Can uterine cancer be detected on a pelvic ultrasound?

Detection of Uterine Cancer on Pelvic Ultrasound

Pelvic ultrasound can detect some features of uterine cancer but cannot definitively diagnose it, with sensitivity and specificity limitations requiring additional diagnostic procedures such as endometrial sampling for confirmation.

Ultrasound Capabilities for Uterine Cancer Detection

• Transvaginal ultrasound (TVUS) is the first-line imaging modality for evaluating abnormal uterine bleeding and can identify suspicious endometrial findings that may suggest uterine cancer 1
• TVUS can display endometrial abnormalities and evaluate endometrial thickness, which may indicate potential malignancy when thickened 1, 2
• MRI demonstrates superior capabilities for identifying malignant uterine pathology with sensitivity and specificity up to 79% and 89% respectively for endometrial cancer, compared to ultrasound's more limited capabilities 1

Limitations of Ultrasound for Uterine Cancer Detection

• Ultrasound cannot definitively distinguish between benign endometrial pathology and endometrial cancer with high certainty 1
• In some cases of type II endometrial cancer, approximately 25% of patients may present with a thin or indistinct endometrial stripe on TVUS, potentially leading to false negatives 3
• About 10% of patients with type II endometrial cancer may have no ultrasound abnormalities whatsoever, highlighting a significant limitation of ultrasound-based detection 3

Recommended Diagnostic Approach

• For postmenopausal women, an endometrial thickness ≤4 mm has a negative predictive value for endometrial cancer of nearly 100%, while thickness ≥5 mm generally requires endometrial tissue sampling 2, 4
• When ultrasound findings are suspicious or inconclusive, endometrial sampling or direct visualization with hysteroscopy is recommended for definitive diagnosis 1
• The American College of Radiology recommends a combined transabdominal and transvaginal approach for complete assessment of pelvic structures when evaluating for potential uterine pathology 2, 1

Role of Additional Imaging Techniques

• Color Doppler evaluation can help identify vessels within endometrial lesions, which may suggest polyps or cancer, though it cannot definitively differentiate between benign and malignant conditions 1
• Sonohysterography (saline infusion into the uterine cavity during ultrasound) can better characterize focal endometrial abnormalities but still cannot reliably distinguish between benign pathology and cancer 1
• MRI is superior for identifying malignant uterine pathology and can display the endometrium even when obscured by leiomyomas or adenomyosis on ultrasound 1

Clinical Pitfalls to Avoid

• Relying solely on endometrial thickness measurement without tissue sampling when thickness exceeds normal thresholds 4
• Assuming a thin endometrial stripe (<5mm) completely excludes cancer in symptomatic patients, particularly with type II endometrial cancers 3
• Failing to perform endometrial sampling in women with postmenopausal bleeding, regardless of endometrial stripe thickness on ultrasound 5, 3