Uterine inversion is a rare but potentially fatal complication of pregnancy. It may be incomplete or complete, depending on whether the fundus is delivered through the cervix. Nearly all cases occur within 24 hours of birth, although subacute (up to 4 weeks) and chronic forms have also been described.
The incidence is said to be between 1 in 2000 and 1 in 50,000 deliveries; this variation is thought to relate to the management of the third stage of delivery. Uterine inversion is more likely to occur when vigorous fundal pressure or cord traction is exerted before adequate placental separation. Coughing and vomiting, fundal insertion of the placenta and uterine atony are all thought to contribute to the risk of uterine inversion.
Problems and special considerations
Uterine inversion is an obstetric emergency. The presentation of the uterus through the cervix, usually with the placenta still attached, causes pain and severe vagal shock, the most important manifestation of which is bradycardia. This is often followed by severe haemorrhage.
Management options
Initial treatment is aimed at basic resuscitation, including intravenous fluids (including blood), oxygen and atropine to treat the bradycardia when indicated.
Replacement of the uterus should take place as soon as possible, since oedema quickly develops in the extruded uterus, hampering efforts to return it to its correct position. Urgent manual replacement may be successful without general anaesthesia in the first few minutes after the patient has collapsed, but general anaesthesia is usually required and should not be delayed. In the absence of shock or haemorrhage, regional anaesthesia may be suitable. Manual replacement of the uterus may be facilitated by uterine relaxation (see Chapter 64, Oxytocic and tocolytic drugs). Traditionally, deep halothane anaesthesia was used but this was associated with marked hypotension and prolonged uterine atony; more recently glyceryl trinitrate, β-adrenergic agonists and magnesium have been used.
If the above method is not successful, hydrostatic pressure may be considered. In this technique, warm isotonic fluid is allowed to run into the uterus. Up to 5 litres of fluid may be required; therefore, there is a risk of systemic absorption. An open abdominal method of treatment has also been described but this is rarely required.
After the uterus has been replaced, oxytocic drugs are required straight away. It is important to remember that the relaxant effects of tocolytic drugs may persist for some time.
Key points
• Uterine inversion may present with collapse, severe bradycardia and haemorrhage.
• Anaesthesia is usually required for replacement of the uterus.
• Uterine relaxation may be required to enable its replacement.
• Good communication between anaesthetists and obstetricians is essential, with minimal delay in initiating treatment.