Urethral stenting for patients with malignant obstruction

A minimally invasive procedure that offers immediate relief of stranguria
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Aug 01, 2011

Malignant urethral obstructions can cause life-threatening biochemical changes in veterinary patients. Most patients experience significant dysuria, and a small percentage develop complete urinary tract obstruction. Urethral stenting is an effective, minimally invasive out-patient procedure that can offer immediate relief of stranguria, as shown in the case below.

Initial findings

  • Signalment: 8-year-old castrated male beagle (48.5 lb; 22 kg)
  • Presenting complaint: Progressively worsening stranguria with near complete urinary obstruction
  • Pertinent history: Four months ago, the dog had a suspected urinary tract infection that did not improve with antibiotic therapy; results of follow-up ultrasonography and examination of prostatic fine-needle aspirate confirmed urothelial carcinoma
  • Medications: Piroxicam (5 mg orally once daily), misoprostol (50 µg orally b.i.d.); owner declined chemotherapy
  • Physical examination findings: Quiet, alert and responsive; body condition score 5/9; multiple soft moveable subcutaneous masses; moderate bilateral hindlimb muscle atrophy; very large caudal abdominal structure consistent with distended urinary bladder; large, firm, lobulated, irregular prostate palpated on rectal examination; lumbar lymph nodes not palpable on rectal examination; urine dripping from prepuce

Diagnostic evaluation

  • Heart rate: 140 beats/min
  • Complete blood count: Mild stress leukogram
  • Serum chemistry profile: ALT 79, AST 39, ALP 420
  • Abdominal radiography: Enlarged, mineralized prostate; hepatomegaly
  • Thoracic radiography: Unremarkable
  • Abdominal ultrasonography: Soft tissue mass located at urinary bladder trigone and extending into and from proximal urethra; intrapelvic urethra not visualized; lumbar lymph nodes normal; no evidence of hydroureter or hydronephrosis; slightly enlarged hyperechoic liver; remaining structures unremarkable
  • Urinalysis/urine culture: Pending

Treatment decisions

This patient was determined to have a complete or near complete urethral obstruction due to the progressive urothelial carcinoma. Emergency department personnel inserted an 8-F urethral catheter, and 400 ml of urine with marked hematuria was removed from the urinary bladder. The dog's rapid heart rate decreased after the bladder drainage.

Discussion with the owner included the following treatment options:

  • Surgery (cystostomy tube)
  • Chemotherapy (after urinary patency restored)
  • Radiation therapy (palliative or full course) with periodic urinary catheterization (two or three times daily) until urethral patency
  • Urethral stenting

Tumor extension into the trigone, as well as prostatic involvement, made complete surgical resection an unlikely option. Medical management (chemotherapy) was discussed, but an acute response permitting urination was unlikely. The owner declined radiation therapy due to the extent of the disease and the potential for significant side effects.

The owner chose urethral stenting, which is a rapid, effective, minimally invasive out-patient procedure shown to provide immediate relief of stranguria by rapid restoration of a patent urethra.