Uterine inversion

Uterine inversion is a rare condition in which the uterus is essentially turned inside out. There are two types: "puerperal" (within six weeks of childbirth) and "non-puerperal". The reason for uterine inversion is unclear. In the puerperal form, it is theorized that excessive traction on the umbilical cord during delivery may cause it.

Epidemiology

Puerperal uterine inversion is estimated to occur in 1/30,000 deliveries. Non-puerperal is even rarer and has been estimated at 5-15% of the rate of puerperal inversion.

Clinical presentation

Described presentations include vaginal bleeding and vaginal mass.

Pathology

Exaggerated umbilical cord traction, with a placental fundal fixation that will lead to excessive fundal pressure in the situation of a loose uterus, are the two considerably popular, suggested causes for uterine inversion ⁴.

Radiographic features

Ultrasound

Uterine inversion can be a difficult diagnosis on ultrasound and often is confirmed with CT or MRI. If there is a vaginal mass, the cervix cannot be distinguished, and the uterine fundus cannot be seen, then it suggests the diagnosis.

• On longitudinal scan:  uterine fundus is upside down (fallen fundus sign)
• On transverse scan: a bull's eye or target-like appearance may be seen

CT and MRI

Although rare, the appearance is pathognomonic on CT and MRI. The uterus is upside down with the fundus in the vagina. The ovaries and adnexa are drawn centrally to the cervix,

A spectrum of uterine inversion has been described with the mildest form as a fundal inversion that does not extend through the cervix and the most extreme form as a uterus and cervix that have completely inverted.

Treatment and prognosis

Given the rarity of the condition, treatment is not standardized, but most sources describe reverting the uterus immediately if there is vaginal bleeding. Failure to revert the uterus in the acute postpartum setting could lead to fatal blood loss and a mortality rate of 15% has been quoted ³.