Evaluation of a risk of malignancy index based on serum CA125, ultrasound findings and menopausal status in the pre-operative diagnosis of pelvic masses

Br J Obstet Gynaecol. 1996 Aug;103(8):826-31. doi: 10.1111/j.1471-0528.1996.tb09882.x.


Objective: To evaluate the ability of a risk of malignancy index (RMI), based on a serum CA125 level, ultrasound findings and menopausal status, to discriminate a benign from a malignant pelvic mass and to discriminate early stage (Figo Stage I) from Stages II, III and IV of ovarian cancer.

Design: A prospective study.

Setting: Department of Gynaecology, Trondheim University Hospital, Trondheim, Norway.

Participants: One hundred and seventy-three women, 30 years or older, consecutively admitted between February 1992 and February 1994 for primary laparotomy of a pelvic mass.

Main outcome measures: The sensitivity, specificity and positive predictive value of serum CA125 level, ultrasound findings and menopausal status, separately and combined into the RMI, to diagnose ovarian cancer.

Results: The RMI was more accurate than any individual criterion in diagnosing cancer. Using a RMI cut-off level of 200 to indicate malignancy, the RMI derived from this dataset gave a sensitivity of 80%, specificity of 92% and positive predictive value of 83%. Applying RMI criteria developed by others, the following test performance was found: sensitivity 71%, specificity 96% and positive predictive value 89%. For the Stages II, III and IV of ovarian cancer the sensitivity increased to approximately 90% without any substantial loss in specificity.

Conclusions: The risk of malignancy index is able to correctly discriminate between malignant and benign pelvic masses. It is a scoring system which can be introduced easily into clinical practice to facilitate the selection of patients for primary surgery at an oncological unit.

MeSH terms

  • Adult
  • Aged
  • Biomarkers, Tumor / blood*
  • CA-125 Antigen / blood*
  • Female
  • Humans
  • Logistic Models
  • Middle Aged
  • Neoplasm Staging / methods
  • Ovarian Neoplasms / diagnosis*
  • Ovarian Neoplasms / diagnostic imaging
  • Ovarian Neoplasms / immunology
  • Postmenopause
  • Premenopause
  • Preoperative Care
  • Prospective Studies
  • Risk Factors
  • Sensitivity and Specificity
  • Ultrasonography


  • Biomarkers, Tumor
  • CA-125 Antigen