Lower urinary obstruction is a common occurrence in domestic cats. It occurs most commonly in male cats and is a complication of any form of feline lower urinary tract disease (FLUTD). Underlying causes of lower urinary obstruction may include bladder crystals and stones, urinary tract infections, idiopathic cystitis, or other causes. It is characterized by an inability to urinate due to an obstructed and spasmodic urethra due resulting in pain, azotemia, and hyperkalemia. Untreated, it will result in death. Treatment involves catheterization to relieve the obstruction, fluid therapy, pain control, and other symptomatic care.
It has been theorized by many clinicians that lavage of the bladder with sterile saline at the time of catheterization could be helpful, under the assumption that this will allow dilution of the urine and removal of crystals, mucous, and debris that may be associated with obstruction. It may, however, lead to increased time under sedation/anesthesia which may be detrimental, especially in unstable cats. The purpose of this study was to determine if there is an effect of bladder lavage on rate of urinary re-obstruction after catheterization. The study was designed as a prospective, unblinded, controlled trial. The primary outcome was re-obstruction after urethral catheterization.
One hundred thirty-seven cats were recruited to the study, 69 in the flush group and 68 in the no-flush group; based on an analysis for sample size. All cats were male. Age, weight, history of obstruction, and presence of crystals did not differ between groups. All cats were de-obstructed with a rigid open-ended polypropylene catheter using sterile 0.9% saline for retropulsion. After successful catheterization this was replaced with a 3.5 or 5 Fr red rubber catheter and sutured into place. Cats in the flush group received a bladder lavage with a volume of saline between 50 and 500mL (average 240mL) until the fluid was clear, and then attached to a closed collection system. Cats in the no-flush group were connected directly to a closed system. Difficulty of catheterization did not differ between groups.
Clinicians scored the difficulty of catheterization on a subjective 1-4 system. Care after catheterization was not standardized and included combinations of fluid therapy, analgesia, antispasmodics (prazosin), and a quiet environment.
The in-hospital recurrence rate was 13% for “flush” group cats, and 19% for “no-flush” cats. These values were not statistically different. Limiting analysis to cats with crystalluria, recurrence rates were 22% for both groups. Median time of catheterization was 37 hours for the flushed cats and 36h for the no flush, a non-significant difference. Duration of hospitalization was 3 days for both groups. These findings indicate that bladder lavage had no effect or rate of re-obstruction.
Several limitations to this study were present. The study was underpowered to detect small differences in outcome, however the authors correctly state that larger samples sizes may be impractical. There was also a lack of standardization in treatment protocols, which may have led to some degree of variation. Finally the lack of blinding is a major limitation, though this may be difficult to accomplish given the nature of the intervention.
The author’s conclude that there was no effect of bladder lavage on the rate of re-obstruction in catheterized cats with lower urinary obstruction. However, as a non-statistically significant difference was present and treatments were not blinded or standardized, they suggest that further research is needed to determine the true effect of bladder lavage in blocked cats.
