Fetal heart rate abnormalities associated with uterine rupture: a case–control study: A new time-lapse approach using a standardized classification

ObjectiveThe aim of this study was to identify fetal heart rate abnormalities (FHRA) in the two hours preceding uterine rupture during trial of labor after a previous C-section compared with successful vaginal birth after cesarean controls.Study designA multicenter case–control study was conducted from 2006 to 2012. Fetal heart rate tracings of the two-hour period preceding delivery were segmented, anonymized and independently classified by two obstetricians according to a standardized grid based on FIGO guidelines (4 grades: 1 – normal, 2 – intermediate, 3 – abnormal, 4 – preterminal). Each case of uterine rupture was matched to 2 controls.Survival curves were generated for both groups using the Kaplan–Meier method to analyze the occurrence of each FHR category across time.ResultsDuring the study period, 39,773 patients gave birth. 2649 involved women with a previous C-section (6.6%). A total of 33 uterine rupture/scar dehiscence cases occurred (0.08% of all births), of which 22 were included. These were matched to 44 controls.FIGO grade-3 FHRA were significantly associated with uterine rupture in the hour preceding its diagnosis: odds ratios were 4.1 (95% CI 1.2–14.0), 4.3 (95% CI 1.4–13.0) and 3.7 (95% CI 1.2–11.3), in the 60–40 min, 40–20 min and last 20 min before childbirth, respectively. Agreement between the two reviewers (Cohen's kappa) was 84% (CI 95%: 0.79–0.89).ConclusionIn the hour preceding uterine rupture, there are often significant FHRA. This leads us to consider the possibility of an earlier C-section when faced with grade-3 FHRA, before the onset of terminal bradycardia jeopardizing maternal and fetal prognosis.