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 < 7 at 5 minutes, gestational age at delivery, age at postnatal surgical resection, and histopathologic findings from postnatal tumor specimens.

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 < 0.01), accompanied by lower hematocrit (25% vs 51%, p < 0.01) and platelet counts (148 vs 220 × 10³/µL, p < 0.01), with increasing MCA peak systolic velocity associated with higher odds of neonatal anemia. Abnormal MCA Dopplers were also associated with higher neonatal mortality (40% vs 0%, p < 0.01), and, in the full cohort, with increased odds of perinatal death (OR 13.3, 95% CI 2.55-106), 5-minute Apgar < 7 (50% vs 10%, p = 0.03), and earlier gestational age at delivery (28 vs 36 weeks, p < 0.01). Final tumor histopathology differed between groups, with immature teratoma present in all liveborn neonates with abnormal MCA Dopplers compared with 45% in the normal MCA group (p < 0.01). Prenatal disease was also more severe in the abnormal MCA group, including higher tumor-to-fetal weight ratio (median 0.67 vs 0.15, p < 0.01), cardiomegaly (93% vs 27%, p < 0.01), hydrops (71% vs 9.1%, p < 0.01), and placentomegaly (50% vs 9.1%, p = 0.01).

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.