Ovarian-Adnexal Reporting and Data System Ultrasound – O-RADS US

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Infographic illustrating the O-RADS Ultrasound (US) scoring system with five categories: O-RADS 1 (normal ovary), O-RADS 2 (almost certainly benign), O-RADS 3 (low malignancy risk), O-RADS 4 (intermediate malignancy risk), and O-RADS 5 (high malignancy risk), used for risk stratification of ovarian and adnexal lesions on ultrasound

What is the O-RADS Ultrasound scoring system?

O-RADS US (Ovarian-Adnexal Reporting and Data System — Ultrasound) is a 5-category risk stratification system developed by the American College of Radiology (ACR) to standardize the reporting of ovarian and adnexal lesions on ultrasound. It assigns each lesion a score from 1 to 5 based on morphological features and malignancy risk.

What do O-RADS US scores 1 through 5 mean?

  • O-RADS 1 — Normal ovaries, no lesion present. Malignancy risk: 0%.
  • O-RADS 2 — Almost certainly benign lesion. Malignancy risk: < 1%. Examples include simple cysts and classic dermoids.
  • O-RADS 3 — Low risk of malignancy: 1–10%. Lesions not meeting benign criteria but lacking high-risk features.
  • O-RADS 4 — Intermediate risk: 10–50%. Irregular solid components or concerning vascularity.
  • O-RADS 5 — High risk: > 50%. Strong morphological or vascular features suspicious for malignancy.

What ultrasound features determine the O-RADS score?

The score is based on:

  1. Lesion composition — unilocular cyst, multilocular, or solid
  2. Wall and septal irregularity — smooth vs. papillary projections
  3. Solid component characteristics — size and echogenicity
  4. Color Doppler vascularity (CS 1–4) — from no flow to markedly increased
  5. Associated findings — ascites, peritoneal nodules

How is O-RADS US different from IOTA or RMI?

System Basis Output
O-RADS US ACR morphology + vascularity Risk category 1–5
IOTA Simple Rules 10 morphological features Benign / Malignant / Inconclusive
RMI CA-125 + USS + menopausal status Numerical score

References

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