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Corpus luteal cyst

Corpus luteal (CL) cysts are a type of functional ovarian cyst that result when a corpus luteum fails to regress following the release of an ovum. When associated with pregnancy, it is the most common pelvic mass encountered within the 1st trimester 1.


The natural history of a normal corpus luteum is to regress by the end of the 1st trimester if pregnancy has occurred. If a corpus luteum fails to regress, and instead enlarges with or without haemorrhage, a corpus luteum cyst is formed. There is some overlap in the definitions of a corpus luteum cyst and a haemorrhagic corpus luteum 5.

Natural course

When associated with pregnancy, most corpus luteal cysts spontaneously involute at the end of the 2nd trimester.

Radiographic features


They can have a range of sonographic appearances depending on the stage of evolution and age of the associated intracystic haemorrhage 3. General characteristics include 7:

  • diffusely thick wall
  • peripheral vascularity
  • <3 cm
  • possible crenulated contour

If the cyst has been present for some time with complicating haemorrhage, a fine internal lace like echo-pattern may be seen.

Colour Doppler interrogation show either no vascularity within the cyst or at times show low resistance blood flow around the cyst also known as hypervascular ''ring of fire''.

  • low-attenuating cyst (25 HU)
  •  <3 cm in diameter with thick
  • slightly irregular cyst
  • iso- or hyperattenuating walls 6 
  • free fluid is often associated 6

Often seen as a round or oval adenxal lesion

  • T1: typically homogeneously hypointense 1
  • T2: typically hyperintense 1-2
  • T1 C+ (Gd): intense wall enhancement may be seen 1

Treatment and prognosis

For a corpus luteum <= 3 cm, no follow up is necessary 7.


Differential diagnosis

It can be difficult to differentiate from a tubal ring in an ectopic pregnancy in some situations and correct clinical interpretation is often required.

See also

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