تمزق الرحم

What is uterine rupture

Uterine rupture is a tear of all three layers of the uterus. Most occur during labour; however, uterine scars following earlier caesarean may rupture during the third trimester before any contractions occur.

تصنيف

• Occult or incomplete rupture refers to a surgical scar separating but the visceral peritoneum staying intact. It is usually asymptomatic and does not require emergency surgery.

• Complete rupture can be:

  • Traumatic:

    • A road traffic collision.

    • Incorrect use of oxytocic agent.

    • A poorly conducted attempt at operative vaginal delivery (typically breech extraction with an incompletely dilated cervix).

• Spontaneous:

  • Most patients have either had a قيصرية or a history of trauma that could have caused permanent damage.¹

  • Patients may have no history of surgery but a weakened uterus due to multiparity, particularly if they have an old lateral cervical laceration.

How common is uterine rupture? (Epidemiology)

حدوث

Uterine rupture is extremely rare, but there seems to be an increasing trend. A Norwegian study looking at four decades of obstetric data showed the incidence per 10,000 deliveries to increase from 1.2 (1967 - 1977) to 6.1 (2000 - 2008).²

The RCOG gives the incidence as 0.5% for a planned vaginal birth after a caesarean (VBAC).³

The incidence is higher in developing countries than developed countries.⁴

عوامل الخطر⁵

• The majority of cases occur in women who have had a previous caesarean section:

  • Classical vertical and T-shaped incisions carry a higher risk of later uterine rupture than the standard modern low transverse approach.

  • An inter-delivery interval of less than 18 months appears to increase the risk.⁶

  • The risk appears to be higher in pregnancies of gestational age greater than 40 weeks, and for women with a previous caesarean, the risk is reduced if they have also had a previous vaginal delivery.³

• Prior uterine surgery (including myomectomy, curettage, induced abortion, manual removal of the placenta).

• Uterine anomalies - eg, undeveloped uterine horn.

• Trauma - eg, traffic collision.

• Use of rotational forceps.

• تعسّر الولادة.

• Induction of labour - prostaglandins should be used with caution during a trial of labour.

• Cervical laceration.

• Medically induced termination after 16 weeks of gestation.

• Placenta percreta or increta.

• Hydramnios.

• Macrosomia and fetal anomaly - eg, hydrocephalus.

• Malpresentation (brow or face).

• الحمل المتعدد.

• سرطانة مشيمائية.

Other procedures with high risk of uterine rupture include internal podalic version and extraction, destructive operations and manoeuvres to relieve shoulder dystocia.

Preventing uterine rupture

Unfortunately, uterine rupture cannot be adequately predicted for women wanting a trial of labour following a previous caesarean section.⁷ Doctors should review the medical history for risk factors and counsel regarding her relative risks, benefits, alternatives and probability of success. Women should be informed that planned VBAC is associated with an approximately 1 in 200 (0.5%) risk of uterine rupture.³

Usually, shared care undertaken with an obstetrician is appropriate for any woman with a previous caesarean section.

A few circumstances (prior classic or T-shaped incision and unavailability of facilities for emergency caesarean delivery) will preclude a trial of labour. In most instances, however, National Institute for Health and Care Excellence (NICE) guidance advises that the decision about mode of birth following a previous caesarean should take into consideration:⁸

• Maternal preferences and priorities.

• A general discussion of overall risks and benefits of repeat caesarean section versus VBAC, including the risk of an unplanned caesarean section.

• Women who have had a previous caesarean section but also a vaginal birth can be advised that they are more likely to achieve a vaginal birth than women who have only had a caesarean birth.

Those who opt for a trial of labour should be offered close monitoring during delivery and care during labour in a unit where there is immediate access to emergency caesareans and an on-site blood transfusion service.⁸

Induction of labour - considerations to reduce the risk of uterine rupture⁹

• NICE guidance states that women with a previous caesarean section can be offered induction of labour but that they should be aware that the risk of uterine rupture and of needing an emergency caesarean are both increased.⁸

• When a planned VBAC is induced, the uterine rupture risk is around three times higher if prostaglandin is used than in a non-prostaglandin-based regimen.¹⁰

• Decisions regarding induction and augmentation of a planned VBAC should be made using a shared decision making model, with advice from a consultant obstetrician.

Symptoms of uterine rupture (presentation)

Management of uterine rupture depends on prompt detection and diagnosis. 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 but any of the following should alert suspicion:

• Cardiotocograph (CTG) abnormalities, especially fetal bradycardia.¹¹

• Severe abdominal pain changing so that it persists between contractions.

• Chest or shoulder tip pain and sudden shortness of breath.

• Scar pain and tenderness.

• Abnormal vaginal bleeding or gross haematuria.

• Cessation of previously efficient uterine contractions.

• Maternal tachycardia, hypotension or shock.

• Movement away of the presenting part. Abdominal palpation may reveal obvious fetal parts as the fetus passes either partially or totally out of the uterus and into the abdominal cavity, with a high risk of intrapartum death.

If there is suspicion of uterine rupture, laparotomy may still be required even after a successful vaginal delivery, to assess damage and to control bleeding.

Diagnosing uterine rupture (investigations)

• Ultrasound can be used to diagnose rupture prior to labour when it may show an abnormal fetal position, endometrial or myometrial defect, extrauterine haematoma or haematoperitoneum.¹²

• Intrauterine pressure catheters are sometimes used but may fail to show loss of uterine tone or contractile patterns following uterine rupture.

Managing uterine rupture

• Resuscitation as necessary.

• Uterine repair if possible; hysterectomy may be indicated if haemorrhage persists - either total or sub-total, depending on the site of rupture and the patient's condition.

• There is no firm evidence regarding which type of thread, knotting or sequence of suturing is more favourable to reduce the risk of uterine rupture after VBAC or hysterotomy after myomectomy.¹³

• In cases of lateral rupture involving lower uterine segment and uterine artery where haemorrhage and haematoma obscure the operative field, ligation of the ipsilateral hypogastric artery to stop bleeding may be needed.

• If a uterine repair has been achieved it is important to note that repeat rupture occurs in approximately 20% of cases.

In all cases of operative delivery, especially where there are risk factors for uterine rupture, a thorough examination of the uterus and birth canal is required.

Complications of uterine rupture

• Postoperative infection.

• Damage to ureter.

• Amniotic fluid embolism.

• Massive maternal haemorrhage and disseminated intravascular coagulation (DIC).

• Pituitary failure.

التكهن¹

• Neonatal mortality after uterine rupture is 6 - 25%.

• Maternal mortality is 10% if an unscarred uterus ruptures, but only 0.1% if a scarred uterus ruptures.

• Women with a previous uterine rupture should not have another attempt at a vaginal delivery - a caesarean at 36 - 37 weeks is recommended for future pregnancies.