MR imaging of bladder and vesicouterine pouch endometriosis

Clinical History

A 40 year old female patient presented with severe pain during micturition beginning almost 10 days prior to her menstrual period and also during her periods for the past 6 months. She also had urgency and increased frequency of urination. She had normal vaginal delivery with no history of surgery.

Imaging Findings

An irregular T2W hyperintense cystic area showing T1W fat sat hyperintense foci suggestive of haemorrhage was seen anterior to the body of the uterus in the vesicouterine pouch and intimately related to and involving the posterior superior aspect of the urinary bladder. Associated significant focal asymmetric thickening of the bladder wall was seen with a T2W hyperintense cystic area and haemorrhagic foci. These findings were suggestive of endometriosis of the vesicouterine pouch with involvement of the urinary bladder wall.

Discussion

Endometriosis is defined as the presence of functional endometrial tissue outside the uterine cavity. Deep pelvic endometriosis is defined as an endometriotic lesion with subperitoneal invasion of about 5 mm or more. The sites commonly affected are the retrocervical region, uterosacral ligaments, rectum, rectovaginal septum, vagina, urinary tract and other extraperitoneal pelvic sites [1].
The incidence of endometriotic lesions of the urinary tract is about 20% with the urinary bladder being the most commonly involved site. Vesical endometriosis can occur spontaneously or due to previous caesarian surgery [2].The metastatic theory is the most widely accepted theory with endometriosis resulting from the metastatic implantation of endometrial tissue from retrograde menstruation and then deposited on the peritoneal
surface or pelvic organs [3].
Patients usually present with frequency, urgency, dysuria, hematuria and tenesmus occurring prior to and or during the menstrual cycle. Symptoms can mimic cystitis [4]. A transabdominal or transvaginal ultrasound can show focal or diffuse bladder wall thickening. However MRI is essential and superior in the diagnosis of infiltrating extraperitoneal endometriosis and identification of lesions hidden by adhesions and in evaluation of subperitoneal lesion extension. Our patient was referred for MRI due to high clinical suspicion of endometriosis.
The classical imaging findings are T2W hypointense nodules in the vesicouterine pouch adherent to the anterior uterine surface with associated obliteration of the anterior cul-de-sac. Focal or diffuse thickening of the bladder wall will be seen on T2-weighted images either confined to the serosa or replacing the normal signal of the muscular layer and extending into the lumen of the urinary bladder. Multiple T2W hyperintense cystic areas and T1W fat saturated hyperintense hemorrhagic foci are also seen [1]. Recent studies have also shown the value of diffusion-weighted imaging in localising the endometriotic implants [5]. In our patient, the lesion appeared hyperintense on DWI images however, no corresponding restriction was noted on ADC map.
Treatment varies with severity, patients age and fertility preferences. Hormonal therapy is the mainstay of treatment with laparoscopy/cystoscopy and partial cystectomy being the other options in severe cases [6, 7]. Cystoscopy performed on our patient revealed a small bullous lesion with haemorrhagic areas in the dome of the urinary bladder.
MRI plays an important role in the diagnosis of deep pelvic endometriosis, providing accurate information and extent of the endometriosis implants, helpful in good pre-surgery planning, especially of the lesions involving both bowel and bladder surface and rectouterine ligaments.

Differential Diagnosis List

Final Diagnosis

Bladder and vesicouterine pouch endometriosis

URL:	https://www.eurorad.org/case/12682
DOI:	10.1594/EURORAD/CASE.12682
ISSN:	1563-4086