Endometriosis is an aberrant growth of endometrium outside of the uterus, particularly in the dependent parts of the pelvis and in the ovaries. Its principal manifestations are chronic pain and infertility (eFigure 18–4). While retrograde menstruation is the most widely accepted cause, its pathogenesis and natural course are not fully understood. The overall prevalence in the United States is 6–10%.
Common sites of endometrial implants (endometriosis). (Reproduced, with permission, from Way LW [editor]. Current Surgical Diagnosis & Treatment, 10th ed. Originally published by Appleton & Lange. Copyright © 1994 by The McGraw-Hill Companies, Inc.)
The clinical manifestations of endometriosis are variable and unpredictable in both presentation and course. Dysmenorrhea, chronic pelvic pain, and dyspareunia, are among the well-recognized manifestations. A significant number of women with endometriosis, however, remain asymptomatic and most women with endometriosis have a normal pelvic examination. However, in some women, pelvic examination can disclose tender nodules in the cul-de-sac or rectovaginal septum, uterine retroversion with decreased uterine mobility, uterine tenderness, or adnexal mass or tenderness.
Endometriosis must be distinguished from pelvic inflammatory disease (PID), ovarian neoplasms, and uterine myomas. Bowel invasion by endometrial tissue may produce blood in the stool that must be distinguished from bowel neoplasm.
Imaging is useful mainly in the presence of a pelvic or adnexal mass. Transvaginal ultrasonography is the imaging modality of choice to detect the presence of deeply penetrating endometriosis of the rectum or rectovaginal septum; MRI should be reserved for equivocal cases of rectovaginal or bladder endometriosis (eFigures 18–5 and 18–6). A definitive diagnosis of endometriosis is made only by histology of lesions removed at surgery.
Endometrioma. A: Transverse sonogram through the pelvis in a patient with a left adnexal mass. A thick-walled left adnexal cystic mass (E) is seen adjacent to the uterus (U). B: Endovaginal sonogram of the left adnexa demonstrates a thick-walled cystic mass with calcification in the wall (C) and echoes (E) within the cyst. While neither of these findings is specific for an endometrioma, they are suggestive of that diagnosis. This patient had this mass for over 1 year without significant change and at laparoscopy was found to have an endometrioma. (Used, with permission, from Peter W. Callen, MD.)
Bilateral endometriomas. A: Sagittal sonogram identifies a sonolucent mass (M) superior to the uterus (U). B: The transverse scan confirms bilateral cystic masses (M). C: A sagittal MRI scan corresponds to the ultrasound examination ...