O-RADS

Ovarian-Adnexal Reporting and Data System

Current: A two-track family: O-RADS US v2022 and O-RADS MRI (2021 lexicon + 2022 risk-stratification, no year-version number)American College of Radiology (ACR)
Ovaries / adnexa (female pelvis)UltrasoundMR

O-RADS is an ACR-maintained framework for describing ovarian and adnexal masses and assigning each a probability of malignancy, so reports are consistent and management is risk-appropriate. It is a family with two independent tracks: an ultrasound track (usually first-line, tuned for sensitivity) and an MRI track (typically a problem-solver for sonographically indeterminate masses, adding specificity). Each track pairs a standardized lexicon of imaging descriptors with a numeric risk category and management guidance. The tracks version differently — ultrasound carries explicit year labels, while MRI is anchored to its 2021–2022 founding papers rather than a year-version number.

Version history & what changed

O-RADS US

  1. O-RADS US v20222022-11Current

    An ACR-convened multidisciplinary update (with IOTA and SRU input) to improve specificity, reduce false positives, and make the system applicable to all pelvic ultrasound reports; added benign-favoring features and sharpened management wording. Validation reports better risk stratification and fewer unnecessary surgeries versus the 2019 system.

  2. O-RADS US risk-stratification system (2019)2019

    The consensus guideline that first turned the US lexicon into a 0–5 risk-and-management system; superseded by v2022, against which it is now the comparison baseline.

  3. O-RADS US lexicon white paper (2018)2018

    The original standardized ultrasound descriptor lexicon for ovarian/adnexal findings; foundational vocabulary later folded into and superseded by the risk-stratification systems.

O-RADS MRI

  1. O-RADS MRI risk-stratification system (2022)2022Current

    The ACR O-RADS Committee's MRI risk-stratification guide, turning lesion composition, signal characteristics, and enhancement of any solid tissue into a 1–5 malignancy-probability score. With the 2021 lexicon it constitutes the operative MRI track; it does not use a 'v2019/v2022' numbering scheme.

  2. O-RADS MRI lexicon white paper (2021)2021Current

    Established the standardized MRI descriptor lexicon for ovarian/adnexal lesions — the vocabulary foundation the 2022 risk system depends on. Foundational and still in force.

How the system is structured

Both O-RADS tracks place a mass on a risk ladder. The ultrasound track uses categories from 0 (assessment incomplete) and 1 (normal/physiologic) up through 5 (high probability of malignancy), with the middle categories spanning almost-certainly-benign to intermediate risk. The MRI track uses an analogous 0–5 scheme, with higher numbers reflecting progressively greater malignancy probability based largely on enhancing solid tissue. Each category links to a suggested management direction. Consult the official ACR O-RADS documents for the precise descriptor definitions, category thresholds, and management recommendations.

  • O-RADS 0Incomplete / non-diagnostic study.
  • O-RADS 1Normal-appearing or physiologic finding (e.g. expected follicle / corpus luteum).
  • O-RADS 2Almost certainly benign (very low malignancy chance).
  • O-RADS 3Low risk of malignancy.
  • O-RADS 4Intermediate risk of malignancy — the band where management nuance and reader variability matter most.
  • O-RADS 5High risk of malignancy.

These are our plain-language summaries. For the exact criteria, thresholds, and management rules, see the official source.

Latest on O-RADS

How it compares

O-RADS US grew out of, and shares vocabulary with, the IOTA group's work, so it sits alongside IOTA tools such as the Simple Rules and the ADNEX risk model, as well as the older GI-RADS. The key difference is that O-RADS bundles a standardized lexicon, an ordinal risk category, and explicit management guidance into one ACR-endorsed package, whereas ADNEX outputs a calculated percentage risk and IOTA Simple Rules give a benign/malignant/inconclusive triage. The O-RADS MRI track is conceptually descended from the earlier ADNEX-MR scoring approach and is positioned as the specificity-raising second step after an indeterminate ultrasound. Head-to-head studies generally find O-RADS, ADNEX, and IOTA Simple Rules broadly comparable in discrimination, with O-RADS favored for standardized reporting.

Evidence & controversy

External validation of O-RADS US reports strong discrimination between benign and malignant adnexal masses, and the v2022 update is associated with improved specificity and fewer false positives than the 2019 version, translating into fewer avoidable operations. O-RADS MRI has shown high sensitivity and specificity in multicenter cohorts, supporting its role for indeterminate masses. Comparative meta-analyses place O-RADS in the same performance tier as the IOTA ADNEX model and Simple Rules, with substantial-to-near-perfect interobserver agreement among trained readers. The most cited limitation is the intermediate category (especially O-RADS MRI 4), where reported malignancy prevalence varies widely, and external validation by less-experienced readers remains comparatively limited.

Frequently asked questions

Are O-RADS US and O-RADS MRI the same system?
They are two tracks of one ACR family; they share the 0–5 philosophy but have separate lexicons, criteria, and publication timelines.
What is the current ultrasound version?
O-RADS US v2022, released in late 2022 and published in Radiology in 2023.
Does O-RADS MRI have a 'v2022' number?
No. The MRI track is defined by its 2021 lexicon white paper and 2022 risk-stratification system; it deliberately does not use the US year-version numbering, so '2021–2022' is the honest label.
Which track comes first in practice?
Ultrasound is typically first-line; MRI is generally reserved for masses ultrasound leaves indeterminate, because MRI adds specificity.
How does O-RADS relate to IOTA / ADNEX?
O-RADS US borrows IOTA terminology but packages a lexicon, risk score, and management advice together under the ACR; ADNEX instead computes a numeric malignancy probability.

Glossary

Adnexa
The ovaries, fallopian tubes, and surrounding supporting tissue.
Solid tissue / solid component
Enhancing non-fatty, non-fluid material within a mass — a central malignancy clue, especially on MRI.
Risk stratification
Sorting masses into ordered probability-of-malignancy tiers to guide next steps.
Lexicon
The agreed set of standardized descriptors and definitions used to characterize a lesion.
IOTA
International Ovarian Tumor Analysis group, whose terminology and models underpin much of O-RADS US.
ADNEX model
An IOTA risk calculator that outputs a percentage probability of malignancy, used as a comparator to O-RADS.
Unilocular / multilocular
Whether a cystic mass has one compartment or several — a basic morphologic descriptor affecting category.

Resources & links

Written by RadPigeon Editorial Team, Radiology news editorial teamMedical review pending
Last reviewed: 29 Jun 2026Last changed: 29 Jun 2026

RadPigeon is an independent radiology news digest and is not affiliated with or endorsed by American College of Radiology (ACR). “O-RADS” is a trademark of its owner and is named here only to refer to the system. Always consult the official source for the exact, current criteria.