Ovarian-Adnexal Reporting and Data System, Ultrasound (O-RADS US,)

O-RADS US applies to the ovaries, lesions involving (or suspected to involve) the ovaries and/or fallopian tubes, and paraovarian cysts, when the intent is to stratify risk of malignancy

Scenarios when O-RADS does not apply include (but are not limited to)

1. Pelvic inflammatory disease, ectopic pregnancy, torsion of a normal ovary
2. Lesions clearly identified as non-ovarian/non-tubal in origin (eg, an exophytic or broad ligament myoma)
3. If the origin of a lesion is indeterminate, imaging options include CT and MR
4. Ovary not seen or surgically absent - O-RADS US: Not applicable
5. O-RADS US 0: Technically inadequate
6. Ovarian visualization expected and required based on exam   indication but not seen,eg: US follow-up of ovarian lesion previously seen or on another modality,High-risk patient (BRCA, etc.), screening US for ovarian cancer.
7. Multiple or bilateral lesions• Each lesion should be separately characterized• Management driven by the lesion with the highest O-RADS score•Separate recommendations should be provided when management of one lesion is independent of the other 

For risk stratification, the O-RADS US system uses five categories (O-RADS 1–5), from normal (1) to high risk of malignancy (5). An O-RADS US  0 (zero) category is used for an incomplete evaluation.

O-RADS 0 - is an incomplete evaluation due to technical factors such as bowel gas, large size of the lesion, location of the adnexa, or inability to tolerate endovaginal imaging.

O-RADS 1-category relevant only in premenopausal patients, physiological findings such as the follicle and corpus luteum are included . To avoid confusion among patients, it is advisable for the ultrasound report to refer to these structures as a follicle and corpus luteum rather than using the term "cyst."

Fig 2: Image shows Ovarian-Adnexal Reporting and Data System (O-RADS) US category 1, normal ovary.

O-RADS 2, the almost certainly benign category (<1% risk of malignancy), comprises the majority of unilocular cysts less than 10 cm .

Simple Cysts:

Fig 3: Image shows Ovarian-Adnexal Reporting and Data System (O-RADS) US category 2, almost certainly benign.

• Unilocular cysts with smooth thin walls, acoustic enhancement, and anechoic internal content.
• Widely considered benign with strong literature support.
• Large studies indicate minimal malignancy risk, especially in premenopausal women.

Classic Benign Lesions:

Fig 4: Image shows Ovarian-Adnexal Reporting and Data System (O-RADS) US category 2, classic benign lesions and associated descriptors.

• Emphasize using specific, classic benign features for accurate diagnosis.
• Avoid generic descriptors to prevent incorrect diagnoses and inappropriate management.
• Lesions with almost certain benign features are usually straightforward, but atypical cases may need further characterization by a US specialist or MRI.
• The goal is to reach a correct diagnosis, avoiding overtreatment

Nonsimple Unilocular Smooth Cysts: For unilocular cysts with smooth inner margins not fitting classic benign categories:

Fig 5: Image shows Ovarian-Adnexal Reporting and Data System (O-RADS) US category 2, almost certainly benign.

• Premenopausal (≤3 cm): No management needed.
• Premenopausal (>3 cm and <10 cm): Follow-up US in 8–12 weeks, preferably in the proliferative phase.
• If cyst persists or enlarges, consider referral to a US specialist or MRI study for further characterization.
• Postmenopausal (≤3 cm): Follow-up in 1 year is an option.
• Additional characterization recommended for all postmenopausal cysts, regardless of size, through US specialist or MRI study.
• Larger premenopausal cysts (>3 cm) and all postmenopausal nonsimple unilocular smooth cysts should be managed by a gynecologist

O-RADS 3 (1% to ,10% Risk of Malignancy)

Fig 6: Image shows Ovarian-Adnexal Reporting and Data System (O-RADS) US category 3, low risk of malignancy

• Over 90% are benign, reducing the need for gynecologic oncologist consultation.

O-RADS 4 (10% to ,50% Risk of Malignancy

• Consultation with gynecologic oncology or referral for management is warranted.
• Menopausal status, US specialist evaluation, MRI, and serum biomarkers (e.g., CA-125) may guide referrals to gynecologic oncologists.

O-RADS 5 (50%–100% Risk of Malignancy)

Fig 7: Image shows Ovarian-Adnexal Reporting and Data System (O-RADS) US category 4, intermediate risk of malignancy

The system states that category 5 US findings (high-risk lesions) should be directly referred to a gynecologic oncologist for management.

Fig 8: Image shows Ovarian-Adnexal Reporting and Data System (O-RADS) US category 5, high risk of malignancy.

The Ovarian-Adnexal Reporting and Data System (O-RADS) MRI risk score was developed by a multi-disciplinary international committee of experts as a codified scoring system for MRI evaluation of ovarian and adnexal lesions.

The O-RADS MRI risk stratification system provides a means for assigning probability of malignancy based on the composition of the lesion, the signal intensity characteristics, and the enhancement pattern of any solid tissue.

1. Apply risk assessment to average-risk patients without acute symptoms for clinical management guidance.
2. Dermoid or mature teratomas have low malignancy risk, assigned an O-RADS MRI risk score of 2.
3. Some dermoids with minimal enhancing tissue maintain a score of 2; fat-containing lesions with substantial enhancing tissue may be scored 4 due to risk of malignancy.
4. The final diagnosis can be reported with the O-RADS MRI score if classic imaging features are present.
5. Dynamic contrast-enhanced MRI with time-intensity curves (TICs) is preferred for risk assessment.
6. Inadequate studies merit an O-RADS MRI risk score of 0.

O-RADS MRI Score 0:

• Assigned when adnexal lesions are incompletely evaluated at MRI.
• Includes cases where portions of the lesion are not assessed or when technically inadequate MRI examinations occur (e.g., missing sequences, significant artifacts).

O-RADS MRI Score 1:

Fig 10: Image shows examples of Ovarian-Adnexal Reporting and Data System (O-RADS) MRI 1 risk score. In postmenopausal women, normal ovaries can contain very small residual follicles, and if the radiologist subjectively assesses the ovaries as normal, the ovaries can be categorized as O-RADS MRI 1.

• Assigned when ovaries are normal.
• In premenopausal women, includes physiologic observations like follicles, hemorrhagic cysts, and corpus luteal cysts measuring 3 cm or less.
• In postmenopausal women, normal ovaries with very small residual follicles can be scored as 1.
• O-RADS MRI risk score does not apply to lesions identified as nonovarian or nonadnexal.

O-RADS MRI Score 2

Fig 11: Image shows examples of Ovarian Adnexal Reporting and Data System (O-RADS) MRI 2 risk score. Unilocular cysts with simple or hemorrhagic fluid 3 cm or smaller in a premenopausal woman would be classified as O-RADS MRI 1. Minimal enhancement of Rokitansky nodule in lesion containing lipid does not change to O-RADS MRI 4.

• Almost certainly benign adnexal lesions.
• PPV for malignancy less than 0.5%.
• Includes unilocular cystic lesions without wall enhancement (proteinaceous, hemorrhagic, endometriotic fluid).
• Lesions with lipid content (mature teratomas or dermoids) are classified as O-RADS MRI 2.
• Lesions with homogenously hypointense signal on T2-weighted and high-b-value DWI scans are O-RADS MRI 2.

O-RADS MRI Score 3

Fig 12: Image shows examples of Ovarian-Adnexal Reporting and Data System (O-RADS) MRI 3 risk score. ^^ = Hemorrhagic cyst smaller than 3 cm in a premenopausal woman would be classified as O-RADS MRI 2.

• Adnexal lesions: Low risk for malignancy.
• PPV for malignancy approximately 5%.
• Includes unilocular cysts with smooth enhancing walls, hemorrhagic or proteinaceous fluid (no solid tissue).
• Multilocular cysts without solid tissue have very low malignancy risk.
• Endometriomas appearing multilocular are classified as O-RADS MRI 2.
• If enhancing solid tissue shows homogenously low signal intensity on T2/DWI scans, it's O-RADS MRI 2.
• If solid tissue doesn't fit the T2/DWI dark pattern, TIC enhancement characteristics dictate the score.

O-RADS MRI Score 4:

Fig 13: Image shows examples of Ovarian-Adnexal Reporting and Data System (O-RADS) MRI 4 risk score. DCE = dynamic contrast enhanced, DWI =diffusion-weighted imaging, FS = fat saturated, PPV = positive predictive value, TIC = time-intensity curve, T1WI = T1-weighted imaging, T2WI = T2-weighted imaging

• Adnexal lesions: Intermediate risk for malignancy.
• PPV for malignancy approximately 50%.
• Lesions contain solid tissue exhibiting intermediate-risk TIC.
• Intermediate TIC shows a PPV of 46.6%.
• If DCE MRI not feasible, lesions with solid tissue enhancing ≤ myometrium at 30–40 seconds on non-DCE MRI are in this category.

O-RADS MRI Score 5

Fig 14: Image shows examples of Ovarian-Adnexal Reporting and Data System (O-RADS) MRI 5 risk score. DCE = dynamic contrast enhanced, DWI = diffusion weighted imaging, FS = fat saturated, PPV = positive predictive value, TIC = time-intensity curve, T1WI = T1-weighted imaging, T2WI = T2-weighted imaging

• Adnexal lesions: High risk for malignancy.
• PPV for malignancy approximately 50%.
• Lesions contain solid tissue exhibiting high-risk TIC.
• High-risk TIC shows a PPV of 85.6%.
• If DCE MRI not feasible, lesions with solid tissue enhancing > myometrium at 30–40 seconds on non-DCE MRI are in this category.