Clinical outcomes associated with abnormal middle cerebral artery Doppler velocities in fetal sacrococcygeal teratoma

Background Sacrococcygeal teratoma is a rare fetal tumor that may cause progressive hemodynamic compromise, fetal anemia, hydrops, and perinatal death. Although middle cerebral artery peak systolic velocity is widely used to assess fetal anemia, its prognostic value in pregnancies complicated by sacrococcygeal teratoma is not well established.Objective To evaluate the association between abnormal fetal middle cerebral artery (MCA) Doppler velocities and neonatal outcomes in pregnancies complicated by fetal sacrococcygeal teratoma (SCT).Study design We conducted a retrospective cohort study of prenatally diagnosed sacrococcygeal teratomas managed at a tertiary fetal center between January 2014 and January 2026. Cases were stratified by fetal middle cerebral artery (MCA) Doppler status (normal vs abnormal), with abnormal defined as a peak systolic velocity ≥ 1.5 multiples of the median (MoM). Prenatal sonographic findings, fetal interventions, and perinatal outcomes were compared between groups. The primary outcome was neonatal hemoglobin concentration at birth. Secondary outcomes included platelet count, neonatal mortality, Apgar score Results Among 36 fetuses with prenatally diagnosed SCT, 14 (39%) had abnormal MCA Doppler velocities. Neonates with abnormal MCA Dopplers had markedly lower hemoglobin concentrations at birth compared with those with normal MCA Dopplers (median 8.4 vs 16.9 g/dL, p Conclusions In this small retrospective cohort of fetuses with sacrococcygeal teratoma, abnormal MCA Doppler velocities were associated with severe neonatal anemia, thrombocytopenia, distinct tumor histopathology, and adverse neonatal outcomes. These findings suggest that MCA Doppler assessment may help identify higher-risk cases but require validation in larger, multicenter cohorts before informing clinical management.