O-RADS Calculator and Report Generator for US & MRI
This calculator includes the latest updates published by the ACR ® in September 2023.
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More about the O-RADS Calculator for US and MRI
How to use the O-RADS Calculator in adnexal mass evaluation
The O-RADS Calculator, including both the O-RADS US Calculator and O-RADS MRI Calculator, is best used as a structured educational and clinical decision-support aid for standardized adnexal mass characterization on ultrasound and MRI. In daily practice, the goal is not to replace radiologist interpretation, but to organize morphology, vascularity, and problem-solving imaging findings into a reproducible ovarian lesion risk assessment that supports multidisciplinary management.[1][2]
For radiologists, the practical value of the ovarian adnexal reporting system is its ability to reduce ambiguity in reports, improve communication with gynecology and gynecologic oncology teams, and support more consistent adnexal mass risk stratification. A structured approach also improves reporting clarity for follow-up recommendations, MRI triage, and referral pathways using the O-RADS US Calculator and O-RADS MRI Calculator.[2][3]
Why standardized adnexal lesion classification matters
Adnexal lesions have historically been described with variable terminology, which can make management recommendations less consistent across readers and institutions. A standardized lexicon helps separate benign-appearing cystic lesions from masses that warrant closer evaluation, MRI problem-solving, subspecialty consultation, or surgical planning. This is particularly important when the imaging report is used to guide ovarian mass malignancy risk estimation and downstream triage.
In this setting, O-RADS ™ classification functions as a reporting framework for ovarian cyst evaluation and adnexal mass characterization. It links imaging features to estimated risk categories and recommended management pathways, while still requiring clinical context, reader expertise, and correlation with symptoms, menopausal status, prior imaging, and laboratory data.[2][3]
Core workflow for practical use
A practical workflow begins by confirming whether the examination is adequate for characterization. If technical limitations prevent confident assessment, the lesion may be considered incomplete and additional imaging may be needed. If the study is diagnostic, the next step is careful lesion analysis, including cystic versus solid composition, locularity, septations, papillary projections, wall contour, internal vascularity, and associated findings such as ascites or peritoneal nodules.
For lesions that remain indeterminate on ultrasound, MRI can provide a more specific gynecologic imaging assessment. This is particularly relevant for lesions that appear complex, vascular, or solid, or for lesions in which benign fibrous tissue, blood products, or proteinaceous material may mimic more suspicious sonographic risk features. In these cases, the O-RADS MRI Calculator may help standardize interpretation.[4]
| Category | General interpretation | Estimated risk | Typical management direction |
|---|---|---|---|
| O-RADS 0 | Incomplete evaluation | Not assigned | Repeat ultrasound or further imaging, often MRI, when characterization is limited |
| O-RADS 1 | Normal physiologic finding | Normal | No adnexal mass follow-up required for the physiologic finding itself |
| O-RADS 2 | Almost certainly benign | Less than 1% | Routine or conservative management, depending on lesion type and clinical setting |
| O-RADS 3 | Low risk | 1% to less than 10% | Short-interval ultrasound follow-up or MRI in selected cases |
| O-RADS 4 | Intermediate risk | 10% to less than 50% | MRI problem-solving, specialist evaluation, or management escalation as clinically appropriate |
| O-RADS 5 | High risk | 50% or greater | Referral for gynecologic oncology-oriented assessment and definitive management planning |
O-RADS classification categories and risk interpretation
The O-RADS ™ score spans incomplete, normal, benign, low-risk, intermediate-risk, and high-risk categories. In general terms, O-RADS 2 lesions include classic benign entities such as simple cysts, dermoids, and endometriomas when they meet expected imaging criteria. O-RADS 3 lesions carry a low but nonzero malignancy risk and often fall into the group where short-interval follow-up or MRI may refine management. O-RADS 4 and 5 lesions warrant more urgent characterization and clinical coordination because of increasing concern for neoplasm.[2][3]
These categories should be interpreted as a structured estimate derived from imaging features, not as a substitute for pathology or clinical judgment. Menopausal status, symptoms, tumor markers, prior imaging stability, and operative context can all influence final management.
O-RADS ultrasound categories and the v2022 update
The O-RADS ultrasound v2022 update refined several aspects of adnexal lesion classification to improve consistency and reduce false-positive categorization. One notable change was clearer treatment of bilocular cysts, which are defined as having exactly two locules. Smooth bilocular cysts are not automatically escalated solely because of a single septation. This helps reduce category inflation in lesions that otherwise behave more like simple cystic masses.[3]
The update also emphasized acoustic shadowing as a benign feature in appropriate lesions, which is particularly relevant in fibrous masses. Another important point is careful distinction between true multilocularity and adjacent follicles separated by normal ovarian parenchyma. Misinterpreting normal tissue as a septation can falsely increase the O-RADS classification and lead to unnecessary escalation.[3]
Color score assignment remains a practical challenge in everyday sonographic risk features assessment. Overcalling vascularity may shift a lesion into a higher O-RADS ultrasound category. For that reason, use of the O-RADS US Calculator is strongest when paired with disciplined lexicon-based interpretation rather than impressionistic scoring alone.
Clinical use of O-RADS in adnexal mass management
The O-RADS Calculator is most useful when it is integrated into a broader clinical workflow. For low-risk lesions, it can support conservative follow-up recommendations and standardized reporting language. For intermediate-risk lesions, it can identify cases that merit MRI pelvis problem-solving, subspecialty review, or closer short-term follow-up. For high-risk lesions, it helps communicate the degree of concern in a structured way that supports referral planning and operative decision-making.
In this context, the framework also strengthens communication between radiologists, gynecologists, and gynecologic oncologists. Standardized reporting of ovarian lesions allows the radiology report to function as a clearer management document rather than a descriptive narrative with variable terminology.[2][3]
For radiologists, the key takeaway is that multimodal ovarian lesion risk assessment may improve decision support in selected indeterminate cases, particularly when used alongside structured tools such as the O-RADS Calculator.
Practical reporting points for the radiologist
When applying the O-RADS ™ score, first confirm that the examination is technically adequate. Then document lesion morphology clearly, including whether the lesion is unilocular, bilocular, or multilocular, whether solid tissue is present, whether septations or papillary projections are present, and whether associated ascites or peritoneal findings are seen.
When MRI is performed, describe whether enhancing soft tissue is present and whether there are features that favor fibrous benign tissue. If serum biomarkers such as CA125 are being incorporated into a broader management pathway, they should be interpreted in the appropriate clinical context rather than as stand-alone determinants of malignancy. This approach keeps the calculator aligned with its intended role as a structured support tool for radiologic interpretation and multidisciplinary discussion.[4]
Limitations of O-RADS risk stratification
No structured system removes all uncertainty from adnexal lesion interpretation. Pitfalls include overcalling vascularity, misclassifying adjacent follicles as septations, mistaking clot or retracted parenchyma for solid tissue, and applying a risk category without adequate attention to technical limitations or patient context. The same lesion may also be interpreted differently depending on image quality, lesion size, menopausal status, and reader experience.
In addition, the estimated risk ranges of O-RADS ™ categories should not be interpreted as fixed outcome predictions for an individual patient. They are intended to support standardized reporting and consistent management discussions. Final clinical decisions remain dependent on radiologist judgment, clinical presentation, laboratory data, specialist input, and when indicated, histopathologic confirmation.[2][3]
Frequently Asked Questions (FAQs)
What defines each O-RADS category from 0 to 5?
O-RADS 0 indicates an incomplete evaluation. O-RADS 1 represents a normal physiologic finding. O-RADS 2 corresponds to an almost certainly benign lesion with an estimated risk below 1%. O-RADS 3 indicates low risk, generally 1% to less than 10%. O-RADS 4 indicates intermediate risk, generally 10% to less than 50%. O-RADS 5 indicates high risk, generally 50% or greater. These categories are based on standardized imaging features and should be interpreted together with the clinical setting.[2][3]
When should an adnexal mass move from ultrasound evaluation to MRI?
MRI is most helpful when ultrasound findings are indeterminate, when a lesion has suspicious or equivocal solid components, when fibrous benign tissue is a consideration, or when a more specific characterization of enhancement is needed. MRI can improve confidence in adnexal lesion classification and may help refine management recommendations for selected O-RADS 3 to 5 lesions, particularly when using an O-RADS MRI Calculator.[4]
What are common pitfalls in O-RADS classification?
Common pitfalls include mistaking adjacent follicles for true septations, overestimating color flow, confusing clot or retracted ovarian tissue with solid components, and escalating a lesion category without confirming whether the examination is technically adequate. These issues can affect both adnexal mass characterization and downstream management recommendations.[3]
How does the O-RADS Calculator influence conservative versus surgical management?
The calculator helps standardize ovarian lesion risk assessment and reporting so that low-risk lesions can be managed more consistently with follow-up or routine care, while higher-risk lesions can be escalated for MRI, specialist consultation, or surgical planning. It supports management discussions, but it does not replace radiologist interpretation, specialist input, or pathology when tissue diagnosis is required.[2][3]
References
- O-RADS US v2022: An Update from the American College of Radiology’s Ovarian-Adnexal Reporting and Data System US Committee Lori M. Strachowski, Priyanka Jha, Catherine H. Phillips, Misty M. Blanchette Porter, Wouter Froyman, Phyllis Glanc, Yang Guo, Maitray D. Patel, Caroline Reinhold, Elizabeth J. Suh-Burgmann, Dirk Timmerman, and Rochelle F. Andreotti Radiology 2023 308:3
- Andreotti RF, Timmerman D, Strachowski LM, et al. O-RADS US risk stratification and management system: a consensus guideline from the ACR Ovarian-Adnexal Reporting and Data System Committee. Radiology. 2020;294(1):168-185. https://pubmed.ncbi.nlm.nih.gov/31687921/
- Strachowski LM, Jha P, Phillips CH, 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. https://pubmed.ncbi.nlm.nih.gov/37698472/
- Reinhold C, Rockall A, Sadowski EA, et al. Ovarian-Adnexal Reporting Lexicon for MRI: A White Paper of the ACR Ovarian-Adnexal Reporting and Data Systems MRI Committee. J Am Coll Radiol. 2021;18(5):713-729. doi:10.1016/j.jacr.2020.12.022
All images in this calculator have been obtained from ACR's white paper mentioned in the references above.
Click here to visit ACR's page for O-RADS.
PGY-5 Radiology and Nuclear Medicine Resident Physician
UT Southwestern Medical Center, USA
excelente
Good
This is very nice BUT need to fix one issue. When you have an ovarian lesion that has septations but NO solid component, the O-RADS algorithm for the next step is to make an assessment of whether the INNER wall and/or septations are smooth or irregular. As of right now (08/05/2023), your calculator does not include this step–instead, it incorrectly asks the user to assess the OUTER contour. Assessment of the OUTER contour is appropriate for a mass with solid components, but not for a cyst (with or without septations) that does not have a solid component. Fix this issue and the calculator will be accurate–but otherwise, nicely done.
Hello Dr. Patel,
Thank you so much for bringing this error to my attention. I have made the necessary changes and now, if the lesion is completely cystic, the calculator will ask for “septations (if applicable) and internal contour†instead of the outer contour. I really appreciate your feedback.
if we are using power doppler for ovarian lesion what is the color score to be followed ? If we use the routine color doppler scoring will it be an exaggeration of the score ?
Excelente
The report generator is brilliant. Bravo!
Thank you very much for this excellent tool, congratulations. Greetings from Ecuador.
great !
Words can’t express my thanks! 🙏
Didn’t work for a unilocular ovarian cyst-without septation. still required i describe septation
Hello and thank you for your feedback. Are you encountering an error in the calculator, or the report generator? Is it for an MRI study, or ultrasound?
Hi there, thank you so much for creating this amazing calculator. I have just come across a slight issue, when I select all the parameters to describe a peritoneal inclusion cyst, mine happens to be 3.2cm, it says the value must be less than 3?
Hello Dr. Brennan,
Thanks for reporting this. The bug has been fixed and the issue is now resolved.