Analysis of the features of the labour and perinatal outcomes in isolated oligohydramnios

Background. The incidence of isolated oligohydramnios in a full-term pregnancy is 0.5–5%. Isolated oligohydramnios is usually associated with increased perinatal morbidity and mortality. For this reason, patients with oligohydramnios undergo the induction of labor. However, induction of labor increases perinatal risks and the percentage of operative delivery. Therefore, the choice of optimal management of patients with isolated oligohydramnios is an actual task of modern obstetrics.

Objective. The aim of the article is to analyze the features of the labour and perinatal outcomes in isolated oligohydramnios as compared to patients with normal amniotic fluid index (AFI) in case of full-term pregnancy revealed by ultrasound.

Materials and methods. The study included 120 patients with a gestational age of 37–42 weeks with a singleton pregnancy in the cranial presentation without obstetric and somatic abnormalities. The main group consisted of 60 patients with AFI less than 2,5 ‰ (negative amniotest). The group of comparison included 60 patients with AFI from 2,5 ‰ to 97,5 ‰ by US. Statistical significance of the differences was evaluated by means of the Student’s test, the Chi-squared two-sided Fisher’s exact test. The groups were arranged according to the age and birth parity.

Results. The main group had a higher percentage of amniotomy (35% versus 15%, p = 0.02), cesarean section (23.3% versus 8.3%, p = 0.02) and intrapartum fetal distress (18.3% versus 6.7%, p = 0.05). However, there was no significant difference in the state of the fetus estimated by the Apgar scale and the further state of the newborns.

Conclusion. Isolated oligohydramnios is not a significant risk factor for adverse neonatal outcomes, but it is an indication for induction of labor, which in itself increases the possibility of fetal distress and surgery.