O-RADS US v2022: Risk Categories and Management for Adnexal Masses
What O-RADS US v2022 Evaluates
O-RADS US v2022 is an ACR ultrasound system for standardized description and risk stratification of ovarian and other adnexal masses. It combines grayscale features, color Doppler mapping, and clinical context into a final category from 0 to 5. The main goal of the system is not to make a histological diagnosis, but to consistently describe findings, assess the likelihood of malignancy, and choose a management pathway.
The category is assigned after answering several questions: is the mass physiological or a true tumor-like finding; is it simple or complex; is there a solid component; how many papillary projections are there; are the walls and septa smooth or irregular; what is the vascularization according to the color score; is there ascites or peritoneal nodules.
Risk Categories and Basic Management
| Category | Risk of Malignancy | Category Meaning | Typical Management |
|---|---|---|---|
| O-RADS 0 | Not assessed | Incomplete study | Repeat ultrasound, expert ultrasound, or another imaging method to complete stratification |
| O-RADS 1 | Normal | Normal ovary, physiological changes | Routine management without special O-RADS control |
| O-RADS 2 | <1% | Almost certainly benign mass | Observation or no additional management depending on the type of mass, size, and menopausal status |
| O-RADS 3 | 1% — <10% | Low risk | Managed by a gynecologist; if morphology is uncertain — expert ultrasound or MRI |
| O-RADS 4 | 10% — <50% | Intermediate risk | Expert ultrasound or MRI for clarification; consider consultation with a gynecologic oncologist |
| O-RADS 5 | ≥50% | High risk | Referral to a gynecologic oncologist and oncologically oriented treatment planning |
O-RADS 1 and 2: Physiology and Almost Benign Findings
O-RADS 1 is used for normal studies. In women of reproductive age, physiological findings include, for example, a follicle up to 3 cm and a corpus luteum up to 3 cm. These are not tumors and do not require oncological routing.
O-RADS 2 corresponds to a risk of less than 1%. This group includes typical benign patterns with correct visualization: simple cyst, smooth-walled unilocular cyst with uncomplicated or heterogeneous content without a solid component, as well as classic benign masses with a typical appearance and size less than 10 cm. Classic patterns include hemorrhagic cyst, endometrioma, dermoid cyst, paraovarian cyst, hydrosalpinx, and peritoneal inclusion cyst.
O-RADS 3: Low Risk, but No Longer 'Almost Certainly Benign'
O-RADS 3 — risk from 1% to less than 10%. This category includes masses with generally favorable morphology but with a factor increasing uncertainty: large size, multilocularity, or certain complexity features without convincing high-risk criteria.
Typical examples: smooth-walled cyst 10 cm or larger; classic benign mass 10 cm or larger; smooth multilocular mass without a solid component with low or moderate vascularization; some solid smooth masses with acoustic shadowing and minimal vascularization. The management is not automatic oncological surgery, but planned management by a gynecologist with possible expert ultrasound or MRI if the description is incomplete or features do not fit a classic pattern.
O-RADS 4: Intermediate Risk
O-RADS 4 indicates a risk from 10% to less than 50%. This is a zone where erroneous underestimation can lead to incorrect routing, and overestimation can lead to unnecessary radicality. Therefore, ACR emphasizes clarifying imaging and the involvement of specialists experienced in managing adnexal tumors.
This category includes masses with more suspicious architecture: large multilocular cysts, multilocular masses with irregular walls or septa, cysts with a solid component and a limited number of papillary projections, as well as solid smooth masses with greater vascularization or without favorable acoustic shadowing. For the protocol, it is important to describe not only the final O-RADS but also the specific features that led to category 4.
O-RADS 5: High Risk
O-RADS 5 is assigned when the risk of malignancy is 50% and above. Key features include highly suspicious solid tissue, multiple papillary projections, especially 4 or more, significant vascularization, irregular solid component, as well as ascites or peritoneal nodules. The presence of extra-ovarian features fundamentally changes the pathway: the study should directly indicate the need for oncological management.
In this category, one should not limit to the phrase 'ovarian mass.' The protocol should record the side, sizes, structure, solid areas, vascularity, condition of the opposite ovary, presence of free fluid, and peritoneal implants if visible.
Key Descriptors Affecting the Category
| Feature | How it Affects O-RADS |
|---|---|
| Size 10 cm | Threshold at which a number of smooth or classic benign masses move from lower category to O-RADS 3 |
| Solid component | Raises the category compared to purely cystic mass; contour and blood flow are important |
| Papillary projection | Solid protrusion into the cyst cavity 3 mm or more; 4 or more projections are a sign of high risk |
| Color score 1–4 | 1 — no blood flow, 2 — minimal, 3 — moderate, 4 — significant; increased vascularity raises risk |
| Ascites or peritoneal nodules | Features that shift the mass into high-risk routing |
What Changed in v2022 Logic
The v2022 update clarified terminology and reduced ambiguity in classification. An important practical emphasis is that not every complex cystic mass automatically belongs to high categories. With smooth walls, absence of solid tissue, and typical benign pattern, the risk can remain low or almost benign.
For the ultrasound diagnostician, this means the need to carefully distinguish septa, true solid component, clot, dermoid fat component, and papillary projections. An error in one descriptor can change the category from O-RADS 2–3 to O-RADS 4–5 and alter the patient's pathway.
How to Formulate a Conclusion
The optimal protocol includes: localization of the mass, three dimensions, type of mass, internal content, walls and septa, presence and size of solid components, number of papillary projections, color score, ascites, peritoneal nodules, and final O-RADS US category. If the category is 0, it should be indicated what specifically prevents evaluation of the mass: incomplete visualization, technical limitations, inability to distinguish adnexal mass from extra-adnexal.
The formulation should be clinically useful: 'O-RADS US 2, almost certainly benign' or 'O-RADS US 5, high risk, referral to a gynecologic oncologist recommended.' If expert ultrasound or MRI was used as the next step, it is better to indicate this in the recommendations rather than mixing it with the descriptive part.
Practical Errors
- Assigning O-RADS without assessing color score in solid tissue.
- Calling a clot a papillary projection without confirming the absence of blood flow and without assessing mobility/morphology.
- Ignoring the 10 cm threshold for a number of smooth and classic benign masses.
- Not describing ascites and peritoneal nodules when suspecting O-RADS 5.
- Using the category as a histological diagnosis: O-RADS sets risk and pathway but does not replace morphological verification.
Frequently asked questions
What risk of malignancy corresponds to O-RADS 4?
O-RADS 4 corresponds to intermediate risk: from 10% to less than 50%. Usually, clarifying expert imaging and consideration of consultation with a gynecologic oncologist are required.
When is a mass classified as O-RADS 5?
O-RADS 5 is assigned when the risk is 50% and above: for example, with highly suspicious solid tissue, 4 or more papillary projections, ascites, or peritoneal nodules.
Can O-RADS US provide a definitive diagnosis of ovarian cancer?
No. O-RADS US standardizes description, assesses risk, and determines management pathway. A definitive diagnosis of malignant tumor requires morphological verification.