Elevated Middle Cerebral Artery Peak Systolic Velocity in Non-Anemic Fetuses: Providing a Better Understanding of Enigmatic Middle Cerebral Artery Peak Systolic Velocity.

Introduction: Our aim was to investigate the incidence, comorbidities, and outcomes of fetuses with an elevated middle cerebral artery peak systolic velocity (MCA-PSV) >1.5 multiples of median (MoM), despite normal hemoglobin (Hgb) levels on fetal blood sampling (FBS).

Methods: A single-center observational retrospective cohort study of all fetuses undergoing FBS and MCA-PSV >1.5 MoM. Only those fetuses with no or mild anemia were included. Indications for Doppler assessment, associated anomalies, and neonatal outcomes were collected.

Results: Overall, 383 fetuses had an MCA-PSV >1.5 MoM and underwent FBS. Twenty-three (6%) fetuses met our inclusion criteria and had no or only mild anemia. Associations with elevated MCA-PSV were elucidated in 12 of the 23 cases (52.2%) and included mild anemia (n = 2), intracranial hemorrhage (n = 3), genetic disease (n = 1), idiopathic nonimmune hydrops (NIH, n = 1), hypoxic-ischemic encephalopathy (n = 1), maternal and or fetal acidosis (n = 3), and fetal growth restriction (n = 1). Favorable perinatal outcomes were observed in truly unexplained 11 cases with no additional anomalies (47.8%).

Conclusion: Elevated MCA-PSV >1.5 MoM with normal Hgb levels is seen in 6% of pregnancies undergoing FBS and is often associated with other significant maternal or fetal problems. Those with unexplained and isolated MCA-PSV elevation have normal outcomes.