American Board of Family Medicine (ABFM) Practice Exam

Which diagnostic test is appropriate for detecting endometriosis?

1. CA-125 assay

2. Transvaginal ultrasonography

3. CT of the pelvis

4. MRI of the pelvis

The correct answer is: Transvaginal ultrasonography

Transvaginal ultrasonography is an important diagnostic tool for detecting endometriosis because it allows for the visualization of pelvic organs and can identify endometrial cysts, also known as endometriomas. This imaging modality is particularly useful for evaluating the ovaries and surrounding structures for signs of endometriosis. It is often the first-line approach due to its accessibility, non-invasive nature, and effectiveness in identifying cystic lesions that may suggest endometriosis. While CA-125 assays can be used as a blood test to help assess the likelihood of endometriosis, they are not definitive for diagnosing the condition, as elevated levels can occur in other conditions as well. Similarly, pelvic CT scans are less commonly used for this specific diagnosis because they do not provide the same detailed images of soft tissues and are not as effective in characterizing endometriosis compared to ultrasonography or MRI. MRI of the pelvis is a valuable tool and can provide detailed images if endometriosis is suspected, but it is often considered after initial assessments with ultrasonography. Thus, transvaginal ultrasonography remains a preferred initial diagnostic approach for endometriosis.