UKOSS update

Complete uterine rupture typically occurs during labour at term amongst women who have had a previous caesarean birth. Atypical rupture, occurring pre-labour, preterm or in women with unscarred uteri, is less common but may be associated with severe morbidity and mortality. The aim of this study was to bring together data from UKOSS with similar data from other countries in the International Network of Obstetric Survey Systems (INOSS: Austria, Belgium, Denmark, Finland, France, Germany, Italy, the Netherlands and Sweden) to describe atypical cases of uterine rupture, namely, uterine rupture occurring in unscarred, preterm or prelabour uteri. A total of 357 atypical uterine ruptures were identified among 3 064 923 women giving birth. Estimated incidence was 0.2 ruptures in unscarred uteri per 10 000 women (95% CI 0.2–0.3), 0.5 (95% CI 0.5–0.6) preterm ruptures per 10 000 women, 0.7 (95% CI 0.6–0.8) prelabour ruptures per 10 000 women, and 0.5 (95% CI 0.4–0.5) ruptures with no previous caesarean per 10 000 in women. Atypical uterine rupture resulted inperipartumhysterectomy in 66 women (18.5%, 95% CI 14.3–23.5%), three maternal deaths (0.84%, 95% CI 0.17–2.5%) and perinatal death in 62 infants (19.7%, 95% CI 15.1–25.3%). Most preterm uterine ruptures occurred in caesareanscarred uteri and most prelabour uterine ruptures in ‘otherwise’ scarred uteri. This study shows that preterm or prelabour uterine ruptures or those occurring in unscarred uteri are extremely uncommon but were associated with severe maternal and perinatal outcomes. This study may increase awareness among clinicians of the possibility of uterine rupture under these less expected conditions.