Threshold for endometrial sampling among postmenopausal patients without vaginal bleeding.

Objective: To provide an optimum threshold for endometrial biopsy sampling among postmenopausal women without vaginal bleeding and an incidentally-found endometrial lining of above 4mm.

Methods: A cohort of postmenopausal women (aged ≥50 years) who underwent pelvic ultrasonography at a tertiary US hospital for indications other than vaginal bleeding was retrospectively evaluated. Women were included if they had an endometrial lining of above 4mm. Logistic regression was performed to determine the probability of endometrial carcinoma and atypical hyperplasia at each increasing millimeter of endometrial thickness from 4 to 20mm.

Results: Among 462 women, carcinoma was identified in 9 (1.9%) and atypical hyperplasia in 7 (1.5%). An endometrial thickness of or above 14 mm was significantly associated with atypical hyperplasia (odds ratio 4.29; 95% confidence interval 1.30-14.20; P=0.02), with a negative predictive value of 98.3%. A thickness of or above 15 mm was associated with carcinoma (odds ratio 4.53; 95% confidence interval 1.20-17.20; P=0.03), with a negative predictive value of 98.5% and a 0.06% risk of cancer.

Conclusion: Irrespective of conventional risk factors, an incidentally-found thickened endometrial lining of less than 15 mm might not warrant endometrial biopsy sampling among postmenopausal women without vaginal bleeding.