Prediction of dual twin survival after laser for twin-to-twin transfusion syndrome

Objectives: To evaluate the predictive value of sonographic parameters at diagnosis of Twin-to-Twin Transfusion Syndrome (TTTS) treated with fetoscopic laser photocoagulation for post-natal 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 (A), compared to 73 (46.5%) with one or no survivors (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. Conclusions: We did not externally validate the calculator of dual survival after laser for TTTS, especially for elevated scores.