No abstract

There is a significant fall in umbilical artery pH and bicarbonate with the presence of labor and increased duration of second stage of labor in healthy term neonates. This should be taken into consideration in evaluating neonatal well-being by cord blood pH and acid-base measurements.

In 105 singleton pregnancies in which cesarean section was performed before the onset of labor, the efficacy of Doppler umbilical velocimetry in identifying fetal acidosis was determined and compared with fetal biophysical profile. Doppler velocimetry showed a significant correlation with the umbilical artery pH and was also a sensitive indicator of fetal acidosis, comparable to the biophysical profile score. Patients were classified T he fetal biophysical profile (nonstress test, fetal breathing movements, fetal movemen ts, fetal tone, amniotic fluid volume) is widely used in current obstetrical practice. Its usefulness in antepartum fetal surveillance has been well documented. 1More recently, Doppler ultrasound has become available as a noninvasive technique to assess both the fetoplacental and the uteroplacental circulations. The rationale for this new technique is that higher impedance indices on the umbilical arteries are associated with adverse pregnancy outcomes,l.J Doppler umbilical artery velocimetry can help detect the fetuses with reduced placental perfusion, 2 which can result in fetal growth failure, hypoxia, and acidosis as a consequence of impaired transfer of nutrients and oxygen to the fetus. 4~6The present investigation was undertaken to determine first, the relationship between the Doppler umbilical artery blood flow velocity waveform and umbilical blood pH and, second, the efficacy of this test in Received lanuary 3, 1991, identifying fetal acidosis. Finally the results were compared with those of the fetal biophysical profile. The add-base state of the fetus was determined by cord blood pH. To minimize the effects of labor on the fetus, the cord blood was sampled only in patients undergoing cesarean section before the onset of labor. MATERIALS AND METHODSThe study population consisted of 105 patients with singleton pregnancies between 29 and 44 weeks gestation, all delivered by cesarean section within 16 hours after both Doppler umbilical velocimetry and deter· mination of fetal biophysical profile. In most of the cases (78%), the cesarean section was performed within 3 hours of both tests. All of the patients had intact membranes and were not in labor. Infants with congenital anomaly also were excluded. Both tests were done after a clinical decision was made to perform cesarean section and informed consent was obtained, and none of the deliveries were deferred because of the testings. The primary indications for cesarean section were elective repeat cesarean section (53%); severe pregnancy-induced hypertension (16% ); breech presentation (9%); fetal macrosomia (4%); older primipara