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O-RADS Ultrasound Calculator – ACR Guidelines — Copy

Ovarian lesions

Normal Ovary
    No lesion
  • Physiologic cyst
  • Follicle
  • Corpus Luteum

Classic Benign Lesion
For any atypical features, use other lexicon descriptors

Refer ACR ORADS US Chart Below

You can hover over/click a few tabs for illustrations for eg. Normal ovaries, classic lesions and color score.

Images for reference have been sourced from the original white paper of the ACR. You can access the full article here: O-RADS US Risk Stratification and Management System: A Consensus Guideline from the ACR Ovarian-Adnexal Reporting and Data System Committee.

ORADS Ultrasound Chart

ACR O-RADS Ultrasound Chart
ACR O-RADS Ultrasound Chart

Decoding O-RADS: A Comprehensive Guide to Ovarian Lesion Assessment

Ovarian cancer, though statistically rare, poses a significant threat due to its lethal nature. The fear of missing ovarian cancer often leads to unnecessary surgeries, causing considerable morbidity for conditions that are non-neoplastic or benign neoplasms. In the pursuit of optimizing care and minimizing unnecessary interventions, the Ovarian-Adnexal Reporting and Data System (O-RADS) emerges as a valuable tool. This blog post delves into the insights surrounding O-RADS, offering a comprehensive guide to understanding risk stratification, lexicon simplification, and the role of ultrasound specialists.

Meta description:

Unlock the secrets of O-RADS with our comprehensive guide. Understand risk stratification, lexicon simplification, and the role of ultrasound specialists. Dive deep into the intricacies of assessment categories and gain practical tips for accurate reporting.


Ovarian cancer, though statistically rare, demands a nuanced approach. Unnecessary surgeries and interventions for non-neoplastic conditions result from the fear of missing ovarian cancer. The associated morbidity is significant, making it imperative to adopt a standardized approach to diagnosis and care. The need for a lexicon that provides accurate risk assessment and optimizes care for women with ovarian cancer is emphasized.

O-RADS Overview

Introduced as a recent addition to the American College of Radiology (ACR) Rads groups, O-RADS focuses on standardized assessment of ovarian lesions. The primary imaging modality is ultrasound, with MRI reserved for more complex problem-solving scenarios. Both ultrasound and MRI arms within O-RADS come equipped with unique lexicons and assessment categories.

Assessment Categories and Management Recommendations

O-RADS defines risk in six categories, incorporating extensive studies. From technically incomplete (Category 0) to high risk (Category 5), each guides management decisions.

CategoryLikelihood of MalignancyManagement Recommendations
0Repeat imaging
10%No follow-up
2<1%Varied management based on factors
31-10%Consider another opinion or MRI
410-50%Involve a gynecologic oncologist
5≥50%Referral to a gynecologic oncologist

Ultrasound Specialist

The concept of an ultrasound specialist is introduced, emphasizing the importance of a physician with a dedicated focus on ultrasound assessment of adnexal lesions. Unlike radiologists, there are no mandated requirements, training, or certification for ultrasound specialists. Their experience plays a crucial role in accurate lesion assessment.

How to Use O-RADS

O-RADS can be employed for every pelvic ultrasound or on a case-by-case basis. It is particularly recommended in scenarios involving non-physiologic adnexal lesions, high-risk screening, or when further evaluation is warranted. The systematic application of O-RADS ensures a standardized approach to risk assessment.

Lexicon Simplification

Physiological Findings:

  • Follicles
  • Corpus Luteum

Classic Benign Lesions:

  • Hemorrhagic Cyst
  • Dermoid Cyst
  • Endometrioma
  • Paraovarian Cyst
  • Paratubal Cyst
  • Hydrocele

Cystic Lesions

Evaluation of cystic lesions is crucial in O-RADS. Distinguishing simple cysts from complex ones involves assessing complete septations and size. For instance, a simple cyst lacks complete septations, while a size larger than 10 cm or irregular shape categorizes it as O-RADS 3.

Simple Cysts:

  • No Complete Septations
  • Size <10 cm (O-RADS 2), >10 cm or Irregular (O-RADS 3)

Complex Cysts:

  • Presence of Septations
  • Differentiation of True Septation from Partial Volume Averaging
  • Solid Components in Cysts Classified Based on Color Score

Solid and Solid-Appearing Lesions

Assessment involves outer contour, vascularity grading, and color scoring.

Assessment AspectConsideration
Outer ContourSmooth or Irregular
Vascularity GradingNone to Very Strong Flow
Color Score RelevanceParticularly in Multilocular Cystic Lesions

Video Tutorials

You can watch this detailed lecture on O-RADS Ultrasound by Dr. Avni Skandhan for reference:

Check out other radiology useful calculators:

Radiology Calculators

More video tutorials for ORADS Ultrasound evaluation of Ovarian Cysts:

Basics of ORADS Classification for Ultrasound :

O-RADS Ultrasound – Learn from Examples:

Frequently asked questions about ORADS Ultrasound:

A few clinically relevant questions for ORADS Ultrasound :

Question A1: What distinguishes a papillary projection from a solid component in the risk stratification table?

Answer: A papillary projection (or nodule) is a solid component protruding from the cyst wall, surrounded by fluid on three sides. In Category 4, we grouped unilocular cysts with no papillary projections with those containing up to 3 papillary projections.

Question A2: Do “solid smooth” and “solid irregular” in risk categories 3, 4, and 5 refer to a lesion or any solid component within a lesion?

Answer: Both terms refer to a solid lesion (≥ 80% solid) in the IOTA/O RADS system. To eliminate confusion, we’ve updated the terms to “solid lesion” in the risk groups on the ACR O RADS web page.

Question A3: Any tips for differentiating characteristic cyst fluids (endometrioma, mucinous tumor, dermoid)?

Answer: Linear appearance of foci is key; O RADS 2 category applies to endometrioma, dermoid cyst, and (indeterminate) non-simple unilocular cyst. Refer to figures for clarification.

Question A4: Why wasn’t “acoustic shadowing” included in risk stratification despite its benign predictive value?

Answer: To maintain simplicity, fewer categories were prioritized initially. Management didn’t significantly change based on “acoustic shadowing,” as concluded from literature and IOTA 1-3 data. Will be considered in the next revision.

Question A5: Tips to distinguish color flow scores 2, 3, and 4? Does spectral Doppler play a role?

Answer: Color score is subjective. Minimal flow (score 2) to strong flow (score 4) depends on overall color Doppler flow in the lesion. Spectral Doppler helps distinguish vascularity from artifact but doesn’t affect color score.

Question A6: Is a cyst with a “daughter cyst” considered multilocular?

Answer: A “daughter cyst” is a septation; entire cyst considered multilocular. Applicable to premenopausal patients; differentiates from “cyst within a cyst.”

Question A7: How does a unilocular cyst with wall calcification fit into the risk stratification system?

Answer: <3mm protrusion is a wall irregularity; ≥3mm is a papillary projection. Flat wall calcification without protrusion is a smooth inner wall. Other descriptors, like “shadowing,” aid malignancy prediction.

Question A8: What is considered “ascites”? Do echoes within the fluid matter?

Answer: Ascites is fluid beyond the cul-de-sac. Echoes within don’t affect risk stratification but may influence management with acute symptoms.


Question C1: Can lesions in high-risk and symptomatic patients be included in O RADS?

Answer: Lexicon and O RADS categories apply to any lesion. However, management aspects are restricted to average-risk patients, varying for high-risk patients.

Question C2: Does O RADS apply to all ovarian and adnexal lesions?

Answer: O RADS applies to lesions involving ovaries/fallopian tubes. If origin is indeterminate but suspected ovarian/fallopian, O RADS may apply; otherwise, it doesn’t.

Question C3: How to manage stable O RADS 3 or 4 lesions?

Answer: Management options are outlined in the published article and on the ACR website; specific guidelines available for each category.

Question C4: When is a study considered O RADS 0, an “incomplete evaluation”?

Answer: O RADS 0 is assigned when the study is incomplete, and further evaluation is needed.

Question C5: Can we risk stratify a changing endometrioma or dermoid?

Answer: Risk stratification is possible using descriptors or the ADNEX model; management may vary for changing lesions.

Question C6: Who is an ultrasound specialist?

Answer: An ultrasound specialist is a physician with a focus on ultrasound assessment of adnexal lesions, but as of now, no mandated requirements or guidelines define this specialist.


The management approach to ovarian lesions is systematic and manageable. O-RADS offers a standardized lexicon for consistent reporting, emphasizing the importance of clinical context for nuanced decision-making. The continuous engagement of the medical community ensures that practitioners stay updated with evolving best practices in ovarian lesion assessment. In conclusion, the O-RADS framework empowers healthcare professionals to navigate the complexities of ovarian lesion evaluation with confidence.

For some reason the preferred search term for O-RADS is o’rads. Probably an indexing error.

Disclaimer: The author makes no claims of the accuracy of the information contained herein; this information is for educational purposes only and is not a substitute for clinical judgment.


  1. O-RADS US Risk Stratification and Management System: A Consensus Guideline from the ACR Ovarian-Adnexal Reporting and Data System Committee.
  2. A simplified approach to ovarian lesions based on the O-RADS US risk stratification and management system

This page was last updated on May 20, 2024 @ 4:13 pm

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