Catheter Encrustation
In theory, a long term urinary catheter can be used for twelve weeks before it needs to be changed. Unfortunately, half of all catheter users have a problem with catheter blockage, meaning that it needs to be changed much more often than this. Some people even need their catheters changing several times a week.
Why does it happen?
This problem is caused by bacteria living on the surface of the catheter. All catheter users have bacteria in their bladder, although they do not usually cause illness. These bacteria live in a layer all over the catheter and coat themselves in a protective material. This layer of bacteria and protective coating is called a biofilm and it prevents antibiotics and bladder washout solutions reaching the bacteria.
A few of these bacteria are able to turn urine, which is normally slightly acidic, alkaline. Normal acidic urine has salts dissolved in it. If the urine is not acidic these salts can no longer be dissolved and they form crystals. These crystals either form in the bladder, which can lead to bladder stones, or in the biofilm on the catheter which causes the catheter to block.
More about the science of encrustation can be found here.
How do I know I have this problem?
When the catheter is changed it should initially drain well. After a few weeks (or days, if you have very bad encrustation) the catheter will drain less well and then block. This will cause leakage of urine and may be uncomfortable. When the catheter is removed, the crystals causing the blockage will be visible if it is cut open.
What can be done?
The problem cannot be cured, but there are ways to lengthen the time it takes for the catheter to block.
The more fluid you drink, the longer the catheter will last. It is important to make sure that you produce dilute urine during the night as well as the day. You should drink plenty before going to bed, and again if you wake up in the night. Catheters with wide channels down the middle will take longer to block than those with narrow channels. You could either change to a larger size of catheter, or if you use a latex based catheter, change to one made from 100% silicone, as these have much wider channels. Unfortunately larger catheters and silicone catheters can be uncomfortable, although this is less of a problem with a suprapubic catheter than a urethral one. Removing any bladder stones that may be present could also help.
Once these methods have been tried you should work out how long, on average, your catheter is now lasting. The best way to reduce problems caused by an encrusting catheter is to change it before it blocks. For example, if it tends to block about every three weeks, change the catheter regularly every two weeks to prevent problems occurring as an emergency. Changing the catheter more often will not do you any harm.
You or your carer may also like to learn how to change your own catheter, so that you can cope better in an emergency.
What else could be tried?
There is very little evidence that any other form of treatment helps, although many have been tried.
Acidic catheter maintenance solutions (bladder washouts) are often used in an attempt to dissolve the crystals. They need to be used regularly throughout the time the catheter is in place. Once it starts to block it is too late. Even when used this way, however, the results are usually disappointing. Antiseptic or antibiotic solutions are also sometimes used, but either don’t work, or only work for a very short time. Some, such as chlorhexidine, may even make the situation worse.
Drinking cranberry juice does not seem to work any better than drinking the same amount of any other fluid. Cranberry tablets or Vitamin C tablets also do not seem to help. Antibiotics do not work, as the bacteria are protected in the biofilm, and their use can sometimes make encrustation worse. However, you should remember that while these treatments don’t improve catheter encrustation, they may be needed for other conditions you may have.
A final note
Just as catheter encrustation may suddenly appear or worsen for no obvious reason, it can also improve. Much more research is needed to find out why, and to develop new treatments, especially as the current ones do not seem to be effective.
You should discuss the information in this article with your own health care professional before making any changes to your management.
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