Evaluation of the impact of intraobserver variability on endometrial dating and the diagnosis of luteal phase defects

Objective: To determine the magnitude of intraobserver variation in dating endometrial biopsies and its impact on clinical management. Design: Blinded histopathologic interpretation of endometrial biopsy specimens 1 year apart by five pathologists. Setting: Large military tertiary care center. Patients: Endometrial biopsy specimens from 51 patients undergoing evaluation for potential luteal phase defects. Interventions: None. Main Outcome Measures: Calculation of the magnitude of the individual and overall intraobserver variation in endometrial dating for the five pathologists and estimation of its potential impact on clinical management. Results: The intraobserver variation was 0.69 ± 0.05 days (means ± SE). There was no significant difference in the magnitude of the variation for 1-day or 2-day dating ranges. The theoretical probability of altering clinical management by having the same pathologist redate a given specimen ranged from 15% to 28%. Conclusion: Histologic dating of endometrial biopsies is subject to a small but highly clinically significant intraobserver variability that may have a major impact on clinical management.