Clinical and sonographic fetal weight estimates in active labor with ruptured membranes.

OBJECTIVE: To determine and compare the accuracy of clinical and sonographic estimates of fetal weight (EFW) in active labor with ruptured membranes.

STUDY DESIGN: Clinical and sonographic EFWs were obtained on 107 term patients in active labor, with cervical dilatation of 4 cm or more and ruptured membranes. Accuracy of birth weight was determined by calculating percentage error, absolute percentage error and ratio of estimates within 10% of actual birth weight for all stages of labor. Statistical analysis was by paired t test, Wilcoxon sign test, chi 2 test and Mann-Whitney U test; P < .05 was considered significant.

RESULTS: Absolute percentage errors were lower by the sonographic method at all stages. Except for the second stage of labor, the rates of birth weight +/- 10% were higher with the sonographic method than with the clinical method (83.17% vs. 60.75% and 84.9% vs. 63.44%, respectively). Estimations performed in the first stage were more accurate than in the second stage with both methods (absolute error of 7.82 +/- 5.5 vs. 12.38 +/- 4.9 for clinical and 5.44 +/- 5.99 vs. 9.08 +/- 3.19 for sonographic).

CONCLUSION: During active labor with ruptured membranes, sonographic EFWs are more accurate than clinical estimations. The accuracy of both methods is reduced during the second stage of labor.