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O-RADS US

Ultrasound risk stratification of adnexal (ovarian and non-ovarian) lesions. Using a standardized lexicon (lesion category, size, solid tissue, and color/vascularity score), assign O-RADS 0–5 with a corresponding probability of malignancy and management pathway. Best applied in the pre-menopausal/general gynecologic population; classic benign lesions have dedicated descriptors.
v2022·reviewed 2026-07-01
  • Solid tissue descriptors (papillary projections, solid components, irregular walls/septa) and the color score are the primary drivers of categories 3–5.
  • Classic benign lesions (dermoid, endometrioma, hemorrhagic cyst, paraovarian cyst) have dedicated descriptors and are generally O-RADS 2 when <10 cm.
  • O-RADS 4 lesions are candidates for problem-solving with O-RADS MRI.
  • Applies to the ultrasound lexicon; a separate O-RADS MRI system exists for further characterization after ultrasound.
How to assign
  1. 1Confirm an adequate study. If incomplete/technically limited → O-RADS 0.
  2. 2Is there a true lesion? A physiologic follicle (≤3 cm) or corpus luteum in a premenopausal ovary → O-RADS 1.
  3. 3Is it a classic benign lesion (simple cyst, hemorrhagic cyst, dermoid, endometrioma, paraovarian cyst) and <10 cm? → O-RADS 2 (management by lesion type + menopausal status).
  4. 4Otherwise classify by lesion type — unilocular vs multilocular cyst vs lesion with solid tissue — and measure size (10 cm threshold).
  5. 5Assess solid tissue (papillary projections, solid components, irregular walls/septa) and assign the IOTA color score 1–4 (no / minimal / moderate / marked flow).
  6. 6Map lesion type + size + solid tissue + color score to the category: unilocular ≥10 cm or smooth multilocular <10 cm (color 1–3) → 3; multilocular ≥10 cm or color 4, multilocular with solid components color 1–2, or a SMOOTH solid lesion color 2–3 → 4; a solid lesion with an IRREGULAR contour (any color score), a smooth solid lesion color 4, a multilocular cyst with solid components color 3–4, or ascites/peritoneal nodularity → 5.
  7. 7For any branch you cannot resolve confidently, consult the full ACR O-RADS US v2022 table rather than guessing.
0Incomplete evaluationTechnically inadequate or incomplete study.

Repeat or complete the ultrasound evaluation.

O-RADS 0. Incomplete evaluation; repeat or complete imaging is recommended.

1Normal ovaryPhysiologic findings in a pre-menopausal ovary: follicle (≤3 cm) or corpus luteum. No true lesion.

No follow-up.

O-RADS 1. Normal ovary (physiologic finding); no follow-up indicated.

2Almost certainly benign<1% risk of malignancy. Simple cysts and classic benign lesions: unilocular smooth cyst <10 cm (simple, or with hemorrhagic/dermoid/endometrioma features <10 cm), typical dermoid, hemorrhagic cyst, endometrioma, or paraovarian cyst, all <10 cm.

Follow-up depends on lesion type and menopausal status (e.g., simple cyst >5 cm pre-menopausal or >3 cm post-menopausal → follow-up); many require no follow-up.

O-RADS 2 (almost certainly benign, <1% malignancy risk). Management per lesion type and menopausal status.

3Low risk1 to <10% risk of malignancy. E.g., unilocular cyst ≥10 cm (simple or with non-simple contents), multilocular cyst <10 cm with smooth walls and color score 1–3, solid smooth lesion with color score 1, or a classic benign lesion ≥10 cm.

Management by a gynecologist or gyn-oncologist; ultrasound follow-up or MRI may be considered.

O-RADS 3 (low risk, 1 to <10% malignancy). Management by gynecology; further imaging (MRI) or follow-up may be considered.

4Intermediate risk10 to <50% risk of malignancy. E.g., multilocular cyst ≥10 cm or with color score 4, multilocular cyst with solid components and color score 1–2, or a smooth solid lesion with color score 2–3. Note: a solid lesion with an irregular contour is O-RADS 5 regardless of color score.

Refer to a gynecologic oncologist; consider MRI for further characterization.

O-RADS 4 (intermediate risk, 10 to <50% malignancy). Gynecologic oncology referral; MRI may aid characterization.

5High risk≥50% risk of malignancy. A smooth solid lesion with color score 4, a solid lesion with an irregular contour (any color score), or a multilocular cyst with solid components and color score 3–4; and/or features of malignancy such as ascites and/or peritoneal nodularity.

Refer to a gynecologic oncologist.

O-RADS 5 (high risk, ≥50% malignancy). Gynecologic oncology referral is recommended.

Sources

  • Strachowski LM, et al. O-RADS US v2022: An Update from the American College of Radiology's Ovarian-Adnexal Reporting and Data System US Committee. Radiology. 2023;308(3):e230685.

Educational reference for clinicians — not medical advice. Verify against the primary source before acting on it; guidelines change. Final decisions rest with the interpreting physician and your institution's protocols.