Study on the morphology and reproducibility of the diagnosis of endometrial lesions utilizing liquid-based cytology.

Background: The objective of the current study was to determine the diagnostic cytomorphologic criteria for liquid-based cytology and to evaluate the reproducibility and usefulness of the cytologic diagnosis in endometrial lesions.

Methods: A total of 162 direct endometrial samplings taken from postmenopausal women were evaluated by 2 skilled cytopathologists in endometrial cytology. The cytologic diagnosis was made according to the 1994 classification scheme of the World Health Organization. After establishment of the criteria, three additional cytopathologists without any experience in liquid-based endometrial cytology examined the same cases to determine interobserver variability. The intraobserver variability also was evaluated by all the observers.

Results: The cytomorphologic criteria were established in the following four diagnostic categories: atrophic endometrium, hyperplasia without atypia, hyperplasia with atypia, and adenocarcinoma. The overall interobserver agreement was nearly perfect with a kappa value of 0.89 during the checking round and ranged from moderate to substantial with kappa values of 0.48-0.80, respectively, in the other diagnostic rounds (P < 0.0001); hyperplasia with atypia was found to be the most difficult category to identify correctly. Furthermore, the intraobserver agreement ranged from substantial to perfect with kappa values of 0.61-1.00 in all diagnostic rounds (P < 0.0001).

Conclusions: Liquid-based cytology allows for standardized and reproducible endometrial preparations, which in turn allows the application of common diagnostic criteria among cytopathologists. Furthermore, liquid-based cytology in combination with endometrial sampling could be a useful tool for the outpatient diagnosis of endometrial lesions, which could reduce unnecessary curettage.