Maternal intravenous hydration and amniotic fluid index in patients with preterm ruptured membranes.

OBJECTIVE: To examine the effect of an intravenous (i.v.) fluid bolus on the amniotic fluid index (AFI) in patients with preterm ruptured membranes.

METHODS: Nonlaboring patients at 24-37 weeks' gestation with documented ruptured membranes were randomized to either no hydration or to an i.v. fluid bolus with 1 L of normal saline administered over 30 minutes. All patients had a baseline AFI measured. The same blinded examiner repeated the examination 90 minutes later.

RESULTS: Six patients were randomized to the hydration group, seven to the control group. The groups were similar in age, gravidity, parity, time since rupture, gestational age, and baseline AFI. In the hydration group, the AFI increased 5.1 cm (95% confidence interval [CI] 2.9-7.3) after the fluid bolus. In the no-hydration group, the change was 0.6 cm (95% CI-1.1 to 2.2). The difference in the change in AFI between groups was 4.5 cm (95% CI 1.3-7.7) (P = .008).

CONCLUSION: The AFI is sensitive to maternal hydration in patients with preterm rupture of membranes and can be increased with an i.v. fluid bolus.