Venous-arterial indices in the prediction of acidemia at birth in pregnancies with placental insufficiency - Revista Brasileira de Ginecologia e Obstetrícia

OBJECTIVE: to investigate whether it is possible to predict acidemia at birth in pregnancies with placental insufficiency using venous-arterial indices: pulsatility index for vein (PIV) of the ductus venosus (DV) over PI of the middle cerebral artery (MCA) and PIV of the DV over PI of the umbilical artery, and establish cut-off values for this prediction. PATIENTS AND METHODS: this was a prospective cross-sectional study involving forty-seven patients with placental insufficiency (umbilical artery resistance and pulsatility indices above the 95th percentile for gestational age) who were submitted to Dopplervelocimetry in the last 24 hours before delivery. All pregnancies were singleton, over 26 weeks of age and without structural or chromosome anomalies. Arterial cord blood was obtained for gasometry immediately after birth. Acidemia was defined as umbilical arterial pH < 7.20 in the absence of uterine contractions and pH < 7.15 in the presence of contractions. Metabolic or mixed acidemia at birth were considered pathological. A ROC curve was calculated for the venous-arterial indices: PIV DV/PI umbilical artery (UA) and PIV DV/PI MCA. A cut-off value was established and sensitivity, specificity, accuracy, positive and negative predictive values and positive and negative likelihood ratios were calculated. RESULTS: The DV/UA PI index was not a good predictor of acidemia at birth. The DV/MCA PI index was related to acidemia at birth (area under the curve 0,785, p = 0,004). The cut-off value was: 0,582, sensitivity 66,7%, specificity 77,1 and accuracy 74,5%. CONCLUSION: the PIV DV/PI MCA ratio is adequate for predicting acidemia at birth in pregnancies with placental insufficiency. The cut-off value was: 0,582.