A 26-year-old nulliparous lady presented with a history of intermittent episodes of left lower quadrant abdominal pain for 3 months. Her menstrual cycles were normal. She had no past history of surgical intervention or pelvic infection. About 9 months ago, she had tuberculosis of D3, D5 spine, and successfully completed anti-tuberculous therapy. Her general and pelvic examination was normal. Contrast enhanced computerized tomography (CECT) imaging of the abdomen and pelvis [Figure 1(a)] and isotope renogram revealed poorly functioning left kidney (split renal function 21%) with hydroureteronephrosis due to left mid-ureteric stricture at S3 vertebra level [Figure 1(b)]. Tuberculous ureteric stricture was suspected. Left retrograde pyelography (RGP) revealed a passable 1.5 cm stricture in mid-ureter [Figure 2(a)]. The stricture segment was dilated with a Cook  ureteroscopic balloon dilator [Figure 2(b)] followed by ureteroscopy which showed a polypoidal mass of 7 mm in the area of stricture [Figure 2(c)]. Cold cup biopsy of the lesion was done and a 6 Fr 26 cm silicone DJ stent was placed. Histopathology of the biopsy revealed endometrial glands with rich vascularity [Figure 3(a)]. Further immunohistochemical studies with special stains revealed estrogen and progesterone receptor positivity in epithelial layer and CD10 positivity in stromal tissue [Figure 3(b-d)]. She was started on oral medroxy progesterone and at follow-up of 6 months, she is doing well.
Endometriosis affecting the ureter is usually extrinsic and unilateral (80%). Theories proposed for pathogenesis are:
Menstrual reflux theory - Refluxing endometrial cells are poorly cleared by the peritoneal scavenging system
Embryonal theory - Ureter and endometrium shares the same embryological development from the Mullerian duct remnants, hence the endometrial rests can develop in the ureter
Loaded sigmoid colon creating hidden microenvironment resulting in asymmetric involvement of left distal ureter
Hematogenous and retrograde lymphatic seeding theory.
Differential diagnosis of isolated ureteral endometriosis will include amyloidosis, fibroepithelial polyp, sloughed papilla, and transitional cell carcinoma. Tuberculous strictures involving the ureter are generally multifocal and diffuse, and rarely present as an isolated short segment stricture. CECT urography may be required to rule out extrinsic compression of ureter, while magnetic resonance imaging (MRI) may be beneficial in ruling out pelvic endometriosis. Diagnostic laparoscopy is still the gold standard in pelvic endometriosis. As the conventional imaging is less beneficial in poorly functioning kidney, ureteroscopy with biopsy will be of more value as in our case. Management of ureteric endometriosis includes double J stenting, ureterolysis, ureteric resection, and anastomosis or ureteric reimplantation. Despite all the surgical ureteric intervention, progressive renal dysfunction occurs in 40%. Endometriosis especially in women of childbearing age group should be considered as differential diagnosis in ureteric obstruction as the renal unit can be salvaged by endoscopic intervention at the earlier stage of the disease course.
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