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Para-ovarian cyst

Para-ovarian cyst (POC), also sometimes known as a para tubal cyst or a hydatid cyst of Morgagni 14, is a type of adnexal cyst that does not arise from the ovary. They account for ~10-20% of adnexal masses 3-4.


They typically occur in women ~ the 3rd to 4th decades.

Clinical presentation

Most are asymptomatic, although patients with large lesions can present with pelvic pain.


They usually occur around the broad ligament and arise from para-mesonephric, mesothelial, or mesonephric remnants. They are usually simple cysts (although some authors include para ovarian cystadenomas under the umbrella of para ovarian cysts and can complicate their definition).

Radiographic features

A para ovarian cyst is easier to recognise if the ipsilateral ovary is demonstrated to be separate from it. 

Pelvic ultrasound

They are typically thin-walled and smoothly marginated. They most often appear as unilocular 'simple' cysts (in ~66%) and rarely as multilocular (~4%). Depending on the definition used the cysts can show a variable number of papillary projections growing from the cyst wall (unilocular-solid cysts) in ~30% of cases ref

Pelvic MRI

Often seen located close to the ipsilateral round ligament and are often of homogenous signal intensity. 

In uncomplicated cases signal characteristics usually follow that of fluid 12.

  • T1: low signal (can be high signal if complicated by haemorrhage)
  • T2: high signal

Other features include

Treatment and prognosis

Large or symptomatic cyst often undergo surgical resection smaller asymptomatic ones are treated conservatively. 

For simple para-ovarian cysts with no suspicious features on ultrasound, follow-up recommendations are the same as for ovarian cysts. According to a consensus statement by the Society of Radiologists in Ultrasound 13 follow up is recommended for cysts that are:

  • 5 to 7 cm in a woman of reproductive age, or
  • 1 to 7 cm in a post-menopausal woman

Irrespective of age, cysts larger than 7 cm warrant further evaluation (with MRI) or surgical review.

Differential diagnosis

For an adnexal cystic lesion consider:

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