IOTA ultrasound rules for ovarian masses

Dr Subhan Iqbal and Dr Henry Knipe et al.

The International Ovarian Tumor Analysis (IOTA) group ultrasound rules for ovarian masses are a simple set of ultrasound findings that classify ovarian masses into benign, malignant or inconclusive masses. These rules apply to masses that are not a classical ovarian mass (e.g. corpus luteum, endometrioma, dermoid cyst), which have pathognomonic imaging features.

Masses can be classified as either benign or malignant using simple ultrasound features. Ovarian masses that cannot be classified (~25% of ovarian masses) into either group are classified as "inconclusive" (either having none or both benign and malignant features) and further evaluation by a specialist in ovarian imaging is recommended. 

If an ovarian lesion has at least one of these features and no malignant features it can be confidently considered benign 1:

  • unilocular cyst
  • smooth multilocular tumor <10 cm
  • solid components <7 mm in diameter
  • presence of acoustic shadows
  • no detectable Doppler signal

If an ovarian lesion has at least one of these features and no benign features it can be confidently considered malignant 1:

  • irregular solid tumor
  • irregular multilocular-solid mass >10 cm in diameter
  • ≥4 papillary structures
  • ascites
  • high Doppler signal (color score 4)

When the rules can be applied (~75% of masses), there is a sensitivity of ~90% and a specificity of ~95%, which is similar to subjective expert evaluation 1

Article information

rID: 40621
System: Gynaecology
Synonyms or Alternate Spellings:
  • International Ovarian Tumour Association (IOTA) ultrasound rules for ovarian masses

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Cases and figures

  • Case 1: inconclusive
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  • Case 2
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