Risk factors and outcomes of uterine rupture before onset of labor vs. during labor: a multicenter study

This study aims to reveal the distinctions between uterine rupture (UR) that occurs before onset of labor and during labor. This multicenter study was conducted across three tertiary hospitals in South China involving obstetrical UR from January 2009 to April 2022. Cases were categorized into two groups based on the timing of UR: prelabor and labor. Among the cases of UR, 42 were classified in the prelabor group, and 27 in the labor group. The prelabor group had a higher prevalence of histories of myomectomies, ectopic pregnancy surgeries, congenital uterine anomalies, and prior URs. Among these ruptures, 45.2 % were located at cesarean section (CS) scars, compared to 81.5 % of cases during labor. Ruptures before onset of labor occurred across all gestational intervals, whereas those during labor, except one, occurred after 32 weeks. The median gestational age was 33 and 39 weeks in each group. Notably, prelabor cases demonstrated longer symptom-to-delivery intervals. Placenta percreta was more common in the prelabor group (16.7 vs. 3.7 % in the labor group). Among labor-related cases, 16 of the 27 occurred during trial of labor after cesarean (TOLAC), and four were identified following vaginal birth after cesarean (VBAC). URs differ by timing relative to labor. Ruptures before onset of labor more often resulted from scars other than CS and placenta percreta, occurring at earlier gestational weeks. This finding highlighted challenges in diagnosis and management. In contrast, ruptures during labor mostly occurred after 32 weeks and were strongly associated with TOLAC/VBAC.