Uterine rupture: risk after a caesarean, warning signs and care

A Scottish NHS guideline from NHS Greater Glasgow and Clyde defines uterine rupture as disruption of the womb muscle that extends to or involves the outer layer, the bladder or the broad ligament. When the muscle is partly or completely disrupted but the outer layer is intact, it is called uterine dehiscence. The guideline describes rupture as a catastrophic event with significant risk to mother and baby, but also stresses that prompt diagnosis and management is associated with better outcomes.

Most reported cases are in women with a previous caesarean birth or other uterine surgery, though the guideline notes cases do occur in an unscarred uterus. Wye Valley NHS Trust gives figures from a large study: uterine rupture in 0.03% of women who had not had a caesarean and 0.22% of women who had.

The Scottish guideline lists risk factors, including previous classical caesarean section, previous myomectomy, placenta accreta, some uterine anomalies and, during labour, obstructed labour, certain oxytocin or prostaglandin use in specific circumstances, and instrumental or assisted breech deliveries. It quotes the risk after one previous caesarean as 1 in 200 (0.5%) in spontaneous labour, 1 in 90 (1.1%) following induction or augmentation, and 1 in 20 (5%) after a previous uterine rupture.

The RCOG leaflet on birth after caesarean says a vaginal birth after caesarean (VBAC) is not advisable if you have had three or more caesareans, your uterus has ruptured in a previous labour, your previous caesarean was classical (involving the upper part of the uterus), or you have other pregnancy complications that need a planned caesarean.

The RCOG says that if you are fit and healthy, both VBAC and an elective repeat caesarean (ERCS) are safe choices with very small risks. About three in four women with a straightforward pregnancy and a natural onset of labour give birth vaginally after one caesarean. Choices should be discussed at an antenatal visit, ideally before 28 weeks. The RCOG lists rupture among the disadvantages of VBAC, at 1 in 200, and describes the advantage of ERCS as a smaller risk of scar rupture, at 1 in 1,000. It also lists the disadvantages of ERCS: longer surgery, wound infection, blood clots, longer recovery and added risk in later pregnancies.

The RCOG advises giving birth in hospital so an emergency caesarean can be done if necessary, contacting the hospital as soon as you think labour has started or your waters break, and continuous monitoring of the baby's heartbeat once regular contractions start, because changes in the heartbeat can be an early sign of a problem with the scar. All pain relief options including an epidural are available. If labour has not started by 41 completed weeks, options discussed include waiting, induction (which can increase scar rupture risk and lower the chance of a successful VBAC) or ERCS.

Wye Valley NHS Trust, describing its own local guideline, advises telephoning triage when contractions start, when waters break, with any blood loss or with any scar pain, noting scar pain can be felt between contractions and may still be felt with an epidural. Local policies differ between units and between the four UK nations, and the trust itself stresses that a guideline does not mean you must follow it.

The Scottish guideline says the commonest sign in a scarred uterus is a change in the baby's heart rate with persistent slowing (55 to 87% of cases), with constant pain and vaginal bleeding less frequent. It describes scar tenderness over the scar or above the pubic bone, pain between contractions or an increasing need for pain relief. An abnormal heart trace, constant pain and bleeding may each be non-specific but, when present together, should be treated as uterine rupture unless proven otherwise.

Other signs of internal bleeding include an unexplained fast pulse, low blood pressure and fainting; contractions may slow or stop, and blood-stained urine or fluid may be seen. Wye Valley NHS Trust summarises the main signs as a fetal heart rate abnormality, abdominal pain and vaginal bleeding. If you are in labour, tell your midwife immediately about any new constant pain, scar pain, bleeding, or a feeling that something has changed. If you are at home with these symptoms, contact your maternity unit straight away or call 999.

The Scottish guideline describes calling for help, stopping any oxytocin drip, involving the senior obstetrician and anaesthetist, resuscitation with intravenous access and blood tests, and preparing for an urgent category 1 caesarean or forceps birth. The womb is then explored and repaired unless the severity of the rupture or bleeding means a hysterectomy is needed, in which case attempts are made to preserve the ovaries. Afterwards the plan should include where you are cared for (for example high dependency care), pain relief, antibiotics, clot prevention, a debrief before discharge and a postnatal consultation, with discussion of future fertility and contraception.

Wye Valley NHS Trust, quoting a large study, describes the outcomes among women who had a rupture: 21% needed 4 units of red blood cells, 20% were admitted to intensive care, 10% had a hysterectomy, and 10% of babies died. These figures describe a rare event in a selected group and should be discussed with your own team rather than applied to yourself.

Whether you had a rupture, a near miss or simply an emergency caesarean during a VBAC attempt, ask for a debrief appointment. If the womb was repaired, your obstetric team will plan future births with you; the RCOG says VBAC is not advisable after a rupture in a previous labour. Emotional effects after a frightening birth are common and support is available through your midwife, GP or health visitor.