Indications for non-surgical removal of urocystoliths
For many years, most uroliths in the urinary bladder were managed either by surgical removal or medical dissolution. Unfortunately, certain mineral types of uroliths, such as calcium oxalate, have a very high recurrence rate and are not currently amendable to medical dissolution. Understandably owners become frustrated if their pet has to undergo multiple cystotomies, and some owners cannot handle the financial burden associated with multiple cystotomies.
Another situation where the option of non-surgical removal of urocystoliths is helpful is in some patients that are diagnosed with urinary bladder stones, and it is uncertain whether the mineral type is amendable to medical dissolution, or if additional diagnostic tests are warranted prior to taking the patient to surgery.
One alternative non-surgical method for removing urocystoliths, called the "jiggle technique." was developed by Dr. Carl Osborne at the University of Minnesota more than two decades ago. More recently, Dr. Jody Lulich, at the University of Minnesota, developed a non-surgical method, called "voiding urohydropropulsion". This method can remove larger urocystoliths than can be removed via the "jiggle technique". Both methods will be discussed.
Additional point to keep in mind is that just because the patient has a bladder stone does not mean you have to automatically remove the stone. Sometimes urocystoliths are detected in asymptomatic patients that are having radiographs or abdominal ultrasound performed for other reasons. It is important to notify the owner of your findings and give them a list of options about how to handle this problem. If they choose to not do anything about the stone, it is important that they monitor their dog's urination daily, and if ever the dog is having difficulty urinating, they need to contact a veterinarian immediately.
The "jiggle technique"
This technique is very simple and relatively inexpensive to perform, does not require any special equipment, and if done properly, carries a minimal amount of risks or complications.
Steps for performing the "jiggle technique"
1. Perform lateral abdominal survey radiographs or double contrast cystography to confirm the presence of urocystolith(s) that are small enough to be removed with this technique.
- Some very small urocystoliths may be difficult to visualize on survey radiographs unless the mineral composition of the urolith is very radiodense.
2. Choice of urinary catheter for use in this procedure is important, and occurrence of urinary tract trauma is greatly affected by catheter choice and catheterization technique.
- Type of catheter used: Urinary catheters are manufactured from a large number of materials, and the two most common types of urinary catheters used in veterinary medicine are manufactured from (red) rubber and polypropylene. Polypropylene catheters (such as tomcat catheters) are more rigid than red rubber catheters and as a result, are more likely to induce trauma to the urinary tract. In addition, the material that polypropylene catheters are made from causes a greater inflammatory reaction in the urethra than does the material that red rubber catheters are made from. Therefore, it is highly recommended that red rubber urinary catheters be used for this procedure and not polypropylene catheters.
- Size of catheter used: Catheters are primarily limited to 8 fr red rubber catheters. Any smaller size red rubber catheter likely will have a lumen that is too small for uroliths to pass through. Therefore, it is unlikely that this procedure could be done in a male cat that does not have a perineal urethrostomy.
3. Whether a patient requires sedation or not is highly dependent upon the demeanor of the patient. It is not always necessary to sedate a dog or cat to successfully perform this procedure. Since you are just catheterizing the patient, if the procedure is done correctly, there should be only a minimal amount of discomfort to the patient.
4. Place the patient in lateral recumbency.
5. Prior to inserting the catheter into the urethra, remove hair from the field and cleans the tip of the penis or prepuce or vulva with gauze pads soaked in mild antimicrobial soap. Hibiclense is one type of soap that is commonly used.
6. The catheter should be sterile, and steps should be taken to minimize contamination during the procedure. Therefore, either wear sterile gloves or use the outer wrap of the catheter to avoid touching it with your bear hands.
- Regardless of precautions taken, contamination of the catheter is not entirely eliminated because the catheter is passed through the distal urethra where bacteria ordinarily reside, even in healthy patients.
- Consequently, truly aseptic catheterization of the urinary tract is probably not possible.
7. The tip of the catheter should be dipped into sterile, water soluble lube before inserting into patient.
8. Insert the catheter into the urethra and pass it up to the urinary bladder. Once catheter is in bladder, place a sterile syringe on the end of the catheter.
- It is important not to over insert the catheter into the bladder to reduce trauma to the bladder mucosa. The catheter should be inserted part of the way into the bladder, but it should not be scraping against the cranial wall. One way to tell how far a urinary catheter is inserted into the bladder is to pass the catheter into the bladder until you can get urine. Then gradually back the catheter out of the bladder, and after each time the catheter is backed out a little, gently apply negative pressure to the syringe. If the tip of the catheter is still in the bladder, you should get back urine into the syringe. Once the catheter is in the proximal part of the urethra, when negative pressure is applied to the syringe, it should meet resistance and no urine. Once negative pressure is found re-insert the catheter about 1 to 2 inches (depending on the size of the dog or cat) back into the bladder.
9. If the urinary bladder is full of urine, you can perform the "jiggle technique" using the urine already present in the bladder. If the bladder is relatively empty, you will need to inject some sterile saline or lactated ringers solution into the bladder.
- The amount of fluid to add depends on the size of the patient. You want the bladder to be only partially full so you may need to palpate the bladder to determine how much fluid to inject. To "jiggle" out a urocystolith, while you are drawing either urine or physiologic saline or LRS out of the bladder, simultaneously place one hand under the bladder (between the bladder and table) and gently agitate the bladder. When the syringe is full, check to see if any stones are present in the syringe. If a stone is present in the syringe, but more stones are present in the bladder, detach the syringe from the urinary catheter and point the tip on the catheter down so the stone falls to the tip. Then inject a small amount of urine into a cup until the stone is out of the syringe. If the procedure needs to be repeated, you can use the remaining fluid in the syringe to start the process over again.
10. If any stones are successfully obtained, send them in for quantitative mineral analysis.
- Even a stone as small as a pin head can be analyzed for its mineral composition.
11. Since you are dragging the urinary catheter through a non-sterile environment (the urethra) into a normally sterile environment (urinary bladder), there is no way to be completely sterile while catheterizing a patient. Giving prophylactic antibiotics may be controversial.
- By itself, microbial contamination of the urinary tract does not necessarily cause infection. However, impairment of normal host defense mechanisms against microbial colonization are already impaired in many patients that have urinary tract disease and can be furthered impaired by performing the procedure. These patients may be at increased risk of developing a catheter induced urinary tract infection. Therefore, I will either start a patient on prophylactic antibiotics 1-2 days before I perform the procedure or give antibiotics post procedure for 5 days. I do not want to give the patient another problem. However, each clinician will have to use their own judgment whether to administer prophylactic antibiotics or not.