Risk stratification for donor twin fetal death by evaluating middle cerebral artery in twin-to-twin transfusion syndrome in absence of twin anemia polycythemia sequence.

OBJECTIVE: To determine the association of high middle cerebral artery peak systolic velocity (MCA-PSV) with fetal demise in donor twins among pregnancies complicated by twin-to-twin transfusion syndrome (TTTS) in the absence of twin anemia polycythemia sequence (TAPS).

METHODS: This prospective cohort study included TTTS cases that underwent laser surgery between 2011 and 2022 at a single center. TAPS cases were excluded from the study. The primary objective was to explore the association of high MCA-PSV (>1.5 multiples of the median) with fetal demise of the donor twin among pregnancies complicated by TTTS. Secondary objectives were: 1) to evaluate if donor or recipient MCA-PSV is associated with an increased risk for their corresponding fetal death using receiving operator characteristic curve analysis; and 2) to compare the proportion of fetuses with low MCA pulsatility index among donor twins with high MCA-PSV and in those with normal MCA-PSV to evaluate the contribution of blood flow redistribution to high MCA-PSV. Multivariable and Poisson regression analysis were performed to explore the association of isolated high donor MCA-PSV and fetal demise, adjusted for TTTS stage, selective fetal growth restriction (sFGR), and other confounders. p<0.05 was considered significant.

RESULTS: Out of 660 TTTS cases, donor MCA-PSV was unavailable in 48 (7.3%) cases. Of the remaining 612 patients, 9 (1.5%) were lost to follow-up, and 96 TAPS cases were excluded. High donor MCA-PSV was seen in 6.5% (33/507) of the study population. High donor MCA-PSV was an independent risk factor for donor fetal demise (adjusted relative risk (aRR) of 4.52; 95% CI: 2.72-7.50), adjusted for confounders. Regression analysis restricted to each Quintero TTTS stage demonstrated that high donor MCA-PSV was an independent risk factor for donor fetal demise in Quintero stage II (aRR of 14.21; 95% CI: 1.09-186.2) and Quintero stage III (aRR of 3.41; 95% CI: 1.82-6.41). Donor MCA-PSV was associated with donor fetal demise (AUC: 0.69; p<0.001), but recipient MCA-PSV was not associated with its corresponding fetal demise (AUC: 0.54; p=0.44). A higher proportion of donor twins in the group with high MCA-PSV had a low MCA pulsatility index than in those with normal MCA-PSV (33.3% vs. 15.5%; p=0.016).

CONCLUSIONS: Elevated donor MCA-PSV without TAPS prior to laser surgery is associated with a 4-fold increased risk for donor fetal demise, adjusted for sFGR, TTTS stage, and other confounders. Doppler evaluation of donor MCA-PSV prior to laser surgery can further stratify TTTS staging to evaluate the risk for donor fetal demise. This article is protected by copyright. All rights reserved.