A 55-year-old postmenopausal woman has a right ovarian mass with a CA-125 of 620 U/mL, solid-cystic morphology on ultrasound, and bilateral involvement. Her Risk of Malignancy Index (RMI) is calculated. Which RMI threshold, according to RCOG/NHS guidelines, warrants referral to a gynaecological oncology centre?
- A RMI > 50
- B RMI > 200 ✓
- C RMI > 100
- D RMI > 250
Correct answer: B. RMI > 200
Explanation
The RMI is calculated as: Ultrasound score (U) × Menopausal status score (M) × CA-125 (IU/mL). An RMI >200 has a sensitivity of ~70% and specificity of ~90% for ovarian malignancy and is the accepted threshold (RCOG Green-top Guideline 62, NHS) for referral to a specialist gynaecological oncology MDT. Values 25–200 are intermediate risk and require further assessment. RMI >250 is sometimes cited as a higher cut-off in some studies but 200 remains the standard UK guideline threshold.
Reference: Shaw's Textbook of Gynaecology, 17th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.