A case-control study using UK data estimates the risk of uterine rupture in subsequent deliveries amongst women who have had a previous caesarean section.
Recent reports of the risk of morbidity due to uterine rupture are thought to have contributed in some countries to a decrease in the number of women attempting a vaginal birth after caesarean section. The aims of this study were to estimate the incidence of true uterine rupture in the UK and to investigate and quantify the associated risk factors and outcomes, on the basis of intended mode of delivery.
Methods and Findings
A UK national case-control study was undertaken between April 2009 and April 2010. The participants comprised 159 women with uterine rupture and 448 control women with a previous caesarean delivery. The estimated incidence of uterine rupture was 0.2 per 1,000 maternities overall; 2.1 and 0.3 per 1,000 maternities in women with a previous caesarean delivery planning vaginal or elective caesarean delivery, respectively. Amongst women with a previous caesarean delivery, odds of rupture were also increased in women who had ≥ two previous caesarean deliveries (adjusted odds ratio [aOR] 3.02, 95% CI 1.16–7.85) and <12 months since their last caesarean delivery (aOR 3.12, 95% CI 1.62–6.02). A higher risk of rupture with labour induction and oxytocin use was apparent (aOR 3.92, 95% CI 1.00–15.33). Two women with uterine rupture died (case fatality 1.3%, 95% CI 0.2–4.5%). There were 18 perinatal deaths associated with uterine rupture among 145 infants (perinatal mortality 124 per 1,000 total births, 95% CI 75–189).
Although uterine rupture is associated with significant mortality and morbidity, even amongst women with a previous caesarean section planning a vaginal delivery, it is a rare occurrence. For women with a previous caesarean section, risk of uterine rupture increases with number of previous caesarean deliveries, a short interval since the last caesarean section, and labour induction and/or augmentation. These factors should be considered when counselling and managing the labour of women with a previous caesarean section.
Please see later in the article for the Editors' Summary
Uterine rupture is a serious complication of pregnancy in which the wall of the uterus (womb) tears during pregnancy or early labor. Signs and symptoms of uterine rupture include fetal heart rate abnormalities, abdominal pain, and vaginal bleeding. If uterine rupture happens during labor, the woman must have an immediate caesarean section (surgical delivery of her baby) to save both her life and that of her baby. The woman's womb and nearby organs can be damaged at rupture or removed during surgery and she may need a blood transfusion because of severe bleeding. Moreover, her baby may develop respiratory distress syndrome and other life-threatening complications. In high income countries, uterine rupture most commonly occurs in women who have delivered a previous pregnancy by caesarean section. In a caesarean section, the baby is delivered through a cut made through the abdominal wall and the uterine wall. The stretching that occurs during pregnancy or the strong contractions of labor can tear the scar left by this cut, resulting in uterine rupture.
Why Was This Study Done?
Women who have had a caesarean delivery are generally encouraged to try to deliver subsequent babies vaginally. However, recent reports of an increased risk of complications (morbidity) and death (mortality) due to uterine rupture are thought to reduce women's willingness to attempt vaginal birth after caesarean (VBAC) in some countries. In the UK, for example, where one in four babies is delivered by caesarean section, a previous caesarean delivery is one of commonest reasons for a repeat section. Obstetricians (doctors who care for women during child birth) need to know as much as possible about the incidence of uterine rupture and about the risk factors for it so that they can advise women who have had a previous caesarean section about their delivery options. In this national case-control study (a study that compares the characteristics of people with and without a specific condition), the researchers estimate the incidence of uterine rupture in the UK by intended mode of delivery and investigate and quantify the risk factors for and outcomes of uterine rupture.
What Did the Researchers Do and Find?
The researchers used the UK Obstetric Surveillance System (UKOSS) to identify all the women in the UK who had a uterine rupture over a 13-month period (159 women, 139 of whom had had a previous caesarean delivery). Controls for the study were women who had not had a uterine rupture but who had previously delivered by caesarean section. Overall, the incidence of uterine rupture was 0.2 per 1,000 maternities. In women with a previous caesarean delivery, 2.1 and 0.3 per 1,000 maternities ended in uterine rupture in women planning vaginal delivery and caesarean delivery, respectively. Amongst women who had had a previous caesarean delivery, the risk of uterine rupture was greater among those who had had two or more previous caesarean deliveries or a caesarean delivery less than 12 months previously, or whose labor was induced. Two women died following uterine rupture (a case fatality of 1.3%) and 18 babies died around the time of birth (a perinatal mortality rate of 124 per 1,000 live births; the UK perinatal mortality rate is 7.5 per 1,000 live births). 15 of the women who had a uterine rupture had their womb removed, 10 had other organs damaged, and nearly half had other complications; 19 of the surviving babies had health problems.
What Do These Findings Mean?
These findings indicate that, in the UK, although uterine rupture is associated with significant mortality and morbidity, it is a rare occurrence even among women who have had a previous caesarean delivery and are planning a vaginal delivery. They also indicate that, for women who have previously had a caesarean section, the risk of rupture increases with the number of previous caesarean deliveries, with a short interval since the last caesarean section, and with labor induction. Although the researchers may not have identified all the women who had a uterine rupture during the study period or may have identified only the worst cases, these findings provide valuable information about the factors that obstetricians need to consider when advising women who have previously had a caesarean section and when managing their labor.
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001184.
This study is linked to a PLoS Medicine
Research Article by Caroline Crowther and a PLoS Medicine
Perspective by Catherine Spong
Wikipedia has a page on uterine rupture (note: Wikipedia is a free online encyclopedia that anyone can edit; available in several languages)
The American Congress of Obstetricians and Gynecologists has information sheets for patients on caesarean sections and on vaginal birth after caesarean delivery
The Royal College of Obstetricians and Gynaecologists in the UK has information for women on birth after previous caesarean
Childbirth Connection, a US-based not-for-profit organization, provides information about caesarean sections and about vaginal birth after caesarean
The National Childbirth Trust, a UK charity, provides information for parents on all aspects of pregnancy and birth, including caesarean sections and vaginal birth after caesarean delivery
The UK charity Healthtalkonline has personal stories from women making decisions about birth after a caesarean section
A personal story of uterine rupture during an attempted VBAC is available
The UK Obstetric Surveillance System studies rare disorders of pregnancy in the UK