Endometriosis and Ultrasound Diagnosis

Frederick R. Jelovsek MD

Do you need to have a surgical procedure in order to diagnose endometriosis? The answer has always been yes -- diagnostic laparoscopy. Endometriosis can be suspected from symptoms such as the new occurrence of menstrual cramps, or painful sexual relations or even on pelvic exam, but the definitive diagnosis has been surgical observation and biopsies. A recent article, Fedele L, et al. Transrectal ultrasonography in the assessment of rectovaginal endometriosis. Obstet Gynecol 1998; 91:444-8, has suggested a new imaging method to make the diagnosis in some cases.

Pelvic and/or back pain, pain with deep penetration during intercourse and rectal bleeding during menses may be signs of endometriosis that has grown deeply into the wall between the vagina and rectum. It occurs relatively infrequently, but when it does, it may be missed at surgical exploration. It can also be missed using traditional diagnostic studies such as transabdominal or transvaginal ultrasound, rectosigmoidoscopy, computerized tomography (CAT scan) or magnetic resonance imaging (MRI).

Fedele and others from the University of Verona, Italy, looked at 140 patients scheduled for surgery for possible endometriosis, using rectal ultrasound. This is a test using sound waves in which a probe about the size of a large finger is put into the rectum. The study should take less than about 5 minutes. The doctors look for areas between the rectum and the vagina and cervix that represent nodules of endometriosis. All patients had the ultrasound study within one week of their surgery. About one fourth of the patients 34/140 had surgical evidence of rectovaginal endometriosis and ultrasound had correctly diagnosed 33 of the 34 patients (sensitivity 97%). Of the other 106 patients, 15 had no evidence of endometriosis and 91 had superficial abdominal lining or ovarian endometriosis but not infiltrating into the rectovaginal septum. The rectal ultrasound was negative in 102 of those 106 patients (specificity 96.2%). As tests go this is fairly accurate.

If these studies can be repeated by other investigators, this may become a more common diagnostic test when a physician suspects endometriosis.