Ureteral Endometriosis Found in One Fifth of Deep Infiltrating Endometriosis Cohort

Ureteral endometriosis, a rare but potentially severe manifestation of deep infiltrating endometriosis, affected 171 of 838 patients — 20.4 percent — in a large retrospective cohort from Renji Hospital, Shanghai Jiao Tong University School of Medicine. The study, published in BMC Women’s Health, reviewed patients with histologically confirmed deep infiltrating endometriosis treated between January 2014 and November 2025 and set out to characterize the clinical and surgical features of ureteral involvement and to identify factors associated with it and with hydroureteronephrosis, the swelling of the ureter and kidney caused by urine buildup.

The condition can lead to irreversible renal impairment, which is why the researchers emphasized early detection. In the cohort, ureteral endometriosis was predominantly unilateral, affecting one side in 143 of 171 patients, or 83.6 percent. Left-sided involvement occurred in 83 patients (48.5 percent) and right-sided involvement in 60 patients (35.1 percent). Hydroureteronephrosis was present in 45 percent of patients with ureteral endometriosis, underscoring how often the disease compromises urinary drainage by the time it is recognized.

Multivariate logistic regression analysis identified several factors independently associated with ureteral endometriosis. Each additional year of age raised the odds modestly (odds ratio 1.04, 95 percent confidence interval 1.01–1.07, p = 0.002). A history of endometriosis-related surgery nearly doubled the odds (OR 1.71, 95 percent CI 1.13–2.57, p = 0.011), and this was reflected in the raw comparison: 30.4 percent of patients with ureteral involvement had prior endometriosis-related surgery versus 18.6 percent of those without, a statistically significant difference (p < 0.001).

Symptoms and physical findings also carried weight. Low back soreness was associated with nearly fourfold higher odds (OR 3.86, 95 percent CI 2.39–6.24, p < 0.001), and urinary frequency with more than fourfold higher odds (OR 4.27, 95 percent CI 1.84–9.92, p < 0.001). On examination, uterosacral ligament nodules (OR 1.75, 95 percent CI 1.19–2.59, p = 0.005) and rectovaginal septum nodules (OR 3.25, 95 percent CI 1.15–9.16, p = 0.026) were each independently linked to ureteral involvement, suggesting that palpable nodularity in these posterior compartments should prompt attention to the urinary tract.

The severity of silent kidney damage emerged clearly from renal function testing. Among the 40 patients who underwent renal scintigraphy, 22 — 55 percent — had moderate-to-severe impairment of differential renal function in the hydroureteronephrotic kidney, and 7 patients, or 17.5 percent, had a nonfunctioning kidney. These figures illustrate the stakes of delayed diagnosis: by the time obstruction becomes apparent, a substantial share of affected kidneys may already have lost considerable function.

The study also distinguished intrinsic from extrinsic disease. Intrinsic ureteral endometriosis, in which endometrial tissue invades the ureteral wall itself, accounted for 8.8 percent of cases overall but was far more frequent among patients with hydroureteronephrosis than among those without — 18.2 percent versus 1.1 percent, a difference that was highly significant (P < 0.001). Hydroureteronephrosis was additionally associated with longer operative times and longer postoperative hospital stays, indicating that established urinary obstruction complicates surgery and recovery.

The authors concluded that ureteral endometriosis was frequently observed in this selected surgical cohort and was frequently associated with hydroureteronephrosis and renal impairment. Because symptoms may remain subtle even when hydroureteronephrosis is present, reliance on clinical presentation alone is insufficient for early detection. They argue that early recognition requires integration of clinical features, imaging, and multidisciplinary management to enable timely diagnosis and prevent irreversible renal damage.

Several caveats frame these findings. The study was retrospective and conducted at a single gynecologic oncology department, and its cohort consisted of surgically managed patients with histologically confirmed deep infiltrating endometriosis — a selected population that likely overrepresents severe disease compared with the broader population of people with endometriosis. The reported 20.4 percent prevalence of ureteral endometriosis therefore applies to this surgical cohort rather than to endometriosis in general. As an observational analysis, the identified associations — including age, prior surgery, symptoms, and nodule location — describe factors linked with ureteral involvement, not proven causes. Even so, the pattern is clinically coherent: posterior deep infiltrating lesions near the ureter, prior operations, and urinary or back symptoms clustered with ureteral disease and with kidney obstruction, giving clinicians a concrete profile of whom to image and evaluate more closely.

For patients and clinicians, the practical message is that deep infiltrating endometriosis is not only a pelvic pain condition. In this cohort, one in five surgical patients had ureteral involvement, nearly half of those had obstructive kidney swelling, and among those tested, more than half showed moderate-to-severe loss of differential renal function in the affected kidney. Combining symptom assessment, pelvic examination for characteristic nodules, and imaging appears central to catching ureteral endometriosis before the damage to the kidney becomes permanent.

Subject of Research: Clinical characteristics and risk factors of ureteral endometriosis in deep infiltrating endometriosis

Article Title: Clinical characteristics of ureteral endometriosis in patients with deep infiltrating endometriosis: a retrospective cohort study

Article References: Hu, Z., Zhao, X., Gu, Y., Liu, Q., Zhu, H., Li, P., Qiu, L., & Liu, K. (2026). Clinical characteristics of ureteral endometriosis in patients with deep infiltrating endometriosis: a retrospective cohort study. BMC Women's Health. https://doi.org/10.1186/s12905-026-05028-3

Image Credits: AI Generated

DOI: 10.1186/s12905-026-05028-3

Keywords: endometriosis, deep infiltrating endometriosis, ureteral endometriosis, hydroureteronephrosis, renal impairment, retrospective cohort, gynecology, renal scintigraphy, urinary obstruction, women's health, Clinical, characteristics