The role of peritoneal washings in the diagnosis of endometriosis.

Endometriosis, the presence of endometrial tissue outside the uterine corpus, is a common finding in reproductive age women. It is classically diagnosed based on the presence of at least two of the following elements: endometrial glands, endometrial stroma, and hemosiderin-laden macrophages (HLMs). Although a common finding in surgical pathology specimens at the time of gynecologic surgery, there is little literature on the role of pelvic washings in diagnosing endometriosis. Our study aimed to examine the characteristics of endometriosis in pelvic washings at the time of gynecologic surgery. We report nine cases of endometriosis diagnosed on pelvic washing. Two had a reported history of endometriosis. Four had endometriosis on the concurrent surgical pathology specimen. Liquid-based cytology was diagnostic of endometriosis in seven patients, including five with glandular cells and HLMs and two with glandular cells, HLMs, and endometrial stromal cells. Cell block was diagnostic of endometriosis in eight patients, including four cases with intact fragments of endometrial glands and stroma. Three cases showed glandular cells and HLMs, while one showed separate fragments of glandular cells and stromal cells. Pelvic washings increased the diagnostic yield for endometriosis at the time of gynecologic surgery, as only four out of nine cases had endometriosis diagnosed on surgical pathology. Cell block in particular aids in the diagnosis, since intact glandular and stromal fragments frequently can be identified.