Right-Sided Mixed Intrinsic and Extrinsic Ureteral Endometriosis Leading to a Nonfunctioning Kidney: A Case Report

Introduction

Endometriosis is an estrogen-dependent condition affecting approximately 10–15% of women of reproductive age and is characterized by the presence of functional endometrial tissue outside the uterine cavity. ¹ Involvement of the urinary tract is uncommon, accounting for less than 1% of cases, with the bladder being most frequently affected, followed by the ureter and kidney. Although rare, ureteral endometriosis is clinically significant because of its insidious course and potential to cause silent ureteral obstruction leading to irreversible renal damage.^2,3

Ureteral endometriosis most commonly involves the distal ureter and shows a marked left-sided predominance. Pathologically, it is classified as extrinsic or intrinsic depending on whether the endometriotic tissue surrounds or infiltrates the ureteral wall; mixed intrinsic and extrinsic involvement is particularly rare. ² We report a case of right-sided mixed ureteral endometriosis presenting with recurrent renal colic and progressing to a non-functioning kidney requiring nephroureterectomy.

Case Report

A 39-year-old woman with a medical history of supraventricular tachycardia and known endometriosis presented with severe right flank pain. She reported similar episodes in previous years. Initial computed tomography urography demonstrated right-sided uretero-hydronephrosis associated with a heterogeneous right latero-uterine cystic mass. Serum creatinine was within normal limits at 1.1 mg/dL.

An attempt at diagnostic ureteroscopy was made but could not be safely performed due to marked narrowing of the right ureteral meatus. Retrograde ureteropyelography was therefore performed and demonstrated distal right ureteral narrowing with upstream hydronephrosis (Figure 1A). A right double-J ureteral stent was placed to relieve the obstruction.

OPEN IN VIEWER

Figure 1.

Imaging findings of right distal ureteral obstruction secondary to suspected ureteral endometriosis. (A) Retrograde ureteropyelography showing distal right ureteral narrowing with upstream hydronephrosis. (B) Axial magnetic resonance imaging showing right uretero-hydronephrosis. (C) Sagittal pelvic magnetic resonance imaging showing a fibrotic lesion involving the distal right ureter. (D) Coronal pelvic magnetic resonance imaging showing a right adnexal endometrioma associated with distal ureteral involvement

Pelvic magnetic resonance imaging was performed and revealed a hemorrhagic cystic lesion of the right ovary measuring 3.5 cm, consistent with an endometrioma, in contact with a fibrotic stellate lesion encasing the distal right ureter and responsible for chronic uretero-hydronephrosis. Subsequently, renal scintigraphy demonstrated absence of tracer uptake and excretion in the right kidney, consistent with a non-functioning renal unit, with compensatory hypertrophy and preserved function of the left kidney. These findings suggested irreversible loss of right renal function. Renal scintigraphy was the first investigation to establish the absence of right renal function. Although a nonfunctioning right kidney had already been demonstrated, definitive surgery was performed after recurrent symptoms and subsequent imaging confirmed persistent progressive distal ureteral disease involving the ureteral orifice region.

The ureteral stent was removed two months later and cystoscopy performed at that time was unremarkable. Approximately one year later, the patient re-presented with recurrent right flank pain. Repeat pelvic magnetic resonance imaging demonstrated persistence of a right ovarian endometrioma measuring 3 cm, associated with subperitoneal endometriotic deposits and a stenosing fibrotic endometriotic nodule located approximately 3 cm from the distal right ureter, resulting in severe uretero-hydronephrosis and a distal ureteral mass. Given the distal ureteral mass-like appearance and intraluminal component, the main differential diagnoses considered before surgery included ureteral endometriosis, urothelial carcinoma, fibrotic ureteral stricture, inflammatory pseudotumor, and deep infiltrating pelvic malignancy. A concomitant endometriotic nodule involving the left uterine torus and uterosacral ligament was also identified, without impact on the left ureter.

A further pelvic magnetic resonance imaging study demonstrated progression of disease, with enlargement of the right adnexal endometrioma to approximately 7 cm and retro-uterine extension. An increase in size of a probable endometriotic implant at the level of the right ureteral orifice was noted, with arborized intravesical extension and persistent severe right uretero-hydronephrosis (Figure 1B-D). Hormonal therapy with goserelin acetate, 10.8 mg subcutaneously every three months, was initiated by the gynecology team for a total duration of six months (Table 1).

OPEN IN VIEWER

Table 1.

Clinical Timeline

Time point	Event	Key finding/management
Initial presentation	Severe right flank pain	CT urography showed right uretero-hydronephrosis associated with a right latero-uterine cystic mass
Initial endoscopic evaluation	Attempted ureteroscopy and retrograde ureteropyelography	Ureteroscopy could not be safely performed because of marked narrowing of the right ureteral meatus; retrograde ureteropyelography showed distal ureteral narrowing; a double-J stent was placed
Shortly after initial MRI	Functional renal assessment	Renal scintigraphy showed absence of right renal uptake and excretion, consistent with a nonfunctioning kidney
Two months later	Stent removal	Cystoscopy was unremarkable
Approximately one year later	Recurrent right flank pain	Repeat MRI showed persistent right ovarian endometrioma and a stenosing distal ureteral endometriotic nodule
Subsequent MRI	Disease progression	Enlargement of the right adnexal endometrioma with intravesical extension near the right ureteral orifice and persistent severe uretero-hydronephrosis
Following multidisciplinary discussion	Definitive surgery	Right nephroureterectomy with open partial cystectomy and right salpingo-oophorectomy
Follow-up	Postoperative assessment	The patient remained asymptomatic; follow-up MRI, laboratory tests, and ultrasound findings were unremarkable

On physical examination, bimanual vaginal assessment revealed a palpable right ureteral mass. The abdomen was soft and non-tender, with no costo-vertebral angle tenderness. Laboratory investigations, including serum creatinine, were within normal limits. Urinalysis revealed microscopic hematuria, with 20 red blood cells per high-power field, and mild leukocyturia, with 6 white blood cells per high-power field, with a sterile urine culture.

Following multidisciplinary discussion, the patient underwent laparoscopic right nephroureterectomy combined with open partial cystectomy and right salpingo-oophorectomy. Intraoperatively, a fibrotic mass was identified encasing and constricting the distal right ureter immediately proximal to its vesical insertion. During partial cystectomy, a polypoid lesion protruding from the right ureteral orifice was observed. A right ovarian endometrioma was also identified and excised (Figure 2). All resected specimens were submitted for histopathological examination.

OPEN IN VIEWER

Figure 2.

Gross surgical specimen including the right kidney, ureter, para-ureteral tissue, and excised bladder cuff. A polypoid lesion protruding from the distal ureter is indicated by the arrow

The postoperative course was uneventful, and the patient was discharged on postoperative day 2. Histopathological analysis demonstrated multifocal intrinsic and extrinsic ureteral endometriosis involving the ureter along its length, associated with end-stage chronic nephritis. Examination also confirmed a right ovarian endometrioma with a normal fallopian tube, while the para-ureteral tissue showed endometriosis associated with a foreign-body granulomatous reaction (Figure 3). The intrinsic component was defined by the presence of endometrial-type glands and stroma within the ureteral wall/lumen, whereas the extrinsic component was defined by endometrial tissue within the periureteral connective tissue. The diagnosis was established morphologically on hematoxylin and eosin staining. Immunohistochemistry was not performed because the glandular and stromal morphology and their distribution were diagnostic.

OPEN IN VIEWER

Figure 3.

Histopathological examination confirming mixed ureteral endometriosis. (A) Intrinsic ureteral endometriosis, showing endometrial glands and stroma involving the ureteral wall/lumen. (B) Extrinsic periureteral endometriosis, showing endometrial tissue within the surrounding connective tissue

Follow-up pelvic magnetic resonance imaging was unremarkable. The patient remained asymptomatic during subsequent follow-up, with normal laboratory and ultrasound findings. Gynecologic follow-up was arranged after surgery, and fertility counseling was discussed given the right salpingo-oophorectomy. The patient later achieved a successful pregnancy.

Patient Perspective

The patient reported anxiety related to recurrent pain and uncertainty surrounding the diagnosis. After surgery, she experienced complete symptom relief, resumed normal daily activities, and later achieved a successful pregnancy, which she considered a reassuring outcome.

Discussion

Ureteral endometriosis is an uncommon manifestation of urinary tract endometriosis but is clinically important because it may progress silently to ureteral obstruction and irreversible renal damage. The disease most commonly involves the distal ureter, usually within a few centimeters of the ureterovesical junction, and has been reported more frequently on the left side. ³ This left-sided predominance has been attributed to pelvic anatomical asymmetry and the relationship between the sigmoid colon and the left pelvic ureter, which may favor implantation or compression rather than provide a protective effect.^4,5 In contrast, our patient presented with right-sided distal ureteral involvement, recurrent flank pain, severe uretero-hydronephrosis, and complete loss of right renal function. ⁶

The most notable feature of this case is the mixed intrinsic and extrinsic pattern of ureteral endometriosis. Extrinsic ureteral endometriosis is characterized by endometrial tissue involving the ureteral adventitia or periureteral connective tissue, leading to external compression. Intrinsic disease is less common and involves the ureteral wall, including the muscularis propria, lamina propria, or lumen. In rare cases, intrinsic disease may present as a polypoid intraluminal lesion.^2,7 In our case, histopathological examination demonstrated multifocal endometriotic involvement of the ureter, with both intraluminal and periureteral disease, confirming mixed intrinsic and extrinsic ureteral endometriosis.

Management of ureteral endometriosis depends on symptoms, degree of obstruction, renal function, extent of disease, and fertility considerations. Hormonal therapy may be considered in selected patients with limited disease, minimal obstruction, and preserved renal function. However, surgery is generally required when significant obstruction, progressive disease, or loss of renal function is present. Conservative surgical options, including ureterolysis, segmental ureterectomy, ureteroureterostomy, ureteroneocystostomy, or Boari flap reconstruction, are appropriate when the renal unit retains meaningful function. ² In contrast, nephrectomy or nephroureterectomy may be required when the affected kidney is non-functioning and the likelihood of functional recovery is negligible.^8,9

In the present case, renal scintigraphy demonstrated absence of right renal function, while histopathological examination confirmed end-stage chronic nephritis. These findings supported irreversible loss of the right renal unit, making conservative or reconstructive procedures unlikely to restore renal function. Nephroureterectomy rather than nephrectomy alone was chosen because the disease involved the distal ureter, with an intraluminal polypoid component and suspected extension near the ureteral orifice; therefore, removal of the ureter and bladder cuff was considered necessary to achieve complete excision of the affected segment. The decision to perform nephroureterectomy with partial cystectomy and right salpingo-oophorectomy was also supported by the associated ovarian endometrioma and the need for coordinated multidisciplinary management ¹⁰ .

Complex pelvic and abdominal pathologies with unusual presentations often require timely multidisciplinary planning and careful operative decision-making, as illustrated in other reported gynecologic and abdominal case reports managed surgically in challenging clinical settings. ⁷ In the present case, multidisciplinary discussion was essential because the patient had a nonfunctioning kidney, distal ureteral disease involving the ureteral orifice region, and associated ovarian endometriosis.

This case highlights the diagnostic difficulty of ureteral endometriosis, particularly when it presents with atypical right-sided involvement and mixed intrinsic-extrinsic disease. It also emphasizes the importance of early recognition, functional renal assessment, and multidisciplinary management in patients with suspected ureteral obstruction due to deep infiltrating endometriosis. The main limitation of this case report is its retrospective nature and the absence of renal salvage given the already non-functioning kidney at the time of definitive management.

The strengths of this case report include the correlation between imaging findings, intraoperative observations, and histopathological confirmation of both intrinsic and extrinsic ureteral involvement. Similar reports of complex pelvic or abdominal pathology have emphasized the importance of timely multidisciplinary surgical planning in unusual presentations requiring careful operative management.

Conclusion

This case highlights the diagnostic complexity of ureteral endometriosis and its potential to cause irreversible renal damage. Right-sided involvement and mixed intrinsic-extrinsic disease are uncommon and may mimic other distal ureteral pathologies. Early recognition, renal functional assessment, and multidisciplinary management are essential to guide appropriate treatment and prevent loss of renal function.