When to perform Transvaginal Ultrasound (TVUS) versus endometrial biopsy for a patient with abnormal uterine bleeding?

Transvaginal Ultrasound vs Endometrial Biopsy for Abnormal Uterine Bleeding

Transvaginal ultrasound (TVUS) should be the initial diagnostic test for patients with abnormal uterine bleeding, followed by endometrial biopsy when indicated based on ultrasound findings, patient age, and risk factors. 1

Initial Diagnostic Approach

• TVUS is the preferred first-line imaging modality for evaluating abnormal uterine bleeding (AUB) as it is less invasive, generally painless, has no complications, and can effectively assess for structural causes of bleeding 1, 2
• TVUS helps differentiate between structural causes (polyps, adenomyosis, leiomyoma, malignancy, hyperplasia) and non-structural causes of AUB 1
• TVUS is particularly useful in premenopausal women for detecting structural abnormalities like polyps and fibroids, with detection rates of approximately 73% 3

When to Perform Endometrial Biopsy

Postmenopausal Women:

• Perform endometrial biopsy when endometrial thickness is ≥3-4mm on TVUS 4
• Biopsy is indicated regardless of TVUS findings in postmenopausal women with persistent or recurrent bleeding 4, 5
• In-office endometrial biopsy has extremely high sensitivity (99.6% for Pipelle devices) for detecting endometrial carcinoma in postmenopausal women 4

Premenopausal Women:

• Perform endometrial biopsy when:
  • Age ≥35 years with AUB 6, 5
  • Endometrial thickness >5mm during early proliferative phase 3
  • Risk factors for endometrial cancer are present (unopposed estrogen exposure, PCOS, tamoxifen therapy, anovulation, nulliparity, diabetes, hypertension) 4
  • Persistent or recurrent undiagnosed bleeding even with normal initial evaluation 4, 5

Special Considerations

• If TVUS cannot adequately visualize the endometrium due to patient factors (body habitus, uterine position) or pathology (adenomyosis, leiomyomas), proceed to endometrial sampling 1
• Saline infusion sonohysterography (SIS) should be considered when:
  • TVUS shows an inadequate endometrial echo
  • Endometrial echo is not sufficiently thin
  • Focal lesions are suspected 6, 1
• SIS has high sensitivity (96-100%) and negative predictive value (94-100%) for assessing uterine and endometrial pathology 1

Limitations and Pitfalls

• TVUS cannot always reliably distinguish between benign proliferation, hyperplasia, polyps, and cancer 2
• Endometrial biopsy has a false-negative rate of approximately 10%, requiring follow-up if symptoms persist despite negative results 4, 5
• Blind endometrial sampling may miss focal lesions, so hysteroscopy with directed biopsy should be considered when:
  • TVUS or SIS suggests focal pathology
  • Symptoms persist despite normal blind sampling 1, 5
• TVUS is not typically recommended in virgins; transabdominal ultrasound can be used instead, though it has lower sensitivity 1

High-Risk Populations

• Women with Lynch syndrome should be offered annual endometrial biopsy beginning at age 30-35 years due to their 30-60% lifetime risk of endometrial cancer 1, 4
• TVUS has limited value in screening for endometrial cancer in premenopausal women with Lynch syndrome but may help evaluate the ovaries 1

Algorithm for Abnormal Uterine Bleeding Evaluation

1. Initial assessment: TVUS to evaluate endometrial thickness and structural abnormalities 1
2. If TVUS shows endometrial thickness <3mm (postmenopausal) or <5mm (premenopausal), with no focal lesions → observation may be appropriate 4, 3
3. If TVUS shows increased endometrial thickness or focal lesions → proceed to endometrial biopsy 4, 3
4. If symptoms persist despite normal TVUS and biopsy → consider hysteroscopy with directed biopsy 1, 7