G. Eric Knox

Management of prolonged pregnancy: Results of a prospective randomized trial

Prolonged pregnancy was rigorously defined in 180 gravid women without other complications. Patients were randomly assigned to be serially followed, either by amniocenteses or by oxytocin challenge tests (OCTs). Induction of labor, based upon only (1) a finding of meconium in the amniocentesis group or (2) a positive test in the OCT group, was nearly three times more frequent in the amniocentesis group. The incidence of meconium, which overall was 22% initially and 44% at delivery, as well as the frequencies of obstetric and perinatal complications, were similar in both management groups. Although meconium was significantly associated with abnormal labor progression, intrapartum fetal distress, and low 1 and 5 minute Apgar scores, induction of labor after discovery of meconium, when compared to nonintervention, did not improve perinatal outcome. It is concluded that a search for meconium is of little value in the management of prolonged pregnancy.

Is pulsed Doppler velocimetry useful in the management of multiple-gestation pregnancies?

Few studies have addressed the significance of umbilical artery pulsed Doppler velocimetry in multiple gestation. Level II ultrasonography and pulsed Doppler studies were performed in 94 twin pairs and seven sets of triplets, which yielded data on 207 fetuses. A systolic/diastolic ratio was calculated for each fetus; abnormal pulsed Doppler velocimetry showed high correlation with adverse pregnancy events. Those with abnormal Doppler findings tended to be born 3 to 4 weeks earlier and to exhibit a greater number of stillbirths and structural malformations, as well as greater morbidity, when compared with fetuses without abnormal Doppler results. Fifteen of 17 infants with abnormal antenatal waveforms suffered serious morbidity. Seven were small for gestational age, and two were borderline for small for gestational age. An additional five infants with abnormal waveforms were appropriate for gestational age but were either recipient or donor in the twin transfusion syndrome. Eleven fetuses with this syndrome are described. Donor twins tended to be severely small for gestational age, with 7 of the 11 infants showing elevated systolic/diastolic ratios. Amniotic fluid volume tended to be diminished in the donors sac but normal or increased in the recipients sac. The observations in the study correlate with suspected physiologic changes of this syndrome. Because present findings suggest that fetuses with abnormal velocimetry suffer increased morbidity and mortality, a more rational method of management that uses Doppler data is suggested for multiple gestations.

The predictability of the small-for-gestational-age infant by real-time ultrasound-derived measurements combined with pulsed Doppler umbilical artery velocimetry.

During a 15-month period 373 level II ultrasound examinations were performed in 256 high-risk patients. In addition, pulsed Doppler spectral recordings of blood flow in the fetal umbilical arteries were made. A systolic/diastolic ratio was then calculated for each fetus. Real-time ultrasound-derived estimated fetal weight with the use of biparietal diameter and abdominal circumference was also calculated. The estimated fetal weights were categorized by placing them in a percentile for gestational age according to published nomograms. Complete birth data and outcomes were obtained in all patients. Both the systolic/diastolic ratio and ultrasound-estimated fetal weight grouped by percentile ranking for gestational age were highly predictive (p = 0.001) of babies who were subsequently born small for gestational age. Seventy-nine percent of the infants small for gestational age had umbilical artery systolic/diastolic ratios greater than or equal to 4, whereas only 21% had normal systolic/diastolic ratios. Forty-three percent of the infants who were small for gestational age had ultrasound-estimated fetal weights less than or equal to 10th percentile for the gestational age at which it was measured. Umbilical artery systolic/diastolic ratios, which reflect an increase in peripheral resistance in the placental circulation, showed a highly predictive and discriminatory index for the evaluation of the fetus suspected of having growth retardation.

Evaluation of gas-liquid chromatography for the rapid diagnosis of amniotic fluid infection: a preliminary report.

Gas-liquid chromatography has been proposed as a possible tool in the rapid diagnosis of amniotic fluid infections. The analysis is based on the identification of specific organic acids derived from bacterial metabolism when organisms are present within the amniotic fluid. We retrospectively subjected 69 samples of amniotic fluid which had been obtained by transabdominal amniocentesis to analysis by gas-liquid chromatography. Forty-seven samples were derived from patients who either were in premature labor or had premature rupture of membranes with associated premature labor. Twenty-two specimens which served as a comparison group were obtained from patients who underwent amniocentesis for assessment of fetal maturity. The results obtained from chromatographic analysis are presented, and the possible applications of this technique to the clinical situation are discussed.