Prelabour uterine rupture: characteristics and outcomes

Objective: To describe the characteristics and outcomes of prelabour uterine ruptures.

Design: Descriptive study based on population data from the Medical Birth Registry of Norway, the Patient Administration System and medical records.

Sample: Maternities with uterine rupture before start of labour in Norway during the period 1967-2008 (8 complete ruptures among 2 334 712 women with unscarred uteri, and 22 complete and 45 partial ruptures among 121 085 women with scarred uteri).

Method: We measured the rate of perinatal deaths and peripartum hysterectomy following ruptures. In addition, we studied the characteristics of ruptures.

Results: The eight complete ruptures in women with unscarred uteri were associated with trauma from traffic accidents (n = 3; 37.5%), previous curettage (n = 3; 37.5%) and congenital uterine malformations (n = 2; 25%), resulting in seven perinatal deaths and two hysterectomies. The 22 complete ruptures in scarred uteri were mostly outside the lower uterine segment (n = 17; 72.7%). Abnormally invasive placenta (AIP) and previous rupture were present in four (18.2%) and three women (13.6%), respectively. They resulted in nine perinatal deaths (39.1%) and two hysterectomies (9.1%). The 45 partial ruptures involved mostly scars in the lower uterine segment (n = 39; 86.7%). None of them resulted in perinatal death or hysterectomy. Perinatal deaths have decreased dramatically in recent years, despite increasing prelabour rupture rates.

Conclusion: Although complete uterine ruptures before labour start were rare, they often resulted in catastrophic outcomes, such as perinatal death. Scars outside the lower segment were associated with a higher percentage of catastrophic prelabour ruptures compared with scars in the lower segment (Video S1).

Tweetable abstract: Complete prelabour uterine ruptures were rare, but resulted in high perinatal deaths, especially if they were in scars outside the lower segment.