Monochorionic monoamniotic twin pregnancies

Update on Management and Outcomes of Monochorionic Twin Pregnancies

The management of multiple pregnancies complicated by monochorionicity continues to evolve as new investigations support a change in clinical practice to optimize outcomes. Monochorionic twins are at risk of unique conditions such as monoamnionicity, conjoined twinning, twin reversed arterial perfusion sequence, twin-twin transfusion syndrome, twin anemia-polycythemia sequence, unequal placental sharing with discordant twin growth or selective fetal growth restriction, and single-twin death that puts co-twins at risk of death or neurologic injury attributable to the shared placenta. Contemporary practice guidelines recommend serial ultrasonographic surveillance of monochorionic pregnancies to increase the early detection of problems and timely management decisions that may include increased surveillance, selective reduction or pregnancy termination, referral for in utero treatment, or earlier delivery than initially planned. Improvements in prenatal diagnosis and antenatal testing and advances in fetal therapy have contributed to more favorable outcomes in these complicated monochorionic gestations.

A novel technique with cool-tip radiofrequency ablation for selective fetal reduction in complicated monochorionic twin

OBJECTIVE

To invent a novel method for selective fetal reduction in monochorionic (MC) twin using cool-tip radiofrequency ablation (RFA) and analysis the perinatal outcome.

MATERIAL AND METHODS

Complicated MC twins including twin-to twin transfusion syndrome (TTTS), selective fetal growth restriction (sFGR) and twin reverse arterial perfusion sequence (TRAP) were enrolled from 2020 to 2024. All cases were indicated for selective fetal reduction due to expected poor outcome. Equilateral triangle method using single puncture 4 times ablation with 17G cool-tip RFA to cord insertion site, umbilical vein and two umbilical arteries for complete stopping the blood flow. The power was starting from 60 W, 80 W, 80 W and 100 W 1 min each site. Outcome were analyzed.

RESULTS

A total of 51 cases were collected and treated in a single medical center. We divided first 20 cases as tradition group using single point ablation and novel 4-point ablation group after 21st cases. The overall co-twin survival rate after RFA procedure was 88 % (45 out of 51) in whole series. However, the co-twin survival rate in the novel 4-point group was better than single point group (93.5 % vs 80 %) with statistically significance. The maternal age, procedure at gestational age, procedure time and preterm birth rate did not show statistically difference between two groups.

CONCLUSIONS

This novel equilateral triangle method to stop all the umbilical blood flow achieved the high successful rate without maternal complication. The 17 g cool-tip RFA worked at low temperature to avoid thermal damage. This might be the new choice of RFA in monochorionic pregnancies.

Differential Diagnosis of Hydrops Fetalis: An Imaging Guide

Hydrops fetalis is a critical diagnosis given the poor prognosis and vast differential of potential causes. After a detailed anatomic survey, the first step in differentiating among the various causes is measurement of the middle cerebral artery peak systolic velocity to evaluate for anemia. Anemia is the key decision point in the diagnostic algorithm that categorizes hydrops. This approach is more practical than an immune versus nonimmune classification because it capitalizes on clues available at the time of sonographic diagnosis and expedites care toward possible therapies, such as intrauterine transfusion. The causes of hydrops that share the underlying physiology of fetal anemia include alloimmunization, which accounts for 10% of cases, congenital infections, hemoglobinopathies, and fetomaternal hemorrhage. After ruling out anemia, the differential diagnosis expands to cardiovascular disorders (20%-28% of cases), genetic abnormalities (10%-30% of cases), fetal masses (eg, congenital lung masses, sacrococcygeal teratomas), and monochorionic twin complications. Even after a thorough evaluation, 15% of hydrops cases remain of unknown cause. There are treatments available for select disorders that have the potential to reverse the signs of hydrops. Several imaging pitfalls should be avoided when establishing the diagnosis of hydrops, such as mistaking abdominal wall muscles, physiologic pericardial fluid, or thick subcutaneous tissue as pathologic fluid accumulation. A practical and comprehensive approach to the diagnostic evaluation for hydrops fetalis avoids delays in diagnosis and expedites potential life-saving treatment of this disorder. ©RSNA, 2025 Supplemental material is available for this article.

Risk of Cord Entanglement After Iatrogenic Monoamnionicity, With Selective and Solomon Laser Treatment for Twin-To-Twin Transfusion Syndrome in Monochorionic Twin Pregnancies

INTRODUCTION

Fetoscopic laser surgery (FLS) is the gold standard treatment for monochorionic (MC) twin pregnancies complicated by twin-twin transfusion syndrome (TTTS). The aim of our study was to evaluate the rate and risk factors for cord entanglement in the presence of iatrogenic monoamnioticity (iMA), a consequence of inadvertent septostomy during FLS.

METHODS

This is a retrospective analysis of two consecutive cohorts of FLS performed either using the selective technique from January 2004 to January 2012, or with the Solomon technique, from that date onwards. Maternal and fetal characteristics, technical details, and obstetrical and perinatal outcomes were recorded. Cord entanglement was identified based on the presence of a galloping sign observed during prenatal ultrasound in the presence of iMA. At our center, mono-amniotic twins are electively delivered at 32 completed weeks.

RESULTS

The mean gestational age of the 558 FLS, 52.3% selective and 47.6% Solomon, was 19.8 weeks (15.1-26.4). Solomon laser coagulation was associated with a lower occurrence of TAPS or TTTS (5.3% vs. 13%, p = 0.001) after the FLS and a higher number of placental abruption (9% vs. 2% p < 0.001) and by more cord entanglement in the presence of iMA (9.4% vs. 2.4% respectively, p < 0.001). The presence of iMA was correlated with a higher occurrence of limb defects (6.2% vs. 1% in non-iMA twins, p 0.001).

CONCLUSIONS

Solomon FLS was associated with a higher risk of cord entanglement and placental abruptio. As a consequence, we delivered twins with iMA earlier.

Prognostic value of cervical length for spontaneous preterm birth in asymptomatic women with twin pregnancy: meta-analysis of individual participant data

Objective

To quantify the prognostic value of mid-trimester cervical length for spontaneous preterm birth in asymptomatic women with twin pregnancy and to assess whether other factors may modify any association.

Designs

A two stage meta-analysis of individual participant data in a Cox proportional hazard model was performed using cervical length as a continuous variable.

Data sources

Medline, Embase, Cochrane, and LILACS, among others, were searched to identify eligible studies; the search was from 1 January 2000 to 30 September 2020. Risk of bias was assessed with the QUIPS tool. Studies were from eight countries between 2001 and 2018.

Eligibility criteria

Individual participant data were sought for eligible studies that reported mid-trimester (defined between 16 and 26 weeks) transvaginal sonographic cervical length and also gestational age at birth in asymptomatic women with twin pregnancy. The primary outcome was spontaneous preterm birth before 37 weeks.

Results

Among 29 eligible studies, authors of 17 studies provided individual participant data for 6437 women with a twin pregnancy (69.1% of individual participant data). Mean cervical length measurement was 39 mm (SD=9, range 1-74 mm). 2889 women (44.9%) delivered before 37 weeks' gestation, and 934 (14.9%) delivered before 34 weeks. Each 1 mm increase in cervical length was associated with a 4.0% reduction in the rate of spontaneous preterm birth before 37 weeks (hazard ratio 0.96 (95% confidence interval 0.95 to 0.97)), and a 6.8% reduction in the rate of spontaneous preterm birth before 34 weeks' gestation (0.93 (0.92 to 0.95)). The prognostic value remained stable in models adjusting for different sets of variables.

Conclusion

The prognostic value of cervical length for spontaneous preterm birth in twin pregnancy is on a continuous scale. No specific cervical length has been identified that can reliably predict or exclude all spontaneous preterm births.

Study registration

CRD42020146987.

Ultrasound diagnosis of first trimester umbilical cord entanglement in monochorionic monoamniotic twins - case report and review of the literature

BACKGROUND

Diagnosis of umbilical cord entanglement (UCE) by ultrasound (US) in monochorionic monoamniotic (MCMA) twins in the second and third trimesters is common. However, only a few cases have been reported on the diagnosis of UCE as early as the first trimester. Herein, we report a case of the earliest-ever sonographic diagnosis of UCE and demonstrate the feasibility of its diagnosis by US.

CASE PRESENTATION

A 32-year-old gravida 2 para 1 woman conceived after assisted reproductive technology (ART) treatment. In transvaginal US examination at 8.5 gestational weeks, two embryos with regular heartbeats in the same amniotic sac and with only one yolk sac were demonstrated. The fetal crown-rump lengths were 20 and 21 mm, appropriate for 8.4 and 8.5 gestational weeks, respectively. HD-flow power Doppler 2D and 3D US demonstrated two tightly entangled umbilical cords of the two fetuses. Spectral Doppler US showed two different heart rates (162 and 167 beats per minute) and blood flow in opposite directions from the point of entanglement of the two umbilical cords. This was consistent with a diagnosis of a first-trimester MCMA pregnancy with UCE. Missed abortion of the two embryos was diagnosed by US examination at 10.5 weeks, and the pregnancy was terminated by dilatation and curettage without further complications.

CONCLUSIONS

UCE in the first trimester may occur as early as eight gestational weeks, and its diagnosis by ultrasound is feasible. UCE diagnosed in the first trimester may be a poor prognostic factor.

Monochorionic Twin Complications and Fetoscopic Interventions

Monochorionic twins are at risk for complications due to the presence of placental vascular anastomoses, including twin-twin transfusion syndrome, twin anemia-polycythemia sequence, selective fetal growth restriction, and twin reversed arterial perfusion sequence. While ultrasound is the primary modality to screen for the development of these complications, MRI plays an important role in assessing monochorionic twin pregnancies for the development of other complications, such as neurologic injury. In this article, the authors review the ultrasound imaging findings associated with monochorionic twin complications, management options, and the role for MRI in these pregnancies.

Advancing fetal diagnosis and prognostication using comprehensive prenatal phenotyping and genetic testing

Prenatal diagnoses of congenital malformations have increased significantly in recent years with use of high-resolution prenatal imaging. Despite more precise radiological diagnoses, discussions with expectant parents remain challenging because congenital malformations are associated with a wide spectrum of outcomes. Comprehensive prenatal genetic testing has become an essential tool that improves the accuracy of prognostication. Testing strategies include chromosomal microarray, exome sequencing, and genome sequencing. The diagnostic yield varies depending on the specific malformations, severity of the abnormalities, and multi-organ involvement. The utility of prenatal genetic diagnosis includes increased diagnostic clarity for clinicians and families, informed pregnancy decision-making, neonatal care planning, and reproductive planning. Turnaround time for results of comprehensive genetic testing remains a barrier, especially for parents that are decision-making, although this has improved over time. Uncertainty inherent to many genetic testing results is a challenge. Appropriate genetic counseling is essential for parents to understand the diagnosis and prognosis and to make informed decisions. Recent research has investigated the yield of exome or genome sequencing in structurally normal fetuses, both with non-invasive screening methods and invasive diagnostic testing; the prenatal diagnostic community must evaluate and analyze the significant ethical considerations associated with this practice prior to generalizing its use. IMPACT: Reviews available genetic testing options during the prenatal period in detail. Discusses the impact of prenatal genetic testing on care using case-based examples. Consolidates the current literature on the yield of genetic testing for prenatal diagnosis of congenital malformations.

Perinatal outcomes and growth discordance of triplet pregnancies based on chorionicity: a retrospective cohort study

BACKGROUND

The worldwide occurrence of triplet pregnancy is estimated to be 0.093%, with a natural incidence of approximately 1 in 8000. This study aims to analyze the neonatal health status and birth weight discordance (BWD) of triplets based on chorionicity from birth until discharge.

METHODS

This was a retrospective study. We reviewed a total of 136 triplet pregnancies at our tertiary hospital between January 1, 2001, and December 31, 2021. Maternal and neonatal outcomes, inter-triplet BWD, neonatal morbidity, and mortality were analyzed.

RESULTS

Among all cases, the rates of intrauterine death, neonatal death, and perinatal death were 10.29, 13.07, and 24.26%, respectively. Thirty-seven of the cases resulted in fetal loss, including 13 with fetal anomalies. The maternal complications and neonatal outcomes of the 99 triplet pregnancies without fetal loss were compared across different chorionicities, including a dichorionic (DC) group (41 cases), trichorionic (TC) group (37 cases), and monochorionic (MC) group (21 cases). Neonatal hypoproteinemia (P < 0.001), hyperbilirubinemia (P < 0.019), and anemia (P < 0.003) exhibited significant differences according to chorionicity, as did the distribution of BWD (P < 0.001). More than half of the cases in the DC and TC groups had a BWD < 15%, while those in the MC group had a BWD < 50% (47.6%). TC pregnancy decreased the risk of neonatal anemia (adjusted odds ratio [AOR] = 0.084) and need for blood transfusion therapy after birth (AOR = 0.119). In contrast, a BWD > 25% increased the risk of neonatal anemia (AOR = 10.135) and need for blood transfusion after birth (AOR = 7.127). TC pregnancy, MCDA or MCTA, and BWD > 25% increased neonatal hypoproteinemia, with AORs of 4.629, 5.123, and 5.343, respectively.

CONCLUSIONS

The BWD differed significantly according to chorionicity. Additionally, TC pregnancies reduced the risk of neonatal anemia and need for blood transfusion, but increased the risk of neonatal hypoproteinemia. In contrast, the BWD between the largest and smallest triplets increased the risk of neonatal anemia and the need for blood transfusion. TC pregnancy, MCDA or MCTA, and BWD > 25% increased the risks of neonatal hypoproteinemia. However, due to the limited number of triplet pregnancies, further exploration of the underlying mechanism is warranted.

New radiofrequency ablation procedure for selective reduction in complicated monochorionic twin or triplet pregnancy using multistep, incremental expansion technique

OBJECTIVE

Radiofrequency ablation (RFA) is the preferred approach for selective reduction in complex monochorionic (MC) multiple pregnancies owing to the ease of operation and minimal invasiveness. To optimize the RFA technique and reduce the risk of adverse pregnancy outcome resulting from the heat-sink effect of RFA therapy, we used an innovative RFA method, in which an electrode needle was expanded incrementally and stepwise. This study aimed to assess the efficacy and safety profile of this novel multistep incremental expansion RFA method for selective fetal reduction in MC twin and triplet pregnancies.

METHODS

This was a single-center retrospective cohort study of all MC multiple pregnancies undergoing RFA between March 2016 and October 2022 at our center. The multistep RFA technique involved the use of an expandable needle, which was gradually expanded during the RFA procedure until cessation of umbilical cord blood flow was achieved. The needle used for the single-step RFA method was fully extended from the start of treatment.

RESULTS

In total, 132 MC multiple pregnancies underwent selective reduction using RFA, including 50 cases undergoing multistep RFA and 82 cases undergoing single-step RFA. The overall survival rates were not significantly different between the multistep and single-step RFA groups (81.1% vs 72.3%; P = 0.234). Similarly, the rates of preterm prelabor rupture of the membranes within 2 weeks after RFA, procedure-related complications, spontaneous preterm delivery and pathological findings on cranial ultrasound, as well as gestational age at delivery and birth weight, did not differ between the two groups. However, there was a trend towards a prolonged procedure-to-delivery interval following multistep RFA compared with single-step RFA (median, 109 vs 99 days; P = 0.377). Moreover, the fetal loss rate within 2 weeks after RFA in the multistep RFA group was significantly lower than that in the single-step RFA group (10.0% vs 24.4%; P = 0.041). The median ablation time was shorter (5.3 vs 7.8 min; P < 0.001) and the median ablation energy was lower (10.2 vs 18.0 kJ; P < 0.001) in multistep compared with single-step RFA. There were no significant differences in neonatal outcomes following multistep vs single-step RFA.

CONCLUSIONS

Overall survival rates were similar between the two RFA methods. However, the multistep RFA technique was associated with a lower risk of fetal loss within 2 weeks after RFA. The multistep RFA technique required significantly less ablation energy and a shorter ablation time compared with single-step RFA in selective fetal reduction of MC twin and triplet pregnancies. Additionally, there was a trend towards a prolonged procedure-to-delivery interval with the multistep RFA technique. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of 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.

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.

Inpatient Management of a Monoamniotic Twin Pregnancy Complicated by Umbilical Cord Entanglement and Selective Intrauterine Growth Restriction

Monoamniotic twin pregnancies are exceedingly rare. These are high-risk pregnancies that present a unique set of challenges for the obstetrician-gynecologist. There is a high risk of intrauterine fetal demise, secondary to co-morbid conditions including, but not limited to, congenital anomalies and umbilical cord entanglement. Successful delivery and favorable neonatal outcomes are predicated on early diagnosis, intensive fetal monitoring, and timely delivery. The management guidelines for these pregnancies rely primarily on retrospective studies and expert consensus, although some substantial conclusions can be made regarding appropriate antepartum and intrapartum care. We present the case of a 38-year-old gravida four, para three, with monoamniotic twins who delivered successfully after inpatient hospitalization at viability, administration of corticosteroids for fetal lung maturity, and vigilant fetal monitoring. We conclude that the combination of early ultrasound, intensive fetal monitoring, and interdisciplinary coordination among generalist obstetrician-gynecologists, maternal-fetal medicine specialists, and nursing staff is paramount for providing the greatest chance of a favorable outcome.