What is a urinary catheter?
A urinary catheter is a plastic tube through which urine is drained from the bladder and then collected in a bag. It is usually made of solid silicone or latex.
A distinction is made between the transurethral catheter and the supra-urethral catheter: The transurethral bladder catheter is inserted into the bladder via the urethra. The suprapubic bladder catheter, on the other hand, is inserted directly into the bladder through a puncture in the abdominal wall.
Catheter types can also be distinguished by their tip. Examples of different catheter tips are
- Nelaton catheter (blunt tip, mostly used in women)
- Tiemann catheter (tapered, curved tip, well suited for difficult catheter installations)
- Mercier catheter (similar to the Tiemann catheter)
- Stöhrer catheter (flexible tip)
The outer diameter of the bladder catheter is given in Charrière (Ch). One Charrière corresponds to approximately one third of a millimeter. Common thicknesses for men are 16 or 18 Ch, while catheters between 12 and 14 Ch are usually used for women.
When do you need a urinary catheter?
The bladder catheter is a standard procedure that is used both for therapeutic reasons and for diagnostic purposes.
Bladder catheter for therapy
- Neurogenic bladder emptying disorder (i.e. bladder emptying disorders due to nerve damage)
- Enlargement of the prostate (e.g. benign prostate enlargement)
- Urinary retention due to medication
- Bladder inflammation or urethritis
The catheter may also be temporarily necessary to ensure urine drainage if the patient is bedridden or if the urethra has been injured, for example in an accident or during surgery. It can also be important for palliative patients who are already too weak to go to the toilet frequently.
The bladder catheter is also used to flush the bladder or to insert medication.
Bladder catheter for diagnostic purposes
If the doctor wants to check the kidney function, he can assess the patient’s urine over a period of 24 hours with regard to quantity and concentration (24-hour urine collection). He can also examine the collected urine for various germs.
Other examinations in which a urinary catheter can be used are
- Imaging of the urinary tract (insertion of contrast medium via the catheter)
- Residual urine monitoring
- Bladder pressure measurement (urodynamics) to check bladder function
- Determination of the urethral width
How is a urinary catheter inserted?
Transurethral bladder catheter: Woman
To insert the urinary catheter, the patient lies on her back with her legs spread out to the side. The doctor or nurse now carefully cleans the genital area with a disinfectant that is especially suitable for the sensitive mucous membranes. Using sterile tweezers, he now grasps the catheter tube and coats it with a little lubricant. This makes it easier to insert the bladder catheter and push it into the bladder.
Once the catheter is correctly positioned in the bladder, urine immediately flows out through the tube. The so-called catheter balloon (near the front end of the catheter) is then expanded with around five to ten milliliters of distilled water so that the catheter cannot slip out of the bladder.
Transurethral bladder catheter: Man
The patient lies on his back for the insertion of the transurethral bladder catheter. The doctor covers the genital area with a sterile drape, carefully pulls back the patient’s foreskin (if the patient is not circumcised) and cleans the penis with a disinfectant suitable for mucous membranes.
Using a syringe, he then injects five to ten milliliters of a lubricant into the urethra. Using gentle pressure, he then pushes the bladder catheter through the urethra into the bladder and secures it there with the catheter balloon.
Suprapubic bladder catheter
Using a special scalpel, the doctor opens the abdominal wall wide enough to insert a hollow needle. This already contains the catheter tube. When urine flows through it, the doctor withdraws the hollow needle and secures the catheter to the abdominal wall with a superficial suture. The exit point is then sterilely bandaged.
What are the risks of a urinary catheter?
The most important complication when inserting a catheter is an infection of the urinary tract: germs can migrate through the catheter tube and spread in the urinary tract. Doctors refer to this as an ascending infection, which in the worst case can lead to blood poisoning (sepsis). The longer the catheter is in place, the greater the risk of infection. This makes careful catheter hygiene all the more important.
A suprapubic catheter carries a lower risk of infection than a transurethral catheter. However, in rare cases, abdominal organs or vessels may be injured during insertion.
In contrast, the urethra can be injured when inserting the transurethral catheter. After the injury has healed, the urethra may be narrowed.
What do I need to be aware of with a urinary catheter?
To ensure that the urine can drain optimally, you should neither kink the catheter tube nor pull on it. Always store the collection bag below bladder level, otherwise there is a risk that the urine already drained will run back through the catheter tube.
With a horizontal urinary catheter, you should ensure that you drink at least 1.5 liters of fluid (unless otherwise prescribed by your doctor). To prevent germs in the urinary tract, you can also acidify the urine slightly by drinking cranberry or cranberry juice instead of water.
If the doctor wants to remove a transurethral bladder catheter, he or she drains the distilled water from the small balloon using a syringe at the end of the catheter tube and pulls the catheter out through the urethra. Anesthesia is not necessary for this. To remove the suprapubic bladder catheter, the doctor pulls the stitches from the skin suture and removes the catheter tube.
