Wow! That’s a mouthful!
Let’s break it down: “Uro” is a Latin prefix referring to the urinary tract. “Hydro” refers to water, or, more broadly, any liquid. “Propulsion,” from the Latin propellere, meaning “to propel,” “the act of driving forward.”
Voiding urohydropropulsion, then, is the act of using a liquid to expel something from the urinary tract. More specifically, we are using a physiologic solution in the bladder to remove urinary bladder and urethral stones. This technique cannot help stones that are in the kidney(s) and/or ureters. However, unlike people, dogs and cats form more stones in their bladders than in their kidneys.
The technique was developed by Dr. Jody Lulich at the University of Minnesota Urolith Center.
The steps are fairly straightforward. It can be practiced in the wide-awake, sedated or fully anesthetized patient. First, aseptically (using a sterile technique), introduce a urinary catheter. Second, instill physiologic saline or lactated Ringer’s solution into the bladder to distend it. Care must be taken not to overdistend and rupture the bladder. Third, place a finger onto the urethra to prohibit flow while removing the catheter. Fourth, orient the patient with the spine vertical (standing up like a human) and have an assistant squeeze the bladder, after which the finger inhibiting flow is removed. The result should be a rush of urine and solution from the bladder, the goal of which is to carry urinary bladder stones in the flow.
Of course, the size of stones that can pass is proportional to the size of the patient’s urethra, which is roughly proportional to the overall body size. While the procedure can theoretically be used in female cats, it’s going to work on only on the largest queens with the smallest stones. Male cats’ urethras are much to small for VU to be practical.
A pet with a really large cystic calculus (bladder stone) is going to need cystotomy: opening the abdomen, incising the urinary bladder and removing the stone that way.
One of the giant advantages of voiding urohydropropulsion is the fact that tiny granules of stone material that might be missed or overlooked in an open surgical technique are more likely to be flushed out.
The procedure can be repeated as many times as necessary, although the practitioner must take into account that inflammation of the urethra and bladder lining occur with each passage of the catheter.
Still, it is much less invasive and less irritating than cystotomy.
We used the technique successfully on little Sophie (pictured above) this week. Observe the many stones visible on the preoperative radiograph (X-ray),
and the total absence of stones on the post-treatment film.
The stones have been sent to the University of Minnesota Urolith Center, where quantitative analysis will tell us whether Sophie has a recurrence of calcium oxalate calculi.
See you next week, Dr. Randolph.