Histologic dating of the endometrium: Accuracy, reproducibility, and practical value

The continued use of the endometrial biopsy for the diagnosis of luteal phase defects (LPDs) and in the general evaluation of the infertile couple is based largely on tradition, the absence of a clearly superior diagnostic modality, the absence of studies that have either validated or repudiated its efficacy with certainty, its ability to assess the endometrial response irrespective of endogenous progesterone levels, its ability to monitor the endometrial response to hormonal therapy in fertility treatments, and, finally, its ability to exclude other intrinsic endometrial anomalies that may be detrimental to the implantation of the conceptus, such as chronic endometritis or neoplasia. However, the intra- and interobserver variability inherent in dating the product of the endometrial biopsy-the endometrium-has led to the current situation, in which, in approximately 20% of cases, variability attributed to the pathologist alone is determinant of whether a given biopsy in "in phase" or out of phase (ie, an assigned postovulatory date that is at least 2 days behind the chronologic date). Thus, studies that clearly delineate which histologic parameters serve as the greatest source of disagreement for pathologists provide a valuable framework for further refinement of the criteria for endometrial dating. Meanwhile, continued use of the criteria of Noyes et al for endometrial dating is recommended until more precise modalities for assessing the adequacy of endometrial maturation are available.