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.