Effect of gestational age at laser therapy on perinatal outcome in monochorionic diamniotic pregnancies affected by twin-to-twin transfusion syndrome

Abstract

Objective: To evaluate the effect of gestational age at laser therapy for twin-to-twin transfusion syndrome (TTTS) on perinatal outcome.

Design and settings: Single retrospective observational cohort.

Population: All consecutive pregnancies affected by TTTS and referred to our department between January 2013 and August 2020.

Methods: Gestational age was modelled both as a categorical and as a continuous variable. Log-binomial regression was used to estimate the odds ratios (crude and adjusted for placental location, Quintero stage and cervical length) as well as the adjusted predicted probability of survival and fetal loss according to gestational age at laser therapy.

Main outcomes: Fetal and neonatal survival, preterm prelabour rupture of membranes (PPROM).

Results: Of the 503 pregnancies referred for TTTS, 431 were treated by laser therapy. Gestational age at laser therapy was positively and significantly associated with the overall survival at birth and at discharge (adjusted odds ratio [aOR] 1.12, 95% CI 1.05-1.19), as with a reduction in double fetal loss (aOR 0.81, 95% CI 0.71-0.92). Conversely, the rate of PPROM before 24 weeks was significantly higher in early cases (32% of PPROM <24 weeks when laser therapy was performed before 17 weeks versus 1.5% after 22 weeks, p < 0.001, aOR 0.60, 95% CI 0.48-0.72). Among the survivors, preterm birth before 28 weeks was significantly related to the gestational age at laser (OR 0.91, 95% CI 0.84-0.99), resulting in a significant impact on neonatal morbidity (OR 0.91, 95% CI 0.85-0.97).

Conclusion: Our results suggest a significant and independent impact of the gestational age at laser surgery on perinatal survival, PPROM and neonatal morbidity.

Keywords: fetal surgery; fetoscopic laser therapy; monochorionic; prognosis; twin-to-twin transfusion syndrome; twins.