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Nonsurgical techniques for bladder stone removal (Proceedings)

Article

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.

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.

Voiding urohydropropulsion

The relationship between the size, shape and surface contour of urocystoliths and the luminal diameter of the urethra is an important factor in the selection of patients for voiding urohydropropulsion. Uroliths larger than the diameter of any portion of the distended urethral lumen cannot pass through it. Obviously the size of stones that can pass through the female dog urethral are greater than those that can pass through the male dog urethra. Although the procedure has been performed successfully in female cats, it is not recommended that the procedure be done in male cats unless they have a perineal urethrostomy. Uroliths with smooth contour are more readily passed through the urethra than or uroliths with irregular contour. As a guideline, smooth urocystoliths less than 5 mm in diameter can usually be removed by voinding urohydropropulsion in dogs weighing more than 8 kg.

     Steps for performing the voiding urohydropropulsion

          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. If possible, prophylactic antibiotics should be started 1-2 days before the procedure is perform. Alternatively, prophylactic antibiotics should be administered one the procedure is completed (see step 11 above from "jiggle technique").

          3. Anesthetize the patient.

          4. Distend the bladder with a sterile physiologic solution (saline or lactated ringer solution) injected through a transurethral catheter.

          5. Remove the catheter; if fluid is expelled through the urethra prematurely, the vulva or urethra can be gently pinched closed using a thumb and finger.

          6. Have one person position the patient so that the vertebral column is approximately vertical.

          7. Gently agitate the urinary bladder by palpation to promote gravitational movement of all urocystoliths into the bladder neck.

          8. Have another person apply steady digital pressure to the urinary bladder to induce micturition and a third person holding a cup under the patient to catch the urine that is voided. Once voiding begins, the bladder is more vigorously compressed. The objective is to sustain maximum urine flow through the urethral lumen to keep it dilated as long as possible.

          9. Repeat steps 4 through 8 if the number of uroliths voided is less than the number detected by radiography. If the number of uroliths detected by radiography are too numerous to count, repeat voiding urohydropropulsion until uroliths are no longer detected in the expelled fluid.

          10. Before waking the patient from anesthesia, repeat a lateral abdominal radiograph or double contrast cystography to confirm all stones have been successfully removed.

Potential complications associated with voiding urohydropropulsion

If patients are carefully selected and good technique is used, voiding urohydropropulsion is a safe procedure. Visible hematuria is the most common complication of voiding urohydropropulsion, but it resolves in most dogs within several hours. Hematuria that develops following this procedure is most likely induced by manual compression of an inflamed urinary bladder. If patients have uroliths with concomitant urinary tract infection, it is recommended to administer appropriate antimicrobial drugs for several days prior to performing the procedure.

Do not perform this procedure in any patient with urethral obstruction.

Urethral obstruction with uroliths can occur if voiding urohydropropulsion is performed in patients with uroliths too large to pass through all segments of the urethral lumen. When this occurs, uroliths are usually easily flushed back into the urinary bladder by retrograde urohydropropulsion. If uroliths cannot be medically dissolved, cystotomy may be necessary to prevent reobstruction.

One of the most common concerns clinicians have with performing this procedure is rupture of the urinary bladder. In a 5 year period, we performed voiding urohydropropulsion in well over 100 dogs. Only twice was the bladder ruptured. In both incidences, a urolith lodged in the urethra, and the person compressing the bladder did not realize this and applied too much pressure on the bladder. If the person compressing the bladder is concerned that they are having to press too hard, re-evaluate the situation. If the patient is only mildly sedated, consider full general anesthesia. Alternatively, repeat a radiograph to make sure that a stone has not become lodged in the urethra. If both of the above things have been done and there is still considerable resistant to manual compression of the urinary bladder, consider discontinuing the procedure, especially if it is suspected that the urinary bladder is inflamed. As you get more experience with this procedure, you will get a feeling for how much pressure you have to typically apply in the procedure.

If you are concerned about trying this procedure, one recommendation to get you over this fear is select a patient that is scheduled for a cystotomy but may have uroliths that can be removed via voiding urohydropropulsion. After the patient is anesthetized and prior to taking it into the surgery room, perform the procedure. Best case scenario is that you successfully remove all of the uroliths and you don't have to perform surgery. Worst case scenario is that if you do rupture the urinary bladder, you have prepared the patient for surgery already.

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