and long-term outcomes of preterm spontaneous twin anemia-polycythemia sequence

Background In monochorionic twin pregnancy, placental anastomosis and inter-twin blood transfusion can result in specific complications, such as twin-twin transfusion syndrome (TTTS) and twin anemia-polycythemia sequence (TAPS). It is well established that adverse outcomes are increased in TTTS, but reports on the neonatal and long-term outcomes of TAPS are lacking. The objective of this study was to evaluate the neonatal and neurodevelopmental outcomes in spontaneous TAPS. Methods The study population consisted of monochorionic twin pregnancies with preterm birth (24-37 weeks of gestation) between November 2003 and December 2016 and in which cord blood was taken at the time of delivery. According to the result of hemoglobin in cord blood, the study population was divided into two groups: a spontaneous TAPS group and a control group. Neonatal and neurodevelopmental outcomes were compared between the two groups. Results During the study period, 11 cases were diagnosed as spontaneous TAPS (6.4%). The TAPS group had lower gestational age at delivery and had a higher risk for cesarean delivery. However, neonates with TAPS were not at an increased risk for neonatal mortality and significant neonatal morbidity. In addition, the frequency of severe cerebral lesion during the neonatal period and the risk of cerebral palsy at 2 years of age were not different between the two groups. Conclusion The spontaneous TAPS diagnosed by postnatal diagnostic criteria was not associated with the increased risk of adverse neonatal and neurodevelopmental outcomes. Further studies are needed to evaluate the morbidity of antenatally diagnosed TAPS.

Outcome of twin-to-twin transfusion syndrome in monochorionic monoamniotic twin pregnancy: systematic review and meta-analysis

OBJECTIVES

To explore the outcome of monochorionic monoamniotic (MCMA) twin pregnancies affected by twin-to-twin transfusion syndrome (TTTS).

METHODS

MEDLINE and EMBASE databases were searched for studies reporting the outcome of MCMA twin pregnancies complicated by TTTS. The primary outcome was intrauterine death (IUD); secondary outcomes were miscarriage, single IUD, double IUD, neonatal death (NND), perinatal death (PND), survival of at least one twin, survival of both twins and preterm birth (PTB) before 32 weeks' gestation. Outcomes were assessed in MCMA twins affected by TTTS not undergoing intervention and in those treated with amniodrainage, laser therapy or cord occlusion. Subgroup analysis was performed including cases diagnosed before 24 weeks. Random-effects meta-analysis of proportions was used to analyze the data.

RESULTS

Fifteen cohort studies, including 888 MCMA twin pregnancies, of which 44 were affected by TTTS, were included in the review. There was no randomized trial comparing the different management options in MCMA twin pregnancies complicated by TTTS. In cases not undergoing intervention, miscarriage occurred in 11.0% of fetuses, while the incidence of IUD, NND and PND was 25.2%, 12.2% and 31.2%, respectively. PTB complicated 50.5% of these pregnancies. In cases treated by laser surgery, the incidence of miscarriage, IUD, NND and PND was 19.6%, 27.4%, 7.4% and 35.9%, respectively, and the incidence of PTB before 32 weeks' gestation was 64.9%. In cases treated with amniodrainage, the incidence of IUD, NND and PND was 31.3%, 13.5% and 45.7% respectively, and PTB complicated 76.2% of these pregnancies. Analysis of cases undergoing cord occlusion was affected by the very small number of included cases. Miscarriage occurred in 19.2%, while there was no case of IUD or NND of the surviving twin. PTB before 32 weeks occurred in 50.0% of these cases.

CONCLUSIONS

MCMA twin pregnancies complicated by TTTS are at high risk of perinatal mortality and PTB. Further studies are needed in order to elucidate the optimal type of prenatal treatment in these pregnancies. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Whole genome miRNA profiling revealed miR-199a as potential placental pathogenesis of selective fetal growth restriction in monochorionic twin pregnancies

INTRODUCTION

Placental-related mechanism of fetal growth restriction (FGR) is still unknown. Here we aimed to profile whole-genome miRNA between selective FGR twin (sFGR-T) and normally larger co-twin (sL-T) in monochorionic (MC) twin pregnancies and to further investigate effect of the miRNA on placental pathogenesis, including angiogenesis and mitochondrial functions.

METHODS

MC twin pregnancies with or without sFGR were recruited, and their placental miRNAs were profiled (n = 3 vs 5). Ratio of placental miRNAs in the sFGR twin pairs (sFGR-T/sL-T) were calculated and compared to that in the control twin pairs (cS-T/cL-T). Differentially expressed miRNAs and associated markers were validated qRT-PCR, immunohistochemistry staining (n = 8 vs 13) and electron microscopy (n = 3 vs 3).

RESULTS

Placental miR-199a-5p was significantly upregulated in sFGR-T (p = 0.004), which was validated by qRT-PCR (1.03 vs 0.56; p = 0.020). Compared to control twin pairs, ratio of CD31-positive vessels and volume density of vessels in sFGR twin pairs was lower (0.65 vs 0.92 and 18.7% vs 36.3%; both p < 0.001), while that of cyclooxygenase 2 (COX2)-positive trophoblast cells was higher (3.50 vs 2.22; p = 0.001), indicating an impaired angiogenesis and oxidative stress in the sFGR placenta. In addition, ratio of mitochondrial DNA (mtDNA) mitochondrial encoded NADH dehydrogenase 1 (MTND1) copy numbers (2.10 vs 0.90; p = 0.013), H-score ratios of mitochondrial markers citrate synthase (CS) and cytochrome c oxidase subunit 4 isoform 1 (COX4, 0.53 vs 0.95, p < 0.001; 0.29 vs 1.06, p < 0.001) in trophoblast cells of sFGR twin pairs were also altered significantly and correlated with angiogenesis. Furthermore, ratio of mitochondrial numbers per trophoblasts (8.67 vs 18.67; p = 0.006) and percentage of swollen mitochondria (84.33 vs 11.33; p = 0.003) were converted significantly, indicating mitochondrial damage.

DISCUSSION

Our results suggested miR-199a-5p may play a role in the placental angiogenesis, oxidative stress and mitochondrial damage and dysfunction as an underlying pathogenesis of sFGR.

A systematic scoping review of clinical indications for induction of labour

BACKGROUND

The proportion of women undergoing induction of labour (IOL) has risen in recent decades, with significant variation within countries and between hospitals. The aim of this study was to review research supporting indications for IOL and determine which indications are supported by evidence and where knowledge gaps exist.

METHODS

A systematic scoping review of quantitative studies of common indications for IOL. For each indication, we included systematic reviews/meta-analyses, randomised controlled trials (RCTs), cohort studies and case control studies that compared maternal and neonatal outcomes for different modes or timing of birth. Studies were identified via the databases PubMed, Maternity and Infant Care, CINAHL, EMBASE, and ClinicalTrials.gov from between April 2008 and November 2019, and also from reference lists of included studies. We identified 2554 abstracts and reviewed 300 full text articles. The quality of included studies was assessed using the RoB 2.0, the ROBINS-I and the ROBIN tool.

RESULTS

68 studies were included which related to post-term pregnancy (15), hypertension/pre-eclampsia (15), diabetes (9), prelabour rupture of membranes (5), twin pregnancy (5), suspected fetal compromise (4), maternal elevated body mass index (BMI) (4), intrahepatic cholestasis of pregnancy (3), suspected macrosomia (3), fetal gastroschisis (2), maternal age (2), and maternal cardiac disease (1). Available evidence supports IOL for women with post-term pregnancy, although the evidence is weak regarding the timing (41 versus 42 weeks), and for women with hypertension/preeclampsia in terms of improved maternal outcomes. For women with preterm premature rupture of membranes (24-37 weeks), high-quality evidence supports expectant management rather than IOL/early birth. Evidence is weakly supportive for IOL in women with term rupture of membranes. For all other indications, there were conflicting findings and/or insufficient power to provide definitive evidence.

CONCLUSIONS

While for some indications, IOL is clearly recommended, a number of common indications for IOL do not have strong supporting evidence. Overall, few RCTs have evaluated the various indications for IOL. For conditions where clinical equipoise regarding timing of birth may still exist, such as suspected macrosomia and elevated BMI, researchers and funding agencies should prioritise studies of sufficient power that can provide quality evidence to guide care in these situations.

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.

Maternal Utero-Placental Perfusion Discordance in Monochorionic-Diamniotic Twin Pregnancies with Selective Growth Restriction Assessed by Three-Dimensional Power Doppler Ultrasound

Background

The aim of this study was to assess the correlation between selective growth restriction (sGR) and co-twin utero-placental perfusion discordance by using three-dimensional power Doppler (3DPD).

Material/Methods

We prospectively recruited 60 sGR and 64 normal monochorionic-diamniotic (MCDA) twin pregnancies. Vascularization index (VI), flow index (FI), and vascularization flow index (VFI) were assessed by 3DPD, while umbilical artery pulsatility index (UA-PI), middle cerebral artery peak systolic velocity (MCA-PSV), pulsatility index (MCA-PI), and cerebroplacental ratio (CPR) were assessed by conventional Doppler imaging.

Results

In sGR co-twins, the VI, FI, VFI, MCA-PI, and CPR were significantly lower, while the UA-PI and MCA-PSV were significantly greater, in the smaller fetuses compared with the larger fetuses; significant differences were also observed in the VI, FI, VFI, CPR, and UA-PI in normal co-twins. Compared with the appropriately grown twins, the discordances of the VI, FI, VFI, UA-PI, MCA-PI, and CPR were increased in the sGR cohort. The discordances of the VI, FI, VFI, UA-PI, MCA-PI, and CPR were associated with birthweight discordance, and the FI discordance and CPR discordance were independently associated with sGR. The combination of the FI and CPR discordance showed a higher predictive accuracy for sGR, with an area under the ROC curve of 0.813, and a sensitivity and specificity of 68.33% and 85.94%, respectively.

Conclusions

MCDA twin pregnancies with birthweight discordance presented utero-placental perfusion deterioration assessed by 3DPD prior to sGR diagnosis. Co-twin utero-placental perfusion discordance was significantly correlated with growth discordance, and this correlation was more predictive of sGR when 3DPD was combined with conventional Doppler imaging.

Is computerized cardiotocography useful in monochorionic twins with selective intrauterine growth restriction?

Objective: To assess the value of using computerized cardiotocography (cCTG) short-term variation (STV) for intrapartum monitoring in monochorionic twins (MC) complicated by selective intrauterine growth restriction (sIUGR).Material and methods: All available cCTGs retrieved from computerized medical records of MC with sIUGR were retrospectively studied regarding the behavior of the STV. sIUGR was defined as intertwin estimated fetal weight (EFW) discordance of ≥20% with the abdominal circumference (AC) below the fifth percentile and/or the EFW of the smaller twin below the 10th percentile. The sIUGR classification system proposed by Gratacos et al. was used using types I-III on the basis of umbilical artery Doppler characteristics of the IUGR twin. The admission (entry) STV and final pre-delivery (last) STV values were analyzed. Cases with intrauterine demise, with structural or chromosomal abnormalities, with twin anemia polycythemia sequence (TAPS) and/or twin-to-twin transfusion syndrome (TTTS) were excluded.Results: During the study period, 64 consecutive cases were managed within our department. Thirty-two cases fulfilled the inclusion criteria for analysis. Mean gestational age at assessment and at delivery was 28.4 ± 2.7 and 31.5 ± 2.2 weeks, respectively. The entry STV and last STV before delivery were not statistically different (mean IUGR STV entry: 9.3 ± 3.4 ms versus last 8 ± 2.2 ms; p = .051; mean co-twin STV entry: 9.1 ± 2.8 ms versus last 9.2 ± 3 ms; p = .87). Neither was the sIUGR-type adjusted STV.Conclusions: In MC pregnancies complicated by sIUGR, the cCTG STV does not distinguish between fetuses, nor does it show differences in cases of fetal deterioration monitored by conventional CTG.

Updated guidance for the management of twin and triplet pregnancies from the National Institute for Health and Care Excellence guidance, UK: What's new that may improve perinatal outcomes?

In September 2019, NICE published updated guidance on the management of multiple pregnancy (NG 137). Many of the previous recommendations for care are upheld but there have been important changes: increased frequency of combined ultrasound/specialist antenatal care appointments for pregnancies containing a monochorionic placenta (twins and triplets), increased frequency of ultrasound monitoring in all triplet pregnancies, changes in the definition of selective growth restriction and its subsequent referral pathways, the introduction of some monitoring for twin (or triplet) anemia polycythemia sequence in monochorionic pregnancies (albeit in complex pregnancies or at an advanced stage), and a recommended timing of birth for any pregnancy with monoamniotic fetuses. New recommendations have been made for mode of delivery, fetal monitoring in labor, maternal analgesia, and the prevention of postpartum hemorrhage. The absence of any recommendation relating to the prevention of preterm birth is notable. The basis and implications of the updates that may improve perinatal outcomes are discussed.

Longitudinal Doppler references for monochorionic twins and comparison with singletons

OBJECTIVES

To construct monochorionic (MC) twin-specific longitudinal Doppler references for umbilical artery pulsatility index (UA-PI), middle cerebral artery (MCA) PI and peak systolic velocity (PSV) and ductus venosus (DV) PI derived from a strictly selected cohort of uncomplicated MC twins. The secondary aim of the study was to compare our findings with singleton reference charts.

METHODS

A retrospective evaluation was made of all consecutive uncomplicated MC twin pregnancies referred to our Unit from 2010 to 2018. Fortnightly serial examinations were performed of UA-PI, MCA-PI, MCA-PSV and DV-PI, according with the clinical protocol, from 20 to 37 weeks of gestation. We included cases with at least four ultrasound examinations, delivery at our hospital and complete neonatal follow up. A two-step method was used to trace the estimated centile curves: estimation of the median was performed with appropriate fractional polynomials by a multilevel model and estimation of the external centiles through the residuals (quantile regression). The comparison with singletons was made by plotting the references derived from the present study on the referred charts commonly used for singletons.

RESULTS

The study group comprised 150 uncomplicated MC twin pairs. Estimated centiles (3rd, 5th, 10th, 50th, 90th, 95th, 97th) of UA-PI, MCA-PI, MCA-PSV and DV-PI in function of the gestational age are presented. The comparison with singletons showed substantial differences, with higher UA-PI and lower MCA-PI and PSV median values in MC twins. Median DV PI values were similar to the values for singletons, while the upper centiles were higher in MC twins.

CONCLUSIONS

This study sets out MC twin-specific longitudinal references for UA-PI, MCA-PI, MCA-PSV and DV-PI derived from the largest series of uncomplicated MC twin pregnancies presently available. The comparison with singleton reference values underscores the deviation from physiology that is intrinsic to these unique pregnancies and supports the need for MC twin-specific charts.

Gestational age, morbidity and mortality among twin births in New South Wales, Australia 2003-2014: A cohort study

BACKGROUND

Evidence suggests that the trend toward early planned births observed among singletons may be evident among twin pregnancies.

AIMS

To describe trends in gestational age at birth, pregnancy characteristics, neonatal morbidity and mortality among twin pregnancies.

MATERIALS AND METHODS

Population-based data linkage study of twin births of ≥30 weeks of gestation without a major congenital anomaly born in 2003-2014 in New South Wales (NSW), Australia. Linked pregnancy and birth, hospital and mortality data were used. Generalised linear regression was used to assess linear trends. Risk difference (RD) and 95% confidence intervals were estimated.

RESULTS

Among 28 076 eligible twin births (14 038 pregnancies), 49% of births occurred prior to 37 weeks and 69% of births were planned (pre-labour caesarean or induction of labour). There were increases over time in the proportion of twin births at preterm gestations (30-34 weeks (RD 2.1, 95% CI 0.1, 4.0), 35-36 weeks (RD 7.5, 95% CI 5.4, 9.7)) and in the rates of planned births (pre-labour caesarean (RD 6.4, 95% CI 4.0, 8.8), induction (RD 4.6, 95% CI 2.6, 6.6)). There was no significant change in stillbirth or neonatal death rates, but there was an increase in neonatal morbidity over the study period. Concurrently, there were increases in the prevalence of gestational diabetes; and decreases in pregnancy hypertension, assisted reproductive technology use, small-for-gestational age and birthweight discordance.

CONCLUSIONS

Gestational age at birth among twin births is decreasing and birth intervention is increasing. There are increasing rates of neonatal morbidity, but no overall change in perinatal mortality.

New reference values for biometrical measurements and sonographic estimated fetal weight in twin gestations and comparison to previous normograms

Objective To construct new reference values for biometrical measurements and sonographic estimated fetal weight (sEFW) in twin gestations and compare them to previously published normograms. Methods A retrospective analysis of sEFW evaluations of twin gestations was performed between 2011 and 2016 in a single university-affiliated medical center. sEFW was calculated using the Hadlock 1985 formula. To avoid selection bias, one evaluation per pregnancy was randomly selected. Following mathematical transformation to obtain normality of values, normograms were constructed using a best-fit regression model for estimation of mean and standard deviation at each gestational age (GA). Normograms were validated by applying all observations to ensure equal distribution at parallel percentiles. Our normograms were then compared to previously published sEFW normograms for twin gestations. Results A total of 864 sEFW evaluations were performed on 195 twin pregnancies at 22-39 gestational weeks. Of them, 390 entered the primary analysis. The rest were left for validation. Seventy percent of the cohort were dichorionic-diamniotic twins (136/195), 16% (32/195) were monochorionic-diamniotic twins and three (1.5%) were monochorionic-monoamniotic twins. Twenty-four fetuses lacked data on chorionicity. The rest were monochorionic twins or were of unknown chorionicity. Values corresponding to the 2.5th, 10th, 50th, 90th and 97.5th percentiles for sEFW are presented for every GA. Validation by applying all 864 evaluations on constructed normograms was achieved. Comparison to previously published twins' sEFW normograms demonstrated wide variation between curves. Conclusion New reference values for biometrical measurements and sEFW in twin gestations are presented for clinical and research use. Comparison to other curves demonstrates the wide variability and need for further investigation on twin's normal growth.

How far is too far? A nationwide cross-sectional study for establishing optimal hospital access time for Korean pregnant women

OBJECTIVES

Access to a delivery unit is a major factor in determining maternal morbidity and mortality. However, there is little information about the optimal access time to a delivery unit. This study aimed to establish the optimal hospital access time (OHAT) for pregnant women in South Korea.

DESIGN

Nationwide cross-sectional study.

SETTING

We used the National Health Insurance System database of South Korea.

PARTICIPANTS

We analysed the data of 371 341 women who had experienced pregnancy in 2013.

PRIMARY AND SECONDARY OUTCOME MEASURES

Access time to hospital was defined as the time required to travel from the patient's home to the delivery unit. The incidence of obstetric complications was plotted against the access time to hospital. Change-point analysis was performed to identify the OHAT by determining a point wherein the incidence of obstetric complications changed significantly. As a final step, the risk of obstetric complications was compared by type among pregnant women who lived within the OHAT against those who lived outside the OHAT.

RESULTS

The OHAT associated with each adverse pregnancy outcomes were as follows: inadequate prenatal care, 41-50 min; preeclampsia, 51-60 min; placental abruption, 51-60 min; preterm delivery, 31-40 min; postpartum transfusion, 31-40 min; uterine artery embolisation, 31-40 min; admission to intensive care unit, 31-40 min; and caesarean hysterectomy, 31-40 min. Pregnant women who lived outside the OHAT had significantly higher risk for obstetric complications than those who lived within the OHAT.

CONCLUSIONS

Our results showed that the OHAT for each obstetric complication ranged between 31 and 60 min. The Korean government should take the OHAT under consideration when establishing interventions for pregnant women who live outside OHAT to reduce maternal morbidity and mortality.

Complex multigestational anomalies

The increase in multiple gestation pregnancies has resulted in significant health care implications for both mother and child. Our ability to diagnose and intervene on an at-risk multi-gestation pregnancy has dramatically improved. It is important for the pediatric surgeon to be equipped with a basic fund of knowledge concerning these pregnancies. An understanding of amnionicity and chorionicity will equip the practitioner with the ability to identify which pregnancies are at risk for specific complications. This article highlights multi-gestation pregnancies that are monochorionic (single shared placenta) and can be complicated by twin-twin transfusion syndrome (TTTS), twin reversed arterial perfusion (TRAP) sequence, twin anemia polycythemia sequence (TAPS), or selective fetal intrauterine growth restriction (sIUGR). The risk of fetal demise is significant in these pregnancies. Understanding recommended surveillance and warning signs can alert surgeons to developing complications. Specialized fetal care centers possess the ability to intervene on these pregnancies in utero.

Dispelling Myths about Antenatal TAPS: A Call for Action for Routine MCA-PSV Doppler Screening in the United States

In the United States, routine middle cerebral artery peak systolic velocity (MCA-PSV) Doppler screening for the detection of antenatal twin anemia-polycythemia sequence (TAPS) is not recommended. The current and only national clinical guideline from the highly-influential Society for Maternal-Fetal Medicine states that, “There is no evidence that monitoring for TAPS with MCA PSV Doppler at any time, including > 26 weeks, improves outcomes, so that this additional screening cannot be recommended at this time.” We argue this recommendation has disproportionate influence on patients and the care they are offered and receive. We use current evidence to highlight and dispel pervasive myths surrounding antenatal TAPS and the value of routine MCA-PSV screening. An ethical framework that illustrates the importance of giving patients the opportunity for routine screening is presented. Findings demonstrate that: (1) both spontaneous and post-laser TAPS is a serious, potentially life-threatening complication, (2) treatment for TAPS is effective and includes expectant management, intrauterine transfusion (IUT), or surgery, (3) and routine MCA-PSV, which has satisfactory diagnostic accuracy, is currently the only way to provide early detection of TAPS. We conclude that routine TAPS screening is a medically proven valuable resource that should be offered to patients in need and to the clinicians who are trying to act toward their benefit.

Indications for, and timing of, planned caesarean section: A systematic analysis of clinical guidelines

BACKGROUND

There has been a worldwide rise in planned caesarean sections over recent decades, with significant variations in practice between hospitals and countries. Guidelines are known to influence clinical decision-making and, potentially, unwarranted clinical variation. The aim of this study was to review guidelines for recommendations in relation to the timing and indications for planned caesarean section as well as recommendations around the process of decision-making.

METHOD

A systematic search of national and international English-language guidelines published between 2008 and 2018 was undertaken. Guidelines were reviewed, assessed in terms of quality and extracted independently by two reviewers.

FINDINGS

In total, 49 guidelines of varying quality were included. There was consistency between the guidelines in potential indications for caesarean section, although guidelines vary in terms of the level of detail. There was substantial variation in timing of birth, for example recommended timing of caesarean section for women with uncomplicated placenta praevia is between 36 and 39weeks depending on the guideline. Only 11 guidelines provided detailed guidance on shared decision-making. In general, national-level guidelines from Australia, and overseas, received higher quality ratings than regional guidelines.

CONCLUSION

The majority of guidelines, regardless of their quality, provide very limited information to guide shared decision-making or the timing of planned caesarean section, two of the most vital aspects of guidance. National guidelines were generally of better quality than regional ones, suggesting these should be used as a template where possible and emphasis placed on improving national guidelines and minimising intra-country, regional, variability of guidelines.

Incidence of Cerebral Injury in Monochorionic Twin Survivors after Spontaneous Single Demise: Long-Term Outcome of a Large Cohort

OBJECTIVES

To evaluate incidence of cerebral injury and outcome in a large series of monochorionic (MC) twin survivors after spontaneous single fetal demise.

METHODS

Retrospective analysis of all MC pregnancies with single fetal demise diagnosed at, or referred to, the Fetal Therapy Unit "U. Nicolini," V. Buzzi Children's Hospital, Milan, Italy, from 2004 to 2015. Survivors evaluation protocol included detailed ultrasound (US) of intracranial anatomy, Doppler investigation of peak systolic velocity in the middle cerebral artery (MCA-PSV), and magnetic resonance (MR). Data were collected on pregnancy characteristics, postnatal brain scan, and MR and neurological follow-up.

RESULTS

Seventy-eight consecutive MC pregnancies were analyzed. Median gestational age (GA) at single fetal demise was 22 weeks (range 15-36); median interval between single demise and live birth was 105 days (range 1-175), with a median GA at birth of 36 weeks (range 23-41). Prenatal MR was performed in 57 of 78 cases (73%). Cerebral injury affected 14/78 (18%) co-twins, 2 of whom were born immediately after single demise, with postnatal diagnosis of cerebral injury; of the other 12 fetuses that were studied before birth, 10 had a prenatal diagnosis of lesion both with US and MR, one only with MR, and in one case, a grade III intraventricular hemorrhage was reported only after delivery, which occurred at 25 weeks, 5 weeks after the single demise. Signs of fetal anemia (MCA-PSV value above 1.55 MoM) were related to a higher risk of prenatal cerebral injury; cases with postnatal diagnosis of lesion were delivered at lower GA.

CONCLUSIONS

Cerebral injury affects 18% of co-twin survivors after single fetal demise in MC twin pregnancies, and evaluation and follow-up of these cases can improve detection rate of such damage.

Role of fetal intertwin difference in middle cerebral artery peak systolic velocity in predicting neonatal twin anemia-polycythemia sequence

OBJECTIVES

To evaluate the relationship between the fetal intertwin difference in middle cerebral artery peak systolic velocity (MCA-PSV) and intertwin difference in hemoglobin (Hb) concentration at birth in monochorionic diamniotic (MCDA) twin pregnancies in order to assess its potential role in the prediction of twin anemia-polycythemia sequence (TAPS).

METHODS

This was a retrospective cohort study of MCDA twin pregnancies delivered between January 2012 and January 2018. All pregnancies with measurements of MCA-PSV within 7 days prior to delivery and in which neonatal Hb concentration was available were included. The correlation between fetal intertwin difference in MCA-PSV, expressed in multiples of the median (MoM), and neonatal intertwin difference in Hb concentration was investigated. Receiver-operating characteristics (ROC) curve analysis was used to assess the performance of fetal intertwin difference in MCA-PSV for predicting intertwin difference in Hb > 90^th centile at birth.

RESULTS

A total of 154 out of 256 MC twin pregnancies fulfilled the inclusion criteria. Fetal intertwin difference in MCA-PSV MoM correlated positively with neonatal intertwin difference in Hb concentration (r = 0.79; P < 0.001). The 90^th centile for intertwin difference in Hb was 7.25 g/dL. There were 15 (9.7%) cases with a Hb difference ≥ 7.25 g/dL at birth. ROC curve analysis showed a high accuracy of fetal intertwin MCA-PSV MoM difference for the prediction of neonatal intertwin Hb difference ≥ 7.25 g/dL at birth (area under the ROC curve, 0.976 (95% CI, 0.935-0.993); P = 0.012). The optimal cut-off for intertwin MCA-PSV MoM difference was 0.373, with a sensitivity of 93.3% (95% CI, 68.1-99.8%) and a specificity of 95.7% (95% CI, 90.8-98.4%). The positive predictive value was 70% (95% CI, 45.7-88.1%) and the negative predictive value was 99.3% (95% CI, 95.9-100%).

CONCLUSION

Our findings show that fetal intertwin MCA-PSV MoM difference is a good predictor of neonatal intertwin Hb concentration difference > 90^th centile and potentially of TAPS. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Risk factors for monozygotic twinning after in vitro fertilization: a systematic review and meta-analysis

OBJECTIVES

To establish the risk factors for monozygotic twin (MZT) and monochorionic twin (MCT) pregnancies after in vitro fertilization (IVF).

DESIGN

Systematic review and meta-analysis.

SETTING

Not applicable.

PATIENT(S)

Women who achieved MZT and non-MZT pregnancies through IVF.

INTERVENTION(S)

Systematic search of Medline from January 1995 to October 2018 with cross-checking of references from relevant articles in English.

MAIN OUTCOME MEASURE(S)

Possible risk factors for MZT or MCT pregnancies after IVF, comprising extended embryo culture, insemination method (conventional IVF and intracytoplasmic sperm injection [ICSI]), embryo biopsy for preimplantation genetic testing for aneuploidies or for monogenic/single-gene defects (PGT-A or PGT-M) programs, assisted hatching (AH), oocytes donation, female age, and embryo cryopreservation.

RESULT(S)

A total of 40 studies were included. Blastocyst transfer compared with cleavage-stage embryo transfer, and female age <35 years were associated with a statistically significant increase in the MZT and MCT pregnancy rate after IVF: (23 studies, OR 2.16, 95% CI, 1.74-2.68, I²=78%; 4 studies, OR 1.29; 95% CI, 1.03-1.62, I²=62%; and 3 studies, OR 1.90, 95% CI, 1.21-2.98, I²=59%; 2 studies, OR 2.34; 95% CI, 1.69-3.23, I²=0, respectively). Conventional IVF compared with ICSI and assisted hatching were associated with a statistically significantly increased risk of MZT pregnancy (9 studies, OR 1.19, 95% CI, 1.04-1.35, I²=0; 16 studies, OR 1.17, 95% CI, 1.09-1.27, I²=29%, respectively). Embryo biopsy for PGT-A or PGT-M, embryo cryopreservation, and oocytes donation were not associated with MZT pregnancies after IVF.

CONCLUSION(S)

Blastocyst transfer is associated with an increased risk of both MZT and MCT pregnancies after IVF. Further evidence is needed to clarify the impact of female age, insemination method and AH on the investigated outcomes.

Twin anemia-polycythemia sequence and routine monitoring practices amongst maternal-fetal medicine specialists in the United States: an initial investigation

Background The purpose of this initial investigation was to begin to understand the routine twin anemia-polycythemia sequence (TAPS) monitoring practices of maternal-fetal medicine specialists (MFM specialists) in the United States in the absence of a formal guideline. Methods This study used an anonymous, online survey of 90 MFM specialists who were practicing in the United States. A $5 gift card to an online store was used to incentivize participants. Descriptive statistics were calculated. Results All MFM specialists reported at least some familiarity (100.00%) with TAPS. Most participants (92.94%) were familiar with methods for monitoring patients for TAPS and nearly all (97.50%) responded that they use 'Doppler MCA-PSV' to make a prenatal TAPS diagnosis. Nearly two-thirds of MFM specialists surveyed (65.06%) reported performing regular TAPS monitoring for patients with monochorionic-diamniotic (MCDA) pregnancies. Conclusion Despite no formal guidelines, the majority of American MFM specialists surveyed are using routine TAPS screening in their management of MCDA twin pregnancies, suggesting that the MFM specialists included in this study consider it a valuable diagnostic tool. Future research should further explore this possible trend toward routine TAPS monitoring amongst MFM specialists in the United States, as well as the potential value of routine TAPS monitoring in MCDA pregnancy.

First-trimester ultrasound measurements and maternal serum biomarkers as prognostic factors in monochorionic twins: a cohort study

BACKGROUND

Monochorionic twin pregnancies are at high risk of adverse outcomes, but it is not possible to predict which pregnancies will develop complications. The aim of the study was to evaluate, in monochorionic twin pregnancies, whether first-trimester ultrasound (nuchal translucency [NT], crown-rump length [CRL]), and maternal serum biomarkers (alpha-fetoprotein [AFP], soluble fms-like tyrosine kinase-1 [sFlt-1] and placental growth factor [PlGF]), are prognostic factors for fetal adverse outcome composite, twin-twin transfusion syndrome (TTTS), growth restriction, and intrauterine fetal death (IUFD).

METHODS

A cohort study of 177 monochorionic diamniotic twin pregnancies. Independent prognostic ability of each factor was assessed by multivariable logistic regression, adjusting for standard prognostic factors. Factors were analysed as continuous data; thus, the reported ORs relate to either 1% change in NT or CRL inter-twin percentage discordance or one unit of measure in each serum biomarker.

RESULTS

The odds of the fetal adverse outcome composite were significantly associated with increased NT inter-twin percentage discordance (adjusted OR 1.03 [95% CI 1.01, 1.06]) and CRL inter-twin percentage discordance (adjusted OR 1.17 [95% CI 1.07, 1.29]). TTTS was significantly associated with increased NT discordance (adjusted OR 1.06 [95% CI 1.03, 1.10]) and decreased PlGF (adjusted OR 0.42 [95% CI 0.19, 0.93]). Antenatal growth restriction was significantly associated with increased CRL discordance (adjusted OR 1.20 [95% CI 1.08, 1.34]). Single and double IUFD were associated with decreased PlGF (adjusted OR 0.34 [95% CI 0.12, 0.98]) and (adjusted OR 0.18 [95%CI 0.05, 0.58]) respectively.

CONCLUSIONS

This study has identified potential individual prognostic factors in the first trimester (fetal biometric and maternal serum biomarkers) that show promise but require further robust evaluation in a larger, prospective series of MC twin pregnancies, so that their usefulness both individually and in combination can be defined.

TRIAL REGISTRATION

ISRCTN 13114861 (retrospectively registered).

Trial of labor after cesarean delivery in twin gestations: systematic review and meta-analysis

BACKGROUND

Trial of labor after cesarean is offered as a routine option for singleton gestations with previous cesarean delivery. However, adequate data are not available to determine whether the approach is equally valid in women with twin gestation.

OBJECTIVE

This systematic review and meta-analysis aimed to assess maternal morbidities associated with trial of labor after cesarean delivery in twin gestations.

STUDY DESIGN

Electronic databases were searched for cohort studies and randomized controlled trials evaluating the association between trial of labor after cesarean delivery in twin gestations and pregnancy outcomes. Maternal mortality and severe morbidities, such as uterine rupture and hysterectomy, were compared between women who had trial of labor and women who had a planned repeat cesarean delivery. Pooled odds ratios were calculated using a random-effects model. Additional analyses were performed to compare trial of labor after cesarean outcomes in singleton and twin gestations.

RESULTS

Eleven cohort studies including a total of 8209 twin gestations with previous cesarean delivery were included in the present study. Of these gestations, 2484 were intended for planned vaginal birth and 5725 were intended for planned repeat cesarean delivery. The rate of uterine rupture in twin gestations was higher in the trial of labor after cesarean group than the elective cesarean group (odds ratio, 10.09, 95% confidence interval, 4.30-23.69, I² = 68%). However, no statistically significant difference was found in the rate of uterine rupture between twin and single gestations attempting trial of labor after cesarean delivery (odds ratio, 1.34, 95% confidence interval, 0.54-3.31, I² = 0%). Women who attempted a trial of labor after cesarean delivery with twins did not have an increased risk of uterine scar dehiscence, hemorrhage, blood transfusion, or neonatal morbidity and mortality compared with elective repeat cesarean delivery. Patients with twins had similar rates of successful vaginal delivery as patients with singletons (odds ratio, 0.85, 95% confidence interval, 0.61-1.18, I² = 36%).

CONCLUSION

This meta-analysis demonstrates that, although trial of labor with twins after previous cesarean delivery is associated with higher rates of uterine rupture compared with elective cesarean delivery, pregnancy outcomes and success rates are similar to a trial of labor after previous cesarean delivery in singleton gestations. Planned vaginal birth for women with twin gestation and previous cesarean delivery may be a safe alternative to a planned repeat cesarean.

Differences in fetal growth patterns between twins and singletons

Objective: Twin fetus growth is delayed during the third trimester compared to singletons. Whether this phenomenon should be considered a normal physiologic characteristic of twins or a pathologic process inherent to twin pregnancies is currently unclear. Information on the growth rate of the individual fetal biometric indices may provide more insight into the mechanisms underlying these differences between twins and singletons. Our aim was to compare fetal growth pattern between twin and singleton fetuses.Methods: This was a retrospective study of women with an uncomplicated twin pregnancy who underwent sonographic fetal weight estimation between 16 and 38 weeks' gestation in a single referral center. Twins-specific regression models were generated for biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), femur length (FL) and fetal weight as a function of gestational age and were compared to published singletons-based curves.Results: Overall 543 women were eligible for the study and underwent a total of 3401 sonographic weight estimations. Estimated weight of twin fetus emerged as lower than that of singletons starting at 26 weeks of gestation, and these differences increased with gestational age, reaching a mean difference of 300-350 g or of ∼10% at term. The growth of all four biometric indices was slower in twins compared to singletons, but the differences were most pronounced for AC which had the largest relative contribution to the lower fetal weight in twins (51.7 ± 7.3%), while the relative contribution of FL, HC, and BPD was smaller (26.4 ± 10.7, 15.5 ± 3.0, and 6.4%±5.7%, respectively). This was also reflected by a higher HC/AC ratio in twins compared with singletons starting at 22 weeks of gestation. The likelihood of a twin fetus being diagnosed as small for gestational age (fetal weight <10th percentile) was significantly lower when the newly developed twins-based curves (rather than singletons-based curves) were used (OR: 0.39, 95%-CI: 0.34-0.44).Conclusion: Twin fetus experience slowing of growth beginning at ∼26 weeks of gestation and a greater degree of asymmetric growth pattern compared with singletons. These findings suggest that the slower growth of twins may reflect a state of "relative growth restriction" compared with singleton gestations.

Prediction of adverse pregnancy outcome in monochorionic diamniotic twin pregnancy complicated by selective fetal growth restriction

OBJECTIVE

To identify key factors associated with adverse perinatal outcome in monochorionic diamniotic twin pregnancy complicated by selective fetal growth restriction (sFGR).

METHODS

This was a retrospective cohort study of all monochorionic diamniotic twin pregnancies diagnosed with sFGR at ≥ 16 weeks' gestation, in a single tertiary referral center between March 2000 and May 2015. The presence of coexisting twin-twin transfusion syndrome (TTTS) was noted. Fetal biometry and Doppler indices, including those of the umbilical artery (UA) and ductus venosus (DV), were recorded at the time of diagnosis. The type of sFGR was diagnosed according to the pattern of end-diastolic flow in the UA of the smaller twin. DV pulsatility indices for veins (DV-PIV) were converted to Z-scores and estimated fetal weight values to centiles, to correct for gestational age (GA). Cox proportional hazards model was used to examine for independent predictors of adverse perinatal outcome, which was defined according to survival and included both intrauterine fetal demise and neonatal death of the FGR twin.

RESULTS

We analyzed 104 pregnancies, of which 66 (63.5%) were diagnosed with Type-I and 38 (36.5%) with Type-II sFGR at initial presentation. In pregnancies complicated by Type-II sFGR, the diagnosis of sFGR was made earlier than in those complicated by Type-I sFGR (mediam GA, 19.6 vs 21.5 weeks; P = 0.012), and Type-II sFGR was associated with increased risk of adverse perinatal outcome (intrauterine demise of the smaller twin, 34.2% vs 10.6%; P = 0.004). Twin pregnancies complicated by sFGR resulting in perinatal demise had a significantly earlier diagnosis (P = 0.002) and lower birth-weight centile of the smaller twin (P < 0.01), those with Type-I sFGR had earlier GA at delivery (P = 0.007) and those with Type-II sFGR had higher DV-PIV Z-score of the smaller twin (P = 0.003), when compared with pregnancies resulting in live birth. Coexisting TTTS had no significant impact on the perinatal outcome of pregnancies diagnosed with either Type-I or Type-II sFGR (P > 0.05 for both). Earlier GA at diagnosis (hazard ratio (HR), 0.70 (95% CI, 0.56-0.88); P = 0.002), Type-II sFGR (HR, 3.53 (95% CI, 1.37-9.07); P = 0.008) and higher DV-PIV Z-score (HR, 1.36 (95% CI, 1.12-1.65); P = 0.001) were significantly associated with increased risk of adverse perinatal outcome of the smaller twin.

CONCLUSIONS

Pregnancies complicated by Type-II sFGR are diagnosed significantly earlier and are associated with increased risk of adverse perinatal outcome compared with those with Type-I sFGR. Coexisting TTTS has no significant impact on the perinatal outcome of pregnancies diagnosed with either Type-I or Type-II sFGR. Earlier GA at diagnosis, Type-II sFGR and higher DV-PIV Z-score are associated significantly with increased risk of adverse perinatal outcome of the smaller twin. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Predictive accuracy of Southwest Thames Obstetric Research Collaborative (STORK) chorionicity-specific twin growth charts for stillbirth: a validation study

OBJECTIVE

Twin pregnancy is associated with a 2-3-fold increased risk of stillbirth compared with singleton pregnancy. Despite the fact that the growth pattern in twins has been shown to be different from that in singletons, it is controversial whether twin-specific growth charts should be used routinely. A major goal of prenatal ultrasound is to identify fetuses with growth restriction at risk of stillbirth. The main aim of this study was to compare the performance of chorionicity-specific twin charts with singleton charts, both customized and non-customized, in the antenatal prediction of small-for-gestational-age (SGA) stillborn and liveborn fetuses.

METHODS

This was a multicenter cohort study analyzing data from the Southwest Thames Obstetric Research Collaborative (STORK) multiple pregnancy cohort (2000-2009) and a second cohort of twin pregnancies at St George's University Hospital (SGH) (2011-2016). The STORK cohort was used to compare the performance of the twin charts and non-customized singleton charts of Poon et al. and the SGH cohort was used to validate the twin-specific charts and compare their performance against customized (Gestation Related Optimal Weight (GROW)) and non-customized (Poon) singleton charts. The primary outcome was the prediction of SGA cases that were stillborn and those that were liveborn in twin pregnancies. Estimated fetal weight (EFW) available from the last examination (24 weeks' gestation and onwards) before delivery or demise was used to classify the fetuses as SGA (EFW < 10^th centile or < 3^rd centile) or appropriate for gestational age. The proportions of predicted SGA stillbirths and SGA live births were calculated using the three different charts.

RESULTS

The STORK cohort consisted of 1850 dichorionic (DC) and 300 monochorionic (MC) twin pregnancies. The SGH cohort consisted of 579 DC and 180 MC twin pregnancies. The stillbirth rates in the STORK and SGH cohorts were 1.1% and 1.3%, respectively. In those liveborn in the STORK cohort, using a 10^th -centile cut-off to define SGA, the non-customized singleton chart classified a significantly greater proportion as SGA than did the twin chart, regardless of chorionicity (P < 0.001). However, there was no significant difference between the twin and the non-customized singleton charts with regard to the proportion of stillbirth cases that were classified as SGA (P = 0.479). In the SGH cohort, the non-customized singleton chart classified 8.5% of all liveborn fetuses as SGA (EFW < 10^th centile) compared with 12.8% using the customized singleton chart and 7.1% using the twin chart (P < 0.001 and P = 0.005, respectively). However, there was no significant difference among the three charts in the proportion of stillbirths classified as SGA, regardless of chorionicity (P = 0.999). Similar results were obtained when the third centile cut-off was used to define SGA.

CONCLUSIONS

Compared with the STORK chorionicity-specific twin charts, the customized and non-customized singleton charts classified prenatally as SGA more liveborn fetuses. However, the three charts classified as SGA a similar proportion of stillborn cases. Our preliminary results suggest that these twin charts could safely reduce unnecessary medical intervention in twin pregnancies. Further research on the topic is needed before clinical recommendations can be made. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Inpatient vs outpatient management and timing of delivery of uncomplicated monochorionic monoamniotic twin pregnancy: the MONOMONO study

OBJECTIVES

Monoamniotic twin pregnancies are at increased risk of perinatal complications, primarily owing to the risk of cord entanglement. There is no recommendation on whether such pregnancies should be managed in hospital or can be safely managed in an outpatient setting, and the timing of planned delivery is also a subject of debate. The aim of this study was to compare the perinatal outcomes of inpatient vs outpatient fetal surveillance approaches employed among 22 participating study centers, and to calculate the fetal and neonatal death rates according to gestational age, in non-anomalous monoamniotic twins from 26 weeks' gestation.

METHODS

The MONOMONO study was a multinational cohort study of consecutive women with monochorionic monoamniotic twin pregnancies, who were referred to 22 university hospitals in Italy, the USA, the UK and Spain, from January 2010 to January 2017. Only non-anomalous uncomplicated monoamniotic twin pregnancies with two live fetuses at 26 + 0 weeks' gestation were included in the study. In 10 of the centers, monoamniotic twins were managed routinely as inpatients, whereas in the other 12 centers they were managed routinely as outpatients. The primary outcome was intrauterine fetal death. We also planned to assess fetal and neonatal death rates according to gestational age per 1-week interval. Outcomes are presented as odds ratio (OR) with 95% CIs. The main outcome was analyzed using both standard logistic regression analysis, in which each fetus was treated as an independent unit, and a generalized mixed-model approach, with each twin pair treated as a cluster unit, considering that the outcome for a twin is not independent of that of its cotwin.

RESULTS

195 consecutive pregnant women with a non-anomalous uncomplicated monoamniotic twin gestation (390 fetuses) were included. Of these, 75 (38.5%) were managed as inpatients and 120 (61.5%) as outpatients. The overall perinatal loss rate was 10.8% (42/390) with a peak fetal death rate of 4.3% (15/348) occurring at 29 weeks' gestation. There was no significant difference in mean gestational age at delivery (31 weeks), birth weight (∼1.6 kg), or emergency delivery rate between the inpatient and outpatient surveillance groups. Based on generalized mixed-model analysis, there was no statistically significant difference in fetal death rates between inpatient management commencing from around 26 weeks compared with outpatient surveillance protocols from 30 weeks (3.3% vs 10.8%; adjusted OR 0.21 (95% CI, 0.04-1.17)). Maternal length of stay in the hospital was 42.1 days in the inpatient group, and 7.4 days in the outpatient group (mean difference 34.70 days (95% CI, 31.36-38.04 days). From 32 + 0 to 36 + 6 weeks, no fetal or neonatal death in either group was recorded. 46 fetuses were delivered after 34 + 0 weeks, and none of them died in utero or within the first 28 days postpartum.

CONCLUSION

In uncomplicated monoamniotic twins, inpatient surveillance is associated with similar fetal mortality as outpatient management. After 31 + 6 weeks, and up to 36 + 6 weeks, there were no intrauterine fetal deaths or neonatal deaths. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Integration of imaging and molecular approaches in selective fetal reduction in twin pregnancies with one carrying a pathogenic genomic aberration

BACKGROUND/PURPOSE

With the evolution of assisted fertility and prenatal diagnostic technology, the prevalence of multi-fetal pregnancy increased, followed by the demand for prenatal intervention if genomic aberration was detected. How to distinguish the affected foetus from the normal co-twin before selective fetal reduction is therefore challenging.

OBJECTIVES

We retrospectively reviewed the cases of dichorionic twins at our centre during 2004-2018, where selective fetal reduction was requested because one foetus carried a pathogenic genomic aberration. Five cases were enrolled, including three foetuses with trisomy 21, one foetus with microduplication and one foetus with microdeletion disorders.

METHOD

We labelled the affected foetus by prenatal ultrasound and rapid molecular tools. For the twins without discriminating sonographic features (e.g., the same gender and no distinct placentae), interphase fluorescence in situ hybridization, rapid microarray and short tandem repeat markers were applied to identify the affected foetus.

RESULTS

Selective fetal reduction was allocated accurately for all individuals. Two cases delivered at term, while two delivered preterm, and one developed fetal loss of the co-twin.

CONCLUSION

We proposed a working scheme of integrating imaging and molecular techniques to correctly identify the affected co-twin before selective fetal reduction to ensure the accuracy of the identification.

Update on twin-to-twin transfusion syndrome

Twin-to-twin transfusion syndrome (TTTS) is a serious complication that affects 10-15% of monochorionic multiple pregnancies. Communicating placental vessels on the chorionic plate between the donor and recipient twin are responsible for the imbalance of blood flow. There is evidence for the superiority of fetoscopic laser ablation over serial amnioreductions regarding survival and neurological outcome for stages II-IV TTTS. However, the optimal management of stage I is still debated. The "Solomon" technique showed a significant reduction in recurrent TTTS and post laser twin anemia-polycythemia sequence (TAPS) in comparison to the selective laser method without improvement in perinatal mortality or neonatal morbidity. Survival rates after fetoscopic laser surgery have significantly increased over the last 25 years. High volume centers report up to 70% double survival and at least one survivor in >90%. Long-term neurodevelopmental impairment occurs in about 10% of children after laser surgery. In this review we discuss the optimal management, innovations in laser technique, long-term neurodevelopmental outcome, and future aspects of TTTS treatment.

Screening of fetal chromosomal aneuploidy diseases using noninvasive prenatal testing in twin pregnancies

OBJECTIVES

This study was aimed to report the clinical characteristics of fetal chromosomal aneuploidy diseases using noninvasive prenatal testing (NIPT) in twin pregnancies and analyze the results in terms of chorionicity, conception, and fetal fraction.

METHODS

A total of 1160 women with twin pregnancies were recruited from 1 October 2015, to 1 August 2017. Next-generation sequencing technology was used to detect fetal aneuploidies, such as trisomy 21, trisomy 18, trisomy 13 and trisomy X.

RESULTS

Aneuploidy was detected using NIPT in 26 fetuses, among which 18 fetal aneuploidies occurred in only one fetus of the twins. The rate of aneuploidy was 1.3% for dichorionic diamniotic twins and 0.5% for monochorionic diamniotic twins, respectively. The rate of aneuploidy was 1.2% for spontaneous pregnancy group and 1.1% for assisted reproductive technologies group.

CONCLUSION

In this study, detection of trisomy 21, trisomy 18, trisomy 13, and X abnormality in twin pregnancies was confirmed to be accurate. The aneuploidies mostly occurred in only one fetus of the twins, and trisomy 21 was the most common type. The prenatal diagnostic standard for NIPT in singleton pregnancies could perform well in twin pregnancies, which means NIPT can be popularized as routine prenatal screening in twin pregnancies.

Perinatal outcome of monochorionic twin pregnancy complicated by selective fetal growth restriction according to management: systematic review and meta-analysis

OBJECTIVE

To explore the impact of severity and management (expectant, laser treatment or selective reduction) on perinatal outcome of monochorionic twin pregnancies complicated by selective fetal growth restriction (sFGR).

METHODS

MEDLINE, EMBASE, CINAHL, ClinicalTrials.gov and The Cochrane Library databases were searched for studies on outcome following expectant management, laser treatment or selective reduction in monochorionic twin pregnancies complicated by sFGR. Only pregnancies affected by sFGR and categorized according to the Gratacós classification (Type I, II or III) were included. The primary outcome was mortality, including single and double intrauterine (IUD), neonatal (NND) and perinatal deaths. Secondary outcomes were neonatal morbidity, abnormal postnatal brain imaging, intraventricular hemorrhage, periventricular leukomalacia, respiratory distress syndrome, admission to neonatal intensive care unit and survival free from neurological complications (intact survival). Meta-analyses of proportions were used to analyze the extracted data according to management, severity of sFGR and fetal size (smaller vs larger twin).

RESULTS

Sixteen observational studies (786 monochorionic twin pregnancies) were included. In pregnancies complicated by Type-I sFGR managed expectantly, IUD occurred in 3.1% (95% CI, 1.1-5.9%) of fetuses and 97.9% (95% CI, 93.6-99.9%) of twins had intact survival. In pregnancies complicated by Type-I sFGR treated using laser therapy, IUD occurred in 16.7% (95% CI, 0.4-64.1%) of fetuses and, in those treated using selective reduction, IUD occurred in 0% (95% CI, 0-34.9%) of cotwins, with no evidence of neurological complications in the survivors. In pregnancies complicated by Type-II sFGR managed expectantly, IUD occurred in 16.6% (95% CI, 6.9-29.5%) and NND in 6.4% (95% CI, 0.2-28.2%) of fetuses, and 89.3% (95% CI, 71.8-97.7%) of twins survived without neurological compromise. In Type-II sFGR pregnancies treated using laser therapy, IUD occurred in 44.3% (95% CI, 22.2-67.7%) of fetuses, while none of the affected cases experienced morbidity and survivors were free of neurological complications. Of pregnancies undergoing selective reduction, IUD of the cotwin occurred in 5.0% (95% CI, 0.03-20.5%) and NND in 3.7% (95% CI, 0.2-11.1%), and 90.6% (95% CI, 42.3-94.3%) of surviving cotwins were free from neurological complications. In pregnancies complicated by Type-III sFGR managed expectantly, IUD occurred in 13.2% (95% CI, 7.2-20.5%) and NND in 6.8% (95% CI, 0.7-18.6%) of fetuses, and 61.9% (95% CI, 38.4-81.9%) of twins had intact survival. In pregnancies complicated by Type-III sFGR treated with laser therapy, IUD occurred in 32.9% (95% CI, 20.9-46.2%) of fetuses and all surviving twins were without neurological complications. Finally, in pregnancies with Type-III sFGR treated with selective reduction, NND occurred in 5.2% (95% CI, 0.8-12.8%) of cotwins and 98.8% (95% CI, 93.9-99.9%) had intact survival.

CONCLUSION

Type-I sFGR is characterized by good perinatal outcome when managed expectantly, which represents the most reasonable management strategy for the large majority of affected cases. Pregnancies complicated by Type-II or -III sFGR treated with fetoscopic laser ablation have a higher rate of mortality but lower rate of morbidity compared with those managed expectantly, supporting the use of fetal therapy at gestations remote from neonatal viability. Data on outcome following selective reduction are scarce. In view of the lack of evidence from randomized controlled trials, prenatal management of sFGR should be individualized according to gestational age at diagnosis, severity of growth discordance and magnitude of Doppler anomalies. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.