Prediction of Dual Twin Survival after Laser for Twin-to-Twin Transfusion Syndrome.

Introduction: Twin-to-twin transfusion syndrome (TTTS) is associated with high perinatal morbidity and mortality. Krispin et al. [Ultrasound Obstet Gynecol. 2023;61(4):511-7] developed a prediction model to estimate the likelihood of dual twin survival after fetoscopic laser photocoagulation (FLPC). This study aimed to evaluate the predictive value of sonographic parameters at diagnosis of TTTS treated with FLPC for postnatal dual twin survival and to validate Krispin et al.'s calculator.

Methods: This is a retrospective cohort study of cases of TTTS treated by FLPC. The primary outcome was dual survival 30 days after delivery. The calculator used preoperative variables: donor's estimated fetal weight (EFW) <10th centile, intertwin growth discordance >25%, anterior placenta, pulsatility index (PI) in the umbilical artery (UA), ductus venosus (DV), and middle cerebral artery (MCA), with scores ranging 0-300.

Results: Among 157 patients, 84 (53.5%) had dual twin survival (Group A), compared to 73 (46.5%) with one or no survivors (Group B). No significant differences were seen in donor's EFW <10th centile (57.1% [A] vs. 57.5% [B], p = 0.96), intertwin growth discordance (26.2% [A] vs. 38.4% [B] p = 0.95), rates of PI >95th centile in the donor's UA and DV, and PI <5th centile in the MCA (p > 0.05). However, a significant difference was found for anterior placenta (38.1% [A] vs. 58.9% [B], p = 0.009). The observed dual survival was higher than predicted for scores ≥100.

Conclusion: We were not able to externally validate the calculator of dual survival after laser for TTTS, especially for elevated scores. Among the parameters analyzed, only anterior placenta was significantly associated with poorer outcomes.