Liquid-based cytology represents an opportunity to re-evaluate endometrial cytology. We evaluated the accuracy of liquid-based endometrial cytology as compared to biopsy in 670 women scheduled for histeroscopy because of thickened endometrium (>4 mm), as evaluated by transvaginal sonography. Endometrial biopsy detected pathology in 41 (6%) of cases (21 of which were adenocarcinomas). Cytologic study found pathology in 62 (9%) cases (19 of which were adenocarcinomas). Two hundred ninety-one biopsies (43%) and 28 (4%) cytologies were inadequate. The sensitivity and the specificity were estimated, respectively, at 95% and 98%; the positive and negative predictive values were estimated, respectively, at 83% and 99%. Cytology provided sufficient material more often than biopsy (P < 0.01). We consider endometrial cytology an efficacious diagnostic opportunity. It could be usefully applied in association with transvaginal sonography. The combination of these procedures might reduce more invasive and expensive diagnostic procedures. Diagn. Cytopathol. 2007;35:398-402. ' 2007 Wiley-Liss, Inc.Key Words: thin-layer; liquid-based; endometrial cytology; endometrial adenocarcinoma; endometrial hyperplasia Endometrial adenocarcinoma is the most common malignancy of the female genital tract. A significant increase in its frequency, both absolute and relative, has been observed during the last decades. This increase is considered the consequence of the extended life expectancy of women, the increase in the incidence of risk factors, and of the reduction of invasive cervical carcinomas. Nowadays, more than 1 in 20 female cancers in Europe are of the endometrium. [1][2][3][4][5][6][7][8][9][10] Contrary to cervical carcinoma, no screening programs have been organized for the early detection of endometrial adenocarcinoma. The lack of screening programs may be related to the precocious presenting symptoms and to the relative good prognosis of the majority of endometrial adenocarcinomas. Early abnormal uterine bleeding, the commonest presenting symptom for the 95% of women, allows diagnosis at stage I in 73% of cases. 11 Moreover, there has not been an endometrial test comparable to cervicovaginal cytology for diagnostic reliability, tolerability, and low cost.Several diagnostic procedures are used for investigating the endometrium, but there is no common agreement for the optimum approach in each circumstance (i.e. symptomatic vs. asymptomatic; with risk factors vs. without risk factors).Endometrial cytology has been hampered in its dissemination by the difficulty in its interpretation due to the common presence of excess blood and overlapping cells. Liquid-based cytology represents an opportunity to reexamine endometrial cytology. We conducted the current study to correlate the results of liquid-based endometrial cytology with the results of endometrial biopsy in a group of 670 women scheduled for hysteroscopy because of thick endometrium (>4 mm), as evaluated by transvaginal sonography (TVS). Our purpose was preliminarily to asce...