Case Study: Incidental Finding of Enlarged Kidney Leads to an Unexpected Endometriosis-Related Diagnosis

"Medical Journeys" is a set of clinical resources reviewed by physicians, meant for the medical team as well as the patients they serve. Each episode of this journey through a disease state contains both a physician guide and a downloadable/printable patient resource. "Medical Journeys" chart a path each step of the way for physicians and patients and provide continual resources and support, as the caregiver team navigates the course of a disease.

This time: A noteworthy case study.

What caused the right kidney of a 42-year-old woman with no related symptoms to swell and retain urine? That's what Weihong Zhao and colleagues at The Second Hospital of Shanxi Medical University in China needed to determine.

As they described in American Journal of Case Reports, physical examination revealed dilation of the right upper ureter. The team performed an intravenous pyelogram (IVP), but it was unable to visualize the right renal pelvis and ureter.

The patient said she did not have frequent urination, urinary urgency, or blood in her urine. She did note, though, that her periods were usually accompanied by painful menstrual cramps.

Vital signs were normal, and CT and contrast-enhanced CT showed effusion of the right kidney and ureter. On MRI imaging of the urinary tract, the team noted dilation of the right renal pelvis and ureter, although the lower segment of the ureter entering the bladder was not visible.

Radionuclide dynamic renal imaging showed that compared with the left kidney, the right kidney had significantly reduced blood perfusion, and the glomerular filtration rate of 12.16 m/min indicated severe renal impairment.

"Cystoscopy showed a clearly visible right ureteral orifice, no urine ejection, and the insertion of the F5 ureter for 10 cm was obstructed, suggesting an obstruction," the case authors wrote.

The patient underwent laparotomy under general anesthesia, and during surgery, clinicians noted obvious swelling and dilation of the middle and upper sections of the right ureter, with adherence of the adjacent tissues. After sufficient dissociation, the team noted that the right ureter was narrowed from the level of the right external iliac artery. "The stenosis was about 3 cm long, and the distal end was approximately 10 cm away from the bladder insertion port," the authors said.

They excised the narrowed segments of the ureter, and separated and removed the surrounding adhesion. The frozen resected tissue was sent to pathology for examination. Clinicians considered the probable diagnosis to be endometriosis. "The two ends of the ureterectomy site were further dissociated and anastomosed," the authors noted. The surgery, however, revealed no evidence of endometriosis in the pelvic cavity.

After the completion of surgery, the team placed an F5 DJ tube in the right ureter under the cystoscope up to the renal pelvis, and inserted it into the pelvis without resistance. Further postoperative paraffin examinations were suggestive of right periureteral endometriosis.

These included, the team wrote, "partial ureteral wall tissue with mild focal uroepithelial hyperplasia and localized submucosal and intermuscular ectopic endometrial glands and mesenchyme, consistent with endometriosis in the right middle ureter; a small amount of smooth muscle, fibrofatty tissue with focal ectopic endometrial glands and mesenchyme, focal hemorrhage, inflammatory cell infiltration, and ferritin deposits."

Immediately after surgery, the patient was treated with six additional doses of a gonadotropin-releasing hormone agonist (GnRH-a), and a levonorgestrel intrauterine release system was placed in the uterus.

The patient recovered from surgery without incident, and returned to the outpatient urology clinic 3 months later for removal of the DJ tube, and as of the following year she had no recurrence of endometriosis, the case authors reported.

Discussion

They explained that involvement of the ureter in endometriosis is a fairly rare form of deeply invasive endometriosis, accounting for only about 0.1-0.4% of cases of endometriosis.

Recent years have seen an increasing incidence of ureteral endometriosis (UE), an aggressive form of the disease that tends to involve the distal ureter, often the left side. Because symptoms of UE tend to be vague and nonspecific, however, the disease may go undiagnosed or be misdiagnosed. Left untreated, UE can lead to ureteral dilatation and hydronephrosis, and potentially cause kidney damage, Zhao and co-authors warned.

UE is categorized as exogenous or endogenous. The exogenous type involves obstruction-caused compression of the surrounding endometrium, while endogenous UE occurs ectopically, when progressive endometrial tissue lesions develop in or at the ureteral wall.

Exogenous UE tends to be more common and more likely to obstruct the urinary tract, the authors noted. In this patient, postsurgical pathology findings of ectopic endometrial glands and stroma in the submucosal and intramural areas of the right middle ureter, along with the severity of the surrounding tissues and peritoneal adhesions evident during the operation pointed to exogenous endometriosis. "Local infiltration of the ureter occurred and eventually involved the ureteral tissue, resulting in hydronephrosis," Zhao and co-authors said.

Symptoms of UE are often atypical, with a reported 76% of patients reporting painful menstrual cramps and 59.6% having pelvic pain, but only about 9.9% experiencing symptomatic ureteral obstruction.

The fact that the patient in this case did not report her menstrual pain because it was "tolerable" should remind clinicians of the possibility of urinary tract endometriosis in cases of dysmenorrhea with hydronephrosis.

Diagnosing UE requires adequate imaging, the case authors noted: "Doppler ultrasonography has lower sensitivity and higher specificity in the diagnosis of endometriosis with deep ureteral infiltration, while contrast-enhanced CT has higher sensitivity and lower specificity."

Thus, ultrasound represents a helpful first-line addition to standard examinations, and supplemental CT scans can enhance diagnostic accuracy and sensitivity, said Zhao and colleagues. "UE presents as hypointense nodules on MRI and hyperintense foci on both T1- and T2-weighted sequences."

MRI is more accurate than CT in detecting deep pelvic endometriosis, the team noted. IVP can be used to identify the location and extent of the obstruction, and renal function is determined using renal imaging.

"Cystoscopy with transurethral catheter placement can determine the distal site of the stenosis and further exclude other causes of stenosis," the team wrote. Although imaging did not detect typical endometriosis lesions in this patient, it did help identify the location of the obstruction and stenosis, and reveal the nature of the lesions, as well as the extent of renal dysfunction. Pathology findings should be used to confirm the final diagnosis.

The approach to treating UE depends on the disease and intraoperative conditions, the authors noted. Ureteral obstruction should be treated surgically. In patients with UE who have not developed hydronephrosis, laparoscopic ureterolysis is the recommended treatment. For severe UE, segmental ureterectomy, along with ureterotomy or ureterostomy are first-line options.

Following surgical treatment, long-term follow-up is vital to reduce the risk of recurrence, Zhao and colleagues emphasized. They cited a 2018 analysis of the long-term health and economic outcomes showing that 6 months of treatment with a GnRH-a is a cost-effective approach to preventing a recurrence.

In the current patient, a partial right ureterectomy and end-to-end anastomosis, immediately followed by six injections of GnRH-a and subsequent placement of the levonorgestrel intrauterine release system was associated with a successful outcome in the first year, the authors said, cautioning, however, that long-term followup is still needed.

Conclusion

Zhao and co-authors concluded that because of its insidious and nonspecific symptoms, UE may have a prolonged course and that left untreated, the condition can have serious consequences such as renal function impairment.

"UE should be listed as one of the differential diagnoses of unexplained hydronephrosis in women of childbearing age, and those with dysmenorrhea should be cognizant of this disease," the team wrote.

Read previous installments of this series:

Part 1: Endometriosis: Understanding the Pathogenesis and Pathophysiology

Part 2: Diagnosing Endometriosis

Part 3: Managing Endometriosis: Research and Recommendations

Part 4: Increasing Abdominal Pain 1.5 Years After C-Section

Part 5: Endometriosis: Fertility and Pregnancy

Part 6: The Latest on What to Know About Managing Endometriomas

Part 7: Enhancing the Doctor-Patient Dialogue About Endometriosis