Multiple Cesareans Increase Risk of Uterine Rupture

A new study reveals that the risk of uterine rupture increases with the number of previous caesarean deliveries, a short interval since the last caesarean section, and with induced labor.

Researchers at the University of Oxford (United Kingdom) conducted a national case-control study involving 159 women with uterine rupture and 448 control women with a previous caesarean delivery, undertaken between April 2009 and April 2010. The aims of the study were to estimate the incidence of true uterine rupture in the United Kingdom, and to investigate and quantify the associated risk factors and outcomes on the basis of intended mode of delivery. In all, two women with uterine rupture died, and there were 18 perinatal deaths associated with uterine rupture among 145 infants.

The results showed that of the 159 women who experienced uterine rupture, 139 had previously delivered by a caesarean section. The estimated incidence of uterine rupture was 0.2 per 1,000 maternities overall, 2.1 per 1,000 maternities in women with a previous caesarean delivery planning vaginal delivery, and 0.3 per 1,000 in women planning elective caesarean delivery. Among women with a previous caesarean delivery, odds of rupture were also increased in women who had two or more previous caesarean deliveries, or in whom less than 12 months had passed since their last caesarean delivery. A higher risk of rupture with labor induction and oxytocin use was apparent. The study was published early online on March 13, 2012, in PLoS Medicine.

“Although uterine rupture is associated with significant maternal and perinatal mortality and morbidity, even amongst women with a previous caesarean section planning a vaginal delivery in their current pregnancy, it is rare, occurring in only one of every 500 women,” concluded lead author Kathryn Fitzpatrick and colleagues of the UK National Perinatal Epidemiology Unit, based at Oxford. “For women with a previous caesarean section, the risk of uterine rupture increases not only with trial of labor but also with the number of previous caesarean deliveries, a short interval since the last caesarean section, and labor induction and/or augmentation.”
Uterine rupture is a potentially catastrophic event during childbirth by which the integrity of the myometrial wall is breached. In an incomplete rupture, the peritoneum is still intact. With a complete rupture, the contents of the uterus may spill into the peritoneal cavity or the broad ligament. A uterine rupture is a life-threatening event for mother and baby.

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