Accuracy of intrapartum estimates of fetal weight. Effect of oligohydramnios.

OBJECTIVE

To study the effect of oligohydramnios on the accuracy of intrapartum clinical and sonographic estimates of fetal weight (EFWs).

STUDY DESIGN

Intrapartum clinical and sonographic EFWs and an amniotic fluid index (AFI) were obtained on 124 term patients. Oligohydramnios was defined as an AFI < or = 5 cm.

RESULTS

Clinical and sonographic EFWs in women with oligohydramnios were significantly less accurate than estimates derived in patients with normal amniotic fluid: P = .03 and .02, respectively. The incidence of clinical and sonographic EFWs within +/-10% of the actual birth weight were 70.1% and 68.4%, respectively (P = NS).

CONCLUSION

In term patients, intrapartum sonographic prediction of birth weight offers no advantage over estimated fetal weight obtained by abdominal palpation. The presence of oligohydramnios significantly reduces the accuracy of intrapartum clinical as well as sonographic EFWs. Therefore, we suggest that intrapartum EFWs be obtained prior to artificial rupture of the membranes.