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

Perinatal outcomes of fetoscopic selective laser photocoagulation for spontaneous twin-anemia polycythemia sequence

OBJECTIVES

Antenatal management of monochorionic pregnancies complicated by twin anemia polycythemia sequence (TAPS) remains sub-optimally defined. Our objective was to evaluate the safety and efficacy of fetoscopic selective laser photocoagulation with respect to fetal and neonatal survival.

METHODS

A case series is reported with patients referred to the Texas Children's Fetal Center for evaluation and management of suspected spontaneous TAPS without concomitant twin-to-twin syndrome from 2014 to 2023. All evaluations were performed by our team and patients with stage II-IV TAPS were offered expectant management, intrauterine transfusion, or laser therapy. Cases of post-laser TAPS were excluded from this study. Pregnancy and neonatal outcomes were obtained from electronic medical records.

RESULTS

During a 10-year time period, 18 patients presented to our center for the management of TAPS. Thirteen patients had stage II-IV TAPS (13/18, 72%) and elected to proceed with laser photocoagulation. All procedures were completed, and "solomonization" was performed for 12/13. Normalization of middle cerebral artery Dopplers in both fetuses was noted after all cases. There was one intrauterine fetal death of the 26 viable fetuses after laser treatment, which was complicated by selective growth restriction. Most patients (12/13) were delivered by Cesarean section at a mean gestational age of 29 ± 3 weeks. Subsequently, there was one ex-donor neonatal death in an infant who had prenatal hydrops. Overall, 30-day postnatal survival was 24/26 fetuses (92.3%).

CONCLUSIONS

In the setting of spontaneous TAPS, laser therapy is feasible and appears to be an effective approach with overall favorable perinatal outcomes.

Cardiac adaptation and malformation in twin-twin transfusion syndrome and selective fetal growth restriction: A systematic review

OBJECTIVES

This systematic review explores cardiac adaptation in monochorionic (MC) twins with twin-twin transfusion syndrome (TTTS) or selective fetal growth restriction (sFGR) and assesses the risk of congenital heart defects (CHDs).

METHODS

Adhering to PRISMA guidelines, 63 studies were reviewed (49 on cardiac adaptation, 13 on CHD, one on both). A narrative synthesis of cardiac adaptation patterns was performed. Additionally, a meta-analysis compared the livebirth prevalence of CHD in TTTS and sFGR against uncomplicated MC twins.

RESULTS

In TTTS recipients, cardiac function may be impaired for diastolic, systolic, as well as global functions, while in donors, cardiac function is generally preserved. In sFGR, large twins may show hypertrophic cardiomyopathy, and small twins may show impaired systolic function. Co-occurrence of TTTS and sFGR magnifies cardiac impact but is often underreported. Meta-analysis for CHD prevalence revealed a relative risk ratio of 3.5 (95% CI: 2.5-4.9) for TTTS and 2.2 (95%CI: 1.3-3.5) for sFGR compared with uncomplicated MC twins.

CONCLUSIONS

This study highlights the well-documented cardiac adaptation in TTTS, contrasting with limited understanding in sFGR. Elevated CHD risks were observed in both conditions. Enhanced cardiovascular surveillance is warranted in complicated MC twin pregnancies. Future research should explore cardiac adaptation in sFGR and its long-term consequences.

Amniotic fluid metabolic fingerprinting contributes to shaping the unfavourable intrauterine environment in monochorionic diamniotic twins

BACKGROUND & AIMS

Amniotic fluid (AF) is the primary intrauterine environment for fetal growth throughout gestation. Selective fetal growth restriction (sFGR) is an adverse complication characterized by unequal growth in twins with nearly identical genetic makeup. However, the influence of AF-mediated intrauterine environment on the development and progression of sFGR remains unexplored.

METHODS

High-throughput targeted metabolomics analysis (G350) was performed on AF samples collected from sFGR (n = 18) and MCDA twins with birth weight concordance (MCDA-C, n = 20) cases. Weighted correlation network analysis (WGCNA) was used to identify clinical features that may influence the metabolite composition in AF. Subsequently, partial least-squares discriminant analysis (PLS-DA) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed to compare the different types of sFGR and MCDA-C twins. Receiver operating characteristic (ROC) and multivariate ROC curves were utilized to explore potential AF markers in twins with sFGR.

RESULTS

In our study, 182 metabolites were quantified in 76 AF samples. WGCNA indicated that the metabolite composition in late AF may not be influenced by gestational age. PLSDA demonstrated distinct variations between the metabolite profiles of AF in the sFGR and MCDA-C twins, with a significant emphasis on amino acids as the primary differential metabolite. The dissimilarities observed in sFGR twins were predominantly attributed to lipid metabolism-related metabolites. In particular, the KEGG enrichment metabolic pathway analysis revealed significant associations of both types of sFGR twins with central carbon metabolism in cancer. The multivariate ROC curves indicated that the combination of carnosine, sarcosine, l-alanine, beta-alanine, and alpha-n-phenylacetylglutamine significantly improved the AUC to 0.928. Notably, the ROC curves highlighted creatine (AUC:0.934) may be a potential biomarker for severe sFGR.

CONCLUSION

The data presented in this study offer a comprehensive metabolic map of the AF in cases of sFGR, shedding light on potential biomarkers associated with fetal growth and development in MCDA twins.

Neurological morbidity in monochorionic twins with selective fetal growth restriction

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

Thick artery-artery anastomoses delay the onset of selective fetal growth restriction in monochorionic diamniotic twins: a 7-year single-center cohort study

Objective

This study aimed to investigate differences in placental characteristics between early- and late-onset selective fetal growth restriction (sFGR) in monochorionic diamniotic twins.

Methods

A total of 253 patients with sFGR between April 2013 and April 2020 were retrospectively analyzed. Placental characteristics of early- and late-onset sFGR were compared.

Results

The gestational age at diagnosis and delivery in the early-onset group was significantly less than that in the late-onset group [22.0 (16.9-23.9) and 28.4 (24.0, 36.3) weeks, P < 0.001; 33.1 ± 2.2 and 33.7 ± 2.5 weeks, P = 0.025]. The birth weight of normal growth and growth-restricted fetuses in the early-onset group was less than the late-onset group [1,990 ± 422 and 2,162 ± 525 g, P = 0.044; 1,320 ± 409 and 1,595 ± 519 g, P = 0.001]. The birthweight discordance ratio in the early-onset group was greater than the late-onset group (0.34 ± 0.12 and 0.29 ± 0.13, P = 0.001). The early-onset group had a significantly lower prevalence of sFGR type I than the late-onset group (37.5 and 62.0%, P = 0.018). The early-onset group had a significantly higher prevalence of sFGR type III than the late-onset group (30.4 and 12.7%, P = 0.048). The early-onset group had a lower prevalence of thick artery-artery anastomoses than the late-onset group (37.5 and 62.0%, P = 0.006). The placental territory discordance ratio in the early-onset group was higher than in the late-onset group [0.60 (0.01, 0.80) and 0.50 (0.01, 0.88), P = 0.018].

Conclusion

Unequal placental territory is the cause for most of the late-onset sFGR. Thick artery-artery anastomoses may delay the onset time of these cases of sFGR.

Placental differences between uncomplicated and complicated monochorionic diamniotic pregnancies on diffusion and multicompartment Magnetic Resonance Imaging

INTRODUCTION

Twin-twin transfusion syndrome (TTTS) and selective fetal growth restriction (sFGR) are common complications in monochorionic diamniotic (MCDA) pregnancies. The Diffusion-rElaxation Combined Imaging for Detailed Placental Evaluation (DECIDE) model, a placental-specific model, separates the T2 values of the fetal and maternal blood from the background tissue and estimates the fetal blood oxygen saturation. This study investigates diffusion and relaxation differences in uncomplicated MCDA pregnancies and MCDA pregnancies complicated by TTTS and sFGR in mid-pregnancy.

METHODS

This prospective monocentric cohort study included uncomplicated MCDA pregnancies and pregnancies complicated by TTTS and sFGR. We performed MRI with conventional diffusion-weighted imaging (DWI) and combined relaxometry - DWI-intravoxel incoherent motion. DECIDE analysis was used to quantify different parameters within the placenta related to the fetal, placental, and maternal compartments.

RESULTS

We included 99 pregnancies, of which 46 were uncomplicated, 12 were complicated by sFGR and 41 by TTTS. Conventional DWI did not find differences between or within cohorts. On DECIDE imaging, fetoplacental oxygen saturation was significantly lower in the smaller member of sFGR (p = 0.07) and in both members of TTTS (p = 0.01 and p = 0.004) compared to the uncomplicated pairs. Additionally, average T2 relaxation time was significantly lower in the smaller twin of the sFGR (p = 0.004) compared to the uncomplicated twins (p = 0.03).

CONCLUSION

Multicompartment functional MRI showed significant differences in several MRI parameters between the placenta of uncomplicated MCDA pregnancies and those complicated by sFGR and TTTS in mid-pregnancy.

Outcome of laser photocoagulation in monochorionic diamniotic twin pregnancy complicated by Type-II selective fetal growth restriction

OBJECTIVES

To evaluate the outcome of monochorionic diamniotic (MCDA) twins complicated by Type-II selective fetal growth restriction (sFGR) who underwent fetoscopic laser photocoagulation and to validate a previously proposed subclassification system for Type-II sFGR in a large multicenter cohort.

METHODS

This retrospective multicenter cohort study included all MCDA twins complicated by Type-II sFGR who underwent laser photocoagulation of placental anastomoses at four large tertiary fetal-care centers between 2006 and 2020. Cases were subclassified according to a recently proposed system based on Doppler evaluation of the ductus venosus (DV) and middle cerebral artery (MCA) into Type-IIA (normal DV flow and MCA peak systolic velocity (PSV) of the growth-restricted fetus) or Type-IIB (absent or reversed flow in the DV during atrial contraction and/or MCA-PSV ≥ 1.5 multiples of the median of the growth-restricted fetus). Demographic characteristics and pregnancy outcomes were compared between the groups. Data are presented as mean ± SD or n (%) as appropriate. P-values < 0.05 were considered statistically significant.

RESULTS

A total of 98 patients with MCDA twins met our inclusion criteria, with 56 subclassified as Type IIA and 42 as Type IIB. Demographic characteristics were similar between the groups; however, Type-IIB cases had a significantly earlier gestational age at diagnosis and at laser surgery, as well as larger intertwin estimated fetal weight discordance, which may be a reflection of disease severity. Postnatal survival of the growth-restricted fetus to 30 days of age was significantly lower in Type-IIB compared to Type-IIA cases (23.8% vs 46.4%; P = 0.034).

CONCLUSIONS

In MCDA twins complicated by Type-II sFGR and treated with laser photocoagulation of placental anastomoses, preoperative Doppler assessment of the DV and MCA helped identify a subset of patients at increased risk of demise of the growth-restricted fetus following intervention. This study provides valuable information for guiding surgical management and patient counseling. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Directive clinique no 440 : Prise en charge de la grossesse gémellaire monochoriale

OBJECTIF

Cette directive clinique passe en revue les données probantes sur la prise en charge de la grossesse gémellaire monochoriale normale et compliquée.

POPULATION CIBLE

Les femmes menant une grossesse gémellaire ou multiple de haut rang. BéNéFICES, RISQUES ET COûTS: L'application des recommandations de cette directive devrait améliorer la prise en charge des grossesses gémellaires (ou multiples de haut rang) monochoriales compliquées et non compliquées. Ces recommandations aideront les fournisseurs de soins à surveiller adéquatement les grossesses gémellaires monochoriales ainsi qu'à détecter et prendre en charge rapidement les complications associées de façon optimale afin de réduire les risques de morbidité et mortalité périnatales. Ces recommandations impliquent une surveillance échographique plus fréquente en cas de grossesse monochoriale qu'en cas de grossesse bichoriale. DONNéES PROBANTES: La littérature publiée a été colligée par des recherches dans les bases de données PubMed et Cochrane Library au moyen de termes MeSH pertinents (Twins, Monozygotic; Ultrasonography, Prenatal; Placenta; Fetofetal Transfusion; Fetal Death; Fetal Growth Retardation). Les résultats ont été restreints aux revues systématiques, aux essais cliniques randomisés et aux études observationnelles. Aucune date limite n'a été appliquée, mais les résultats ont été limités aux contenus en anglais ou en français. MéTHODES DE VALIDATION: Les auteurs principaux ont rédigé le contenu et les recommandations et ils se sont entendus sur ces derniers. Le conseil d'administration de la SOGC a approuvé la version définitive aux fins de publication. Les auteurs ont évalué la qualité des données probantes et la force des recommandations en utilisant le cadre méthodologique GRADE (Grading of Recommendations Assessment, Development and Evaluation). Voir l'annexe A en ligne (tableau A1 pour les définitions et tableau A2 pour l'interprétation des recommandations fortes et conditionnelles [faibles]). PROFESSIONNELS CONCERNéS: Spécialistes en médecine fœto-maternelle, obstétriciens, radiologues, échographistes, médecins de famille, infirmières, sages-femmes, résidents et autres fournisseurs de soins de santé qui s'occupent de femmes menant une grossesse gémellaire ou multiple de haut rang. RéSUMé POUR TWITTER: Directive canadienne (SOGC) pour le diagnostic, la surveillance échographique et la prise en charge des complications de la grossesse gémellaire monochoriale (p. ex., STT, TAPS, retard de croissance sélectif, cojumeau acardiaque, monoamnionicité et mort d'un jumeau). DÉCLARATIONS SOMMAIRES: RECOMMANDATIONS.

Guideline No. 440: Management of Monochorionic Twin Pregnancies

OBJECTIVE

This guideline reviews the evidence-based management of normal and complicated monochorionic twin pregnancies.

TARGET POPULATION

Women with monochorionic twin or higher order multiple pregnancies.

BENEFITS, HARMS, AND COSTS

Implementation of these recommendations should improve the management of both complicated and uncomplicated monochorionic (and higher order multiple) twin pregnancies. They will help users monitor monochorionic twin pregnancies appropriately and identify and manage monochorionic twin complications optimally in a timely manner, thereby reducing perinatal morbidity and mortality. These recommendations entail more frequent ultrasound monitoring of monochorionic twins compared to dichorionic twins.

EVIDENCE

Published literature was retrieved through searches of PubMed and the Cochrane Library using appropriate MeSH headings (Twins, Monozygotic; Ultrasonography, Prenatal; Placenta; Fetofetal Transfusion; Fetal Death; Fetal Growth Retardation). Results were restricted to systematic reviews, randomized controlled clinical trials, and observational studies. There were no date limits, but results were limited to English or French language materials.

VALIDATION METHODS

The content and recommendations were drafted and agreed upon by the principal authors. The Board of the SOGC approved the final draft for publication. The authors rated the quality of evidence and strength of recommendations using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. See online Appendix A (Tables A1 for definitions and A2 for interpretations of strong and conditional [weak] recommendations).

INTENDED AUDIENCE

Maternal-fetal medicine specialists, obstetricians, radiologists, sonographers, family physicians, nurses, midwives, residents, and other health care providers who care for women with monochorionic twin or higher order multiple pregnancies.

TWEETABLE ABSTRACT

Canadian (SOGC) guidelines for the diagnosis, ultrasound surveillance and management of monochorionic twin pregnancy complications, including TTTS, TAPS, sFGR (sIUGR), acardiac (TRAP), monoamniotic twins and intrauterine death of one MC twin.

SUMMARY STATEMENTS

RECOMMENDATIONS.

Prediction of dual survival following fetoscopic laser photocoagulation for twin-twin transfusion syndrome

OBJECTIVE

To develop a model based on factors available at the time of diagnosis of twin-twin transfusion syndrome (TTTS) for predicting the probability of dual twin survival following fetoscopic laser photocoagulation (FLP) using a machine-learning algorithm.

METHODS

This was a retrospective study of data collected at two university-affiliated tertiary fetal centers between 2012 and 2021. The cohort included monochorionic diamniotic twin pregnancies complicated by TTTS that underwent FLP. Data were stratified based on survival 30 days after delivery, and cases with dual survival were compared to those without dual survival. A random forest machine-learning algorithm was used to construct a prediction model, and the relative importance value was calculated for each parameter that presented a statistically significant difference between the two study groups and was included in the model. The holdout method was applied to check overfitting of the random forest algorithm. A prediction model for dual twin survival 30 days after delivery was presented based on the test set.

RESULTS

The study included 537 women with monochorionic diamniotic twin pregnancy, of whom 346 (64.4%) had dual twin survival at 30 days after delivery and were compared with 191 (35.6%) cases that had one or no survivors. Univariate analysis demonstrated no differences in demographic parameters between the groups. At the time of diagnosis, the dual-survival group had lower rates of estimated fetal weight (EFW) < 10th centile for gestational age in the donor twin (56.4% vs 69.4%; P = 0.004), intertwin EFW discordance > 25% (40.8% vs 56.5%; P = 0.001) and anterior placenta (40.5% vs 50.0%; P = 0.034). Comparison of Doppler findings between the two groups demonstrated significant differences in the donor twin, with a lower rate of pulsatility index (PI) > 95th centile in the umbilical artery and ductus venosus and a lower rate of PI < 5th centile in the fetal middle cerebral artery in the dual-survival group. Relative importance values for each of these six parameters were calculated, allowing the construction of a prediction model with an area under the receiver-operating-characteristics curve of 0.916 (95% CI, 0.887-0.946).

CONCLUSIONS

We developed a predictive model for dual survival in monochorionic twin pregnancies following FLP for TTTS, which incorporates six variables obtained at the time of diagnosis of TTTS, including donor EFW < 10th centile, intertwin EFW discordance > 25%, anterior placenta and abnormal PI in the umbilical artery, ductus venosus and middle cerebral artery of the donor twin. This clinically applicable tool may improve treatment planning and patient counseling. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

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.

Umbilical venous diameter and flow in monochorionic diamniotic twin pregnancy: association with placental sharing and fetal demise

OBJECTIVE

To examine the association of umbilical venous diameter and flow in monochorionic diamniotic twin pregnancy with placental sharing and fetal demise.

METHODS

This was a prospective longitudinal cohort study of a consecutive series of monochorionic diamniotic twin pregnancies that underwent ultrasound assessments at 12, 16, 20 and 28 weeks' gestation. Fetal biometry (crown-rump length at 12 weeks or estimated fetal weight (EFW) thereafter) and cord insertion sites were recorded at each visit, as well as the diameter of the umbilical vein (UV) in both the intra-abdominal part and a free loop of the umbilical cord. Time-averaged maximum velocity in the intra-abdominal part of the UV was measured to calculate UV-flow. Univariate and multivariate linear regression analyses were performed to assess the relationship between intertwin ratios of these variables and placental sharing at 12, 16, 20 and 28 weeks' gestation. Placental sharing was calculated by dividing the larger by the smaller placental share, as measured on placental injection studies after birth. Additionally, the Mann-Whitney U-test and receiver-operating-characteristics-curve analysis were used to explore the relationship between the occurrence of fetal demise and intertwin differences in fetal biometry, cord insertion sites, UV diameters and flow at 12, 16, 20 and 28 weeks.

RESULTS

Of 200 consecutive monochorionic twin pregnancies enrolled, injection studies were performed in 165 (82.5%) placentas. On univariate analysis, intertwin differences in fetal biometry, cord insertions and UV variables were associated significantly with placental sharing at 12, 16, 20 and 28 weeks' gestation. On multivariate analysis, intertwin differences in fetal biometry, cord insertions and all three UV variables remained associated significantly with placental sharing at 12 and 16 weeks. However, at 20 and 28 weeks, only the intertwin EFW ratio was associated consistently with placental sharing. Fetal demise of one or both twins complicated 26 (13.0%) pregnancies. Differences in EFW and cord insertion sites were not associated significantly with fetal demise, while at 16 weeks, differences in intra-abdominal UV diameter and flow were associated with an increased risk of subsequent fetal demise.

CONCLUSIONS

At 12 and 16 weeks' gestation, intertwin differences in UV diameter and flow reflect placental sharing more accurately than do differences in fetal growth and cord insertion sites. At 16 weeks, discordance in intra-abdominal UV diameter and flow is also associated with an increased risk of fetal demise. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

DISCUSSION

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

Gestational Age at Birth and outcome in Monochorionic Twins with Different Types of Selective Fetal Growth Restriction: A Systematic Literature Review

This systematic review aims to assess the gestational age at birth and perinatal outcome (intrauterine demise (IUD), neonatal mortality and severe cerebral injury) in monochorionic (MC) twins with selective fetal growth restriction (sFGR), according to Gratacós classification based on umbilical artery Doppler flow patterns in the smaller twin. Seventeen articles were included. Gestational age at birth varied from 33.0-36.0 weeks in type I, 27.6-32.4 weeks in type II, and 28.3-33.8 weeks in type III. IUD rate differed from 0-4% in type I to 0-40% in type II and 0-23% in type III. Neonatal mortality rate was between 0-10% in type I, 0-38% in type II, and 0-17% in type III. Cerebral injury was present in 0-2% of type I, 2-30% of type II and 0-33% of type III cases. The timing of delivery in sFGR varied substantially among studies, particularly in type II and III. The quality of evidence was moderate due to heterogenous study populations with varying definitions of sFGR and perinatal outcome parameters, as well as a lack of consensus on the use of the Gratacós classification, leading to substantial incomparability. Our review identifies the urgent need for uniform antenatal diagnostic criteria and definitions of outcome parameters. This article is protected by copyright. All rights reserved.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The Delphi definition for selective fetal growth restriction may not improve detection of pathologic growth discordance in monochorionic twins

BACKGROUND

A consensus definition of selective fetal growth restriction (sFGR) in monochorionic diamniotic (MCDA) twins was recently proposed following a Delphi procedure involving an international panel of experts. The new definition augments the traditional definition with additional sonographic criteria.

OBJECTIVE

We sought to determine whether the augmentations of the "Delphi definition" identified additional morbidity and mortality compared to a traditional definition. We also sought to determine the benefit of each definition in identifying pathologic growth restriction relative to uncomplicated MCDA twins.

STUDY DESIGN

This is a retrospective analysis of unselected MCDA twins that underwent fortnightly ultrasound surveillance at a single center between 2011 and 2020. Patients with concomitant twin-to-twin transfusion (TTTS) syndrome, twin anemia polycythemia sequence (TAPS) or twin reverse arterial profusion (TRAP) sequence at the time of sFGR diagnosis were excluded. Diagnosis of sFGR by the Delphi definition required either an estimated fetal weight (EFW) < 3^rd percentile or presence of two of the following four observations in the smaller twin: i) EFW < 10^th percentile, ii) EFW discordance > 25%, iii) abdominal circumference < 10^th percentile, iv) umbilical artery pulsatility index (UA PI) > 95^th percentile. Diagnosis by the traditional definition required EFW < 10^th percentile and EFW discordance > 25%. To determine the efficacy of the augmentations in the Delphi definition, three groups were compared: Group I - uncomplicated MCDA twins, Group II - twins with sFGR by the traditional definition (and therefore the Delphi definition), Group III - twins with sFGR solely by the Delphi definition. Demographic characteristics, subsequent development of TTTS or TAPS, pregnancy outcomes and neonatal outcomes were compared.

RESULTS

There were 325 patients with MCDA twins meeting inclusion criteria. Of these, 213 (Group I, 66%) were uncomplicated, 37 (Group II, 11%) met the traditional definition for sFGR, 112 (35%) met the Delphi definition for sFGR with 75 (67%) meeting solely the Delphi definition (Group III). Demographic characteristics were similar between groups. Patients in Group II delivered earlier than uncomplicated twins (32.1 vs. 35.7 wks, p <0.01) and patients in Group III (32.1 vs 35.6, p < 0.01). They were also more likely to have critical UA Doppler abnormalities (38% vs. 4%, p < 0.01) and be delivered for deteriorating fetal status (30% vs. 5%, p < 0.01) compared with patients in group III. Overall, survival was lower in Group II than Groups I and III (89% vs. 96% and 100% respectively, p = 0.04). Composite neonatal morbidity and mortality was also greater in Group II (30%) compared with either Group I (6%, p < 0.01) or Group III (9%, p < 0.01). Rates of composite neonatal morbidity and mortality were similar between Groups I and III (p = 0.28).

CONCLUSIONS

Addition of AC and PI UA thresholds, as well as isolated EFW < 3% for diagnosis of sFGR, as proposed by the Delphi definition, increased diagnosis of sFGR, however there was no added benefit in identification of growth discordant pregnancies at risk for adverse outcomes. Prospective analysis of MCDA twins is required to contextualize these findings.

A study on the correlation of placental characteristics and the onset of selective intrauterine growth restriction

OBJECTIVE

To investigate the correlation between placental characteristics and the onset of selective intrauterine growth restriction (sIUGR) and to explore the influence of placental characteristics on sIUGR onset.

METHODS

A retrospective cohort study was conducted at our hospital from April 2013 to April 2019. The pregnancy data and placental perfusion of 114 sIUGR patients who had received conservative treatment and delivered in our hospital were included. Correlation analysis was conducted between the total diameter of placental anastomoses, placental territory discordance, umbilical cord insertion point distance ratio, and the onset time of sIUGR.

RESULTS

The prevalence of AA anastomoses was 88.6% (101/114), with an average total diameter of 2.8  ±  1.5 mm, the prevalence of AV anastomoses was 93.9% (107/114), with an average diameter of 5.4  ±  3.6 mm, and the prevalence of VV anastomoses was 18.4% (21/114), with an average diameter of 4.0  ±  1.9 mm. There was a significant negative correlation between the time of sIUGR onset and the placental territory discordance ratio with a Spearman correlation coefficient of -0.306 (P  =  0.001).

CONCLUSIONS

The larger the placental territory discordance, the earlier onset time of sIUGR.

Monochorionic diamniotic twin pregnancies

About one in five twin pregnancies are monochorionic diamniotic. In these twins, transfusion imbalances may develop due to the invariably present vascular anastomoses. The most severe imbalance is twin-twin transfusion syndrome, which presents as a significant amniotic fluid difference diagnosed on ultrasound scan, usually before 26 weeks. Another transfusion imbalance is twin anemia polycythemia sequence, a severe hemoglobin difference occurring mainly after 26 weeks in previously uncomplicated pregnancies. Fetoscopic laser coagulation of the anastomoses addresses the cause of these transfusion imbalances. Besides transfusion imbalances, the monochorionic placenta may be unevenly divided, or one part may be dysfunctional, leading to an intertwin growth difference of more than 20%. Here, laser ablation of the anastomoses will usually not cure the problem but aims to protect the appropriately growing twin if the growth-restricted co-twin dies. In monochorionic twins, structural anomalies are twice as common as in singleton pregnancies, probably due to a teratogenic effect of the embryonic splitting or because of transfusion imbalances. In contrast, chromosomal anomalies appear less common, possibly because they more likely result in an early demise. Selective reduction is feasible in monochorionic pregnancies but carries increased risks of loss, miscarriage, and early birth than a selective reduction in a dichorionic setting. Finally, if one monochorionic twin dies spontaneously, its co-twin may acutely exsanguinate into the demised co-twin, which may result in the loss of both twins or brain damage in the surviving twin. This update addresses the pathophysiology, diagnosis, and management of these common complications in monochorionic diamniotic twin pregnancies.

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.

Outcome of monochorionic twin pregnancy complicated by Type-III selective intrauterine growth restriction

OBJECTIVE

Type-III selective intrauterine growth restriction (sIUGR) is associated with a high and unpredictable risk of fetal death and fetal brain injury. The objective of this study was to describe the prospective risk of fetal death and the risk of adverse neonatal outcome in a cohort of twin pregnancies complicated by Type-III sIUGR and treated according to up-to-date guidelines.

METHODS

We reviewed retrospectively all monochorionic diamniotic twin pregnancies complicated by Type-III sIUGR managed at nine fetal centers over a 12-year period. Higher-order multiple gestations and pregnancies with major fetal anomalies or other monochorionicity-related complications at initial presentation were excluded. Data on fetal and neonatal outcomes were collected and management strategies reviewed. Composite adverse neonatal outcome was defined as neonatal death, invasive ventilation beyond the resuscitation period, culture-proven sepsis, necrotizing enterocolitis requiring treatment, intraventricular hemorrhage Grade > I, retinopathy of prematurity Stage > II or cystic periventricular leukomalacia. The prospective risk of intrauterine death (IUD) and the risk of neonatal complications according to gestational age were evaluated.

RESULTS

We collected data on 328 pregnancies (656 fetuses). After exclusion of pregnancies that underwent selective reduction (n = 18 (5.5%)), there were 51/620 (8.2%) non-iatrogenic IUDs in 35/310 (11.3%) pregnancies. Single IUD occurred in 19/328 (5.8%) pregnancies and double IUD in 16/328 (4.9%). The prospective risk of non-iatrogenic IUD per fetus declined from 8.1% (95% CI, 5.95-10.26%) at 16 weeks, to less than 2% (95% CI, 0.59-2.79%) after 28.4 weeks and to less than 1% (95% CI, -0.30 to 1.89%) beyond 32.6 weeks. In otherwise uncomplicated pregnancies with Type-III sIUGR, delivery was generally planned at 32 weeks, at which time the risk of composite adverse neonatal outcome was 29.0% (31/107 neonates). In twin pregnancies that continued to 34 weeks, there was a very low risk of IUD (0.7%) and a low risk of composite adverse neonatal outcome (11%).

CONCLUSIONS

In this cohort of twin pregnancies complicated by Type-III sIUGR and treated at several tertiary fetal centers, the risk of fetal death was lower than that reported previously. Further efforts should be directed at identifying predictors of fetal death and optimal antenatal surveillance strategies to select a cohort of pregnancies that can continue safely beyond 33 weeks' gestation. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Pregnancy outcomes and placental characteristics of selective intrauterine growth restriction with or without twin anemia polythemia sequence

INTRODUCTION

To investigate differences in the pregnancy outcomes and placental characteristics of selective intrauterine growth restriction (sIUGR) with or without twin anemia polythemia sequence (TAPS).

METHODS

sIUGR patients were assigned into two groups based on the occurrence of TAPS. The pregnancy outcomes and placental characteristics were compared. A diameter of ≥2 mm was defined as thick anastomosis.

RESULTS

The prevalence of artery-to-artery (AA) (45.5% vs 88.6%, P = 0.002) and thick AA (0% vs 53.5%) in TAPS group were lower than non-TAPS group. The overall diameter of AA (0.5 (0.4-1.3) vs 2.5 (0.3-7.1) mm, P = 0.001) in TAPS group was smaller than non-TAPS group. The prevalence of thick artery-to-vein (AV) (0% vs 36.0%) in TAPS group was lower than non-TAPS group. Also, the overall diameter of AV (0.9 (0.6-2.1) vs 4.8 (0.3-17.8) mm, P < 0.001) in TAPS group was smaller than non-TAPS group. The total quantity (2 (1-6) vs 6 (1-16), P = 0.001), and the overall diameter of anastomoses (1.1 (0.6-4.7) vs 7.5 (0.5-22.4) mm, P < 0.001) were smaller in TAPS group than non-TAPS group. The placental territory discordance ratio of TAPS group was smaller than non-TAPS group (0.39 (0.13-0.56) vs 0.56 (0.01-0.88), P = 0.008). The umbilical cord insertion distance ratio in TAPS group was higher than non-TAPS group (0.81 ± 0.12 vs 0.57 ± 0.20, P < 0.001).

DISCUSSION

The placental anastomoses of sIUGR with TAPS were small. sIUGR with TAPS had smaller differences in placental share and larger distances between umbilical cord insertions.

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.

Critical Coarctation of the Aorta in Selective Fetal Growth Restriction and the Role of Coronary Stent Implantation

INTRODUCTION

Monochorionic twins are at increased risk of congenital heart defects (CHDs). Up to 26% have a birth weight <1,500 g, a CHD requiring neonatal surgery, therefore, poses particular challenges.

OBJECTIVE

The aim of the study was to describe pregnancy characteristics, perinatal management, and outcome of monochorionic twins diagnosed with critical coarctation of the aorta (CoA).

METHODS

We included monochorionic twins diagnosed with critical CoA (2010-2019) at 2 tertiary referral centers, and we systematically reviewed the literature regarding CoA in monochorionic twins.

RESULTS

Seven neonates were included. All were the smaller twin of pregnancies complicated by selective fetal growth restriction. The median gestational age at birth was 32 weeks (28-34). Birth weight of affected twins ranged as 670-1,800 g. One neonate underwent coarctectomy at the age of 1 month (2,330 g). Six underwent stent implantation, performed between day 8 and 40, followed by definitive coarctectomy between 4 and 9 months in 4. All 7 developed normally, except for 1 child with neurodevelopmental delay. Three co-twins had pulmonary stenosis, of whom 1 required balloon valvuloplasty. The literature review revealed 10 cases of CoA, all in the smaller twin. Six cases detected in the first weeks after birth were treated with prostaglandins alone, by repeated transcatheter angioplasty or by surgical repair, with good outcome in 2 out of 6.

CONCLUSIONS

CoA specifically affects the smaller twin of growth discordant monochorionic twin pairs. Stent implantation is a feasible bridging therapy to surgery in these low birth weight neonates.

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.