Key Challenges with the O-RADS Ultrasound Classification System

In a recently published article, radiology researchers from Harvard Medical School discussed 10 challenging clinical scenarios that may limit, prohibit, or require modification of the first version of the Ovarian-Adnexal Reporting and Data System ultrasound (O-RADS US) system to help ensure accurate diagnosis and optimal patient management.

Published by the American College of Radiology (ACR) in 2020, the O-RADS US classification system has key governing concepts to be aware of, according to the authors of the article, published in the American Journal of Roentgenology. They noted the system is reserved for the diagnosis and stratification of lesions that involve or are suspected of involving the ovaries and/or fallopian tubes. The authors emphasized that the first version of O-RADS US is not broadly applicable to all pelvic lesions. Another aspect of O-RADS US is an assumption with the management strategies that the patient being assessed has an average risk of ovarian cancer and lacks acute symptoms, according to the authors.

“Several studies have validated this system as an effective and excellent diagnostic tool for predicting malignancy risk. However, potential challenges exist in determining when to apply O-RADS in individual patients and in determining the optimal management of certain adnexal lesions, as highlighted in the O-RADS US introductory ‘governing concepts,’” wrote Yang Guo, MD, who is affiliated with the Department of Radiology at Brigham and Women’s Hospital and Harvard Medical School, and colleagues.

Accordingly, the authors reviewed pertinent diagnostic considerations and takeaway points for a variety of clinical scenarios in which sole reliance on the O-RADS US system may prove to be challenging. The clinical scenarios range from pelvic masses of an indeterminate compartment and inflammation and infection that mimic adnexal neoplasms to solid masses with and without posterior acoustic shadowing and adnexal mass in patients with a history of ovarian malignancy or high-risk genetic status.

One of the challenging scenarios discussed is determining whether a middle compartment mass has uterine or ovarian origin. The authors note that color Doppler ultrasound showing multiple vessels between the uterus and a juxta-uterine mass suggest a uterine origin of the mass. This “bridging vascular” sign reveals feeding vessels from the uterine arteries, according to Guo and colleagues. They note other key signs of uterine origin include a “claw” sign, which shows uterine tissue draping over the mass in question, and the attachment of a mass to the round ligament of the uterus, which is highly likely to be a uterine leiomyoma.

When it comes to non-infectious and non-neoplastic processes that may simulate adnexal tumors, Guo and colleagues noted that there can be a lack of clarity on ultrasound images. They point out that massive ovarian edema (MOE) and ovarian fibromatosis can mimic a solid ovarian mass and other conditions with similar ultrasound presentations to ovarian cancer include sarcoidosis and granulomatosis inflammation of the ovaries associated with Crohn’s disease.

“These findings can be challenging to distinguish from a neoplastic process,” added Guo and colleagues. “However, when suspected, O-RADS should not be applied.”

The article authors also noted that the first version of O-RADS US does not include posterior acoustic shadowing as a factor for categorization and risk stratification of lesions.

“ … Validation studies of O-RADS US have shown that the risk of malignancy is low in solid masses with posterior acoustic shadowing, supporting posterior acoustic shadowing as a helpful feature to downgrade a lesion,” maintained Guo and colleagues.