Should ureteric assessment be included in the transvaginal ultrasound assessment for women with suspected endometriosis?

Urinary tract endometriosis has been reported to affect 1% of women with pelvic endometriosis, and approximately 10%of these women will have ureteric endometriosis. In a recent study, which included 627 women with histologically confirmed deep infiltrating endometriosis (DIE), severe ureteric endometriosis (i.e. ureteric stenosis resulting in hydronephrosis) was found in 4.6% of women. This study also found a higher rate of intrinsic endometriosis (i.e. DIE infiltration of the ureteral muscularis) than had been previously reported in the literature (38% vs. 20%). More than 50% of women with ureteric endometriosis will have non‐specific symptoms or be completely asymptomatic. The inability to identify these women early in the disease process is a major concern, as ureteric endometriosis can cause ureteric obstruction with hydronephrosis and eventually lead to renal failure. An additional consideration is the complex surgical management required for women with obstructive ureteric disease.

With the evolution of transvaginal sonography (TVS) imaging for the detection of DIE, women with suspected endometriosis and/or chronic pelvic pain are recommended to undergo systematic evaluation for bowel and non‐bowel DIE (i.e. bladder, uterosacral ligaments (USL)). Ureteric endometriosis is known to occur in the presence of endometriomas and other DIE lesions, with up to 97% of women with severe ureteric endometriosis having associated bowel endometriosis. The TVS assessment of the pelvic sidewall/periureteric area has been largely overlooked in the literature, which is likely due to the fact that visualisation of the ureters is an advanced ultrasound skill that is practiced by few sonologists.

In a recent publication by Pateman, et al., the researchers were able to identify the pelvic segments of normal ureters and measure the median diameter of ureters for 245 women, concluding that visualisation of the ureters could be integrated into the routine pelvic ultrasound examination for women with pelvic pain or suspected pelvic endometriosis. Exacoustos, et al. also conducted a study which included the TVS examination of the right and left pelvic ureter in 100 women with suspected endometriosis and found the sensitivity, specificity, PPV and NPV for ureteric endometriosis to be 62 and 69%, 98 and 96%, 80 and 73%, 95 and 94%, respectively. The researchers concluded that intrinsic endometriosis affecting the ureter was low (2.8% in this study sample) and that extrinsic disease constricting the ureter should be suspected in cases of parametrial and USL involvement. The fact that TVS showed a high PPV and specificity for ureteral location of the disease was attributed to the point that is easier to follow the normal ureter course in the pelvis without endometriotic lesions.

There does not appear to be a consensus regarding whether routine ultrasound assessment of the kidneys and/or ureters should be performed for women with suspected endometriosis. Indeed, the incidence of obstructive ureteric endometriosis is low and its silent presentation has made it difficult to identify these women pre‐operatively. Ultrasound features such as endometrioma and pelvic DIE occur frequently with ureteric endometriosis, therefore, renal and ureteric ultrasound assessment could be reserved for women with endometrioma/pelvic DIE detected at TVS. The development of specialised ultrasound training programs for the detection of DIE has changed the way in which we manage women with potential bowel DIE. We believe that pattern recognition by experienced operators for ureteric endometriosis may not only expedite the early diagnosis of this serious condition, but also allow for improved surgical planning and the prevention of irreversible renal consequences.