Amniotic fluid index versus single deepest vertical pocket: A meta-analysis of randomized controlled trials

Abstract

Objective To compare the use of the amniotic fluid index with the single deepest vertical pocket measurement, during antepartum fetal surveillance, in preventing adverse pregnancy outcome. Search strategy We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (January 2008), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2008, Issue 2), MEDLINE (1966 to May 2008), and the metaRegister of Controlled Trials (May 2008). We handsearched the citation lists of relevant publications, review articles, and included studies. Selection criteria Randomized controlled trials involving women with a singleton pregnancy, whether at low or high risk, undergoing ultrasound measurement of amniotic fluid volume as part of antepartum assessment of fetal well-being that compared the amniotic fluid index and the single deepest vertical pocket measurement. Data collection and analysis Both authors independently assessed eligibility and quality, and extracted the data. Results Four trials (3125 women) met the inclusion criteria. When the amniotic fluid index was used, significantly more cases of oligohydramnios were diagnosed (risk ratio (RR) 2.33, 95% CI 1.67–3.24), and more women had inductions of labor (RR 2.10, 95% CI 1.60–2.76) and cesarean delivery for fetal distress (RR 1.45, 95% CI 1.07–1.97). There is no evidence that one method is superior to the other in the prevention of poor peripartum outcomes, including: admission to a neonatal intensive care unit; an umbilical artery pH of less than 7.1; the presence of meconium; an Apgar score of less than 7 at 5 minutes; or cesarean delivery. Conclusion Single deepest vertical pocket measurement is the method of choice for the assessment of amniotic fluid volume.