Postmenopausal Bleeding (PMB)

Etiology and Frequency

• Berek & Novak's Gynecology, p. 478

• Endometrial atrophy is the most common endometrial finding overall, accounting for 60-80% of cases. Women with atrophic endometrium are typically menopausal for about 10 years.
• Uterine leiomyomas should never be accepted as a cause of PMB - this is a diagnosis of exclusion.
• Traumatic bleeding from atrophic vagina accounts for up to 15% of all causes.
• Endometrial cancer: 90% of patients with endometrial cancer present with postmenopausal bleeding, but less than 10-15% of PMB overall represents cancer.
• Berek & Novak's Gynecology, p. 2151

Risk Factors for Malignancy

• Obesity (excess peripheral estrogen conversion)
• Unopposed exogenous estrogen therapy (risk 4-8x higher; increases with dose and duration)
• Tamoxifen use (associated with endometrial polyps and malignancy)
• Hypertension (associated with malignant polyps)
• Estrogen-secreting ovarian tumor
• Familial hereditary cancer syndromes (Lynch syndrome)

Evaluation

History and Physical

• Full pelvic examination to detect local lesions
• Cervical cytology (Pap smear) - essential, though only 30-50% of endometrial cancers show abnormal results
• Assess for non-genital sources: test urine and stool for blood
• Inspect vulva, vagina, cervix for visible lesions - biopsy any grossly visible cervical lesion

Transvaginal Ultrasound (TVUS)

• First-line imaging investigation
• Endometrial thickness (ET) ≤4 mm correlates with low risk of malignancy - endometrial sampling may be deferred
• ET >4 mm requires endometrial biopsy
• Important caveat: Recent data show the ≤4 mm cutoff may under-diagnose endometrial cancer in Black patients
• Sonohysterography (saline infusion) is a useful adjunct for identifying polyps
• Sabiston Textbook of Surgery, p. 2795

Endometrial Sampling

• ET >4 mm on TVUS
• Suspected focal lesion on imaging
• Difficulty visualizing the endometrium
• Persistent bleeding despite normal ultrasound (even with ET ≤4 mm)
• Any unexpected bleeding on HRT

1. Office endometrial aspiration biopsy - first-line; 90-98% diagnostic accuracy vs. D&C; adequate tissue in >95% of cases
2. Hysteroscopy + D&C - reserved for: cervical stenosis preventing office biopsy, bleeding recurrence after negative biopsy, inadequate specimen

• Hysteroscopy is more accurate than biopsy alone for identifying polyps and submucous myomas

Endometrial Hyperplasia - Classification

• 40-50% of women with EIN/atypical hyperplasia have concurrent carcinoma
• Risk of progression: ~30% for atypical/EIN vs. low risk for hyperplasia without atypia
• Hysterectomy is the definitive treatment for EIN in postmenopausal women
• Berek & Novak's Gynecology, p. 481-482

Management by Cause

Special Situations

• Women on continuous combined HRT may have irregular unpredictable bleeding for the first several months - low risk of hyperplasia/neoplasia
• Women on sequential HRT (progestin given cyclically) may have expected withdrawal bleeds; any significant change (absence of expected bleed followed by resumption, markedly increased flow) warrants endometrial sampling
• Missed doses causing irregular bleeding are benign but should be distinguished from pathological causes

• Associated with endometrial polyps with cystic glandular dilation, stromal condensation, and squamous metaplasia
• Endometrial malignancy can also occur - all bleeding requires evaluation
• Berek & Novak's Gynecology, p. 480

• May prevent bleeding despite endometrial pathology
• May result in hematometra or pyometra (purulent vaginal discharge) - associated with poor prognosis when due to underlying cancer

Key Clinical Pearls

1. Any PMB (even "spotting") = malignancy must be excluded before attributing to benign cause
2. 10-20% of all PMB is caused by malignancy
3. Normal TVUS (ET ≤4 mm) does not eliminate the need for biopsy if bleeding persists
4. Pap smear is inadequate to rule out endometrial cancer
5. Fibroids are never the explanation for PMB
6. The threshold of ET ≤4 mm has known racial disparities in sensitivity