Dr. Pixel mascot
Dr Pixel 2.0Women's imaging diagnosis

PLATFORM FOR EDUCATION AND DECISION SUPPORT IN WOMEN'S IMAGING

Português|English

O-RADS US › Adnexal

Menopausal status

Understand the system

How O-RADS works for adnexal masses

O-RADS US (Ovarian-Adnexal Reporting and Data System), from the American College of Radiology (ACR), stratifies the malignancy risk of adnexal masses into 6 categories (0 to 5), based on ultrasound features standardized by the IOTA lexicon. Each category carries an associated malignancy risk and a recommended management.

From the normal ovary to high risk

O-RADS US category scale and malignancy risk

O-RADS 2
<1%
Almost certainly benign
O-RADS 3
<10%
Low risk
O-RADS 4
10–<50%
Intermediate risk
O-RADS 5
≥50%
High risk
O-RADS 0 — Incomplete evaluation
Off the risk scale: lesion features cannot be accurately assessed due to technical factors. Management: repeat ultrasound (US) or MRI.
O-RADS 1 — Normal ovary
Off the risk scale: no ovarian lesion. No management needed.

Categories, risk, and management

CategoryFindingsMalignancy riskManagement
O-RADS 0The lesion features relevant to risk stratification cannot be accurately assessed due to technical factors.Not assessableRepeat ultrasound (US) or MRI.
O-RADS 1No ovarian lesion. Normal ovary.NormalNo management needed.
O-RADS 2Simple smooth unilocular cysts and classic benign lesions (hemorrhagic, dermoid, endometrioma, paraovarian, peritoneal inclusion cyst, hydrosalpinx).<1%Management depends on the selected lesion type and size — from "none" to follow-up US at 6–12 months.
O-RADS 3Typically benign ovarian lesions ≥10 cm and other low-risk findings (large smooth cysts, irregular inner wall <3 mm, multilocular <10 cm with smooth wall, solid lesions with smooth surface).<10%If not surgically removed, consider follow-up US at 6 months. If stable, follow-up US at 24 months from the initial exam; if enlarging, consider follow-up US at 12 and 24 months and manage per gynecology. For solid lesions, consider specialist US or MRI (O-RADS MRI score).
O-RADS 4Multilocular cyst without solid component ≥10 cm or with color score (CS) = 4, unilocular/multilocular cyst with a solid component, solid lesion with smooth surface and CS = 2–3.10–<50%Imaging options include specialist US (if available) and MRI (with O-RADS MRI score). Management by gynecology with consultation with gynecologic oncology, or directly by gynecologic oncology.
O-RADS 5Unilocular cyst with ≥4 papillary projections, multilocular cyst with solid component and CS = 3–4, solid lesion with CS = 4 or irregular surface, ascites and/or peritoneal nodules.≥50%Management by gynecologic oncology.

What is the color score (CS)?

The color score (CS) measures the degree of intralesional vascularity on Doppler: 1 = none, 2 = minimal flow, 3 = moderate flow, 4 = very strong flow. It is one of the criteria that define the O-RADS category of solid and multilocular lesions. Another lexicon term is the papillary projection (PP): a subtype of solid component surrounded by fluid on 3 sides.

Common questions

Frequently asked questions about O-RADS US

What is the O-RADS US system?+
O-RADS US (Ovarian-Adnexal Reporting and Data System) is a system from the American College of Radiology (ACR) that stratifies the malignancy risk of adnexal masses into 6 categories (0 to 5), based on ultrasound features standardized by the IOTA lexicon. Each category carries an associated malignancy risk and a recommended management.
What is the difference between O-RADS 2 and O-RADS 3?+
O-RADS 2 (risk <1%) includes simple smooth unilocular cysts and classic benign lesions (hemorrhagic, dermoid, endometrioma, paraovarian, peritoneal inclusion cyst, hydrosalpinx). O-RADS 3 (risk <10%) includes these same typically benign lesions when they reach ≥10 cm, plus cysts with irregular inner wall <3 mm, smooth-walled multilocular cysts <10 cm, and solid lesions with a smooth surface.
What is the recommended management for O-RADS 4?+
Imaging options include specialist US (if available) and MRI with an O-RADS MRI score, per gynecologic oncologist protocol. Management is by gynecology with consultation with gynecologic oncology, or directly by gynecologic oncology.
What is the recommended management for O-RADS 5?+
Management is by gynecologic oncology, given the high malignancy risk (≥50%).
What is the color score (CS) used in O-RADS?+
The color score (CS) measures the degree of intralesional vascularity on Doppler: 1 = none, 2 = minimal flow, 3 = moderate flow, 4 = very strong flow. It is one of the criteria that define the O-RADS category of solid and multilocular lesions.
What is a papillary projection (PP) in the O-RADS lexicon?+
It is a subtype of solid component surrounded by fluid on 3 sides. The number of papillary projections directly influences the category: unilocular cysts with 0–3 papillary projections tend to be O-RADS 4, while ≥4 papillary projections characterize O-RADS 5.