Umbilical vein blood volume flow rate and umbilical artery pulsatility as ‘venous–arterial index’ in the prediction of neonatal compromise

Objective To assess the diagnostic power of the umbilical venous–arterial index (VAI) for the prediction of poor fetal outcome. Subjects and methods This was a retrospective, cross‐sectional clinical study in which normalized umbilical vein blood volume flow rate (nUV) (mL/min/kg estimated body weight), umbilical artery pulsatility index (UAPI), the newly developed VAI (nUV/UAPI), and the uterine artery resistance index (UTRI) were determined in 85 fetuses once (17–41 gestational weeks) during pregnancy using standard ultrasound Doppler equipment. A risk score based on umbilical blood pH, 1‐min Apgar score, birth weight, duration of gestation, type of respiratory support, and referral to the pediatric department was constructed, and fetuses were assigned to a control or a pathological group accordingly. Logistic regression and analysis of fitted receiver–operating characteristics curves were performed to evaluate the diagnostic power of nUV, UAPI, UTRI, and VAI. Results The incidence of compromised neonates was 17.6%. The area under the receiver–operating characteristics curve was larger for VAI than for UTRI or for UAPI ( P < 0.002). At a cut‐off value of 100 mL/min/kg, the sensitivity of VAI to predict poor neonatal outcome was 85% with a 15% false‐positive rate. Conclusion Determination of the VAI has a greater diagnostic power to predict poor fetal outcome than the pulsatility index in the umbilical artery or the resistance index in the uterine artery. Copyright © 2002 International Society of Ultrasound in Obstetrics and Gynecology