41: The pattern of labor preceding uterine rupture


      Although antepartum and early labor risk factors for a uterine rupture in a trial of labor after cesarean (TOLAC) have been identified, the course of labor in an impending uterine rupture has not been described. In order to assist clinicians in the management of TOLAC, we sought to characterize the labor pattern of women who experience uterine rupture.

      Study Design

      This is a secondary analysis of a nested case-control study of women attempting TOLAC within a multicenter retrospective cohort study of women with a prior cesarean. Women who experienced uterine rupture (cases) were compared to women who underwent TOLAC without a uterine rupture (controls); for this study, controls were included only if they reached 10-cm dilation. Subjects with more than one prior cesarean were excluded. Univariate and multivariate analyses were performed; interval censored regression was used to estimate the median time spent to progress 1-cm in dilation and the total time from 4-10-cm dilation.


      Within the retrospective cohort of 13,706 who attempted a TOLAC, 670 subjects who did not experience a uterine rupture were randomly selected as controls. For this analysis of labor curves in subjects with only one prior cesarean, 102 cases and 297 controls were included. The time to progress 1-cm of dilation was similar between cases and controls until 7-cm of dilation. At 7-cm dilation, subjects who experienced uterine rupture spent significantly longer times progressing 1-cm in dilation compared to controls (median time (hours) from 7-8 cm 0.39 vs 0.15, p1-hour compared to controls.


      Of women attempting TOLAC, those who experienced a uterine rupture were significantly more likely to progress more slowly beyond 7-cm compared to women who do not experience a uterine rupture. Poor progress after the active phase of labor should raise suspicion for risk of uterine rupture in TOLAC.
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