Endometriosis : a radiological review

Abstract

Endometriosis is a chronic gynaecological disorder primarily affecting women of reproductive age of uncertain aetiology. It is pathologically defined as the presence of functioning endometrium outside the uterus. Its physical presentation, clinical course and radiological appearances are varied. Endometriosis most commonly affects the ovaries and adjacent pelvic structures. Deposits on serosal surfaces lead to fibrosis and subsequent adhesions, strictures and tubal obstruction. Ultrasound is useful in identifying and characterising adnexal endometriotic cysts by their characteristic ultrasonographic appearance including low level internal echoes. X-ray computed tomography plays a limited role in identification of an ovarian mass and sequelae of endometriosis such as bowel obstruction, pelvic effusions, ureteric obstruction and haemorrhagic pleural effusions. Magnetic resonance imaging plays an important role in characterising and quantifying adnexal and extra adnexal disease. It is particularly useful in identifying small deposits on the serosal surfaces of small and large bowel. These may appear as fibrotic linear areas or spiculate foci. Disease affecting the uterine ligaments and tubes often leads to obstructive hydrosalpinx with resultant sub fertility. Involvement of the urinary bladder and distal ureters may lead to stricturing and subsequent hydronephrosis. MRI is useful in characterising endometriotic deposits in unusual locations such as subcutaneous tissues and in relation to surgical scars. Disease of the pelvic side wall may involve the sacral plexus with resultant deep pelvic and lower limb referred pain. These sites are amenable to MRI investigation. MRI is playing an increasingly important role in the pre operative staging of endometriosis, enabling more focal targeting of disease during laparoscopy.