Ultrasound of Adnexa by IOTA 2026: ADNEX, Two-step, O-RADS
What the IOTA 2026 Update Changed
The IOTA 2026 consensus clarifies the language used by ultrasound physicians to describe adnexal tumors and links this language to modern risk algorithms: modified benign descriptors, the ADNEX model, and the two-step strategy. The document is published by the International Ovarian Tumor Analysis Group as an updated opinion on terms, definitions, and measurements for sonographic features of adnexal tumors IOTA 2026.
The practical meaning of the revision: the conclusion must be reproducible. It is not enough to write "complex cyst" or "cystic-solid mass." It is necessary to specify the morphological type, sizes, solid elements, papillary projections, locularity, shadows, ascites, and blood flow in IOTA terms.
Minimal Description Protocol
The description begins with localization: right or left adnexa, ovarian, paraovarian, tubal, or unclear origin. If normal ovarian tissue is visualized separately from the mass, this should be noted. Then, the maximum diameter of the mass and its internal architecture are recorded.
The protocol should consistently reflect: cystic or solid structure; number of locules; presence of septa; internal wall; solid components; papillary projections; acoustic shadows; free fluid or ascites; color Doppler score. These features are needed not only for the textual conclusion but also for correct input into ADNEX.
IOTA Morphological Categories
Basic morphology should be explicitly named: unilocular cystic mass, multilocular cystic mass, unilocular-solid, multilocular-solid, or predominantly solid. This classification is better than vague formulations like "complex" or "mixed" mass because it is directly linked to risk models.
A locule is a cystic compartment separated by a septum. For ADNEX, a binary feature is important: more than 10 locules or not. Septa, wall structures, and solid areas are described by the most suspicious component, not by the average impression of the mass.
Solid Component and Papillary Projection
A solid component is a tissue area that is not purely cystic content. For the ADNEX model, the maximum diameter of the largest solid component is entered separately; if there are no solid elements, the value is entered as 0 mm. Papillary projections are considered solid protrusions into the cyst cavity and are accounted for separately by quantity.
An important numerical boundary of IOTA: a papillary projection is a protrusion of solid tissue into the cystic cavity with a height of at least 3 mm. For ADNEX, the number of papillary projections is coded in categories 0, 1, 2, 3, or >3. Small wall irregularities should not be summed with true papillary projections without measurement.
ADNEX: What Data to Enter
ADNEX is an IOTA multifactorial model for assessing the probability of benignity and malignancy subtypes. Clinical and ultrasound variables are entered: age, type of center, maximum diameter of the mass, maximum diameter of the largest solid component, number of papillary projections, feature of >10 locules, acoustic shadows, ascites, and CA-125 if available. The model can be used without CA-125, but this should be clear from the clinical context.
| Parameter | How to Code by IOTA/ADNEX | Practical Error |
|---|---|---|
| Maximum Diameter of the Mass | Largest size of the mass in mm | Indicating only the size of the cyst without the solid node |
| Largest Solid Component | Maximum diameter in mm; 0 mm if absent | Summing several solid areas |
| Papillary Projections | 0, 1, 2, 3, or >3; projection height ≥3 mm | Counting wall debris as papillation |
| Locules | Feature of >10 locules: yes or no | Writing "multilocular" without counting the threshold |
| Acoustic Shadows | Yes or no | Not distinguishing shadow from attenuation due to depth |
| Ascites | Yes or no | Not separating physiological fluid from ascites |
| CA-125 | Enter if available; model applicable without it | Delaying ultrasound feature description until laboratory |
Color Doppler: How to Write
IOTA uses a semi-quantitative color score from 1 to 4: 1 — no blood flow detected, 2 — minimal, 3 — moderate, 4 — marked. In the protocol, it is important to specify where the blood flow is assessed: in the wall, septa, papillary projections, or solid component. The color score itself does not replace the morphological description.
Modified Benign Descriptors: First Step
The two-step strategy does not start with a calculator but with recognizing a typical benign pattern. If the mass fully corresponds to a modified benign descriptor, it can be described as typically benign and related to a low-risk category. This group usually includes masses with a characteristic benign sonographic appearance, such as a simple cyst, typical endometrioma, typical dermoid cyst, hydrosalpinx, paraovarian or paratubal cyst, peritoneal inclusion cyst.
The key rule: the descriptor is applicable only with a typical picture. If there is an atypical solid component, papillary projections, marked vascularization, ascites, or other suspicious features, the mass should not be "calmed" with a benign label; ADNEX should be used.
Two-step: Working Algorithm
- Step 1. Describe the mass using standard IOTA terms and check if it matches a modified benign descriptor.
- Step 2. If there is no typical benign descriptor or the features are mixed, enter the variables into ADNEX.
- Step 3. Compare the total malignancy risk from ADNEX with O-RADS categories if such linkage is used in the institution.
- Step 4. In the conclusion, indicate not only the risk category but also the features that formed it: solid component, papillary projections, >10 locules, ascites, shadows.
Linkage to O-RADS
In the updated IOTA 2026 logic, it is convenient to compare the model risk with O-RADS categories. This does not cancel the full description: the risk category should be a consequence of the listed ultrasound features, not the only line of the conclusion.
| Category | Malignancy Risk Range | How to Use in Protocol |
|---|---|---|
| O-RADS 2 | <1% | Almost certainly benign mass with corresponding morphology |
| O-RADS 3 | 1–<10% | Low risk; indicate features that allowed not to raise the category |
| O-RADS 4 | 10–<50% | Intermediate risk; solid elements and papillary projections are important |
| O-RADS 5 | ≥50% | High risk; be sure to describe ascites, solid component, extent of visible changes |
How to Formulate the Conclusion
The optimal structure of the conclusion: localization; IOTA morphological category; sizes; content; solid components and papillary projections; locules; acoustic shadows; ascites; color score; result of modified benign descriptor or ADNEX; final risk category. For example: "Left-sided multilocular-solid adnexal mass, maximum diameter ... mm, largest solid component ... mm, papillary projections 2, locules >10 no, acoustic shadows no, ascites no, color score 3. Does not correspond to typical benign descriptor; evaluated by ADNEX."
This format allows the clinician to understand why the mass is assigned to a certain risk and provides an opportunity to recheck the input into the calculator. This is the main practical goal of the IOTA 2026 consensus.
Frequently asked questions
Is it necessary to enter CA-125 into ADNEX?
CA-125 is entered if the value is available. The ADNEX model can be used without CA-125, but it is preferable to understand which option was used in the protocol.
What is more important for ADNEX: overall size or solid component?
Both parameters are needed: the maximum diameter of the entire mass and the maximum diameter of the largest solid component. If there is no solid tissue, 0 mm is indicated for this field.
When to use two-step instead of ADNEX right away?
The two-step begins with recognizing a typical modified benign descriptor. If the picture is not fully typical or there are suspicious features, proceed to the second step — risk calculation by ADNEX.