[Ductus venosus Doppler velocimetry to predict acidemia at birth in pregnancies with placental insufficiency]. / Dopplervelocimetria do ducto venoso na predição da acidemia fetal.

ABSTRACT

OBJECTIVES: To investigate the possibility of predicting acidemia at birth in pregnancies with placental insufficiency by Doppler velocimetry of the ductus venosus and to establish the best parameter and cut-off points in this prediction. METHODS: This was a prospective cross-sectional study, involving 47 single pregnancies with placental insufficiency after 26 weeks of gestation, carried out at the "Hospital São Paulo (UNIFESP) and Maternidade-Escola Assis Chateaubriand (UFC)". Placental insufficiency was defined as the umbilical artery pulsatility index above the 95th percentile for gestational age. Fetuses with chromosomal or structural anomalies were excluded. The time interval between the Doppler velocimetry and the birth was of less than 24 hours. The umbilical arterial blood samples were collected immediately after birth. Acidemia was defined as umbilical arterial pH < 7.2 in the absence of uterine contractions and < 7.15 in the presence of contractions. Metabolic or mixed acidemia at birth was considered pathological. Receiver operating characteristics (ROC) curves were calculated for S, D and A-velocities, pulsatility index for veins and the S/A ratio and (S-A)/S ratio of the ductus venosus. Parameters were compared using the MacNemar Test RESULTS: S, D and A-velocities of the ductus venosus were poor predictors of acidemia at birth. The pulsatility index for veins (area under the curve 0.79, p=0.003), S/A ratio and (S-A)/S ratio (area under the curve 0.818, p=0.001) of the DV were strongly related to fetal acidemia. The cut-off points calculated were pulsatility index for veins = 0.76; S/A ratio = 2.67 and (S-A)/S ratio = 0.63. CONCLUSIONS: The angle-independent indices of the DV Doppler are adequate for the diagnosis of fetal acidemia in gestations with placental insufficiency. No statistically significant differences were observed between these parameters.