Q. I’m a C4 quad and I’ve used an indwelling Foley catheter to manage my bladder since I was injured seven years ago. A friend of mine is a C5 quad, uses a suprapubic indwelling catheter and recently had to have a bladder stone removed. His urologist explained to him the stone was likely caused by the suprapubic.
I see a urologist on a regular basis and so far the Foley works for me and I haven’t had any problems.
Does an indwelling catheter increase the risk of bladder stones? If I did have a stone, how would I know it? Is there anything I can do to reduce the chances of getting one?
A. Good questions, Janice. A literature search shows that bladder stones are common in people with a spinal cord injury — a 2006 study from Kessler Institute for Rehabilitation states that bladder stones are the second most common urological complication in people with SCI (urinary tract infections are the first). The Kessler study says that approximately 36 percent of people using indwelling catheters develop stones within eight years.
Paula Wagner, a urology nurse practitioner from U.C. Davis Medical Center in Sacramento, Calif., explains a couple of the reasons bladder stones are more common in people with neurogenic bladders than in the general population. One of the culprits is inflammation of the bladder due to recurring urinary tract infections. Another culprit is failing to fully empty the bladder — stagnant urine in the bladder is a breeding ground for stones.
Wagner says people with indwelling catheters, either Foley indwelling, or suprapubic, have higher rates of stones than the general SCI population because an indwelling catheter is both an irritant to the bladder and leads to more bacteria in the bladder. She adds that if a bladder with a Foley or suprapubic makes a lot of mucus, it is important to irrigate it on a regular basis with sterile saline or Neosporin Gu (see April Bladder Matters) because mucus can lead to UTIs as well as stones.
People who have had bladder augmentation (surgery to enlarge the bladder) are also at higher risk for bladder stones, says Wagner. This is because most bladder augmentations are made from part of the intestine — the intestine makes mucus to facilitate food transport and it continues to make mucus when it is used in bladder augmentation, which can lead to UTIs and stones. Wagner’s office recommends that they continue to irrigate their bladder every other day.
The 2006 Kessler study — “Accuracy of Predicting Bladder Stones Based on Catheter Encrustation in Individuals With Spinal Cord Injury” — further explains how stones can form in a bladder with an indwelling catheter. The catheter is a foreign body in the bladder, and bacteria latch on to it and start growing a biofilm — urinary crystals also become part of the biofilm, from there bacteria start to grow that alkalinize the urine and create an environment that enables the beginning of bladder stones to form.
The study points out an important “red flag” for people using indwelling catheters — when changing the catheter, carefully examine the old catheter, including the eyelets (drain holes), for any kind of encrustation or crystalline structure clinging to the catheter. The study found that when an indwelling catheter has any encrustation like stones or granular pieces on it, there is a high probability of bladder stones. Any type of encrustation on the end of a catheter should be brought to the attention or your urologist.
Detecting and Removing Stones
The Kessler study also reported that bladder stones are difficult to detect on a KUB (kidney, ureter, bladder) X-ray because they are often very small and usually composed of softer “organic matrix of bacterial glycocalyces and host proteins,” rather than the crystallized minerals that form kidney stones (which do show up on X-rays). Because of this, the preferred method of looking for bladder stones in somebody that uses an indwelling catheter is a cystoscopy — a catheter with a tiny camera on the end goes through the urethra and into the bladder and looks for stones or other abnormalities.
Wagner says her office recommends a yearly ultrasound and KUB for all her patients with neurogenic bladders to rule out stones. She says that for her patients who have had indwelling catheters for more than five years, she suggests adding a cystoscopy to the yearly check-up list and getting an ultrasound and KUB X-ray every six months to check for stones.
“The reason we like to stay ahead of things with ultrasound and bladder X-ray (and cystoscopy for people with indwelling catheters) is because if we catch stones early, when they are small or there are just a few we can take a cystoscope and go into the bladder and grab the stone in a simple outpatient procedure,” says Wagner.
If bladder stones are not found a timely manner there may be too many to grab with a cystoscope or they can grow too large to be removed with through the urethra. This narrows the choice to surgery, usually through the abdomen. For some stones, lithotripsy shock wave removal may be an option (see February 2011 Bladder Matters).
One of the ways to help reduce the risk of bladder stones is to make sure you are completely emptying your bladder. Residual urine left in the bladder allows minerals in the urine to crystallize and can lead to stones. It also provides a Petri dish for bacteria to grow into a UTI. This is an important issue for people that void into an external condom catheter — and don’t catheterize intermittently — to discuss with their urologist, who may want to run a urodynamics test to make sure their bladder is completely emptying. In the case of people who do intermittent internal catheterization, it is important to use proper technique to make sure you are completely emptying your bladder with each catheterization. See April 2011 Bladder Matters for more on this.
Another reason it for getting a yearly urological checkup with all the proper tests is that often bladder stones have no symptoms — although a recurring UTI is a red flag for a possible bladder stone because they often form around bacteria. A course of antibiotics will knock the UTI out but not the bacteria hiding in the stone, and the UTI pops right back up.
Level of injury, and whether the injury is complete or incomplete play a part in whether a person feels symptoms of a bladder stone. Some symptoms that may be a bladder stone — and should always prompt you to see your doctor — include: lower abdominal pain, low back pain, blood in the urine, or abnormally dark-colored urine, unexplained fatigue, appetite loss, or autonomic dysreflexia.
The steps you can take to reduce the chance of developing a bladder stone — or at least catch it in its early stages — are the same steps for all good bladder health. Get a yearly urology exam. If you have an indwelling catheter or bladder augmentation, be sure to irrigate to flush out mucus. Catheterize on a regular basis and make sure your bladder is fully drained to avoid stagnant urine. Catheterize often enough to keep your bladder volumes less than about 400cc (about 1.7 cups). Last, but never least, drink plenty of fluid — water is best — to stay hydrated and help flush everything out of the bladder. The rule of thumb is, drink enough fluid to keep your pee clear to straw colored.
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