Incarcerated uterus

Dr Craig Hacking and Radswiki et al.

An incarcerated uterus or trapped uterus describes an extremely rare situation where a retroverted or retroflexed gravid uterus fails to ascend into the abdominal cavity.

This is an uncommon presentation and is said to occur in 1 in 3000 pregnancies. Uncomplicated retroversion may be seen in as many as 9% of the pregnancies.

  • diffuse pain
  • in the first trimester may result in transient urinary retention
  • rectal pressure or constipation

Entrapment of a portion of a gravid retroverted uterus. As the the gravid uterus increases in size, it may get caught at the sacral promontory, bending the gravid retroverted uterus.

Associated with posterior or fundal fibroids, endometriosis, uterine structural abnormalities such as didelphic or a bicornuate uterus, previous gynecologic surgery resulting in adhesions, and a spectrum of abnormal placental villous adherence. The incarcerated uterus is prone to uterine rupture.

  • cervix may be difficult to identify
  • cervix is anterior and superior to the gravid uterus
  • the fetus is positioned deep within the cul-de-sac
  • the maternal urinary bladder is malpositioned and lies anterior, rather than inferior to the products of conception
  • the lower uterine segment is displaced anteriorly giving an appearance of a myometrium with central cavity between the urinary bladder and the fetus and may be mistaken for an ectopic or an abdominal pregnancy

The first case of incarceration of the gravid uterus was described by William Hunter in 1754.

On imaging consider

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Article information

rID: 14579
Section: Pathology
Tag: cases
Synonyms or Alternate Spellings:
  • Trapped uterus
  • Uterine incarceration
  • Classic sacculation

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Cases and figures

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    Case 1: MRI of incarcerated Uterus
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