Ovarian cyst

Ovarian cysts are commonly encountered in gynecological imaging, and vary widely in etiology, 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 cm (see the 1-2-3 rule).

Ultrasound is usually the first imaging modality for assessment of ovarian lesions.

Imaging features of simple ovarian cysts:

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

The Society of Radiologists in Ultrasound made in 2019 the following recommendations regarding reporting of simple adnexal cysts of suspected ovarian origin based on size and menopausal status 2:

  • premenopausal women
    • ≤3 cm: no need to report; if described, consider calling a "follicle" rather than a "cyst" to reduce patient anxiety
      • impression: normal ovaries/adnexa
      • recommendation: no follow-up
    • >3 to ≤5 cm: report presence of simple cyst(s) and largest cyst diameter
      • impression: benign finding in the physiologic size range
      • recommendation: no follow-up
    • >5 cm: report with all cyst diameters
      • impression: benign simple cyst
      • recommendation:
        • >5 to ≤7 cm: follow-up either in 2-6 months for resolution/re-characterization or in 6-12 months for growth rate assessment, but no follow up is needed if the cyst is exceptionally well-visualized/characterized and documented with confidence by the imager
        • >7 cm: follow-up either in 2-6 months for resolution/re-characterization or in 6-12 months for growth rate assessment
    • follow-up of cyst (previously >5 cm): describe in report with all cyst diameters if not resolved
      • decreased in size
        • impression: benign inconsequential finding; decrease in size excludes neoplasm
        • recommendation: no further follow-up needed
      • similar in size
        • impression: benign simple cyst with stability over ≥12 months, most likely nonneoplastic or very slow growing benign neoplasm
        • recommendation: follow-up at 2 years from initial study to document stability and understand growth rate
      • increased in size
        • impression: enlarging simple cyst, most likely a benign neoplasm
        • recommendation: follow-up in 1 year to evaluate any further changes in size
  • postmenopausal women
    • ≤1 cm: no need to report
      • impression: normal ovaries/adnexa
      • recommendation: no follow-up
    • >1 to ≤3 cm: report presence of simple cyst(s) and largest cyst diameter
      • impression: benign inconsequential finding
      • recommendation: no follow-up
    • >3 cm: report with all cyst diameters
      • impression: benign simple cyst
      • recommendation:
        • >3 to ≤5 cm: follow-up either in 3-6 months for resolution/re-characterization or in 6-12 months for growth rate assessment, but no follow up is needed if the cyst is exceptionally well-visualized/characterized and documented with confidence by the imager
        • >5 cm: follow-up either in 3-6 months for resolution/re-characterization or in 6-12 months for growth rate assessment
    • follow-up of cyst (previously >3 cm): describe in report with all largest cyst diameters if not resolved
      • decreased in size
        • impression: benign simple cyst; decrease in size excludes neoplasm
        • recommendation: no further follow-up needed
      • similar in size
        • impression: benign simple cyst
        • recommendation: follow-up at 2 years from initial study to document stability
      • increased in size
        • impression: enlarging simple cyst, most likely a benign neoplasm
        • recommendation: follow-up in 1 year to evaluate any further changes in size

Note that these guidelines do not apply to hemorrhagic ovarian cysts.

  • large (>3 cm) or symptomatic cysts may undergo surgical resection
  • smaller asymptomatic cysts are treated conservatively
  • risk of malignancy in septated ovarian cysts with no papillary projections or solid components are also considered low and are usually followed up on ultrasound 5,6
Ultrasound - gynaecology

Article information

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

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Cases and figures

  • Figure 1: gross pathology
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  • Case 1: hemorrhagic ovarian 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: hemorrhagic ovarian cyst
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  • Left ovary
    Case 5: hemorrhagic cyst
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