Elevated middle cerebral artery peak systolic velocity and risk of death in donor twin affected by twin–twin transfusion syndrome but not twin anemia–polycythemia sequence

Abstract

ABSTRACTObjectivesTo determine the association between elevated (> 1.5 multiples of the median (MoM)) middle cerebral artery (MCA) peak systolic velocity (PSV) and fetal demise of the donor twin in pregnancies complicated by twin–twin transfusion syndrome (TTTS) in the absence of twin anemia–polycythemia sequence (TAPS). Secondary objectives were to evaluate if donor or recipient MCA‐PSV is associated with a risk for their corresponding fetal death, and to compare the proportion of donor fetuses with low MCA pulsatility index (PI) among donor twins with high MCA‐PSV and those with normal MCA‐PSV to evaluate the contribution of blood‐flow redistribution to the fetal brain in donor twins with high MCA‐PSV.MethodsThis 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. Multivariable and Poisson regression analysis were performed to explore the association between isolated elevated donor MCA‐PSV and fetal demise, adjusted for TTTS stage, selective fetal growth restriction (sFGR) and other confounders.ResultsOf 660 TTTS cases, donor MCA‐PSV was not recorded in 48 (7.3%) cases. Of the remaining 612 patients, nine (1.5%) were lost to follow‐up and 96 TAPS cases were excluded; thus, 507 cases were included in the study. High donor MCA‐PSV was seen in 6.5% (33/507) of cases and was an independent risk factor for donor fetal demise (adjusted relative risk (aRR), 4.52 (95% CI, 2.72–7.50)), after adjusting for confounders. Regression analysis restricted to each Quintero TTTS stage demonstrated that high donor MCA‐PSV was an independent risk factor for fetal demise of the donor in Quintero Stage II (aRR, 14.21 (95% CI, 1.09–186.2)) and Quintero Stage III (aRR, 3.41 (95% CI, 1.82–6.41)). Donor MCA‐PSV in MoM was associated with fetal demise of the donor (area under the receiver‐operating‐characteristics curve (AUC), 0.69; P < 0.001), but recipient MCA‐PSV in MoM was not associated with fetal demise of the recipient (AUC, 0.54; P = 0.44). A higher proportion of donor twins in the group with high MCA‐PSV had a low MCA‐PI compared to the group with normal MCA‐PSV (33.3% vs 15.5%; P = 0.016).ConclusionsElevated donor MCA‐PSV without TAPS prior to laser surgery for TTTS 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 may help stratify TTTS staging to evaluate the risk of donor fetal demise. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.