A 6-year old male castrated domestic shorthair cat was evaluated for a right ureteral obstruction. Three weeks prior to examination, he was evaluated by his primary veterinarian for anorexia and vomiting, at which azotemia was diagnosed and the patient was treated with a course of antibiotics (amoxicillin trihydrate/clavulanate potassium). He improved initially, but his signs recurred within days of completion of a 14 day course of antimicrobial therapy. Abdominal ultrasound was performed when there was recurrence of his clinical signs and revealed bilateral hydronephrosis and hydroureter with right nephroliths and ureteroliths. Medical management with intravenous fluid diuresis, intravenous antibiotic therapy (enrofloxacin and ampicillin), mannitol, and prazosin. His azotemia did not improve with 48 hours of medical management, though the left renal pelvis sized decreased from 8 mm to 5 mm while the right was unchanged. He was referred for further evaluation.
How can ureteral stents be placed the following groups of patients:
- Female dogs?
- Male dogs > 15 kg?
- Male dogs < 15 kg?
- Female cats?
- Male cats?
The patient was placed under general anesthesia for surgical ureteral stent placement. A marker catheter was placed within a 10 French red rubber catheter and placed in the colon for calibration under fluoroscopy. A ventral distal cystotomy was performed and the ureteral openings visualized. A 0.018” angled hydrophilic guidewire was advanced retrograde into the ureter and renal pelvis under direct visualization and fluoroscopic guidance. The guidewire was advanced until there were two coils of wire were in the renal pelvis. A 0.034” dilator was advanced over the wire to the level of the dilated ureter to facilitate ureteral dilation. The ureteral dilator was removed and a 2.5 French x 12 cm ureter stent was passed over the wire into the renal pelvis. When the stent was positioned within the renal pelvis, the wire was slowly withdrawn under constant fluoroscopic guidance to ensure proper positioning of the stent coil within the renal pelvis. The bladder was closed routinely, and the abdomen lavaged prior to closure.
How is the ureteral stent length selected? Based on the radiographs obtained at recheck examination, is the stent length appropriate for this patient?
What are the mechanisms by which ureteral stenting provides relief of ureteral obstructions?
What other patient management/monitoring procedures should be considered for all patients for whom a ureteral stent is being placed?
What important management and monitoring parameters should be considered in all patients with ureteral stents?
What complications (both short and long term) can be seen with ureteral stenting?