Impact of middle cerebral artery pulsatility index on donor survival in twin-twin transfusion syndrome

Objective: To assess outcomes in twin-twin transfusion syndrome (TTTS) according to middle cerebral artery pulsatility index (MCA-PI) prior to fetoscopic laser photocoagulation (FLPC) surgery.

Methods: A retrospective cohort analysis of monochorionic-twin pregnancies complicated by TTTS who underwent FLPC at two fetal centers (2012-2021). The cohort was stratified according to abnormal MCA-PI of the donor twin, defined as below fifth centile for gestational age.

Results: Abnormal MCA-PI of the donor twin was detected in 46 (17.7%) cases compared to 213 (83.3%) controls with no such abnormality. The abnormal PI group presented with higher rates of sFGR (56.5% vs. 36.8% in controls, p = 0.014) and lower donor survival rates within 48 h after FLPC (73.9 vs. 86.8%, p = 0.029). Donor twin survival rates at the time of delivery and 30 days after birth were lower in the abnormal MCA-PI. Multivariate logistic regression analysis controlling for sFGR and MCA-PI <fifth centile demonstrated the latter to be independently associated with lower survival rates at the time of delivery and 30 days after birth [OR = 0.497 95%CI (0.250-0.986) p = 0.045, and OR = 0.499 95%CI (0.252-0.986), p = 0.046, respectively]. Recipient's survival rates did not differ between the groups.

Conclusions: Donor survival at the time of delivery and 30 days after birth was lower in TTTS cases with MCA-PI<fifth centile for gestational age prior to laser surgery. This parameter may be considered when evaluating prognosis for TTTS.