Direct cytological sampling and examination of the endometrium is not generally practiced, which is surprising as the endometrium is exceedingly easy to sample. Over the years, as we gained more experience with specimen acquisition, processing, and interpretation, we found endometrial cytology to be an effective method both for ensuring endometrial normalcy and for discovering and diagnosing malignant and premalignant states. In comparing endometrial cytology to biopsy, we found that, among samples obtained by individuals experienced in specimen collection, cytology outperforms outpatient biopsy in terms of tolerance of the procedure by the patient, adequacy of the sample among postmenopausal women, and detection of occult neoplasms.
By using the Tao brush (also known as the Indiana University Medical Center endometrial sampler) and devising a technical strategy to ensure the simultaneous creation of cell blocks and cytological samples from a single collection, we moved our appreciation of endometrial brush collection into an arena whose significance equals other methods of specimen collection and interpretation. Cytology performs equally as well as biopsy in detecting hyperplasia and carcinoma. If nothing else, by reliably identifying benign normal endometrial states, it serves to confidently exclude more than 70% of women from unnecessary follow-up testing.
Because the Tao brush samples only the superficial 2 mm of the endometrium, the method is not designed to detect endometrial polyps, leiomyomas, stromal tumors, and tumors of the uterine wall musculature. However, it is useful for detecting benign estrogen-excess states such as disordered proliferation and various degrees of benign hyperplasia and for separating these from neoplastic states such as endometrial intraepithelial neoplasm (EIN), endometrial gland dysplasia (EmGD), and cancer. Nonetheless, it cannot always subclassify benign hyperplastic states of the endometrium without the aid of cell blocks.