Risk of malignancy index in ovarian tumors

Last revised by Francis Fortin on 6 Jul 2017

The risk of malignancy index (RMI) in ovarian tumors is a validated clinical tool used for risk stratification of ovarian lesions, to guide further management 1-3.


The score incorporates the patient's menopausal status (M), ultrasound features of the lesion (U), and the serum CA-125 level.

RMI = U x M x CA-125 (U/ml)

U score
  • 0 = no features of malignancy on ultrasound
  • 1 = one feature of malignancy on ultrasound
  • 3 = two or more features of malignancy on ultrasound

Features of malignancy on ultrasound include 1,2:

  • irregular solid or multiloculated cystic mass
  • solid components on cyst wall
  • high Doppler flow in solid components
  • ascites, peritoneal nodules, or other evidence of metastases
M score
  • 1 = premenopausal
  • 3 = postmenopausal
  • RMI score greater than 200: high risk, with referral to specialist gynecological cancer service, and staging CT advised
  • RMI score 25-200: intermediate risk, with MRI recommended to further evaluate the lesion
  • RMI score less than 25: low risk, with repeat clinical assessment advised, with MRI if ultrasound features are borderline 1

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