Uterine Rupture

Complete uterine rupture is a catastrophic event where a full thickness tear develops, opening the uterus directly into the abdominal cavity. It requires rapid surgical attention to safeguard maternal and infant outcomes. Most occur during labour except in the case of uterine scars following earlier caesarean where approximately 1/3 rupture during third trimester.
Occult or incomplete rupture is where a surgical scar separates but the visceral peritoneum stays intact, it is usually asymptomatic and does not require emergency surgery.
Complete rupture can be:

• Traumatic: usually due to motor vehicle accident, incorrect use of oxytocic agent or poorly conducted attempt at operative vaginal delivery (typically breech extraction with an incompletely dilated cervix). Other procedures with high risk of uterine rupture include internal podalic version and extraction, difficult forceps delivery, destructive operations and manoeuvres to relieve shoulder dystocia.
• Spontaneous: most patients either have had caesarian section ¹ or a history of trauma that could have caused permanent damage. Patients may have no history of surgery but a weakened uterus due to multiparity particularly if they have an old lateral cervical laceration.

Incidence

1/1148-1/2250 deliveries.²

Risk Factors

• Prior uterine surgery (including myomectomy, vigorous curettage, induced abortion, manual removal of the placenta). However, most frequent cause of a uterine scar is a previous caesarian section. Classical vertical and T-shaped incisions carry a higher risk of later uterine rupture than the standard modern low transverse approach.
• Uterine anomalies (eg undeveloped uterine horn)
• Trauma (eg RTA)
• Use of rotational forceps
• Obstructed labour
• Induction of labour - suspected association only. Prostaglandins should be used with caution during a trial of labour.
• Cervical laceration
• Placenta percreta or increta
• Hydramnios
• Macrosomia and fetal anomaly (eg hydrocephalus)
• Malpresentation (brow or face)
• Multiple pregnancy
• Choriocarcinoma

Management of uterine rupture depends on prompt detection and diagnosis. Unfortunately, the classic signs (sudden tearing uterine pain, vaginal haemorrhage, cessation of uterine contractions, regression of the fetus) have been shown to be unreliable and frequently absent.
Prolonged, late or variable decelerations and bradycardia seen on fetal heart rate monitoring are the most common and often the only manifestations of uterine rupture. In 3/4 of cases signs of fetal distress will appear before pain or bleeding.
Sudden appearance of gross haematuria is indicative of rupture.
Increasing pain and bleeding may occur as the size of rupture increases with possible signs of hypovolemic shock and haemoperitoneum. Exsanguination prior to surgery is unlikely (because of reduced vascularity of scar tissue) unless a uterine artery has been lacerated but the placenta may completely separate and fetus pass either partially or totally out of the uterus and into the abdominal cavity with a high risk of intrapartum death.
Laparotomy may still be required even after a successful vaginal delivery if there is suspicion of uterine rupture to assess damage and control bleeding.

Ultrasound can show abnormal fetal position or extension of fetal extremities or haemoperitoneum.
Intrauterine pressure catheters are sometimes used but may fail to show loss of uterine tone or contractile patterns following uterine rupture.

As the presenting signs of uterine rupture are so frequently nonspecific, the initial management is the same as for other causes of acute fetal distress - urgent surgical delivery. Response time seems critical - best outcomes being achieved where surgical delivery is achieved within 17 minutes of the onset of fetal distress on electronic monitoring⁴.
In all cases of operative delivery, especially where there are risk factors for uterine rupture, a thorough examination of uterus and birth canal is required.
In most cases of complete uterine rupture, hysterectomy is the preferred treatment either total or sub-total depending on site of rupture and patient's condition. In cases of lateral rupture involving lower uterine segment and uterine artery where haemorrhage and haematoma obscure the operative field, ligation of ipsilateral hypogastric artery to stop bleeding may be needed.
Where future child bearing is important and risks are acceptable, can attempt rupture repair (repeat rupture occurring in approx. 20% of cases).

Post-operative infection, damage to ureter, amniotic fluid embolus, massive maternal haemorrhage and DIC, pituitary failure. 4.2% maternal mortality, 46% perinatal mortality and morbidity ^{5 6}

Unfortunately uterine rupture cannot be adequately predicted for women wanting a trial of labour following a previous caesarian section.
Doctors need to review a woman's medical history for risk factors and counsel regarding her relative risks, benefits, alternatives and probability of success. Usually, shared care undertaken with an obstetrician is appropriate for any woman with a previous section.
A few circumstances (prior classic or T-shaped incision, contracted pelvis, unavailability of facilities for emergency caesarian delivery) will preclude a trial of labour. In most instances, however, the decision about mode of birth following a previous caesarian should take into consideration⁷:

• maternal preferences and priorities
• a general discussion of overall risks and benefits of caesarian section
• risk of uterine rupture - uterine rupture is a rare complication even in those who have had a previous caesarian (35 per 10,000 women undergoing trial of labour and 12 per 10,000 having a planned repeat caesarian section)
• risk of perinatal mortality and morbidity: the risk of an intrapartum death is small in planned vaginal birth (10 per 10,000) but higher than those having a planned repeat caesarian (1 per 10,000). The effect of planned vaginal birth or repeat caesarian section on cerebral palsy is uncertain.

Those who opt for a trial of labour should be offered continuous electronic fetal monitoring during delivery and care during labour in a unity where there is immediate access to emergency caesarians and an on-site blood transfusion service. Ideally delivery should take place in a unit with more than 3000 births pa⁸.
NICE guidance states that women with a previous caesarian section can be offered induction of labour but they should be aware that the risk of uterine rupture is increased (to 80 per 10,000 using non-prostaglandin agents and to 240 per 10,000 with prostaglandins)⁷.
Pregnant women with previous caesarian section and vaginal births have a higher likelihood of a vaginal birth compared to women who have only a previous caesarian delivery⁸.
Women with more than one previous caesarian section seem to be at higher risk of uterine rupture (1.4% compared to 0.6% in women with only 1 previous section, not statistically significant)⁹