Fetoscopic laser coagulation of the vascular equator versus selective coagulation for twin-to-twin transfusion syndrome: an open-label randomised controlled trial

doi:10.1016/S0140-6736(13)62419-8

The Lancet

Volume 383, Issue 9935, 21–27 June 2014, Pages 2144-2151

https://doi.org/10.1016/S0140-6736(13)62419-8 Get rights and content

Summary

Background

Monochorionic twin pregnancies complicated by twin-to-twin transfusion syndrome are typically treated with fetoscopic laser coagulation. Postoperative complications can occur due to residual vascular anastomoses on the placenta. We aimed to assess the efficacy and safety of a novel surgery technique that uses laser coagulation of the entire vascular equator (Solomon technique).

Methods

We undertook an open-label, international, multicentre, randomised controlled trial at five European tertiary referral centres. Women with twin-to-twin transfusion syndrome were randomly assigned by online randomisation (1:1) with permuted blocks to the Solomon technique or standard laser coagulation. The primary outcome was a composite of incidence of twin anaemia polycythaemia sequence, recurrence of twin-to-twin transfusion syndrome, perinatal mortality, or severe neonatal morbidity. Analyses were by intention to treat, with results expressed as odds ratios (ORs) and 95% CIs. This trial is registered with the Dutch Trial Registry, number NTR1245.

Findings

Between March 11, 2008, and July 12, 2012, 274 women were randomly assigned to either the Solomon group (n=139) or the standard treatment group (n=135). The primary outcome occurred in 94 (34%) of 274 fetuses in the Solomon group versus 133 (49%) of 270 in the standard treatment group (OR 0·54; 95% CI 0·35–0·82). The Solomon technique was associated with a reduction in twin anaemia polycythaemia sequence (3% vs 16% for the standard treatment; OR 0·16, 95% CI 0·05–0·49) and recurrence of twin-to-twin transfusion syndrome (1% vs 7%; 0·21, 0·04–0·98). Perinatal mortality and severe neonatal morbidity did not differ significantly between the two groups. Outside of the common and well-known complications of twin-to-twin transfusion syndrome and its treatment, no serious adverse events occurred.

Interpretation

Fetoscopic laser coagulation of the entire vascular equator reduces postoperative fetal morbidity in severe twin-to-twin transfusion syndrome. We recommend that fetoscopic surgeons consider adopting this strategy for treatment of women with twin-to-twin transfusion syndrome.

Funding

Netherlands Organization for the Health Research and Development (ZonMw 92003545).

Introduction

Monochorionic twin pregnancies are associated with a perinatal mortality rate of 11%.1, 2 Most complications, such as twin-to-twin transfusion syndrome, can be attributed to the presence of inter-twin vascular anastomoses on the monochorionic placenta. If left untreated, twin-to-twin transfusion syndrome can result in an overall mortality rate of 73–100%.³

The preferred treatment for twin-to-twin transfusion syndrome is fetoscopic laser coagulation of the vascular anastomoses, which is associated with survival rates of both fetuses of 35–67%.4, 5, 6, 7, 8, 9 Among the surviving children, 4–16% have signs of cerebral injury and 13–17% have neurodevelopmental morbidity.10, 11, 12

The goal of fetoscopic laser surgery is to coagulate all of the placental vascular anastomoses. However, in up to 33% of treated pregnancies, some inter-twin vascular connections remain patent.13, 14 These residual patent anastomoses can cause severe complications such as twin anaemia polycythaemia sequence (13%) or recurrent twin-to-twin transfusion syndrome (14%).¹⁵

To minimise the occurrence of residual anastomoses and their complications, we developed a modified fetoscopic laser surgery technique called the Solomon technique, in which the entire vascular equator is coagulated. The rationale of the Solomon technique is coagulation of the whole vascular equator (including tiny anastomoses that might not be visualised). Laser coagulation (in both the selective and Solomon techniques) occurs only at the chorionic surface. In the Solomon trial, we compared the efficacy and safety of the Solomon technique with standard laser coagulation and examined whether the Solomon technique can prevent the occurrence of residual anastomoses and their associated complications.

Section snippets

Study design and participants

We did an open-label, international, multicentre, randomised controlled trial at five European tertiary referral centres (University Hospital Leuven, Leuven, Belgium; University Hospital of Strasbourg, Strasbourg, France; Birmingham Women's Hospital, University of Birmingham, Birmingham, UK; Buzzi Hospital Milan, Milan, Italy; and Leiden University Medical Centre, Leiden, Netherlands). Women with monochorionic, diamniotic twin pregnancies up to 26 weeks' gestation complicated by twin-to-twin

Results

Between March 11, 2008, and July 12, 2012, 274 of 393 potentially eligible women were enrolled and were randomly assigned to either the Solomon group (n=139) or the standard treatment group (n=135). Because of poor visibility at fetoscopy, four women underwent an alternative, ultrasound-guided procedure (cord occlusion n=2, amniodrainage n=2; figure 1). Two women in the Solomon group were excluded after randomisation because of an incorrect assessment of their eligibility: upon fetoscopy, one

Discussion

In this randomised controlled trial, we found that fetoscopic laser coagulation of the entire vascular equator (Solomon technique) significantly reduced the incidence of twin anaemia polycythaemia sequence and recurrent twin-to-twin transfusion syndrome in monochorionic pregnancies complicated by twin-to-twin transfusion syndrome. The Solomon technique did not seem to be associated with an increase in any identifiable adverse outcome or complication. However, this study was not powered to

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Cited by (259)

Management of short cervix in twin-to-twin transfusion syndrome: a role for pessary placement following fetoscopic laser surgery?
2024, American Journal of Obstetrics and Gynecology
Preterm labor and delivery is a major concern for patients with twin-to-twin transfusion syndrome undergoing fetoscopic laser surgery. A preoperative short cervix is a risk factor for preterm labor. Pessary placement is a short-acting intervention that may be useful to reduce this adverse event.
This study aimed to investigate the relationship between pessary placement and preterm delivery in monochorionic twin pregnancies with twin-to-twin transfusion syndrome and a short cervix before fetoscopic laser surgery.
This was a retrospective study in 2 centers, including all pregnancies affected by twin-to-twin transfusion syndrome that underwent fetoscopic laser surgery with the Solomon technique between 2013 and 2022 (center A) and 2014 and 2022 (center B) with a preoperative cervical length below 25 mm. This study explored the correlation between cervical length and fetoscopic laser surgery–to–delivery interval following active or expectant management and compared perinatal outcomes between patients managed expectantly and patients managed with pessary placement, using multivariate analysis to control for potential confounders. Patients with a cervical length below 5 mm were not included in the comparative analysis.
Of 685 patients, 134 met the inclusion criteria. Moreover, 21 patients were treated with a cervical cerclage and excluded from the analysis, leaving 113 patients for the final analysis. There was a significant negative correlation between cervical length at fetoscopic laser surgery and the risk of early delivery (adjusted odds ratio, 0.66; 95% confidence interval, 0.49–0.81; P<.001). The use of a pessary correlated with fewer patients delivering before 28 weeks of gestation (adjusted odds ratio, 0.28; 95% confidence interval, 0.09–0.75), fewer double neonatal demise (adjusted odds ratio, 0.2; 95% confidence interval, 0.05–0.75). Posthoc subgroup analysis suggested that these improvements were essentially noticeable for cervical lengths between 5 and 18 mm, where pessary placement was associated with an increased fetoscopic laser surgery–to–delivery interval (+24 days; 95% confidence interval, 0.86–42; P=.042) and later gestational age at delivery (+3.3 weeks; 95% confidence interval, 0.86–42; P=.035).
Patients with a moderately shortened cervix, between 5 and 18 mm, may benefit from pessary placement after fetoscopic surgery for twin-to-twin transfusion syndrome, resulting in a reduction of adverse neonatal outcomes, double neonatal demise, and severe preterm delivery.
Directive clinique n<sup>o</sup> 440 : Prise en charge de la grossesse gémellaire monochoriale
2023, Journal of Obstetrics and Gynaecology Canada
Cette directive clinique passe en revue les données probantes sur la prise en charge de la grossesse gémellaire monochoriale normale et compliquée.
Les femmes menant une grossesse gémellaire ou multiple de haut rang.
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.
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.
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]).
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.
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).
- 1.
  La morbidité et la mortalité relatives à la grossesse gémellaire sont le plus souvent associées : 1) à la chorionicité; 2) à la prématurité; 3) au retard de croissance intra-utérin; et 4) aux anomalies congénitales (élevée).
- 2.
  En cas de grossesse monochoriale, le placenta présente presque toujours des anastomoses vasculaires entre l’insertion placentaire des deux cordons (élevée).
- 3.
  En plus de la prématurité et de la croissance discordante, la grande majorité des complications de grossesse gémellaire surviennent en contexte de monochorionicité (élevée).
- 4.
  Le syndrome transfuseur-transfusé touche environ 10 à 15 % des grossesses gémellaires monochoriales (élevée).
- 5.
  Le diagnostic du syndrome transfuseur-transfusé repose sur les marqueurs échographiques indiquant une discordance significative des volumes de liquide amniotique et des volumes vésicaux (élevée). La dysfonction cardiaque chez le jumeau receveur ou la croissance discordante coexistent souvent, mais ne sont pas des critères essentiels pour le diagnostic (élevée).
- 6.
  La coagulation laser fœtoscopique des anastomoses vasculaires placentaires est le meilleur traitement du syndrome transfuseur-transfusé se manifestant avant 28 à 30 semaines d’aménorrhée et est à privilégier à l’amniodrainage ou la septostomie (élevée).
- 7.
  La coagulation laser par la technique de Solomon diminue le risque de récidive du syndrome transfuseur-transfusé et de la séquence d’anémie-polycythémie (élevée).
- 8.
  La séquence d’anémie-polycythémie survient spontanément dans 4 à 5 % des grossesses gémellaires monochoriales (moyenne). Comparativement au syndrome transfuseur-transfusé, elle apparaît généralement plus tard dans la grossesse (habituellement > 24-26 semaines d’aménorrhée) (moyenne). La séquence d’anémie-polycythémie peut coexister avec le syndrome transfuseur-transfusé et est observée dans jusqu’à 13 % des cas de syndrome transfuseur-transfusé où l’intervention de coagulation laser fœtoscopique était incomplète (élevée).
- 9.
  Les marqueurs échographiques de la séquence d’anémie-polycythémie sont la discordance croissante des pics systoliques de vélocité de l’artère cérébrale moyenne, ce qui évoque une anémie chez l’un des fœtus et une polycythémie chez l’autre, souvent sans discordance significative du volume de liquide amniotique (élevée). L’échogénicité placentaire divergente et le foie d’aspect en « ciel étoilé » chez le jumeau receveur sont d’autres signes possibles (moyenne).
- 10.
  Le retard de croissance sélectif en contexte de grossesse gémellaire monochoriale se définit comme un poids fœtal estimé en deçà du 3^e percentile chez un des jumeaux ou une combinaison d’au moins 2 des 4 critères suivants : 1) poids fœtal estimé en deçà du 10^e percentile; 2) périmètre abdominal en deçà du 10^e percentile; 3) discordance de poids fœtal estimé de 25 % ou plus; ou 4) indice de pulsatilité de l’artère ombilicale du plus petit jumeau au-delà du 95^e percentile (élevée).
- 11.
  En cas de grossesse gémellaire monochoriale, la discordance de poids fœtal estimé de plus de 25 % et les anomalies du Doppler de l’artère ombilicale sont des facteurs de risques indépendants d’une issue périnatale défavorable (élevée).
- 12.
  Les marqueurs échographiques de la séquence de perfusion artérielle inversée sont un cojumeau amorphe acardiaque généralement œdémateux, dont la perfusion rétrograde se fait par le cojumeau sain faisant office de « pompe » via l’anastomose artério-artérielle placentaire (élevée).
- 13.
  Un gros cojumeau acardiaque (c.-à-d. un ratio de périmètre abdominal de ≥ 50 % entre les cojumeaux acardiaque et pompe) peut mettre le cojumeau pompe à risque d’insuffisance cardiaque à haut débit (élevée). Le risque global de mort intra-utérine du cojumeau pompe est d’environ 30 % avant 18 semaines d’aménorrhée (élevée).
- 14.
  Dans une grossesse gémellaire monochoriale, si l’un des cojumeaux meurt, le cojumeau survivant peut être à risque de morbidité neurologique et de mort intra-utérine (élevée). Les changements dans le cerveau du cojumeau survivant peuvent ne pas être visibles à l’imagerie avant plusieurs semaines après la mort de son cojumeau (moyenne).
- 15.
  Les marqueurs échographiques de la grossesse gémellaire monoamniotique sont l’absence d’une membrane amniotique séparatrice, la présence d’un seul placenta, la proximité de l’insertion placentaire des cordons, la concordance de sexe et, souvent, l’emmêlement des cordons (élevée).
- 16.
  Le syndrome transfuseur-transfusé se développe dans seulement 2 à 4 % des grossesses gémellaires monoamniotiques (élevée).
- 17.
  Les anomalies structurelles, particulièrement les anomalies cardiaques, sont plus fréquentes dans les grossesses monochoriales que dans les grossesses bichoriales ou monofœtales (élevée).
- 18.
  Les jumeaux conjoints sont extrêmement rares, et les structures et organes partagés déterminent le potentiel d’intervention chirurgicale et de survie (élevée).
- 1.
  En cas de grossesse gémellaire spontanée, il est recommandé d’utiliser la plus grande des deux longueurs céphalo-caudales pour estimer l’âge gestationnel (conditionnelle, moyenne).
- 2.
  La viabilité, l’âge gestationnel, la chorionicité et l’amnionicité doivent être évalués entre 11 SA + 0 j et 13 SA + 6 j pour toutes les grossesses multiples (forte, élevée).
- 3.
  Si la chorionicité ne peut être déterminée par échographie avec certitude, il y a lieu de suivre la progression de la grossesse comme si elle était monochoriale (conditionnelle, moyenne).
- 4.
  Les jumeaux doivent être identifiés à l’échographie prénatale en fonction de leur position latérale (droite/gauche) ou verticale (haut/bas) au lieu de leur proximité du col de l’utérus, et cette identification doit idéalement demeurer la même pour les examens échographiques subséquents (forte, moyenne).
- 5.
  Une échographie morphologique détaillée doit être réalisée vers 18 à 20 semaines d’aménorrhée pour toutes les grossesses gémellaires monochoriales (forte, élevée). Lorsque l’expertise est disponible, une échographie morphologique précoce peut être effectuée entre 12 et 14 semaines d’aménorrhée (conditionnelle, moyenne).
- 6.
  Dans toute grossesse gémellaire, il faut mesurer la longueur du col, par échographie abdominale ou endovaginale, lors de l’échographie morphologique et, idéalement, une fois de plus vers 23 ou 24 semaines d’aménorrhée (forte, moyenne).
- 7.
  Il y a lieu d’effectuer une surveillance par échographie aux 2 semaines dès 16 semaines d’aménorrhée, et ce, jusqu’à l’accouchement, pour toute grossesse monochoriale, afin de détecter le syndrome transfuseur-transfusé, la séquence d’anémie-polycythémie et le retard de croissance sélectif (forte, élevée).
- 8.
  Tout examen échographique réalisé à partir de 16 semaines d’aménorrhée en contexte de grossesse gémellaire monochoriale doit impliquer la mesure de la croissance (biométrie fœtale), du volume vésical et de la plus grande citerne de liquide amniotique des deux côtés de la membrane, en plus de la mesure Doppler du pic systolique de vélocité de l’artère cérébrale moyenne et de l’artère ombilicale pour chaque fœtus (forte, élevée).
- 9.
  En cas de grossesse gémellaire monochoriale non compliquée, l’accouchement devrait être réalisé entre 36 et 37 semaines d’aménorrhée. À moins d’autres contre-indications obstétricales, l’accouchement vaginal est une option adéquate (forte, élevée).
- 10.
  Il y a lieu d’évaluer le ductus venosus en cas de soupçons de syndrome transfuseur-transfusé ou de retard de croissance sélectif (forte, élevée). En cas de soupçons de syndrome transfuseur-transfusé, il faut évaluer la structure et la fonction cardiaques chez le jumeau receveur (forte, élevée).
- 11.
  Il est recommandé, en cas de syndrome transfuseur-transfusé, de consulter un des centres de traitement laser fœtal au Canada dans les plus brefs délais ou d’y orienter la patiente d’urgence, car la coagulation laser fœtoscopique des anastomoses vasculaires placentaires est le meilleur traitement pour ce syndrome (forte, élevée).
- 12.
  Un examen échographique doit être réalisé une fois par semaine pendant 4 semaines après la coagulation par laser fœtoscopique, puis toutes les 2 semaines après la résolution clinique parallèlement au suivi prénatal partagé avec le centre de médecine fœto-maternelle régional ou coordonné par le centre (forte, élevée). L’examen doit inclure une évaluation du volume de liquide amniotique dans les deux cavités, la mesure du volume vésical, l’évaluation du Doppler (pic systolique de vélocité de l’artère cérébrale moyenne, indice de pulsatilité de l’artère ombilicale et spectre du ductus venosus), la recherche d’anomalies intracrâniennes en plus de la mesure de la longueur du col et l’inscription de toute séparation chorion-amnios (forte, élevée).
- 13.
  L’anatomie intracrânienne fœtale doit être réévaluée en détail au moins 4 semaines après l’intervention laser (forte, moyenne).
- 14.
  En contexte de grossesse gémellaire monochoriale, lorsque se manifestent des complications, notamment la séquence d’anémie-polycythémie, le retard de croissance sélectif, la séquence de perfusion artérielle inversée, la monoamnionicité, une anomalie discordante ou la mort d’un jumeau, il est recommandé d’orienter la patiente vers le programme régional de médecine fœto-maternelle ou le centre régional de traitement fœtal, ou à tout le moins de les consulter (forte, élevée), de sorte que toutes les options de prise en charge puissent être explorées. Aucune prise en charge optimale de la séquence d’anémie-polycythémie n’a encore été déterminée (conditionnelle, moyenne).
- 15.
  Lorsqu’on soupçonne un retard de croissance sélectif, il faut intensifier la surveillance fœtale et transférer la prise en charge de la grossesse à un centre régional de médecine fœto-maternelle ayant l’expertise nécessaire, ou à tout le moins continuer la prise en charge en consultation avec un tel centre (forte, moyenne).
- 16.
  En cas de retard de croissance sélectif, la détermination du moment de l’accouchement doit prendre en compte l’âge gestationnel, les signes de répercussions hémodynamiques, tels qu’observés par le Doppler de l’artère ombilicale, de l’artère cérébrale moyenne et du ductus venosus, et le bien-être biophysique (forte, moyenne).
- 17.
  En contexte de grossesse monochoriale, lorsque la mort d’un jumeau est détectée tôt dans la grossesse, on doit recourir à l’échographie Doppler couleur pour écarter la possibilité de séquence de perfusion artérielle inversée en confirmant l’absence de flux sanguin chez le jumeau présumément décédé (forte, élevée).
- 18.
  En contexte de séquence de perfusion artérielle inversée, en particulier en présence d’un gros cojumeau acardiaque, il faut envisager l’occlusion de la circulation vers le cojumeau acardiaque, soit par laser, par ablation par radiofréquence des vaisseaux intrafœtaux ou par coagulation bipolaire (conditionnelle, moyenne).
- 19.
  Dans la grossesse gémellaire monochoriale, après la mort spontanée d’un jumeau, il faut rapidement instaurer la surveillance de l’anémie fœtale en mesurant le pic systolique de vélocité de l’artère cérébrale moyenne, car l’anémie est en corrélation avec le risque de lésion neurologique hypotensive (forte, élevée). La transfusion intra-utérine peut s’avérer bénéfique pour le jumeau survivant (conditionnelle, moyenne). Il y a lieu de recourir à la neurosonographie fœtale et, idéalement, à l’IRM pour détecter toute lésion cérébrale potentielle; toutefois, il faut parfois jusqu’à 3 ou 4 semaines après la mort du cojumeau avant que les lésions soient observables à l’échographie (forte, élevée).
- 20.
  Il faut s’assurer de ne pas méprendre une grossesse monochoriale biamniotique pour une grossesse monoamniotique lorsqu’un anamnios est observé pour un des jumeaux (p. ex., en cas de syndrome transfuseur-transfusé) (conditionnelle, moyenne).
- 21.
  Comme le risque d’anomalies cardiaques est élevé dans les grossesses gémellaires monoamniotiques, il faut effectuer une échographie morphologique détaillée en portant une attention particulière à la composante d’évaluation cardiaque fœtale (forte, élevée).
- 22.
  La grossesse gémellaire monoamniotique doit être surveillée de près dès le seuil de viabilité (en soins ambulatoires ou en hospitalisation), et la césarienne planifiée est recommandée vers 33 semaines d’aménorrhée (conditionnelle, moyenne).
- 23.
  Le dépistage des aneuploïdies peut être offert en cas de grossesse monochoriale, soit par dépistage prénatal sérique combiné (c.-à-d., dépistage au premier trimestre ou dépistage prénatal intégré, selon l’option disponible) ou par analyse de l’ADN libre circulant dans le sang maternel (conditionnelle, moyenne).
- 24.
  Les tests prénataux invasifs (amniocentèse ou prélèvement de villosités choriales) doivent être offerts en présence d’une anomalie structurelle ou d’un résultat anormal au dépistage d’anomalies génétiques (forte, élevée). Il y a lieu d’envisager l’amniocentèse dans chacune des deux cavités en cas d’anomalies discordantes pour écarter la rare possibilité d’anomalies chromosomiques discordantes de la grossesse monochoriale (forte, élevée).
- 25.
  Lorsqu’indiquée pour anomalies discordantes en contexte de grossesse monochoriale, l’interruption sélective doit toujours être effectuée selon une méthode d’occlusion vasculaire et jamais par injection intravasculaire fœtale (forte, élevée).
Guideline No. 440: Management of Monochorionic Twin Pregnancies
2023, Journal of Obstetrics and Gynaecology Canada
This guideline reviews the evidence-based management of normal and complicated monochorionic twin pregnancies.
Women with monochorionic twin or higher order multiple pregnancies.
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.
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.
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).
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.
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.
- 1.
  Morbidity and mortality in twin pregnancies are most commonly related to: (1) chorionicity, (2) prematurity, (3) fetal growth restriction, and (4) congenital anomalies (high).
- 2.
  Virtually all monochorionic placentas have vascular anastomoses between the two placental cord insertions (high).
- 3.
  Besides prematurity and growth discordance, the vast majority of twin complications arise in monochorionic twin pregnancies (high).
- 4.
  Twin–twin transfusion syndrome affects approximately 10%–15% of monochorionic twin pregnancies (high).
- 5.
  The diagnosis of twin–twin transfusion syndrome is based on ultrasound findings of significant discordance in both amniotic fluid volume and bladder size (high). Cardiac dysfunction in the recipient twin or growth discordance often co-exist, but are not essential criteria for the diagnosis (high).
- 6.
  Fetoscopic laser ablation of the placental vascular anastomoses is the best treatment for twin-twin transfusion syndrome presenting before 28-30 weeks gestation, rather than amnioreduction or septostomy (high).
- 7.
  The Solomon laser technique decreases the risk of twin–twin transfusion syndrome recurrence and twin anaemia-polycythaemia sequence (high).
- 8.
  Twin anaemia-polycythaemia sequence occurs spontaneously in 4%–5% of monochorionic twin pregnancies (moderate). It typically develops later in pregnancy than twin–twin transfusion syndrome (usually >24–26 weeks gestation) (moderate). Twin anaemia-polycythaemia sequence may co-exist with twin–twin transfusion syndrome and has been reported in up to 13% of cases of TTTS in which the fetoscopic laser ablation procedure was incomplete (high).
- 9.
  Ultrasound features of twin anaemia-polycythaemia sequence are increasingly discordant middle cerebral artery peak systolic velocities, suggestive of anaemia in one fetus and polycythaemia in the other, often without significant amniotic fluid discordance (high). Other signs may include differential placental echogenicities and a “starry sky” liver in the recipient twin (moderate).
- 10.
  Selective fetal growth restriction in monochorionic twin pregnancies has been defined as an estimated fetal weight (EFW) of one twin below the 3^rd percentile, or at least 2 of the following four variables: (1) EFW <10^th percentile, (2) abdominal circumference <10^th percentile, (3) EFW discordance ≥25%, or (4) umbilical artery pulsatility index of the smaller twin >95^th percentile (high).
- 11.
  In monochorionic twins, estimated fetal weight discordance >25% and abnormal umbilical artery Doppler waveforms are independent risk factors for an adverse perinatal outcome. (high).
- 12.
  The ultrasonographic features of twin reversed arterial sequence are an amorphous, usually edematous, acardiac twin, which is retrogradely perfused via a placental artery-to-artery anastomosis by its healthy “pump” co-twin (high).
- 13.
  A large acardiac twin (e.g., an acardiac:“pump” twin abdominal circumference ratio ≥50%) may put its “pump” co-twin at risk of high-output cardiac failure (high). The overall risk of intrauterine death of the “pump” twin is approximately 30% before 18 weeks gestation (high).
- 14.
  If one of a monochorionic twin pair dies, the surviving co-twin may be at risk of neurological morbidity and intrauterine death (high). Imaging may not detect changes in the co-twin’s brain for several weeks after the death of its sibling (moderate).
- 15.
  Ultrasound features of monoamniotic twins include the absence of a dividing amniotic membrane, a single placenta, close proximity of placental cord roots, concordant sex and, commonly, cord entanglement (high).
- 16.
  Only 2%–4% of monoamniotic twins will develop twin–twin transfusion syndrome (high).
- 17.
  Structural anomalies, particularly cardiac, are more common in monochorionic twins than in dichorionic twins or singletons (high).
- 18.
  Conjoined twins are extremely rare and the organs/structures that are shared will determine the potential for surgical intervention and survival (high).
- 1.
  In spontaneously conceived pregnancies, we recommend using the larger of the two crown–rump lengths to estimate gestational age (conditional, moderate).
- 2.
  Viability, gestational age, chorionicity and amnionicity should be assessed between 11⁰ and 13⁶ weeks gestation in all multiple pregnancies (strong, high).
- 3.
  If chorionicity cannot be confidently established sonographically, pregnancies should be monitored as if they were monochorionic (conditional, moderate).
- 4.
  Twins should be labelled on antenatal ultrasound according to their lateral (right/left) or vertical (top/bottom) orientation, rather than their proximity to the cervix, and, ideally, that labelling should be maintained across all subsequent ultrasound examinations (strong, moderate).
- 5.
  A detailed anatomy scan should be performed at approximately 18–20 weeks gestation for all monochorionic twins (strong, high). Where the expertise is available, an early anatomy ultrasound can be performed at 12–14 weeks gestation (conditional, moderate).
- 6.
  In all twin pregnancies, cervical length should be assessed, either transabdominally or transvaginally, at the time of the anatomical ultrasound scan and, ideally, once more at around 23–24 weeks gestation (strong, moderate).
- 7.
  All monochorionic pregnancies should undergo ultrasound surveillance every 2 weeks from 16 weeks gestation until delivery to detect twin–twin transfusion syndrome, twin anaemia-polycythaemia sequence and selective fetal growth restriction (strong, high).
- 8.
  Ultrasound assessment of all monochorionic twins from 16 weeks onwards should include measurement of growth (fetal biometry), fetal bladder filling, and the single deepest pocket of amniotic fluid on both sides of the membrane, as well as umbilical and middle cerebral artery peak systolic velocity Doppler studies for each fetus (strong, high).
- 9.
  Monochorionic twins without complications should be delivered between 36 and 37 weeks gestation. Unless there are other obstetric contraindications, vaginal delivery is appropriate (strong, high).
- 10.
  If twin–twin transfusion syndrome or significant selective fetal growth restriction is suspected, the ductus venosus should be assessed (strong, high). Cardiac structure and function should be assessed in the recipient twin whenever twin–twin transfusion syndrome is suspected (strong, high).
- 11.
  For cases of twin–twin transfusion syndrome, urgent consultation with or referral to one of the fetal therapy laser centres in Canada is recommended, as fetoscopic laser ablation of placental vascular anastomoses is the best therapy for twin–twin transfusion syndrome (strong, high).
- 12.
  Ultrasonography should be performed weekly for 4 weeks after fetoscopic placental laser and then every 2 weeks following clinical resolution, with ongoing antenatal care shared or co-ordinated with the regional maternal–fetal medicine centre (strong, high). Assessment should include amniotic fluid volume in both sacs, bladder sizes, Doppler waveforms (middle cerebral artery peak systolic velocity, umbilical artery pulsatility index and ductus venosus), and intra-cranial anatomies, as well as measurement of cervical length and documentation of any chorio-amnion separation (strong, high).
- 13.
  Fetal intracranial anatomy should be carefully re-evaluated after an interval of at least 4 weeks following a laser procedure (strong, moderate).
- 14.
  Whenever monochorionic twin complications are encountered, including twin anaemia-polycythaemia sequence, selective fetal growth restriction, twin reversed arterial perfusion sequence, monoamnioticity, discordance for an anomaly, or a single intrauterine death, referral to, or at least consultation with, the regional maternal–fetal medicine program or fetal therapy centre is recommended (strong, high), so that all management options can be explored. The optimal management of twin anaemia-polycythaemia sequence has yet to be determined. (conditional, moderate).
- 15.
  When selective fetal growth restriction is suspected, fetal surveillance should be intensified and the pregnancy managed by referral to, or at very least with input from, a regional maternal–fetal medicine centre with expertise in this condition (strong, moderate).
- 16.
  In selective fetal growth restriction, timing of delivery should take into account gestational age, evidence of haemodynamic compromise as assessed by umbilical and middle cerebral artery and ductus venosus Doppler studies, and biophysical wellbeing (strong, moderate).
- 17.
  Whenever the death of one monochorionic twin is diagnosed early in pregnancy, colour Doppler ultrasonography should be used to exclude twin reversed arterial perfusion sequence, by confirming the absence of blood flow in the suspected demised twin (strong, high).
- 18.
  In twin reversed arterial perfusion sequence, especially with a large acardiac twin, occlusion of the circulation to the acardiac twin, either by laser, radio frequency ablation of the intra-fetal vessels or bipolar cautery should be considered (conditional, moderate).
- 19.
  After the spontaneous death of one monochorionic twin, surveillance for fetal anaemia by middle cerebral artery peak systolic velocity measurement should be instituted rapidly, as anaemia correlates with the risk of a hypotensive neurological injury (strong, high). The surviving twin may benefit from intrauterine transfusion (conditional, moderate). Fetal neurosonography and, ideally, MRI should be used to identify any potential cerebral injury; however, ultrasonographic evidence of injury may take 3-4 weeks to develop after the death of the co-twin (strong, high).
- 20.
  Care should be taken not to misdiagnose monochorionic-diamniotic pregnancies as monoamniotic, when one twin has anhydramnios (e.g., the donor in twin–twin transfusion syndrome) (conditional, moderate).
- 21.
  Monoamniotic twins are at high risk of cardiac abnormalities and should undergo a detailed anatomical ultrasound with particular emphasis on fetal cardiac evaluation (strong, high).
- 22.
  Monoamniotic twins should be monitored closely from viability onwards (either as out-patients or in-patients) and should undergo an elective caesarean delivery at approximately 33 weeks gestation (conditional, moderate).
- 23.
  Aneuploidy screening can be offered in monochorionic pregnancies as either combined prenatal serum screening (i.e., first-trimester screening or integrated prenatal screening, as available provincially) or cell-free fetal DNA analysis of maternal blood (conditional, moderate).
- 24.
  Invasive prenatal testing (chorionic villus sampling or amniocentesis) should be offered in the presence of a structural anomaly or abnormal genetic screening (strong, high). Amniocentesis from both sacs should be considered for discordant anomalies because of the rare possibility of heterokaryotypic anomalies in monochorionic twins (strong, high).
- 25.
  If indicated for discordance for an anomaly, selective termination of pregnancy in monochorionic twins must always be performed by a vascular occlusion method and never by intravascular fetal injection (strong, high).
The Arabin cervical pessary for the prevention of preterm birth in twin-to-twin transfusion syndrome treated by fetoscopic laser coagulation: a multicenter randomized controlled trial
2023, American Journal of Obstetrics and Gynecology
Miscarriage and preterm birth are leading causes of loss and disability in monochorionic twins after laser treatment of twin-twin transfusion syndrome.
This study aimed to investigate the use of cervical pessary to reduce preterm birth before 32 weeks of gestation in monochorionic diamniotic twin pregnancies after fetal surgery for twin-twin transfusion syndrome.
In this open-label multicenter randomized trial, pregnant women carrying monochorionic diamniotic twins requiring fetoscopic laser coagulation for twin-twin transfusion syndrome were randomly assigned in a 1:1 ratio to pessary placement or conservative management. The primary outcome was birth before 32 weeks of gestation. The secondary outcomes were birth before 28, 30, 34, or 37 weeks of gestation; preterm premature rupture of membranes; fetal and neonatal survival; and a composite of maternal and neonatal complications. The estimated sample size was 364 patients, with 182 cases in each arm of the study. The analysis was performed according to the intention-to-treat principle. Moreover, 2 interim analyses were planned.
The trial was stopped prematurely after the first planned interim analysis for futility. Overall, 137 women were included in the analysis, 67 in the pessary group and 70 in the conservative management group. Preterm birth before 32 weeks of gestation occurred in 27 of 67 women (40.3%) in the pessary group and in 25 of 70 women (35.7%) in the conservative management group (adjusted odds ratio, 1.19; 95% confidence interval, 0.58–2.47; P=.63). No differences between groups were observed in the rate of deliveries before 28, 30, 34, and 37 weeks of gestation. Overall survival to delivery was 91.2% (125/137) for at least 1 twin, and 70.8% (97/137) for both twins, with no difference between groups. Neonatal survival at 30 days was 76.5% (208/272). There was no difference between the groups in maternal or neonatal morbidity.
In monochorionic diamniotic twin pregnancies requiring fetal therapy for twin-twin transfusion syndrome, routine use of cervical pessary did not reduce the rate of preterm birth before 32 weeks of gestation.
Perinatal outcomes of twin-to-twin transfusion syndrome associated with evidence of twin anemia polycythemia using different standardized definitions
2022, European Journal of Obstetrics and Gynecology and Reproductive Biology
Citation Excerpt :
While TTTS is caused by an acute shift of vascular volume from donor to the recipient twin through unidirectional connections, TAPS represents a chronic process caused by very small unbalanced anastomoses that allow transfusion of red blood cells between the twins [1]. TTTS is characterized by oligo-polyhydramnios sequence and is seen in 9–15 % of monochorionic twins [2,3]. On the other hand, TAPS is characterized by anemia-polycythemia sequence without amniotic fluid volume discordance.
To evaluate the survival of twin-to-twin transfusion syndrome (TTTS) and concomitant twin anemia polycythemia sequence (TAPS) compared to TTTS without TAPS at the time of fetoscopic laser photocoagulation (FLP).
TTTS pregnancies undergoing FLP were divided to three groups including (i) traditional TAPS definition of middle cerebral artery (MCA) peak systolic velocity (PSV) < 1 multiple of the median (MoM) in recipient and > 1.5 MoM in the donor fetus, (ii) delta MCA-PSV > 0.5 MoM and (iii) delta MCA-PSV > 1.0 MoM.
A total of 353 monochorionic twins underwent FLP for TTTS. Based on the traditional definition, 335 (94.9 %) had TTTS only and 18 (5.1 %) had TTTS + TAPS. There were 245 (69.4 %) TTTS only and 108 (30.6 %) TTTS + TAPS considering delta MCA-PSV > 0.5 MoM and 339 (96 %) TTTS only and 14 (4 %) TTTS + TAPS considering delta MCA-PSV > 1.0 MoM. No significant differences in survival were noted at birth or 30-days after delivery between TTTS and TTTS with TAPS patients using the traditional definition, delta > 0.5 MoM or delta > 1.0 MoM.
The rate of neonatal survival at birth or at 30-days of life following FLP for TTTS only and TTTS with TAPS were not different based on any of the clinically used TAPS definitions.
Predictors of fetal death, neonatal survival and neurological outcomes in severe twin-twin transfusion syndrome treated by laser ablation of placental vessels
2024, Prenatal Diagnosis

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ArticlesFetoscopic laser coagulation of the vascular equator versus selective coagulation for twin-to-twin transfusion syndrome: an open-label randomised controlled trial

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Fetoscopic laser coagulation of the vascular equator versus selective coagulation for twin-to-twin transfusion syndrome: an open-label randomised controlled trial