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Should I do a decompressive cystocentesis in my blocked cat? | VETgirl Veterinary CE Podcasts

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How do you like to treat blocked cats in your practice? Do you have an opinion about the use of decompressive cystocentesis (DC)? If you aren’t familiar with it, this procedure involves performing cystocentesis in cats with urethral obstruction (UO) prior to placement of a urinary catheter. Some argue that it makes patients comfortable more quickly by relieving bladder distention, and also makes it easier to pass a urinary catheter due to reduced back pressure. Others feel strongly that decompressive cystocentesis increases the risk of bladder rupture and uroabdomen.

So, in today’s VETgirl online veterinary continuing education podcast, we review whether or not the use of decompressive cystocentesis can be used as a management strategy in cats with urethral obstruction. (VETgirl’s philosophy? No.). Hall et al out of University of Minnesota, wanted to evaluate the use of DC in cats that then had a urinary catheter placed for ongoing management. So they looked retrospectively at 47 cats that had decompressive cystocentesis performed and an indwelling urinary catheter placed with hospitalization for at least six hours. In this study, they found that the majority of the cats were neutered (45/47), while two were intact. 41/47 cats were domestic short-, medium or longhair cats; the remaining six were purebred. Overall, the median age was 6 years (range 2-22 yrs) with median body condition of 6/9 and mean body weight 5.8 kg. History and physical exam findings were what you would expect for cats with urethral obstruction, with stranguria, vocalization, vomiting, anorexia and excessive grooming of the perineum commonly reported (19-70%). Most cats (60%) were normothermic with normal heart rates (median 200/min) (See VETgirl’s awesome study on TPR of blocked cats and how it correlates with the severity of hyperkalemia). In Hall et al’s study, they found that 40/46 cats had an elevated BUN and 13/32 had an elevated creatinine, with approximately 1/3 of the cats (15/46) being hyperkalemic.

Urine obtained via cystocentesis was submitted for culture in 32 cats and only 1 cat had positive growth (E. coli). No cats had diagnostic abdominocentesis performed. Imaging of the abdomen (which included survey radiographs, ultrasound, double contrast cystourethrogram) was performed in 40 cats (most, 34/40, were radiographs). Of the cats with radiographs performed, 19/34 had focal loss of peritoneal detail consistent with effusion. However, a fair number of these cats may have had imaging performed prior to cystocentesis (up to 20/34 cats) based on urinary bladder distention on the films. Eleven of those 20 cats had effusion.

Since this was a retrospective study, treatment of cats with decompressive cystocentesis and urethral obstruction wasn’t standardized, but commonly included placement of an IV catheter, sedation, decompressive cystocentesis and placement of an indwelling urinary catheter with a closed collection system. 27/47 cats had a red rubber catheter placed, 12/47 had a Slippery Sam, and the catheter type wasn’t identified in 8 cats. For the 39 cats with identifiable duration of catheterization, the mean duration was 27.9 hours. Median hospitalization time was 40 hours (41 hours for survivors, 24 hours for non-survivors).

Overall, 91% (43/47) of cats survived to discharge, while 4 were euthanized due to: urinary obstruction following urinary catheter removal (n=2), suspected pyelonephritis and persistent azotemia (n=1) and persistent azotemia and hyperkalemia with suspected oliguric renal failure (n=1). The cat with suspected oliguric renal failure had a necropsy performed and peritoneal effusion was noted but not analyzed or identified as urine, and no leakage was noted grossly. 3/43 cats that were discharged re-presented within 72 hours; of these 3 cats, one was re-hospitalized for urethral obstruction again and discharged to survival while the other two were treated for stranguria without evidence of urethral obstruction. None were suspected or identified as having uroperitoneum.

This small retrospective study found similar overall survival rates (91%) to previous studies for cats with urethral obstruction. For these cats with decompressive cystocentesis performed as part of their therapy, followed by placement of an indwelling urinary catheter, none were diagnosed with a bladder rupture during hospitalization.
While a fair number of cats in this study had abdominal radiographs suggestive of focal peritoneal effusion, about half of those cats likely had radiographs performed prior to decompressive cystocentesis. A proposed mechanism of peritoneal effusion accumulation in cats with urethral obstruction includes altered lymphatic drainage due to changes in hydrostatic pressures.

Compared to a previous study of decompressive cystocentesis in cats, in which 3/15 cats were diagnosed with uroperitoneum and 1/15 hemoperitoneum, no cats in this study were diagnosed with either. A major difference in these two studies is that the previous study involved only multiple decompressive cystocentesis procedures (an average of 3 per cat) to manage urethral obstruction, whereas the cats in this study had a single decompressive cystocentesis performed and then an indwelling urinary catheter placed. Hall et al proposed that keeping the bladder decompressed with an indwelling catheter post-decompressive cystocentesis may help to keep intraluminal hydrostatic pressures low, reducing the risk of urine leakage from the DC site. This is a small retrospective study with no control population, so ideally a larger, randomized prospective study would be performed. However, it does suggest that decompressive cystocentesis in combination with placement of an indwelling urinary catheter can be an effective management strategy for cats with UO.

So, what can we take away from this VETgirl podcast? This study suggests that decompressive cystocentesis followed by placement of an indwelling urinary catheter is safe for cats with urethral obstruction; however, it should be emphasized that decompressive cystocentesis should be followed by catheter placement and hospitalization, and should not be used as a solitary treatment for cats with urethral obstruction due to risk of uroperitoneum and hemoperitoneum.

References:
1. Cooper ES, Owens TJ, Chew DJ et al. A protocol for managing urethral obstruction in male cats without urethral catheterization. J Am Vet Med Assoc 2010;(11):1261-1266.

2. Hall J, Hall K, Powell L, Lulich J. Outcome of male cats managed for urethral obstruction with decompressive cystocentesis and urinary catheterization: 47 cats. JV Vet Emerg Crit Care 2015;25(2):256-262.

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