Perinatal outcome of monochorionic triamniotic triplet pregnancy: multicenter cohort study

OBJECTIVE

Monochorionic (MC) triplet pregnancies are extremely rare and information on these pregnancies and their complications is limited. We aimed to investigate the risk of early and late pregnancy complications, perinatal outcome and the timing and methods of fetal intervention in these pregnancies.

METHODS

This was a multicenter retrospective cohort study of MC triamniotic (TA) triplet pregnancies managed in 21 participating centers around the world from 2007 onwards. Data on maternal age, mode of conception, diagnosis of major fetal structural anomalies or aneuploidy, gestational age (GA) at diagnosis of anomalies, twin-to-twin transfusion syndrome (TTTS), twin anemia-polycythemia sequence (TAPS), twin reversed arterial perfusion (TRAP) sequence and or selective fetal growth restriction (sFGR) were retrieved from patient records. Data on antenatal interventions were collected, including data on selective fetal reduction (three to two or three to one), laser surgery and any other active fetal intervention (including amniodrainage). Data on perinatal outcome were collected, including numbers of live birth, intrauterine demise, neonatal death, perinatal death and termination of fetus or pregnancy (TOP). Neonatal data such as GA at birth, birth weight, admission to neonatal intensive care unit and neonatal morbidity were also collected. Perinatal outcomes were assessed according to whether the pregnancy was managed expectantly or underwent fetal intervention.

RESULTS

Of an initial cohort of 174 MCTA triplet pregnancies, 11 underwent early TOP, three had an early miscarriage, six were lost to follow-up and one was ongoing at the time of writing. Thus, the study cohort included 153 pregnancies, of which the majority (92.8%) were managed expectantly. The incidence of pregnancy affected by one or more fetal structural abnormality was 13.7% (21/153) and that of TRAP sequence was 5.2% (8/153). The most common antenatal complication related to chorionicity was TTTS, which affected just over one quarter (27.6%; 42/152, after removing a pregnancy with TOP < 24 weeks for fetal anomalies) of the pregnancies, followed by sFGR (16.4%; 25/152), while TAPS (spontaneous or post TTTS with or without laser treatment) occurred in only 4.6% (7/152) of pregnancies. No monochorionicity-related antenatal complication was recorded in 49.3% (75/152) of pregnancies. Survival was apparently associated largely with the development of these complications: there was at least one survivor beyond the neonatal period in 85.1% (57/67) of pregnancies without antenatal complications, in 100% (25/25) of those complicated by sFGR and in 47.6% (20/42) of those complicated by TTTS. The overall rate of preterm birth prior to 28 weeks was 14.5% (18/124) and that prior to 32 weeks' gestation was 49.2% (61/124).

CONCLUSION

Monochorionicity-related complications, which can impact adversely perinatal outcome, occur in almost half of MCTA triplet pregnancies, creating a challenge with regard to counseling, surveillance and management. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Interventions to prevent preterm delivery in women with short cervix before fetoscopic laser surgery for twin-twin transfusion syndrome

OBJECTIVE

Preoperative short cervical length (CL) remains a major risk factor for preterm birth after laser surgery for twin-twin transfusion syndrome (TTTS), but the optimal intervention to prolong pregnancy remains elusive. The objective of this study was to compare secondary methods for the prevention of preterm birth in twin pregnancies with TTTS undergoing fetoscopic laser photocoagulation (FLP), in the setting of a short cervix at the time of FLP, in five North American Fetal Treatment Network (NAFTNet) centers.

METHODS

This was a secondary analysis of data collected prospectively at five NAFTNet centers, conducted from January 2013 to March 2020. Inclusion criteria were a monochorionic diamniotic twin pregnancy complicated by TTTS, undergoing FLP, with preoperative CL < 30 mm. Management options for a short cervix included expectant management, vaginal progesterone, pessary (Arabin, incontinence or Bioteque cup), cervical cerclage or a combination of two or more treatments. Patients were not included if the intervention was initiated solely on the basis of having a twin gestation rather than at the diagnosis of a short cervix. Demographics, ultrasound characteristics, operative data and outcomes were compared. The primary outcome was FLP-to-delivery interval. Propensity-score matching was performed, with each treatment group matched (1:1) to the expectant-management group for CL, in order to estimate the effect of each treatment on the FLP-to-delivery interval.

RESULTS

A total of 255 women with a twin pregnancy complicated by TTTS and a short cervix undergoing FLP were included in the study. Of these, 151 (59%) were managed expectantly, 32 (13%) had vaginal progesterone only, 21 (8%) had pessary only, 21 (8%) had cervical cerclage only and 30 (12%) had a combination of treatments. A greater proportion of patients in the combined-treatment group had had a prior preterm birth compared with those in the expectant-management group (33% vs 9%; P = 0.01). Mean preoperative CL was shorter in the pessary, cervical-cerclage and combined-treatment groups (14-16 mm) than in the expectant-management and vaginal-progesterone groups (22 mm for both) (P < 0.001). There was no significant difference in FLP-to-delivery interval between the groups, nor in gestational age at delivery or the rate of live birth or neonatal survival. Vaginal progesterone was associated with a decrease in the risk of delivery before 28 weeks' gestation compared with cervical cerclage and combined treatment (P = 0.03). Using propensity-score matching for CL, cervical cerclage was associated with a reduction in FLP-to-delivery interval of 13 days, as compared with expectant management.

CONCLUSIONS

A large proportion of pregnancies with TTTS and a short maternal cervix undergoing FLP were managed expectantly for a short cervix, establishing a high (62%) risk of delivery before 32 weeks in this condition. No treatment that significantly improved outcome was identified; however, there were significant differences in potential confounders and there were also likely to be unmeasured confounders. Cervical cerclage should not be offered as a secondary prevention for preterm birth in twin pregnancies with TTTS and a short cervix undergoing FLP. A large randomized controlled trial is urgently needed to determine the effects of treatments for the prevention of preterm birth in these pregnancies. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Core outcome set for research studies evaluating treatments for twin-twin transfusion syndrome

OBJECTIVE

To develop, using a Delphi procedure and a nominal group technique, a core outcome set (COS) for studies evaluating treatments for twin-twin transfusion syndrome (TTTS), which should assist in standardizing outcome selection, collection and reporting in future research studies.

METHODS

An international steering group comprising healthcare professionals, researchers and patients with experience of TTTS guided the development of this COS. Potential core outcomes, identified through a comprehensive literature review and supplemented by outcomes suggested by the steering group, were entered into a three-round Delphi survey. Healthcare professionals, researchers, and patients or relatives of patients who had experienced TTTS were invited to participate. Consensus was defined a priori using the 15%/70% definition of the Core Outcome Measures in Effectiveness Trials (COMET) initiative. The modified nominal group technique was used to evaluate the consensus outcomes in a face-to-face consultation meeting and identify the final COS.

RESULTS

One hundred and three participants, from 29 countries, participated in the three-round Delphi survey. Of those, 88 completed all three rounds. Twenty-two consensus outcomes were identified through the Delphi procedure and entered into the modified nominal group technique. The consensus meeting was attended by 11 healthcare professionals, two researchers and three patients; 12 core outcomes were prioritized for inclusion in the COS. Fetal core outcomes included live birth, pregnancy loss (including miscarriage, stillbirth, termination of pregnancy and neonatal mortality), subsequent death of a cotwin following single-twin demise at the time of treatment, recurrence of TTTS, twin anemia-polycythemia sequence and amniotic band syndrome. Neonatal core outcomes included gestational age at delivery, birth weight, brain injury syndromes and ischemic limb injury. Maternal core outcomes included maternal mortality and admission to Level-2 or -3 care setting. One aspirational outcome, neurodevelopment at 18-24 months of age, was also prioritized.

CONCLUSIONS

Implementing the COS for TTTS within future research studies could make a substantial contribution to advancing the usefulness of research in TTTS. Standardized definitions and measurement instruments are now required for individual core outcomes. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Variation in outcome reporting in randomized controlled trials of interventions for prevention and treatment of fetal growth restriction

OBJECTIVE

Although fetal growth restriction (FGR) is well known to be associated with adverse outcomes for the mother and offspring, effective interventions for the management of FGR are yet to be established. Trials reporting interventions for the prevention and treatment of FGR may be limited by heterogeneity in the underlying pathophysiology. The aim of this study was to conduct a systematic review of outcomes reported in randomized controlled trials (RCTs) assessing interventions for the prevention or treatment of FGR, in order to identify and categorize the variation in outcome reporting.

METHODS

MEDLINE, EMBASE and The Cochrane Library were searched from inception until August 2018 for RCTs investigating therapies for the prevention and treatment of FGR. Studies were assessed systematically and data on outcomes that were reported in the included studies were extracted and categorized. The methodological quality of the included studies was assessed using the Jadad score.

RESULTS

The search identified 2609 citations, of which 153 were selected for full-text review and 72 studies (68 trials) were included in the final analysis. There were 44 trials relating to the prevention of FGR and 24 trials investigating interventions for the treatment of FGR. The mean Jadad score of all studies was 3.07, and only nine of them received a score of 5. We identified 238 outcomes across the included studies. The most commonly reported were birth weight (88.2%), gestational age at birth (72.1%) and small-for-gestational age (67.6%). Few studies reported on any measure of neonatal morbidity (27.9%), while adverse effects of the interventions were reported in only 17.6% of trials.

CONCLUSIONS

There is significant variation in outcome reporting across RCTs of therapies for the prevention and treatment of FGR. The clinical applicability of future research would be enhanced by the development of a core outcome set for use in future trials. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Outcome of fetoscopic laser ablation for twin-to-twin transfusion syndrome in dichorionic-triamniotic triplets compared with monochorionic-diamniotic twins

OBJECTIVE

To compare outcome of dichorionic-triamniotic (DCTA) triplet gestations with that of a paired cohort of monochorionic-diamniotic (MCDA) twin gestations undergoing laser therapy for treatment of twin-to-twin transfusion syndrome (TTTS).

METHODS

All DCTA triplets treated at four referral centers between specified dates were included. A matched cohort group of MCDA twin gestations affected by TTTS was used for comparison.

RESULTS

Sixteen sets of DCTA triplets treated with laser photocoagulation of placental anastomoses were compared with 32 matched sets of MCDA twins. All of the 'singleton' fetuses in the triplet gestations survived to birth and to the end of the neonatal period. There were no differences in single or double survival or the rate of non-survivors to birth and at age 28 days. A mean 3-week difference was found in the procedure-to-delivery interval in DCTA triplets vs MCDA twins (60 ± 35.8 days vs 83.6 ± 33.2 days; P = 0.029). A mean difference of 3 weeks was also found in the gestational age at delivery in DCTA triplets vs MCDA twins (28.5 ± 3.5 weeks vs 31.9 ± 5 weeks; P = 0.024). A similar post-laser fetal growth pattern in donors and recipients of both groups was noted.

CONCLUSIONS

DCTA triplet gestations with TTTS have a similar rate of post-laser survival but deliver earlier than can be expected for twins treated with laser. These findings have potential implications for the risk of prematurity and long-term outcomes.

Risk factors associated with preterm delivery after fetoscopic laser ablation for twin-twin transfusion syndrome

OBJECTIVE

Despite improved perinatal survival following fetoscopic laser ablation (FLA) for twin-twin transfusion syndrome (TTTS), prematurity remains an important contributor to perinatal mortality and morbidity. The objective of the study was to identify risk factors for complicated preterm delivery after FLA.

METHODS

Retrospective cohort study of prospectively collected data on maternal/fetal demographics and pre-operative, operative and postoperative variables of 459 patients treated with FLA in three USA fetal centers. Multivariate linear regression was performed to identify significant risk factors associated with preterm delivery, which were cross-validated using the k-fold method. Multivariate logistic regression was performed to identify risk factors for early compared with late preterm delivery based on median gestational age at delivery of 32 weeks.

RESULTS

There were significant differences in case selection and outcomes between the centers. After controlling for the center of surgery, multivariate analysis indicated that a lower maternal age at procedure, a history of previous prematurity, shortened cervical length, use of amnioinfusion, a cannula diameter of 12 French (Fr), lack of a collagen plug placement and iatrogenic preterm premature rupture of membranes (iPPROM) were significantly associated with a lower gestational age at delivery.

CONCLUSIONS

Specific fetal/maternal and operative variables are associated with preterm delivery after FLA for the treatment of TTTS. Further studies to modify some of these variables may decrease the perinatal morbidity after laser therapy.

Magnetic resonance imaging of the placenta identifies placental vascular abnormalities independently of Doppler ultrasound

OBJECTIVE

To evaluate the relationship between placental vascular pathology detected by prenatal magnetic resonance imaging (MRI) and perinatal outcome.

METHODS

This was a retrospective, hospital-based, cross-sectional study in which all fetal MRI examinations of singleton pregnancies with vascular placental pathology (i.e. infarction with/without hemorrhage, subchorionic thrombi/hemorrhages, intervillous thrombi/hemorrhages, or retroplacental hematoma) in the period 2002-2007 were included. The extent of the pathology was expressed as a percentage of the total placental volume. Abnormalities of umbilical artery Doppler ultrasound examinations within 7 days between MRI and ultrasound examination were noted. Death in utero or postnatally was the primary outcome. Gestational age at MRI and at birth and the occurrence of intrauterine growth restriction (IUGR) were noted. Logistic regression analysis was performed to assess the impact of gestational age at MRI, extent of the vascular lesion and presence of pathological Doppler ultrasound measurements on the prediction of mortality.

RESULTS

Fifty-nine structurally normal singleton pregnancies with placental vascular abnormalities were included in the analysis. Mortality rate was 36%; among the survivors, 87% were born before 37 + 0 gestational weeks and 50% suffered from IUGR. In 55% of the pregnancies pathological umbilical artery Doppler findings were identified, of which 27% were non-survivors. Mortality was predicted by earlier gestational age at fetal MRI for placental pathology (P < 0.05) and increasing extent of the vascular lesion (P < 0.05), but not by the presence of pathological Doppler ultrasound data. Accuracy of the prediction was 82%, sensitivity was 67% and specificity 89%.

CONCLUSION

MRI-detected vascular placental pathologies may help to identify pregnancies at risk for adverse outcome and fetal death independently of umbilical artery Doppler status.