What is the initial management for a patient presenting with Abnormal Uterine Bleeding due to Endometrial causes (AUB-E)?

Initial Management of AUB-E (Abnormal Uterine Bleeding - Endometrial Causes)

For patients with AUB-E, endometrial tissue sampling is mandatory and should be performed immediately in any woman with risk factors for endometrial cancer, including age >45 years, postmenopausal status, obesity, diabetes, hypertension, unopposed estrogen exposure, tamoxifen use, or Lynch syndrome. 1

Diagnostic Algorithm

Step 1: Exclude Pregnancy and Assess Stability

• Test β-hCG in all reproductive-age women before proceeding with further evaluation 1
• Assess hemodynamic stability; urgent evaluation is needed if bleeding saturates a large pad/tampon hourly for ≥4 hours 1

Step 2: Initial Imaging - Transvaginal Ultrasound (TVUS)

• Combined transabdominal and transvaginal ultrasound with Doppler is the first-line imaging study to identify structural endometrial causes 1
• TVUS is the first-line screening test for endometrial cancer, particularly in postmenopausal bleeding 2

Critical thresholds for endometrial thickness:

• Postmenopausal women: Endometrial thickness ≥5 mm requires endometrial tissue sampling, as thickness ≥4 mm has nearly 100% negative predictive value for cancer 2
• Premenopausal women: No validated absolute upper limit exists; endometrial thickness is NOT a reliable indicator of pathology, as polyps or other pathology may be present even with thickness <5 mm 2

Step 3: Endometrial Sampling - Mandatory in High-Risk Patients

Endometrial biopsy is mandatory in the following scenarios:

• Age >45 years 1
• Postmenopausal status 1
• Obesity, diabetes, hypertension 1
• Unopposed estrogen exposure or tamoxifen use 1
• Lynch syndrome 1
• Perimenopausal women (lower threshold due to higher risk for endometrial hyperplasia/cancer) 1

Important caveat: Blind endometrial biopsies should no longer be performed as the sole diagnostic strategy in perimenopausal and postmenopausal women with AUB, as focal endometrial cancer can be missed 3

Step 4: Advanced Imaging When TVUS is Inconclusive

Saline Infusion Sonohysterography (SIS):

• Use when initial TVUS demonstrates a focal endometrial abnormality 2
• Has 96-100% sensitivity and can distinguish leiomyomas from polyps with 97% accuracy 1
• Sterile saline is the accepted standard endometrial contrast agent 2
• Critical limitation: Cannot distinguish between benign endometrial pathology and endometrial cancer with high certainty; endometrial sampling or hysteroscopy remains necessary 2

MRI Pelvis (with gadolinium-based IV contrast preferred):

• Consider when the uterus is incompletely visualized by ultrasound or findings are indeterminate 2
• Can identify endometrial cancer with sensitivity/specificity up to 79%/89% 2
• Diffusion-weighted sequences should be strongly considered 2
• Abnormal signal on diffusion-weighted images and irregularity of the endometrial-myometrial interface are the most helpful features in differentiating benign from malignant pathologies 2

Step 5: Hysteroscopy with Directed Biopsy - Gold Standard

• Hysteroscopy with directed biopsy is the gold standard approach for most accurate evaluation of endometrium to rule out focal endometrial cancer 3
• Recommended when sonohysterography or imaging shows suspected endometrial pathology 2
• A single-stop approach combining office hysteroscopy, directed biopsy for focal lesions, and vacuum sampling of normal-appearing endometrium is the most minimally invasive yet accurate approach 3

Medical Management After Diagnosis

Once malignancy is excluded, medical therapy is first-line treatment unless contraindicated or structural pathology requires surgery:

• Combined oral contraceptives are first-line for most patients with anovulatory bleeding 1
• Cyclic progestins are appropriate alternatives when estrogen is contraindicated 1
• Levonorgestrel-releasing intrauterine system is highly effective for anovulatory bleeding 1
• NSAIDs reduce bleeding by 20-50% and are most effective for ovulatory menorrhagia 1
• Tranexamic acid is a non-hormonal alternative that significantly reduces bleeding 1

Referral Indications

Refer to gynecology when:

• Endometrial sampling shows hyperplasia or malignancy 1
• Failed medical management 1
• Postmenopausal bleeding with endometrial thickness ≥4 mm 1

Common Pitfalls to Avoid

• Do not rely on endometrial thickness alone in premenopausal women - pathology can exist even with thin endometrium 2
• Do not perform blind D&C as sole diagnostic strategy - hysteroscopy with directed biopsy is superior for detecting focal lesions 3
• Do not assume sonohysterography can rule out malignancy - tissue diagnosis is always required when pathology is suspected 2
• Do not skip endometrial sampling in high-risk patients regardless of imaging findings 1