[Amniotic fluid analysis as a screening test in term and post-term pregnancy]

To verify the hypothesis that isolated oligohydramnios in low-risk term or post-term pregnancy does not increase the risk of trauma to the fetus compared with a control group.

This prospective study compared a group of patients with low-risk pregnancy and oligohydramnios (AFI = or <50) and a control group which on ultrasonography performed 24 hours before delivery had an AFI volume >50 and = or <250 mm. The evaluation criteria included incidence of induction, modality of delivery and neonatal outcome. Statistical analysis was carried out using Student's "t"-test and the data set of categories was compared using the chi square test.

From January 1997 to April 1999, 105 cases of oligohydramnios were compared with a control group (105 patients) matched for maternal age, gestation period and parity. The incidence of induction, fetal distress and variable deceleration was significantly higher in the group with AFI = or <50. The incidence of vacuum extractor, cesarean section, duration of labor and late deceleration did not differ between the two groups. No significant differences in neonatal outcome were found between the two groups.

In patients with oligohydramnios without risk factors, the modality of delivery and neonatal outcome do not differ compared with those with normal amniotic fluid volume.