Factors attributing to the failure of endometrial sampling in women with postmenopausal bleeding.

Objective: To determine which doctor- and patient-related factors affect failure of outpatient endometrial sampling in women with postmenopausal bleeding, and to develop a multivariable prediction model to select women with a high probability of failed sampling.

Design: Prospective multicenter cohort study.

Setting: Three teaching hospitals in the Netherlands.

Population: Women presenting with postmenopausal bleeding with an indication for endometrial sampling.

Methods: Multivariable logistic regression was performed to evaluate the impact of doctor's training level and patient's characteristics on failure of sampling.

Main Outcome Measures: Failure of endometrial sampling, classified as technical failure or insufficient tissue for diagnosis.

Results: In 74 (20.8%) of the 356 included women, sampling technically failed, and in 84 (29.8%) the amount of tissue was insufficient for diagnosis. Nulliparity [odds ratio (OR) 3.8, 95% confidence interval (CI) 1.8-7.9] and advanced age (OR 1.03 per year, 95% CI 1.00-1.06) were associated with technical failure. Advanced age was associated with insufficient sampling (OR 1.04 per year, 95% CI 1.01-1.07), and endometrial thickness >12 mm decreased the chance of insufficient sampling (OR 0.3, 95%CI 0.1-0.8). The prediction model for total failure had an area under the ROC curve of 0.64 (95% CI 0.58-0.70).

Conclusions: In women with postmenopausal bleeding, the failure rate of endometrial sampling is relatively high and is associated with nulliparity and advanced age. Endometrial thickness >12 mm decreased the chance of failure. A multivariable prediction model for total failure based on patient characteristics has a moderate capacity to discriminate between women at high or low risk of failure.