Uterine Inversion

Uterine inversion either partial or complete, is a rare but serious obstetric complication. It usually occurs in the second stage of labour and is a life-threatening complication requiring prompt diagnosis and definitive management. It very rarely occurs in non-pregnant patients and is then usually associated with prolapsing uterine fibroids¹ although it can occur with other tumours.^2,3

Incidence varies widely from as many as 1 per 1,584 deliveries⁴ to as few as 1 per 20,000 deliveries. It is vanishingly rare in non-pregnant patients.¹

Part of the uterus indents towards, and eventually prolapses through, the dilated cervix. It requires relaxation of the uterus to allow the initial indentation, followed by resumption of contractions in such a way that inversion ensues. Terminology is used to describe the degree of inversion which may be:

• First degree - the inverted fundus extends to, but not through the cervix.
• Second degree - the inverted fundus extends through the cervix but remains within the vagina.
• Third degree - the inverted fundus extends outside the vagina.
• Total inversion - the vagina and uterus are inverted.

Various aetiological factors have been linked to uterine inversion, although there may be no obvious cause. Identified aetiological factors include:

• Short umbilical cord
• Excessive traction on the umbilical cord
• Excessive fundal pressure
• Fundal implantation of the placenta
• Retained placenta and abnormal adherence of the placenta⁵
• Chronic endometritis
• Vaginal births after previous caesarean section
• Rapid or long labours
• Previous uterine inversion⁶
• Certain drugs such as magnesium sulphate (drugs promoting tocolysis)
• Unicornuate uterus⁷

It is not usually considered to be a consequence of mismanagement of the third stage of labour despite the factors listed above. However when the rate is high it has been ascribed to poor management of the third stage of labour.⁴ Active management of the third stage of labour may reduce the incidence.⁸

Uterine inversion may present:

• Acutely - within 24 hours of delivery
• Subacutely - over 24 hours and up to the 30th postpartum day
• Chronic - more than 30 days after delivery⁹

It presents most often with symptoms of a post-partum haemorrhage. The classic presentation is of:

• Post-partum haemorrhage^10,11
• Sudden appearance of a vaginal mass
• Cardiovascular collapse (varying degrees)

The sudden appearance of a large dark red mass accompanying the placenta is alarming. Pain is extreme. The diagnosis is usually then immediately obvious and confirmed by inability to feel the fundus. Diagnosing a first degree inversion is much more difficult. Obesity can make diagnosis more difficult. Chronic cases are unusual and difficult to diagnose. They may present with spotting, discharge and low back pain. Ultrasound may be required to confirm the diagnosis. Complete inversion is accompanied by extreme cardiovascular collapse, more than might be expected from the degree of blood loss alone.

• Prolapse of a uterine tumour
• Gestational trophoblastic disease
• Occult genital tract disease
• Marked uterine atony
• Undiagnosed second twin

If not clinically very obvious, ultrasound can be used to identify the inversion.^12,13

The important principles are:

• Treatment should follow a logical progression.
• Hypotension and hypovolaemia require aggressive fluid and blood replacement.¹⁴ Steps may include:
  • Get help. This should include the most experienced anaesthetic help available.
  • Secure further intravenous access with large bore cannulae and commence fluids. Resuscitation is usually started with crystalloid such as normal saline or Hartmann's solution although some people prefer colloids from the outset.
  • Insert a urinary catheter.
• Immediate uterine repositioning is essential for acute puerperal inversion. Measures may include:
  • Get help and prepare theatres for a possible laparotomy.
  • Administer tocolytics to allow uterine relaxation. For example:
    • Nitroglycerin (0.25-0.5 mg) intravenously over 2 minutes
    • Or terbutaline 0.1-0.25 mg slowly intravenously
    • Or magnesium sulphate 4-6 g intravenously over 20 minutes
  • Attempt prompt replacement of the uterus. This is best done manually and quickly as delay can render replacement progressively more difficult. Replace the uterus (with placenta if still attached) by slowly and steadily pushing upwards.
  • If this fails then a general anaesthetic is usually required.¹⁵ The uterus may then replaced by placing a fist on the fundus and gradually pushing it back into the pelvis through the dilated cervix manually.
  • Maintain bimanual uterine compression and massage until the uterus is well contracted and bleeding has stopped.
  • If this is unsuccessful a surgical approach is required. Laparotomy for surgical replacement is more usual (find and apply traction to the round ligaments) but a vaginal or even laparoscopic approach can be used.¹⁶
  • General anaesthetic or uterine relaxant is then stopped and replaced with uterotropics (oxytocin or ergometrine or prostaglandins).
  • Start antibiotics and continue the uterotropic for at least 24 hours. Monitor closely after replacement to avoid reinversion.

Complications include endomyometritis, damage to intestines or uterine appendages.

The condition carries a good prognosis if managed correctly.