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

Cardiac function and neurological development in complicated monochorionic pregnancies: Current evidence and clinical implications

Monochorionic twin pregnancies, characterized by a shared placenta and unique vascular architecture, face significantly elevated risks of perinatal complications compared to dichorionic and singleton pregnancies. This review examines the pathophysiology, cardiovascular, and neurological adaptations in three primary complications of monochorionic pregnancies: Twin-to-Twin Transfusion Syndrome (TTTS), Selective Fetal Growth Restriction (sFGR), and Twin Anemia Polycythemia Sequence (TAPS). TTTS disrupts hemodynamic balance, leading to distinct cardiac dysfunctions and increased neurodevelopmental injury (NDI). In sFGR, unequal placental sharing induces cardiovascular and neurological disparities between twins, while TAPS causes chronic anaemia and polycythemia with associated risks of brain injury. Advances in fetal therapy, such as fetoscopic laser surgery, have significantly improved survival, yet long-term sequelae remain concerning. This review emphasizes the importance of specialised prenatal care, multidisciplinary management, and comprehensive postnatal follow-up to mitigate adverse outcomes. The findings call for further research into the mechanisms of fetal adaptation and injury, aiming to refine diagnostic tools and therapeutic strategies.

Predicting Adverse Neurodevelopmental Outcomes in Premature Neonates with Intrauterine Growth Restriction Using a Three-Layered Neural Network

Background/Objectives: There is a constant need to improve the prediction of adverse neurodevelopmental outcomes in growth-restricted neonates who were born prematurely. The aim of this retrospective study was to evaluate the predictive performance of a three-layered neural network for the prediction of adverse neurodevelopmental outcomes determined at two years of age by the Bayley Scales of Infant and Toddler Development, 3rd edition (Bayley-III) scale in prematurely born infants by affected by intrauterine growth restriction (IUGR). Methods: This observational retrospective study included premature newborns with or without IUGR admitted to a tertiary neonatal intensive care unit from Romania, between January 2018 and December 2022. The patients underwent assessment with the Amiel-Tison scale at discharge, and with the Bailey-3 scale at 3, 6, 12, 18, and 24 months of corrected age. Clinical and paraclinical data were used to construct a three-layered artificial neural network, and its predictive performance was assessed. Results: Our results indicated that this type of neural network exhibited moderate predictive performance in predicting mild forms of cognitive, motor, and language delays. However, the accuracy of predicting moderate and severe neurodevelopmental outcomes varied between moderate and low. Conclusions: Artificial neural networks can be useful tools for the prediction of several neurodevelopmental outcomes, and their predictive performance can be improved by including a large number of clinical and paraclinical parameters.

Counselling in Fetal Medicine: Complications of Monochorionic Diamniotic Twin Pregnancies

Twin pregnancies are at increased risk of morbidity and mortality compared to singletons. Among all twins, monochorionic pregnancies are at higher risk of specific and non-specific complications compared to dichorionic pregnancies. Therefore, it is of great importance to properly counsel future parents with monochorionic pregnancies regarding the risks of adverse outcomes and the modalities of monitoring and intervention of the potential complications. Conditions related to the monochorionicity include twin-to-twin transfusion syndrome (TTTS), twin reversed arterial perfusion sequence (TRAP), and twin anemia polycythemia syndrome (TAPS); other complications include selective fetal growth restriction (sFGR) and congenital anomalies. This review aims to summarize the information available in the current literature regarding the complications in monochorionic diamniotic twin pregnancies, including outcomes and guideline recommendations about the clinical surveillance, management, and timing of interventions of these conditions that should be included in counselling in routine clinical practice.

Ductus Venosus Agenesis in Monochorionic Twin Pregnancies Complicated by Fetal Growth Restriction: When to Deliver?

Introduction: The prevalence of ductus venosus agenesis (ADV) in singleton pregnancies ranges from 0.04% to 0.15%, while its prevalence in twins remains largely unknown. To our knowledge, in the literature, there is only a single case report of a monochorionic diamniotic (MCDA) pregnancy complicated by ADV. Fetuses with ADV are at increased risk for congenital cardiac disease, heart failure, and fetal growth restriction (FGR). Consequently, these pregnancies have a heightened risk of experiencing an adverse outcome, like stillbirth and neonatal or infant death. Closer antenatal monitoring is warranted when ADV is suspected. Currently, there are no guidelines regarding the standard of care in cases of ADV and no recommendations for the timing of delivery in either singleton or twin pregnancies. Cases: This study aims to provide a comprehensive overview of the management of twin pregnancies complicated by ADV, featuring two cases of MC twins with concurrent sFGR and ADV in one twin. Discussion: These pregnancies experienced completely different outcomes, underscoring the necessity for personalized management tailored to the specific risk factors present in each pregnancy. Typically, in MCDA pregnancies with severe sFGR (type II and III), delivery represents the most reasonable option when venous Doppler abnormalities are identified. However, the absence of the DV complicates the management and the process of decision-making regarding the timing of delivery in cases of sFGR and ADV. We emphasize that effective decision-making should be guided by the presence of additional risk factors, including velamentous insertion, significant estimated fetal weight discordance, and progressive deterioration of the Doppler over time. Conclusions: Our experience suggests that these factors are strongly correlated with poorer outcomes. Given this context, could it be acceptable, in the case of MC pregnancy complicated by severe sFGR and ADV, with worsening findings and additional risk factors (e.g., velamentous insertion, severe birth weight discrepancy), to anticipate the time of delivery starting from 30 weeks of gestational age?

FERN: is it possible to conduct a randomised controlled trial of intervention or expectant management for early-onset selective fetal growth restriction in monochorionic twin pregnancy - protocol for a prospective multicentre mixed-methods feasibility study

INTRODUCTION

Selective fetal growth restriction (sFGR) in monochorionic twin pregnancy, defined as an estimated fetal weight (EFW) of one twin <10th centile and EFW discordance ≥25%, is associated with stillbirth and neurodisability for both twins. The condition poses unique management difficulties: on the one hand, continuation of the pregnancy carries a risk of death of the smaller twin, with a high risk of co-twin demise (40%) or co-twin neurological sequelae (30%). On the other, early delivery to prevent the death of the smaller twin may expose the larger twin to prematurity, with the associated risks of long-term physical, emotional and financial costs from neurodisability, such as cerebral palsy.When there is severe and early sFGR, before viability, delivery is not an option. In this scenario, there are currently three main management options: (1) expectant management, (2) selective termination of the smaller twin and (3) placental laser photocoagulation of interconnecting vessels. These management options have never been investigated in a randomised controlled trial (RCT). The best management option is unknown, and there are many challenges for a potential RCT. These include the rarity of the condition resulting in a small number of eligible pregnancies, uncertainty about whether pregnant women will agree to participate in such a trial and whether they will agree to be randomised to expectant management or active fetal intervention, and the challenges of robust and long-term outcome measures. Therefore, the main objective of the FERN study is to assess the feasibility of conducting an RCT of active intervention vs expectant management in monochorionic twin pregnancies with early-onset (prior to 24 weeks) sFGR.

METHODS AND ANALYSIS

The FERN study is a prospective mixed-methods feasibility study. The primary objective is to recommend whether an RCT of intervention vs expectant management of sFGR in monochorionic twin pregnancy is feasible by exploring women's preference, clinician's preference, current practice and equipoise and numbers of cases. To achieve this, we propose three distinct work packages (WPs). WP1: A Prospective UK Multicentre Study, WP2A: a Qualitative Study Exploring Parents' and Clinicians' Views and WP3: a Consensus Development to Determine Feasibility of a Trial. Eligible pregnancies will be recruited to WP1 and WP2, which will run concurrently. The results of these two WPs will be used in WP3 to develop consensus on a future definitive study. The duration of the study will be 53 months, composed of 10 months of setup, 39 months of recruitment, 42 months of data collection, and 5 months of data analysis, report writing and recommendations. The pragmatic sample size for WP1 is 100 monochorionic twin pregnancies with sFGR. For WP2, interviews will be conducted until data saturation and sample variance are achieved, that is, when no new major themes are being discovered. Based on previous similar pilot studies, this is anticipated to be approximately 15-25 interviews in both the parent and clinician groups. Engagement of at least 50 UK clinicians is planned for WP3.

ETHICS AND DISSEMINATION

This study has received ethical approval from the Health Research Authority (HRA) South West-Cornwall and Plymouth Ethics Committee (REC reference 20/SW/0156, IRAS ID 286337). All participating sites will undergo site-specific approvals for assessment of capacity and capability by the HRA. The results of this study will be published in peer-reviewed journals and presented at national and international conferences. The results from the FERN project will be used to inform future studies.

TRIAL REGISTRATION NUMBER

This study is included in the ISRCTN Registry (ISRCTN16879394) and the NIHR Central Portfolio Management System (CPMS), CRN: Reproductive Health and Childbirth Specialty (UKCRN reference 47201).

The Number of Syncytial Knots and the Intensity of VEGF Expression in the Villi of the Monochorionic Diamniotic Placenta in Selective Fetal Growth Restriction

A comparative study was carried out to analyze the number of syncytial knots and the intensity of expression of vascular endothelial growth factor (VEGF) in the villi of the monochorionic diamniotic placenta in pregnancies complicated by the syndrome of selective fetal growth restriction (sFGR). We performed a morphological analysis of 32 monochorionic diamniotic placentas after term delivery which were divided into two groups. The main group included the placentas of 15 puerperas whose pregnancies were complicated by sFGR. The control group included twin placentas of 17 puerperas without signs of sFGR. The number of syncytial knots was determined by histological studies, and the levels of VEGF expression in syncytiotrophoblast and capillary endotheliocytes of the placental villi were determined by immunohistochemical studies. The study showed an increase in the number of syncytial knots in the villi of the placental part of the fetus with sFGR which indicated the development of preplacental hypoxia. A significant increase in the level of VEGF expression in the syncytiotrophoblast and vascular endothelium of the villi should be considered as a manifestation of a compensatory adaptational response to hypoxia, though it is insufficient to prevent the development of sFGR.

Clinical Outcome of Monochorionic Diamniotic Twins with Intrauterine Growth Restriction

OBJECTIVE

This study investigated the clinical outcome of monochorionic diamniotic (MCDA) twins with selective intrauterine growth restriction (sIUGR).

STUDY DESIGN

International Peace Maternal and Child Health Hospital of Shanghai ultrasound database was investigated to identify all MCDA delivered from January 2013 to December 2017. After identifying 43 pairs of MCDA twins with sIUGR and 282 pairs of normal MCDA twins, we compared clinical outcomes between the two groups.

RESULTS

Compared with normal twins, sIUGR fetuses had significantly shorter gestational age at delivery, smaller average birth weight of both twins, more significant intertwin difference in birth weight, lower Apgar scores, and higher intrauterine fetal demise (IUFD) rate, and smaller placental weight. The rate of abnormal umbilical cord insertions and abnormal blood flow in the ductus venosus (DV) and middle cerebral artery (MCA) is significantly higher in the sIUGR group. In addition, the subtype analysis of sIUGR groups indicated the poorest outcomes in type II with no significant difference between type I and III.

CONCLUSION

MCDA twins with sIUGR generally exhibited limited clinical outcomes than normal MCDA twins. These limitations are mainly associated with abnormal umbilical cord insertions and blood flow in the DV and MCA. Clinical outcomes differed among the three types of sIUGR, with type II having the worst prognosis and the highest IUFD rate.

KEY POINTS

· sIUGR generally exhibited limited clinical outcomes than normal MCDA twins.. · These limitations are mainly associated with blood flow of the DV and MCA.. · sIUGR with type II has the worst prognosis and the highest IUFD rate..

Predictors of Poor Outcomes in Monochorionic Diamniotic Twin Pregnancies Complicated by Selective Fetal Growth Restriction

INTRODUCTION

The aim of the study was to identify predictors of poor outcomes in monochorionic diamniotic twin (MCDA) pregnancies with selective fetal growth restriction (sFGR), irrespective of the umbilical artery (UA) Doppler abnormalities.

METHODS

Single-center retrospective analysis of MCDA twins diagnosed with sFGR that opted for expectant management between 2010 and 2021. The presence of any of the following variables in the growth-restricted fetus: low amniotic fluid volume (DVP ≤2 cm), lack of a cycling bladder, absent or reversed flow in the ductus venosus (DV) with atrial contraction, and elevated middle cerebral artery peak systolic velocity (MCA-PSV) defined as ≥1.50 multiples of the median was categorized as complicated. sFGR cases were classified as simple in the absence of the above-mentioned variables.

RESULTS

Overall, 63.3% of cases qualified as simple, and 36.7% were complicated. Intertwin EFW discordance was higher in the complicated category (26 vs. 33%, p = 0.0002). The median gestational age at delivery was earlier (33 weeks vs. 30.5 weeks, p = 0.002), and the likelihood of survival was lower in the complicated category (p < 0.0001). The likelihood of two survivors to discharge was lower in type I complicated cases (70% in complicated type I vs. 97.1% in simple type I, p = 0.0003). On logistic regression analysis, an increase in the "complicated" score negatively correlated with two survivors to discharge (p < 0.0001). An ROC curve was created, and the AUC was 0.79. Increasing intertwin EFW discordance also decreased the probability of two survivors to discharge.

CONCLUSION

The presence of oligohydramnios, lack of a cycling bladder, abnormal DV Doppler, and elevated MCA-PSV in the growth restricted fetus is associated with poor perinatal outcomes and a lower likelihood of having two survivors to discharge. The addition of intertwin EFW discordance to these variables helped improve the survival predictability.

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.

Risk factors associated with stillbirth and adverse perinatal outcomes in dichorionic twin pregnancies complicated by selective fetal growth restriction: a cohort study

OBJECTIVE

The main aim of this study was to investigate the perinatal outcomes of dichorionic twin pregnancies complicated by selective fetal growth restriction (sFGR).

DESIGN

Retrospective cohort study.

SETTING

Tertiary reference centre.

POPULATION

Dichorionic twin pregnancies complicated by sFGR between 2000 and 2019 in St George's University Hospital.

METHODS

Regression analyses were performed using generalised linear models and mixed-effects generalised linear models where appropriate to account for pregnancy level dependency in variables. Time to event analyses were performed with mixed-effects Cox regression models.

MAIN OUTCOME MEASURES

Stillbirth, neonatal death or neonatal unit admission with morbidity in one or both twins.

RESULTS

A total of 102 (of 2431 dichorionic twin pregnancies) pregnancies complicated by sFGR were included in the study. The Cochrane-Armitage test revealed a significant trend for increased adverse perinatal outcome rates with more severe forms of umbilical artery flow impedance, i.e. reversed, absent, positive with resistant flow and positive flow without resistance. A multivariable model including maternal and conception characteristics had poor predictive accuracy for stillbirth (area under the curve: 0.68, 95% confidence interval [CI] 0.55-0.81) and composite adverse perinatal outcomes (area under the curve: 0.58, 95% CI 0.47-0.70). When umbilical artery Doppler parameters were added to the models, the area under the curve values improved to 0.95 (95% CI 0.89-0.99) and 0.83 (95% CI 0.73-0.92) for stillbirth and composite adverse perinatal outcomes, respectively.

CONCLUSION

In dichorionic twin pregnancies complicated by sFGR, the umbilical artery Z-scores were associated with both intrauterine death and adverse perinatal outcomes.

Selective intrauterine growth restriction without concomitant twin-to-twin transfusion syndrome, natural history, and risk factors for fetal death: A systematic review and meta-analysis

OBJECTIVE

This study aimed to evaluate the natural history of selective intrauterine growth restriction in monochorionic twin pregnancies based on the Gratacós classification, including progression of, improvement in, or stability of umbilical artery Dopplers and progression to twin-to-twin transfusion syndrome or twin anemia polycythemia syndrome. We also aimed to investigate risk factors for smaller twin demise.

DATA SOURCES

A systematic search was performed to identify relevant studies published in English up to June 2022 using the databases PubMed, Scopus, and Web of Science STUDY ELIGIBILITY: We used retrospective and prospective studies published in English that reported on selective intrauterine growth restriction without concomitant twin-to-twin transfusion syndrome.

STUDY APPRAISAL AND SYNTHESIS METHODS

Articles that investigated selective intrauterine growth restriction progression and outcomes by umbilical artery Doppler end-diastolic flow (Gratacós classification) were included. Type I included selective intrauterine growth restriction cases with positive end-diastolic flow, type II included those cases with persistently absent end-diastolic flow, and type III included cases with intermittent absent or reversed end-diastolic flow. Pregnancies in which a diagnosis of twin-to-twin transfusion syndrome or twin anemia polycythemia sequence was made before the diagnosis of selective intrauterine growth restriction were not included in the analysis. A random effects model was used to pool the odds ratios and the corresponding 95% confidence intervals. Heterogeneity was assessed using the I2 value.

RESULTS

A total of 17 studies encompassing 2748 monochorionic pregnancies complicated by selective intrauterine growth restriction were included in the analysis. The incidence of stable, deteriorating, or improving umbilical artery Dopplers in type I cases was 68% (95% confidence interval, 26-89), 23% (95% confidence interval, 7-40), and 9% (95% confidence interval, 0.0-100), respectively. In type II cases, the incidence was 40% (95% confidence interval, 18-81), 50% (95% confidence interval, 23-82), and 10% (95% confidence interval, 4-37), respectively, and in type III cases, the incidence was 55% (95% confidence interval, 2-99), 23% (95% confidence interval, 9-43), and 22% (95% confidence interval, 6-54), respectively. The risk for progression to twin-to-twin transfusion syndrome was comparable between type I (7%) and type III (9%) cases and occurred in 4% (95% confidence interval, 0-67) of type II cases with no significant subgroup differences. Progression to twin anemia polycythemia syndrome was highest in type I cases (12%) and comparable between type II (2%) and III (1%) cases with no significant subgroup differences. Risk factors for smaller twin demise were earlier gestational age at diagnosis (mean difference, -2.69 weeks; 95% confidence interval, -4.94 to -0.45; I2, 45%), larger intertwin weight discordance (mean difference, 34%; 95% confidence interval, 1.35-5.38; I2, 28%), deterioration of umbilical artery Dopplers for each of type II and III cases (odds ratio, 3.05; 95% confidence interval, 1.36-6.84; I2, 24%; and odds ratio, 4.5; 95% confidence interval, 2.31-8.77; I2, 0.0%, respectively), and absent or reversed ductus venosus a-wave for each of type II and III cases (odds ratio, 3.35; 95% confidence interval, 2.28-4.93; I2, 0.0%; and odds ratio, 2.36; 95% confidence interval, 1.08-5.13; I2, 0.0%, respectively). Progression to twin-to-twin transfusion syndrome was not significantly associated with smaller twin demise for each of type II and III selective intrauterine growth restriction cases.

CONCLUSION

These findings improve our understanding of the natural history of the types of selective intrauterine growth restriction and of the predictors of smaller twin demise in type II and III selective intrauterine growth restriction cases. The current data provide vital counseling points and support the need for modifications of the current selective intrauterine growth restriction classification system to include the variations in umbilical artery and ductus venosus Dopplers to better identify a cohort that might benefit from fetal intervention for which future multicenter prospective randomized trials are needed.

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.

Minimally Invasive Fetal Surgery and the Next Frontier

Most patients with congenital anomalies do not require prenatal intervention. Furthermore, many congenital anomalies requiring surgical intervention are treated adequately after birth. However, there is a subset of patients with congenital anomalies who will die before birth, shortly after birth, or experience severe postnatal complications without fetal surgery. Fetal surgery is unique in that an operation is performed on the fetus as well as the pregnant woman who does not receive any direct benefit from the surgery but rather lends herself to risks, such as hemorrhage, abruption, and preterm labor. The maternal risks involved with fetal surgery have limited the extent to which fetal interventions may be performed but have, in turn, led to technical innovations that have significantly advanced the field. This review will examine congenital abnormalities that can be treated with minimally invasive fetal surgery and introduce the next frontier of prenatal management of fetal surgical pathology.

Natural evolution and risk factors for adverse outcome in selective intrauterine growth restriction under expectant management: A retrospective observational study

OBJECTIVE

To evaluate the natural evolution of and risk factors for the adverse outcome of monochorionic twins with selective intrauterine growth restriction (sIUGR) under expectant management.

METHODS

Retrospective study conducted in a single tertiary referral center. The clinical characteristics and neonatal outcomes of 153 patients with sIUGR under expectant management were evaluated, and the risk factors leading to adverse outcomes were explored.

RESULTS

Fifty-one patients (33.3%) showed a changed pattern in umbilical artery Doppler at the last examination, occurring in all types of sIUGR. Compared with type Ia, the gestational age of diagnosis was earlier, the estimated fetal body weight difference at diagnosis was greater, and the rate of severe neonatal complications in both fetuses was significantly higher in type Ib (P < 0.05). Univariate and multivariate logistic regression analyses showed that type II (odds ratio [OR] 5.41, 95% confidence interval [CI] 2.34-12.51; P < 0.001) and type III (OR 9.11, 95% CI 3.02-27.50; P < 0.001) were associated with adverse perinatal outcomes in sIUGR.

CONCLUSION

Type II and III sIUGR are independent risk factors predicting adverse outcomes of sIUGR. Different types of sIUGR could convert to each other. The outcome of type Ib is poorer than that of type Ia.

Perinatal outcomes of fetoscopic laser surgery for twin-twin transfusion syndrome in triplet pregnancy: cohort study, systematic review and meta-analysis

OBJECTIVES

The aims of this study were to investigate the perinatal outcome of dichorionic triamniotic (DCTA) and monochorionic triamniotic (MCTA) triplet pregnancies complicated by twin-twin transfusion syndrome (TTTS) treated with fetoscopic laser photocoagulation (FLP) in two academic fetal centers, and to conduct a systematic review of previously published data to investigate perinatal survival in this targeted population.

METHODS

The first part of the study was a retrospective cohort study of prospectively collected data of consecutive triplet pregnancies with TTTS that underwent FLP at two fetal treatment centers between 2012 and 2020. Demographic, preoperative and operative variables and postoperative outcome were collected. Perinatal outcomes were investigated. The second part of the study was a systematic review and meta-analysis of studies evaluating the outcome of DCTA and/or MCTA triplet pregnancies, including our cohort study. PubMed, Web of Science and Scopus were searched from inception to September 2020. Primary outcomes were fetal survival (survival to birth), neonatal survival (survival to 28 days of age) and gestational age (GA) at birth.

RESULTS

A total of 31 sets of triplets with TTTS managed with FLP were included in the cohort study. Of these, 24 were DCTA and seven were MCTA. There were no significant differences in preoperative and operative variables between the two groups. There were also no significant differences between groups in GA at delivery or perinatal survival rate, including fetal and neonatal survival of at least one triplet, at least two triplets and all three triplets. Nine studies, including our cohort study, were included in the systematic review (156 DCTA and 37 MCTA triplet pregnancies treated with FLP). The overall fetal and neonatal survival was 79% (95% CI, 75-83%) and 75% (95% CI, 71-79%), respectively, in DCTA cases and 74% (95% CI, 52-92%) and 71% (95% CI, 49-89%), respectively, in MCTA cases. The rate of preterm birth before 28 weeks and before 32 weeks' gestation was 14% (95% CI, 4-29%) and 61% (95% CI, 50-72%), respectively, in DCTA triplets and 21% (95% CI, 3-45%) and 82% (95% CI, 62-96%), respectively, in MCTA triplets.

CONCLUSIONS

Triplet pregnancies with TTTS are at high risk of adverse perinatal outcome and preterm birth, regardless of chorionicity. The rate of survival after FLP in MCTA triplets was higher in our study than that reported in previous studies and is currently comparable with survival in DCTA triplets, which could be due to improved surgical skills. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Prediction of fetal death in monochorionic twin pregnancies complicated by Type-III selective fetal growth restriction

OBJECTIVE

Monochorionic diamniotic twin pregnancies complicated by Type-III selective fetal growth restriction (sFGR) are at high risk of fetal death. The aim of this study was to identify predictors of fetal death in these pregnancies.

METHODS

This was an international multicenter retrospective cohort study. Type-III sFGR was defined as fetal estimated fetal weight (EFW) of one twin below the 10^th percentile and intertwin EFW discordance of ≥ 25% in combination with intermittent absent or reversed end-diastolic flow in the umbilical artery of the smaller fetus. Predictors of fetal death were recorded longitudinally throughout gestation and assessed in univariable and multivariable logistic regression models. The classification and regression trees (CART) method was used to construct a prediction model of fetal death using significant predictors derived from the univariable analysis.

RESULTS

A total of 308 twin pregnancies (616 fetuses) were included in the analysis. In 273 (88.6%) pregnancies, both twins were liveborn, whereas 35 pregnancies had single (n = 19 (6.2%)) or double (n = 16 (5.2%)) fetal death. On univariable analysis, earlier gestational age at diagnosis of Type-III sFGR, oligohydramnios in the smaller twin and deterioration in umbilical artery Doppler flow were associated with an increased risk of fetal death, as was larger fetal EFW discordance, particularly between 24 and 32 weeks' gestation. None of the parameters identified on univariable analysis maintained statistical significance on multivariable analysis. The CART model allowed us to identify three risk groups: a low-risk group (6.8% risk of fetal death), in which umbilical artery Doppler did not deteriorate; an intermediate-risk group (16.3% risk of fetal death), in which umbilical artery Doppler deteriorated but the diagnosis of sFGR was made at or after 16 + 5 weeks' gestation; and a high-risk group (58.3% risk of fetal death), in which umbilical artery Doppler deteriorated and gestational age at diagnosis was < 16 + 5 weeks' gestation.

CONCLUSIONS

Type-III sFGR is associated with a high risk of fetal death. A prediction algorithm can help to identify the highest-risk group, which is characterized by Doppler deterioration and early referral. Further studies should investigate the potential benefit of fetal surveillance and intervention in this cohort. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Neonatal management and outcome in complicated monochorionic twins: What have we learned in the past decade and what should you know?

Monochorionic (MC) twin pregnancies are at increased risk of neonatal morbidity and mortality due to the shared placenta with vascular connections that can give rise to various complications, including twin-twin transfusion syndrome, twin anemia polycythemia sequence (TAPS), selective fetal growth restriction, and other hematological imbalances at birth. Each complication presents its own challenges and considerations in the neonatal period. Measurement of hemoglobin levels and reticulocyte count is required to establish a correct diagnosis. Placenta dye injection is needed to properly distinguish between the various conditions. Risk factors for adverse outcome in MC twins include prematurity, severe cerebral injury, and the type of MC pregnancy complication. We, therefore, recommend cerebral ultrasound examinations in all complicated MC twins at birth to rule out a severe brain injury. Lastly, we strongly encourage screening for hearing loss using automated auditory brainstem response in all spontaneous TAPS donors to prevent permanent speech development delay.

What fetal medicine specialists should know about the monochorionic placenta

Monochorionic twins are at risk of transfusion imbalances as long as they are connected to the shared placenta during their intrauterine journey. This review article addresses the macroscopic examination of the monochorionic placenta at the time of birth and explains placental dye injection studies to document the vascular anastomoses and placental sharing. We elaborate on the different types of anastomoses, the importance of how the placenta is divided between the twins, and the angioarchitecture in twin-twin transfusion syndrome, twin anemia polycythemia sequence and selective fetal growth restriction.

How to better distinguish between Type II and III selective fetal growth restriction in monochorionic twin pregnancies?

OBJECTIVES

To determine additional variables, next to umbilical artery (UA) Doppler, to help differentiate between Type II and III selective fetal growth restriction (sFGR).

METHODS

Retrospective analysis categorizing monochorionic diamniotic twin pregnancies with sFGR and abnormal UA Doppler as either Type II or III sFGR based on the diameter of the artery-to-artery (AA) anastomosis of ≤ 2 mm or > 2 mm, respectively on placental examination after birth. This exploratory study compared maternal characteristics, pregnancy outcome, placental characteristics, and ultrasound features between the two groups.

RESULTS

We included 40 sFGR placentas, 13 were classified as Type II and 27 as Type III. Maternal age was higher in Type II. Small Type II twins had lower birth weights for gestational age and birth weight discordance was higher in Type II. Type III placentas were more unevenly divided, but Type III pairs differed less in birth weight than expected relative to their placental discordance. Type III placentas more commonly had a vein-to-vein anastomosis and larger artery-to-vein anastomoses than Type II placentas, and proximate cord insertions were only observed in Type III. On the ultrasound scan at first diagnosis, small Type II twins were more growth-restricted. An AA anastomosis was detected in half of the Type III cases and in none of the Type II group. Signs of high-output cardiac strain were observed only in large Type III twins. In contrast, placental dichotomy was detected in nearly half of the Type II cases and only one Type III case.

CONCLUSIONS

The presence of an AA anastomosis, signs of cardiac strain in the large twin, and proximate cord insertions suggested Type III sFGR, whereas placental dichotomy and a severe growth restriction were typically present in Type II. Prospective studies need to validate if these markers help prenatal differentiation between Type II and III sFGR.

Early- and late-onset selective fetal growth restriction in monochorionic twin pregnancy with expectant management

OBJECTIVE

This study aimed to identify selective fetal growth restriction (sFGR) in monochorionic twin (MCT) pregnancy with expectant management.

METHODS

We retrospectively analyzed cases of sFGR between January 2015 and December 2019 in Peking University Third Hospital. We included sFGR according to the International Society of Ultrasound in Obstetrics and Gynecology diagnostic criteria. We excluded those cases where a significant fetal structural abnormality, twin reversed arterial perfusion (TRAP), genetic syndrome or aneuploidy; cases terminated for maternal complications or for personal reasons; pregnancies that had a fetal intervention, such as fetoscopic laser photocoagulation (FLP) for vascular anastomoses, fetal reduction by radiofrequency ablation (RFA) and microwave ablation (MVA). We didn't excluded those cases that had amnioreduction therapy. According to the gestational age at onset (before 24 weeks or after), data were analyzed to identify the risk factors associated with fetal prognostic outcomes. Primary outcomes included survival of at least one twin and both twins. Secondary outcomes included gestational age of delivery, live birth weight, Apgar <7 in 5 min, admission to the neonatal unit and neonatal death. Kruskal-Wallis rank tests were used to compare non-normally distributed data, whereas categorical data were matched using Fisher's exact test or χ² tests. ANOVA was used to compare normally distributed data, followed by a post-hoc Bonferroni analysis. Multivariate binary logistic regression was used to identify the factors connected with intrauterine death.

RESULTS

There were 119 pregnancies that qualified for investigation, 75 (63.0%) were categorized as early-onset sFGR and 44 (37.0%) as late-onset sFGR. The rate of survival of at least one twin (82.7% vs. 95.5%), survival of both twins (73.3% vs. 88.6%) were all reduced in the early-onset sFGR group, compared to the late-onset sFGR group. Babies born alive of fetal growth restriction (FGR) and appropriate growth for gestational age (AGA) fetuses showed similar results in the two groups regarding birth weight, 5-min Apgar score <7, neonatal death, and 28-day survival rate. A multivariable model was used to predict the intrauterine death of at least one twin. The odds ratio were significantly higher for superimposed twin-twin transfusion syndrome (TTTS) (OR 17.915, 95%CI 3.699∼86.756) and Types Ⅱ/Ⅲ sFGR (OR 4.619, 95%CI 1.074∼19.869).

CONCLUSIONS

In MCT pregnancies, early-onset sFGR had a poorer survival of at least one or both twins, but there was no statistical difference in the prognosis after live birth, neither for FGR babies nor those of AGA. Superimposed TTTS and Types Ⅱ/Ⅲ sFGR had a worse perinatal outcome. This information could be provided to the parents during prenatal counselling.

Prediction of post-laser fetal death in selective growth restriction complicating twin-twin transfusion syndrome using standardized definitions

OBJECTIVE

Selective fetal growth restriction (sFGR) complicating twin-twin transfusion syndrome (TTTS) is associated with a 3-6-fold increased risk of fetal demise after fetoscopic laser surgery (FLS). Identifying these patients is challenging due to varying definitions of sFGR used in the literature. The objective of this study was to determine the association of three currently used definitions for sFGR with demise of the smaller twin, typically the donor, following FLS for TTTS.

METHODS

This was a retrospective cohort study of monochorionic diamniotic twin pregnancies undergoing FLS for TTTS between January 2015 and December 2018. Classification of the cohort as sFGR or non-sFGR was performed using three different definitions: (1) estimated fetal weight (EFW) of one twin < 10^th centile and intertwin EFW discordance > 25%, according to the International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) (Definition A); (2) EFW of one twin < 3^rd centile, according to the solitary criterion for sFGR reported in a Delphi consensus (Definition B); and (3) presence of at least two of four of the following criteria: EFW of one twin < 10^th centile, abdominal circumference of one twin < 10^th centile, intertwin EFW discordance of ≥ 25% and umbilical artery pulsatility index of the smaller twin > 95^th centile, according to the contributory criteria for sFGR in monochorionic diamniotic twin pregnancies reported in the Delphi consensus (Definition C). Pearson's χ² and univariate and multivariate logistic regression analyses were performed to assess the association of classification as sFGR according to the different definitions with fetal demise within 48 h after FLS.

RESULTS

A total of 124 pregnancies underwent FLS for TTTS during the study period. Of these, 46/124 (37.1%) were identified as having sFGR according to the ISUOG criteria (Definition A), 57/124 (46.0%) based on EFW < 3^rd centile (Definition B) and 70/124 (56.5%) according to the Delphi contributory criteria (Definition C). There were no differences in maternal body mass index, recipient twin amniotic fluid volume, gestational age (GA) at intervention or GA at delivery between sFGR and non-sFGR cases for any of the three definitions. There were also no differences in the rates of postprocedure recipient demise or Doppler abnormalities in the recipient. Regardless of the definition used, sFGR cases showed a significantly higher rate of postprocedure donor twin demise compared with that in non-sFGR cases (Definition A: 28.3% vs 3.8%, P < 0.01; Definition B: 22.8% vs 4.5%, P = 0.02; Definition C: 22.9% vs 0%, P < 0.01). For all of the sFGR definitions, the rate of Stage-III TTTS was increased in sFGR compared to non-sFGR cases (Definition A: 65.2% vs 35.9%, P ≤ 0.01; Definition B: 59.6% vs 35.8%, P = 0.04; Definition C: 62.9% vs 25.9%, P < 0.01). All cases of donor demise met the criteria for sFGR according to Definition C. Classification as sFGR according to Definition C was associated with a significantly higher rate of post-FLS donor demise compared to Definitions A and B (χ² , 15.32; P < 0.01). Logistic regression analysis demonstrated that sFGR cases had an increased risk of donor demise (Definition A: odds ratio (OR), 4.97 (95% CI, 1.77-13.94), P < 0.01; Definition B: OR, 4.39 (95% CI, 1.36-14.15), P = 0.01) and that staging of TTTS was also predictive of demise (OR, 2.26 (95% CI, 1.14-4.47), P = 0.02). After adjusting for GA at intervention and stage of TTTS, the results were similar (Definition A: OR, 6.48 (95% CI, 2.11-24.56), P = 0.002; Definition B: OR, 4.16 (95% CI, 1.35-15.74), P = 0.02).

CONCLUSIONS

The rate of fetal demise following FLS for TTTS is increased in the presence of sFGR. Improving diagnosis of sFGR should improve counseling and may affect management. The Delphi method of defining sFGR based on the presence of at least two of four contributory criteria had the highest predictive value for donor demise following FLS for TTTS. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Twin twin transfusion syndrome with and without selective fetal growth restriction: Predictors of donor demise

OBJECTIVE

Evaluate survival in twin twin transfusion syndrome (TTTS) with and without selective fetal growth restriction (sFGR) after fetoscopic laser surgery (FLS).

METHODS

Retrospective study of monochorionic diamniotic twins undergoing FLS. The cohort was classified as TTTS and TTTS with sFGR. Baseline, intra-operative and postoperative variables were analyzed. Mann-Whitney U, Pearson chi-square, Fisher's exact, t-test and receiver operating characteristic (ROC) curve analysis were performed.

RESULTS

Four hundred and ninety-two pregnancies were included, 304 (61.78%) TTTS and 188 (38.22%) TTTS with sFGR. No difference in donor outcomes. TTTS group had higher donor estimated fetal weight (EFW%) percentile (19.7 ± 18.8 vs. 2.2 ± 2.1, p < 0.001). Significant predictors for demise at 30 days were 37% intertwin weight discordance (IWD) with donor EFW% < first (area under ROC curve [AUC] = 0.85, p = 0.001) or IWD >25% and intertwin umbilical artery pulsatility index discordance (DUAPI) ≥0.4 (AUC = 0.71, p = 0.001).

CONCLUSION

Combination of IWD of 37% and donor EFW% <first was most predictive for demise 30 days after birth. DUAPI ≥0.4 was also associated with increased risk for demise.

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.

Second-trimester abdominal circumference discordance and adverse perinatal outcomes in monochorionic twins

OBJECTIVE

The perinatal outcomes in second-trimester abdominal circumference (AC) discordant twins are yet to be established. The aim of this study was to ascertain perinatal risks associated with second-trimester AC discordance in monochorionic (MC) twins.

METHOD

We conducted a retrospective study of all MC twin pregnancies over a 7-year period. Intertwin AC discordance at 14-26 gestational weeks was analyzed in relation to Doppler abnormalities, obstetric complications, and perinatal adverse outcomes.

RESULTS

A total of 246 MC twin pregnancies were included in the analysis. The smaller twins of second-trimester AC discordant pairs were at increased prevalence of abnormal umbilical artery flow (50% versus 24%, p < .001) and low positive A wave of ductus venous flow (24% versus 9%, p = .002). The second-trimester AC discordant twins were at increased risk of oligohydramnios in smaller twin (OR = 2.44, 95% CI = 1.37-4.32, p < .01), cardiomegaly in larger twin (OR = 2.95, 95% CI = 1.01-8.60, p < .05), birth weight of either twin below the 10th percentile for gestational age (OR = 5.56, 95% CI = 2.67-11.59, p < .001), birth weight discordance > 25% (OR = 9.41, 95% CI = 4.46-19.87, p < .001), IUFD (OR = 3.26, 95% CI = 1.76-6.05, p < .001), and severe neonatal morbidity (OR = 1.83, 95% CI = 1.03-3.26, p < .05). The intact survival rate in discordant and concordant twin pairs was 70% and 89%, respectively (p < .001).

CONCLUSIONS

Early and increase fetal surveillance of the second-trimester AC discordant twins should be utilized to establish perinatal risks, thus allowing prenatal care to improve.

Placental characteristics in different types of selective fetal growth restriction in monochorionic diamniotic twins

INTRODUCTION

This study aimed to explore the differences in placental characteristics among three types of selective fetal growth restriction (sFGR) in monochorionic diamniotic twin pregnancies.

MATERIAL AND METHODS

A total of 123 placentas with sFGR between April 2013 and October 2019 were retrospectively analyzed after dye injection. Placental characteristics were compared among the three types.

RESULTS

The gestational age at diagnosis and delivery was less in sFGR II and III than in sFGR I (22.9 [21.7-33.6], 23.3 [20.0-26.1] and 25.7 [19.0-35.0] weeks, p < 0.001; 32.3 [31.6-35.1], 34.1 [29.9-34.7] and 35.5 [34.0-37.0] weeks, p < 0.001). The birthweight discordance ratio was less in sFGR I than in sFGR II (0.28 [0.14-0.43] and 0.30 [0.23-0.37], p < 0.001). The prevalence of a thick artery-artery anastomosis was higher in sFGR III than in sFGR I or II (81.8%, 44.9% and 48.6%, p = 0.010). The placental territory discordance ratio was higher in sFGR II and III than in sFGR I (0.60 [0.17-0.88], 0.60 [0.01-0.80] and 0.50 [0.01-0.71], p = 0.001).

CONCLUSIONS

Compared with sFGR I, the earlier onset time of sFGR II and III might be due to their higher placental territory discordance. The prevalence of thick artery-artery anastomoses was expected to be higher in sFGR III than in sFGR I or II.

Controversies in the management of twin pregnancy

Despite many advances in antenatal care, twin pregnancies still experience more adverse outcomes, in particular perinatal morbidity and mortality. They also pose a multitude of challenges and controversies, as outlined in this Review. Moreover, they are less likely to be included in clinical trials. Many issues on classification and management remain under debate. Efforts at standardizing diagnostic criteria, monitoring protocols, management and outcome reporting are likely to reduce their perinatal risks. The top 10 most important research uncertainties related to multiple pregnancies have been identified by both clinicians and patients. More robust research in the form of randomized trials and large well-conducted prospective cohort studies is needed to address these controversies. © 2020 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Perinatal outcome of monochorionic diamniotic twin pregnancy complicated by selective intrauterine growth restriction according to umbilical artery Doppler flow pattern: single-center study using strict fetal surveillance protocol

OBJECTIVE

To determine the perinatal outcome of monochorionic diamniotic (MCDA) twin pregnancies complicated by selective intrauterine growth restriction (sIUGR), which were classified according to the umbilical artery (UA) Doppler flow pattern of the IUGR twin.

METHODS

This was a retrospective cohort study of all MCDA twin pregnancies diagnosed with sIUGR and managed at a single tertiary referral center between 2012 and 2018. Cases were classified according to the UA Doppler flow pattern of the IUGR twin as Type I (positive end-diastolic flow), Type II (persistently absent/reversed end-diastolic flow) or Type III (intermittently absent/reversed end-diastolic flow). Patients with Type-II or -III sIUGR were hospitalized at 26-28 weeks of gestation for increased fetal surveillance. Perinatal and immediate and long-term neurodevelopmental outcomes were stratified according to the UA Doppler flow pattern at the final examination. Intact survival rate was defined as the number of infants surviving without neurological impairment, divided by the total number of fetuses. Composite adverse outcome, defined as any mortality, presence of severe brain lesions on postnatal transcranial ultrasound or severe neurological morbidity, was also assessed.

RESULTS

Of 88 MCDA twin pregnancies with sIUGR included in the study, 28 underwent selective termination by cord occlusion using radiofrequency ablation, resulting in a perinatal survival rate of 89.3% and a median gestational age (GA) at delivery of 33.8 (interquartile range (IQR), 28.8-38.2) weeks for the large cotwin. Expectant management was employed in 60 cases. In 26 (43.3%) cases in the expectant-management group, the classification according to the UA Doppler flow pattern changed during gestation, resulting in 26 (43.3%) cases of Type-I, 22 (36.7%) cases of Type-II and 12 (20.0%) cases of Type-III sIUGR at the final examination. The perinatal survival rate of both twins with sIUGR Types I, II and III at the final examination was 100%, 81.8% and 75.0%, respectively (P = 0.04). Two cases of double fetal death and one case of single fetal death occurred 1-4 weeks after the Doppler pattern had changed from Type I or Type II to Type III. The median GA at delivery was 34.8 (IQR, 33.1-35.7) weeks in Type I, 30.3 (IQR, 28.6-32.1) weeks in Type II and 32.0 (IQR, 31.3-32.6) weeks in Type III (P < 0.01). The total intact survival rate was 100% for Type I, 77.3% for Type II and 75.0% for Type III (P < 0.001). Multivariate analysis demonstrated that early GA at diagnosis (odds ratio (OR), 0.83 (95% CI, 0.69-0.99); P = 0.04) and the presence of Type II or III vs Type I at the last examination (OR, 13.16 (95% CI, 1.53-113.32); P = 0.02) were associated with preterm birth < 32 weeks' gestation. Early GA at diagnosis was also associated with the composite adverse outcome (OR, 0.60 (95% CI, 0.36-0.99); P = 0.04).

CONCLUSIONS

The classification system of MCDA pregnancy complicated by sIUGR, according to the UA Doppler flow pattern of the IUGR twin at final examination, is associated with perinatal outcome. Importantly, the UA Doppler flow pattern can change during gestation, which has an impact on the risk of fetal death. Nevertheless, under strict fetal surveillance, the perinatal outcome of these pregnancies is favorable. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Maternal and Perinatal Factors Associated With Twin Pregnancies in Ecuador

There are few studies on twins in Ecuador and Latin America. It requires a better understanding of perinatal conditions, especially from an ethnic perspective. This work aims to assess perinatal factors related to twin pregnancy in Ecuadorian Mestizo individuals. We performed an epidemiological, observational and cross-sectional study at the Hospital San Francisco and Hospital Nueva Aurora in Quito, Ecuador, from November 2019 to January 2020. It included 203 newborns from twin pregnancies, including mothers with and without pathological history. The average gestational age was 31 weeks, and the APGAR score at first minute was 6.86, with significant differences. Regarding the metabolic balance, the mean pH was 6.14; and bicarbonate was 11.57, with significant differences. Twins had intrauterine growth restriction in 6.9% of cases, with significant differences (p = .003); 81.4% required supplemental oxygen, with significant differences (p = .002); 93% required noninvasive mechanical ventilation (NIMV), with significant differences (p = . 003); 93% required inotropic and sedation, with substantial differences; 69% required antibiotics (≥21 days), with significant differences (p = .014); and 17.2% needed between 8 to 14 days of hospitalization, and 51% more than 28 days, with significant differences. The studied mothers' demographic profile was mostly Mestizos, with an average age of 32 years, and 93% had a poverty status. Most of the twins were diamniotic monochorial and were discordant twins. It found jaundice, premature anemia and sepsis in 100% of twins and hyaline membrane disease in 89.66% of twins. Twins of women with relevant prenatal care had more premature births (30.4 ± 2.6 weeks), more acid-base imbalance, APGAR at ≥7 min in 90% of cases, and patent ductus arteriosus in all. There was also a greater need for double intensive phototherapy than twins of healthy women.

Outcome of monochorionic twin pregnancy with selective fetal growth restriction at 16, 20 or 30 weeks according to new Delphi consensus definition

OBJECTIVES

To report the outcome of selective fetal growth restriction (sFGR) diagnosed according to the new Delphi consensus definition, and determine potential predictors of survival, in a cohort of unselected monochorionic diamniotic twin pregnancies.

METHODS

This was a retrospective study of monochorionic diamniotic twin pregnancies followed from the first trimester onward, which were diagnosed with sFGR at 16, 20 or 30 weeks' gestation. sFGR was defined according to the new Delphi consensus criteria as presence of either an estimated fetal weight (EFW) < 3^rd centile in one twin or at least two of the following: EFW of one twin < 10^th centile, abdominal circumference of one twin < 10^th centile, EFW discordance ≥ 25% or umbilical artery pulsatility index of the smaller twin > 95^th centile. The primary outcomes were the overall survival rate (up to day 28 after birth) and risk of loss of one or both twins. We further determined possible predictors of survival using uni- and multivariate generalized estimated equation modeling.

RESULTS

We analyzed 675 pregnancies, of which 177 (26%) were diagnosed with sFGR at 16, 20 or 30 weeks. The overall survival rate was 313/354 (88%) with 146/177 (82%) pregnancies resulting in survival of both twins, 21/177 (12%) in survival of one twin and 10/177 (6%) in loss of both twins. Subsequent twin anemia-polycythemia sequence (TAPS) developed in 6/177 (3%) and twin-twin transfusion syndrome (TTTS) in 17/177 (10%) pregnancies. All TAPS fetuses survived. The survival rate in sFGR pregnancies that subsequently developed TTTS was 65% (22/34), compared with 91% (279/308) in those with isolated sFGR (no subsequent TAPS or TTTS) (P < 0.001). The majority of sFGR cases were Type I (110/177 (62%)) and had a survival rate of 96% (212/220), as compared with a survival of 55% (12/22) in those with Type-II (P < 0.001) and 83% (55/66) in those with Type-III (P = 0.006) sFGR. The majority of sFGR pregnancies (130/177 (73%)) were first diagnosed at 16 or 20 weeks (early onset), with a survival rate of 85% (221/260), as compared with a survival of 98% (92/94) in sFGR first diagnosed at 30 weeks (late onset) (P = 0.04). A major anomaly in at least one twin was present in 28/177 (16%) sFGR cases. In these pregnancies, survival was 39/56 (70%), compared with 274/298 (92%) in those without an anomaly (P < 0.001). Subsequent development of TTTS (odds ratio (OR), 0.18 (95% CI, 0.06-0.52)), Type-II sFGR (OR, 0.06 (95% CI, 0.02-0.24)) and Type-III sFGR (OR, 0.21 (95% CI, 0.07-0.60)) and presence of a major anomaly in at least one twin (OR, 0.12 (95% CI, 0.04-0.34)), but not gestational age at first diagnosis, were independently associated with decreased survival.

CONCLUSIONS

Isolated sFGR is associated with a 90% survival rate in monochorionic diamniotic twin pregnancies. The subsequent development of TTTS, absent or reversed end-diastolic flow in the umbilical artery of the smaller twin and the presence of a major anomaly adversely affect survival in sFGR. Copyright © 2020 ISUOG. Published by John Wiley & Sons Ltd.

Are Twin Pregnancies Complicated by Weight Discordance or Fetal Growth Restriction at Higher Risk of Preeclampsia?

Studies have reported controversial findings on the association between fetal growth restriction (FGR) or intertwin weight discordance and the risk of hypertensive disorders of pregnancy (HDP) in twin pregnancies. The aim of this study was to investigate the association between twin growth disorders and HDP. Twin pregnancies resulting in two live births at St George’s Hospital between 2000 and 2019 were included. FGR or small-for-gestational-age (SGA) at birth was assessed using singleton and twin reference charts. Intertwin discordance [(large birthweight − small birthweight)/(large birthweight) × 100%)] was calculated. Logistic regression models were performed. SGA (aOR 2.34, 95% CI 1.60–3.44, p < 0.001), intertwin discordance ≥25% (aOR 2.10, 95% CI 1.26–3.49, p = 0.004) and their co-existence (aOR 2.03, 95% CI 1.16–3.54, p = 0.013) were significantly associated with HDP. After adjusting for the known maternal risk factors of HDP and the intertwin discordance, SGA (using the twin charts) was the strongest independent risk factor associated with HDP (aOR 2.12, 95% CI 1.40–3.22, p < 0.001) and preeclampsia (aOR 2.34, 95% CI 1.45–3.76, p < 0.001). This study highlights that the presence of at least one SGA twin is significantly associated with HDP during pregnancy. Therefore, maternal blood pressure should be closely monitored in twin pregnancies complicated by SGA with or without intertwin discordance.

Expectant Management of Monochorionic-Triamniotic Triplets Complicated by Selective In Utero Growth Restriction: Report of 2 Cases

The optimal management of monochorionic-triamniotic (MCTA) triplet pregnancies is not clearly established, and there is no literature to guide management of MCTA complicated with selective intrauterine growth restriction (sIUGR). This gap in knowledge and the concern for higher risk of severe complications have led some medical societies to recommend selective termination of nontrichorionic triplet pregnancies. We sought to report the favourable outcomes of two MCTA complicated by sIUGR expectantly managed at Sainte-Justine Hospital, Montreal, Canada. The first case is of a 42-year-old woman with spontaneous MCTA triplets diagnosed at 18 weeks with type II sIUGR who opted for expectant management. The second patient was a 22-year-old woman with a spontaneous MCTA triplet pregnancy diagnosed at 18 weeks with type III sIUGR. Our experience shows that close serial ultrasounds could potentially allow physicians to foresee fetal deterioration. In our opinion, expectant management should be considered as a management option for MCTA complicated by sIUGR.

Notching and Pulsatility Index of the Uterine Arteries and Preeclampsia in Twin Pregnancies

Increased uterine artery Doppler indices have been shown to be associated with preeclampsia and adverse pregnancy outcomes in singleton and twin pregnancies. At 20–22 weeks of gestation, we assessed the use of notching, the highest, lowest, and mean pulsatility index (PI), and the combination of notching and PI of the uterine arteries to screen for preeclampsia. This was done in a cohort of 380 twin pregnancies. The results showed that the combination of notching and the highest PI above the 95th centile of the uterine arteries gives the best screening characteristics for preeclampsia in twin pregnancies. We calculated sensitivities for preeclampsia for notching, highest PI, and the combination of notching and the highest PI of 50%, 45% and 91%, with specificities of 96%, 96% and 93%, respectively. The present findings demonstrate that notching, increased highest PI, and the combination of notching and the highest PI of the uterine arteries is associated with an increased risk of preeclampsia in twin pregnancies. We observed the highest sensitivity and specificity by using the combination of notching and the highest PI of the uterine arteries.

The Association Between Hypertension in Pregnancy and Preterm Birth with Fetal Growth Restriction in Singleton and Twin Pregnancy: Use of Twin Versus Singleton Charts

OBJECTIVE

To compare the rates of fetal growth restriction (FGR) in singleton and twin pregnancies using singleton and twin-specific birthweight standards.

METHODS

The study included liveborn twin and singleton pregnancies between January 2000 and January 2019. Hypertensive disorders of pregnancy (HDP) included gestational hypertension and pre-eclampsia. The study outcomes were FGR or small-for-gestational-age (SGA) at birth as assessed using singleton and twin reference charts.

RESULTS

The analysis included 1473 twin and 62,432 singleton pregnancies. In singleton pregnancies the risk of PTB <34 weeks without HDP (OR 2.82, p < 0.001), delivery ≥34 weeks with HDP (OR 2.38, p < 0.001), and PTB <34 weeks with HDP (OR 13.65, p < 0.001) were significantly higher in the pregnancies complicated by FGR compared to those without. When selective fetal growth restriction (sFGR) was assessed using the singleton standard, the risk of PTB <34 weeks without HDP (OR 1.03, p = 0.872), delivery ≥34 weeks with HDP (OR 1.36, p = 0.160) were similar in the pregnancies complicated by sFGR compared to those without, while the risk of PTB <34 weeks with HDP (OR 2.41, p = 0.025) was significantly higher in the pregnancies complicated by sFGR compared to those without. When sFGR was assessed using the twin-specific chart, the risk of PTB <34 weeks without HDP (OR 3.55, p < 0.001), delivery ≥34 weeks with HDP (OR 3.17, p = 0.004), and PTB <34 weeks with HDP (OR 5.69, p < 0.001) were significantly higher in the pregnancies complicated by sFGR compared to those without. The stronger and more consistent association persisted in the subgroup analyses according to chorionicity. The strength of association in dichorionic twin pregnancies resembles that of the singletons more closely and consistently when the FGR was diagnosed using the twin-specific charts.

CONCLUSION

FGR in twin pregnancies has a stronger and more consistent association with HDP and PTB when using twin-specific rather than singleton charts. This study provides further evidence supporting the use of twin-specific charts when assessing fetal growth in twin pregnancies.

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.

Selective intrauterine growth restriction (SIUGR) type II: proposed subclassification to guide surgical management

Background: Optimal surgical management of monochorionic diamniotic twins complicated by selective intrauterine growth restriction (SIUGR) type II is unknown. Surgical management may involve selective laser photocoagulation of communicating vessels (SLPCV), which offers the possibility of dual twin survivors versus umbilical cord occlusion (UCO) of the SIUGR twin.Objective: To identify patient characteristics associated with SIUGR twin survival for those undergoing SLPCV.Study design: All patients studied were those who underwent fetal treatment for SIUGR type II at our center from 2006-2018. SIUGR type II was defined as an estimated fetal weight <10th percentile with persistent absent and/or reversed end diastolic flow in the umbilical artery of the SIUGR twin, in the absence of twin-twin transfusion syndrome. Patients were offered SLPCV versus UCO, and those undergoing SLPCV, patient characteristics associated with 30-day survival of the SIUGR twin were examined using bivariate analysis and multiple logistic regression models.Results: Fifty-four consecutive SIUGR type II patients were treated, 45 via SLPCV and nine via UCO. Of the 45 SLPCV cases, there were 16 (35.6%) with SIUGR twin (and dual) survival. SIUGR twin survival appeared associated with middle cerebral artery (MCA) peak systolic velocity (psv) <1.5 multiples of the median, and forward atrial systolic flow in the ductus venosus (DV). In a post hoc analysis, we subsequently categorized patients as: SIUGR type IIa (N = 32 (71.1%)): normal MCA psv, and normal DV waveform, versus SIUGR type IIb (N = 13 (28.9%)): MCA psv ≥1.5 multiples of the median, and/or DV with absent or reversed atrial systolic flow. Thirty-day survival of the SIUGR twin was 50% for type IIa and 0% for type IIb.Conclusion: Over one-third of SIUGR type II patients experienced dual survival after treatment with laser surgery. Normal MCA psv and normal DV waveforms were associated with SIUGR type II survival of the SIUGR twin. Post hoc exploration and subclassification of SIUGR type II patients by preoperative Doppler indices created two groups, one (type IIa) with 50% survival and one (type IIb) with 0% survival of the SIUGR twin after laser surgery. Upon further confirmation, these findings may provide guidance for counseling patients and conducting fetal therapy.

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.