Cord-containing amniotic fluid pocket: a useful measurement in the management of oligohydramnios

To test the hypothesis that among patients with a low amniotic fluid (AF) index, those who have a large cord-containing AF pocket will have a lower risk for adverse perinatal outcome than women with a small cord-containing pocket.

Gravidas with an antepartum AF index no greater than 5 cm were studied prospectively. The vertical diameter of the single largest cord-containing pocket, which was excluded from the calculation of the AF index, was measured. Women with rupture of the membranes, multiple gestation, or fetal anomalies were excluded.

Fifty-one women with gestational ages of 35-43 weeks were analyzed. Among 35 who had a cord-containing pocket of no more than 5 cm, eight (23%) had fetal distress necessitating operative delivery and eight neonates had cord arterial pH below 7.20. None of these complications occurred in the 16 women who had a cord-containing pocket above 5 cm (P < .05). The mean AF index (2.9 versus 2.8 cm) was not significantly different between the groups.

Among women with a low AF index, a cord-containing pocket above 5 cm identifies a subgroup of women at lower perinatal risk compared with those with a smaller cord-containing pocket. The need for intervention may be reduced in women with a cord-containing pocket greater than 5 cm.