Peritoneal endometriosis: scanning electron microscopy and histology of minimal pelvic endometriotic lesions.

In 36 patients with laparoscopically diagnosed endometriosis, biopsies were taken from different areas of the pelvic peritoneum bearing foci of endometriosis. The biopsies were studied by scanning electron microscopy and by light microscopy. Combined use of these techniques resulted in the differentiation of three topographically and morphologically different types of endometriotic lesions: intraperitoneal endometriotic polyps with no glandular openings but associated with deeper endometriotic glands and stroma; intraperitoneal endometriotic foci with surface epithelium, glands, and stroma; and retroperitoneal small lesions with few glands and scant stroma. The morphologic features of endometriotic foci indicate that they do not follow the typical cyclic changes described for the uterine endometrium. Our microanatomic characterization of endometriosis is discussed in relation to the conflicting data concerning peritoneal fluid constituents and infertility in patients with minimal endometriotic lesions.