Prelabour uterine rupture: characteristics and outcomes

To describe the characteristics and outcomes of prelabour uterine ruptures.

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

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).

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

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.

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).

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