Ureteral Stricture

A ureteral stricture is a narrowing of the ureteral lumen that impedes antegrade urine flow. It leads to proximal dilation, hydronephrosis and reduced renal function. The incidence after ureteroscopy is 1 to 3 percent, and after radiotherapy about 2 to 4 percent.

Causes:

• Iatrogenic injury, the commonest: ureteroscopy with stone impaction, pelvic or colorectal or vascular surgery, hysterectomy, and radiation.
• Chronic impacted stones.
• Infection (genitourinary tuberculosis, schistosomiasis).
• Radiation therapy (late fibrosis months to years later).
• Retroperitoneal fibrosis and endometriosis.
• Malignant ureteral involvement (urothelial carcinoma or extrinsic pelvic tumours).
• Ischaemia after transplantation, and BK virus infection in kidney transplant recipients.

Congenital strictures at the ureteropelvic or ureterovesical junctions (primary obstructive megaureter) form a separate group.

Strictures are classified by site (upper, mid or lower ureter), length (short below 2 cm, long above 2 cm) and cause (benign or malignant).

• Often silent, discovered by hydronephrosis and rising creatinine on routine imaging (silent loss of renal function is the major hazard).
• Flank pain (dull or colicky), especially with diuresis, recurrent urinary tract infection or pyelonephritis, and haematuria.
• Fever and sepsis from infected obstructed system (pyonephrosis).
• Reduced urine output, and uraemia in bilateral obstruction or in a solitary kidney.
• Hypertension from renal damage.
• Examination: flank tenderness, palpable kidney, and signs of infection.

• Ultrasound: hydronephrosis, hydroureter proximal to the stricture.
• Contrast CT urography, or MR urography when the creatinine is high, and the contrast is not recommended: shows the site and length of stricture and dilated ureter above.
• Retrograde and antegrade pyelography: precise demonstration of stricture length and location, in a combined study ("up and down gram") for completely obliterated segments.
• Diuretic renography (MAG3): function of the affected kidney and the degree of obstruction (T1/2 above 20 minutes).
• Ureteroscopy with biopsy when malignancy is possible (urothelial carcinoma), and cytology.
• Blood tests: creatinine, eGFR, urinalysis and culture; tuberculosis testing (urine acid fast bacilli, PCR) and schistosomiasis serology in endemic regions.
• Exclusion of extrinsic compression: CT for tumour, retroperitoneal fibrosis and endometriosis.

• Drainage first: for infected obstruction, urgent decompression by double-J stent or percutaneous nephrostomy. Give intravenous antibiotics guided by culture (ceftriaxone 1 to 2 g daily, or piperacillin tazobactam 4.5 g every 8 hours, or gentamicin 5 mg/kg daily for severe sepsis) and supportive care.
• Treat the underlying cause:
  • Genitourinary tuberculosis: antituberculous therapy with the usual four drug regimen (isoniazid 5 mg/kg, rifampicin 10 mg/kg, pyrazinamide 25 mg/kg and ethambutol 15 mg/kg daily for 2 months, then isoniazid and rifampicin for 4 months). Give corticosteroids (prednisolone 20 to 40 mg daily for 4 to 6 weeks) during early treatment to reduce fibrosis.
  • Schistosomiasis: praziquantel 40 mg/kg in two divided doses.
  • Retroperitoneal fibrosis: steroids and tamoxifen.
  • Endometriosis: hormonal therapy.
  • BK nephropathy: reduction of immunosuppression.
• Endoscopic treatment for short strictures (below 1 to 2 cm), benign, non-ischaemic, and of recent onset. Options are balloon dilation (retrograde or antegrade, balloon 6 to 8 mm at 12 to 15 atmospheres for 5 minutes) or endoureterotomy (cold knife or holmium laser, incision in the lateral wall, 'full thickness' incision). Then stent for 4 to 6 weeks with a 7 to 8.5 Fr stent.
• Success is 50 to 70 percent overall. It is lower with longer strictures (above 2 cm), ischaemic or radiation strictures, and a poorly functioning kidney.
• Surgical reconstruction for failure, long strictures, and ischaemic strictures:
  • Lower ureter: ureteroneocystostomy (reimplantation) with a psoas hitch (bladder fixed to the psoas muscle to bridge up to 5 to 6 cm) or Boari flap (bladder flap, bridging 10 to 15 cm).
  • Mid ureter: ureteroureterostomy (with spatulated end-to-end anastomosis), or transureteroureterostomy to the contralateral ureter.
  • Upper ureter or long segments: ureterocalicostomy, ileal ureter substitution (when over 8 to 10 cm), buccal mucosa onlay graft or appendiceal onlay, or autotransplantation (renal relocation into the iliac fossa).
  • Approach: open, laparoscopic or robotic (similar success, 90 percent).
• Permanent stents or nephrostomy tubes (changed every 3 to 6 months) are used in malignant obstruction or poor candidates for surgery. Metal stents may be considered in malignant or extrinsic obstruction.
• Malignant strictures: nephroureterectomy for localised urothelial carcinoma, and chemotherapy for metastatic disease. For extrinsic pelvic tumours, urinary diversion or stenting.
• Nephrectomy for non-functioning kidney with symptoms (function below 10 percent).
• Follow up: ultrasound and renography at 3, 6 and 12 months, then yearly; creatinine. Stricture recurrence is most common in the first year.