When is hysteroscopy indicated versus endometrial biopsy versus pelvic ultrasound for abnormal uterine bleeding?

Diagnostic Approach for Abnormal Uterine Bleeding

For patients with abnormal uterine bleeding, combined transabdominal and transvaginal ultrasound of the pelvis with Doppler is the most appropriate initial imaging study, followed by endometrial biopsy when indicated, with hysteroscopy reserved for specific scenarios requiring direct visualization or targeted sampling. 1

Initial Evaluation: Pelvic Ultrasound

• Combined transabdominal and transvaginal ultrasound (TVUS) with Doppler is the first-line imaging modality for all women with abnormal uterine bleeding 1, 2
• TVUS allows assessment of:
  • Endometrial thickness and echogenicity
  • Structural causes (polyps, fibroids, adenomyosis)
  • Adnexal pathology 1
• In postmenopausal women, endometrial thickness ≤4 mm has a negative predictive value for endometrial cancer approaching 100%, often eliminating the need for biopsy 3, 4
• In premenopausal women, no validated upper limit exists for endometrial thickness as it varies with menstrual cycle phase 1, 3
• Abnormal endometrial echogenicity or texture may indicate pathology regardless of thickness 1

When to Perform Endometrial Biopsy

• Postmenopausal women with:
  • Endometrial thickness >4 mm on TVUS
  • Irregular endometrial appearance regardless of thickness 3, 4, 5
• Premenopausal women with:
  • Risk factors for endometrial cancer
  • Persistent abnormal bleeding despite normal TVUS
  • Abnormal endometrial appearance on TVUS 1

When to Perform Sonohysterography

• When initial TVUS demonstrates a focal endometrial abnormality 1, 6
• To differentiate between diffuse endometrial thickening and focal lesions 1
• When polyps are suspected on initial ultrasound 1
• To guide the selection of appropriate biopsy technique:
  • Diffuse thickening → blind endometrial biopsy
  • Focal thickening → hysteroscopic biopsy 4, 7

When to Perform Hysteroscopy

• When sonohysterography identifies focal lesions requiring targeted biopsy 7, 5
• When endometrial sampling is unsuccessful or inadequate 5, 6
• For direct visualization and biopsy of suspected endometrial polyps 1, 5
• For removal of intracavitary lesions (polyps, submucous fibroids) 5, 6

When to Consider MRI

• When the uterus is incompletely visualized with ultrasound 1
• To differentiate between adenomyosis and leiomyomas when ultrasound is inconclusive 1
• For assessment of suspected malignancy (endometrial cancer, leiomyosarcoma) 1
• For preoperative planning before uterine-sparing procedures 1

Common Pitfalls to Avoid

• Relying solely on endometrial thickness in premenopausal women 1, 3
• Failing to perform endometrial biopsy in postmenopausal women with endometrial thickness >4 mm 3, 4
• Not considering sonohysterography when focal lesions are suspected 1, 4
• Incorrect measurement technique on TVUS (oblique plane, including myometrium) 3
• Overlooking adenomyosis as a cause of abnormal bleeding, especially when coexisting with leiomyomas 1

Special Considerations

• In women with high risk for endometrial cancer (Lynch syndrome, tamoxifen use, obesity), lower threshold for endometrial biopsy regardless of imaging findings 1
• Detection of adenomyosis on TVUS may be limited when leiomyomas are present (sensitivity drops from 97.8% to 33.3%) 1
• Diffusion-weighted imaging should be included in MRI protocols to improve diagnostic accuracy for uterine pathology 1