Diagnostic Testing for Endometrial Polyps
Transvaginal ultrasound (TVUS) combined with transabdominal ultrasound is the most appropriate initial imaging test for diagnosing endometrial polyps in reproductive-age women with abnormal uterine bleeding, followed by saline infusion sonohysterography (SIS) if focal lesions are suspected, and ultimately hysteroscopy with biopsy for definitive diagnosis when imaging is inconclusive or tissue diagnosis is required. 1, 2
Initial Diagnostic Approach
Start with transvaginal ultrasound as first-line imaging:
- TVUS should be combined with transabdominal ultrasound to fully assess pelvic structures, with the transvaginal approach providing superior spatial and contrast resolution for detecting endometrial polyps 1
- Color Doppler imaging should be incorporated as a standard component, as visualization of a vascular pedicle has 62-98% specificity and 50-94% negative predictive value for detecting endometrial polyps 1
- Optimal timing matters: Perform TVUS on days 11-13 of the menstrual cycle (follicular phase) for maximum diagnostic accuracy, achieving 82.5% sensitivity and 73% specificity 3
- TVUS can detect endometrial polyps but cannot reliably determine the etiology of endometrial thickening, requiring tissue sampling in many cases 1
Important caveat: In premenopausal women, endometrial thickness is not a reliable indicator of pathology—polyps may be present even with thickness <5 mm 1
Second-Line Imaging When Indicated
Proceed to saline infusion sonohysterography when:
- Initial TVUS findings are unclear or suggest intracavitary lesions 2, 4
- You need to distinguish between leiomyomas and endometrial polyps (97% accuracy) 4
- SIS provides 96-100% sensitivity and 94-100% negative predictive value for uterine and endometrial pathology 2, 4
- SIS is more accurate than TVUS alone for endometrial assessment and confirms the presence of intracavitary lesions 4, 5
Definitive Diagnosis
Hysteroscopy with directed biopsy is the gold standard:
- Hysteroscopy allows direct visualization of the endometrial cavity and targeted biopsy of suspicious lesions 2, 6
- This should be reserved for cases where medical treatment has failed, imaging suggests focal lesions possibly missed by endometrial sampling, or SIS identifies intracavitary masses requiring surgical management 2, 4
- In-office hysteroscopy has the highest diagnostic accuracy with high cost-benefit ratio for detecting endometrial pathology 5
- Histopathological analysis is mandatory due to the 1.5-3% risk of malignancy in polyps, which increases with age and postmenopausal status 7, 6, 5
Critical Pitfalls to Avoid
- Never rely on transabdominal ultrasound alone in non-virgins—the transvaginal approach provides superior endometrial assessment 4
- Avoid blind dilation and curettage (D&C) for diagnosis, as it is inaccurate for detecting focal endometrial pathology and should not be used 5
- Do not assume normal endometrial thickness excludes polyps in premenopausal women—many studies show polyps can be present with thickness <5 mm 1
- Color Doppler parameters (resistive index, pulsatility index) and polyp size cannot predict histologic type and cannot replace surgical removal with pathologic evaluation 8
When to Escalate
Proceed directly to hysteroscopy with biopsy if:
- Persistent or recurrent bleeding occurs despite normal initial imaging 2
- Patient has risk factors for endometrial cancer (obesity, diabetes, unopposed estrogen, tamoxifen use, Lynch syndrome) 2, 4
- TVUS cannot adequately visualize the endometrium due to body habitus, uterine position, adenomyosis, or leiomyomas 2
- Office endometrial biopsy is negative but symptoms persist (10% false-negative rate) 2