Ovarian cyst

Ovarian cysts are commonly encountered in gynaecological imaging, and vary widely in aetiology, from physiologic, to complex benign, to neoplastic.

Small cystic ovarian structures should be considered normal ovarian follicles unless the patient is pre-pubertal, post-menopausal, pregnant, or the mean diameter is >3.0 cm.

Types of cysts

Ultrasound is usually the first imaging modality for assessment of ovarian lesions. Simple ovarian follicular cysts are:

  • anechoic;
  • intraovarian or exophytic;
  • have an imperceptible wall;
  • cause posterior acoustic enhancement, which may not be as obvious with harmonic or compound imaging; and
  • have a visible far wall.

A cyst may become large enough to obscure the ovary from which it is arising.

  • large (>3 cm) or symptomatic cysts may undergo surgical resection.
  • smaller asymptomatic cysts are treated conservatively.
Follow-up guidelines

According to a consensus statement by the society of radiologists in ultrasound 2, for simple ovarian cysts with no suspicious features on ultrasound, current follow-up guidelines state:

In women of reproductive age:

  • ≤3 cm
    • normal physiologic finding; at the discretion of the interpreting physician whether or not to describe them in the imaging report
    • do not need follow-up
  • >3 and ≤5 cm
    • should be described in the imaging report with a statement that they are almost certainly benign
    • do not need follow-up
  • >5 and ≤7 cm
    • should be described in the imaging report with a statement that they are almost certainly benign
    • increased risk of ovarian torsion 4
    • yearly follow-up with ultrasound recommended
  • >7 cm
    • may be difficult to assess completely with ultrasound and further imaging with MR or surgical evaluation should be considered

In post-menopausal women :

  • ≤1 cm
    • are clinically inconsequential; at the discretion of the interpreting physician whether or not to describe them in the imaging report
    • do not need follow-up
  • >1 and ≤7 cm
    • should be described in the imaging report with statement that they are almost certainly benign
    • yearly follow-up, at least initially, with ultrasound recommended
    • some practices may opt to increase the lower size threshold for follow-up from 1 cm to as high as 3 cm
    • one may opt to continue follow-up annually or to decrease the frequency of follow-up once stability or decrease in size has been confirmed
    • cysts in the larger end of this range should still generally be followed on a regular basis
  • >7 cm
    • since these may be difficult to assess completely with ultrasound, further imaging with MRI or surgical evaluation should be considered

Haemorrhagic ovarian cysts have a different follow up schedule than simple cysts.


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Article Information

rID: 4622
System: Gynaecology
Synonyms or Alternate Spellings:
  • Ovarian cysts
  • Simple ovarian cysts

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    Left ovary
    Case 1: haemorrhagic cyst
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    Case 2
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    T2W axial pelvis
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    Case 3
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    Case 4: haemorrhagic ovarian cyst
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    Case 5: haemorrhagic ovarian cyst
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    Haemorrhagic ovar...
    Case 6: haemorrhagic cyst with peripheral vascularity
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