Pictorial review Imaging features of pelvic endometriosis

Although laparoscopy remains the investigation of choice in the diagnosis of endometriosis, imaging does play a significant role in its management. This pictorial review concentrates on the techniques used in the imaging of endometriosis. Endometriosis is characterized by the presence of ectopic endometrial tissue outside the uterus. Originally described by Von Rokitansky in 1860 (1), endometriosis occurs in up to 10% of women and is found almost exclusively in women of reproductive age. The exact pathogenesis is unclear but theories include: (1) metaplastic transformation of peritoneal epithelium into functional endometrium; (2) peritoneal seeding by way of retrograde menstruation; and (3) endometrium in the peritoneal cavity from retro- grade flow activates differentiation of mesenchy- mal cells (induction theory) (2). The commonest sites for endometrial implanta- tion within the pelvis are the ovaries, broad and round ligaments, Fallopian tubes, cervix, vagina and pouch of Douglas. The gastrointestinal tract may be involved in about 12% of cases and the urinary tract is affected in about 1%. Symptoms include pelvic pain, dysmenorrhoea and dyspar- unia. 30-40% of patients suffer with infertility (3). The hallmarks of endometriosis are endome- triomas (multiloculated cystic lesions), peritoneal implants (solid endometrial tissue) and adhesions.