Urinary endometriosis: MR imaging appearance with surgical and histological correlations

The goals of the study were to describe the MR imaging features of endometriosis of the urinary tract and identify those that suggest intrinsic involvement of ureteric wall.

Thirty-five women with proven urinary tract endometriosis and who had preoperative MR imaging between 2001 and 2011 were included retrospectively. MR images were intrepreted by one junior and one senior radiologists. To characterize the intrinsic parietal involvement, the ureteric circumference involved by the lesion of endometriosis was noted.

Thirty-eight ureteric and 13 bladder lesions were analyzed. They were found in association in nine women. Ureteric lesions were bilateral in seven women. Of the 38 ureteric lesions, 27 were extrinsic and 11 intrinsic at histopathological analysis. Sixteen women with extrinsic lesions and 10 with intrinsic ones were correctly identified on MR imaging. When the ureter was included less than 360° in the lesion, extrinsic involvement was confirmed in 80% of cases.

MR imaging appears to be more sensitive (91%vs 82%) but less specific (59% vs 67%) than surgery for the diagnosis of intrinsic form of ureteric location.