Urinary catheter

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A urinary catheter is used to drain collected urine from the bladder. It is always necessary when a patient can no longer urinate independently, for example due to a narrowing of the urinary tract or a nerve dysfunction. Read all about the procedure, when it is done, and the risks involved.

What is a urinary catheter?

A urinary catheter is a plastic tube through which the urine is drained and then collected in a bag. It usually consists of full silicone or latex.

A distinction is made between the transurethral catheter and the suprabic catheter. The transurethral urinary catheter is inserted into the bladder through the urethra. The suprapubic urinary catheter, on the other hand, is placed directly into the urinary bladder through a puncture in the abdominal wall.

In addition, one can differentiate between the catheter types based on their tip. Examples of different catheter tips are:

• Nelaton catheter (blunt tip, mostly used on women)
• Tiemann catheter (tapered, curved tip, well suited for difficult catheter systems)
• Mercier catheter (similar to the Tiemann catheter)
• Stöhrer catheter (flexible tip)

The outside diameter of the urinary catheter is given in Charrière (Ch). A charrière corresponds to about a third of a millimeter. Common strengths for men are 16 or 18 Ch, while catheters between 12 and 14 Ch are mostly used for women.

When do you need a urinary catheter?

The urinary catheter is a standard procedure that is used for therapeutic reasons as well as for diagnostic purposes.

Urinary catheter for therapy

The urinary catheter is generally used when the patient can no longer urinate on his own. This can be the case with the following underlying diseases:

• Neurogenic voiding disorder
• Enlargement of the prostate
• Urinary retention from medication
• Inflammation of the bladder or urethra

Even if you are bedridden or if the urethra has been injured, for example in an accident or during an operation, the catheter can temporarily provide urinary drainage. For palliative patients who are already too weak to go to the toilet frequently, urinary diversion via the urinary catheter is an alternative.

The urinary catheter is also used to flush the bladder or to introduce medication.

Urinary catheters for diagnostic purposes

If the doctor wants to check the kidney function, he can assess the amount and concentration of the patient's urine over a period of 24 hours. He can also examine the collected urine for various germs.

Other examinations where a urinary catheter can be used include:

• Imaging of the urinary tract (injection of contrast medium via the catheter)
• Residual urine control
• Bladder pressure measurement (urodynamics) to check the urinary bladder function
• Determination of the urethral width

How do you insert a urinary catheter?

If the doctor or nurse wants to insert the urinary catheter, particular attention must be paid to thorough hygiene and sterile work to prevent infections.

Transurethral urinary catheter: woman

To insert the urinary catheter, the patient lies on her back with her legs spread to one side. The doctor or nurse then carefully cleans the genital area with a disinfectant that is especially suitable for the sensitive mucous membranes. He now grabs the catheter tube with sterile tweezers and smears a little lubricant on it. This allows him to easily insert the urinary catheter and advance it into the urinary bladder. If the catheter is correctly positioned in the bladder, urine will immediately flow out through the tube. The so-called catheter balloon is then expanded with about five to ten milliliters of distilled water so that the catheter can no longer slip out of the bladder.

Transurethral urinary catheter: male

To insert the transurethral urinary catheter, the patient lies on his back. The doctor covers the genital area under sterile conditions, carefully pulls back the patient's foreskin and cleans the penis with a disinfectant suitable for the mucous membrane. He uses a syringe to inject five to ten milliliters of lubricant into the urethra. With gentle pressure, the doctor pushes the urinary catheter over the urethra into the urinary bladder and fixes it there with the catheter balloon.

Suprapubic urinary catheter

After carefully disinfecting the abdominal wall, the doctor covers the patient's abdomen with a sterile cloth, leaving out the puncture region. After a local anesthetic, the doctor will pierce about two to three centimeters above the pubic bone with a syringe about five centimeters deep into the abdominal wall. If he can suck in urine with the syringe, the correct position in the bladder is ensured. As a rule, however, he checks the position and fill level of the bladder again using ultrasound.

With a special prick scalpel, he now opens the abdominal wall so that he can insert a hollow needle. The catheter tube is already located in this. When this urine flows through, the doctor withdraws the needle and fixes the catheter to the abdominal wall with a superficial suture. The exit point is now connected in a sterile manner.

What are the risks of a urinary catheter?

The main complication of catheter insertion is a urinary tract infection. Germs can migrate through the catheter tube and spread through the urinary tract. The doctor describes this as an ascending infection, which in the worst case scenario can lead to blood poisoning (sepsis). The longer the catheter is in place, the greater the risk of infection. Careful catheter hygiene is all the more important. In addition, the urethra can be injured when the catheter is inserted, which, when it heals, can narrow the urethra.

A suprapubic catheter has a lower risk of infection. In rare cases, however, the puncture can injure abdominal organs or vessels.

What do I have to consider with a urinary catheter?

The catheter exit point should be cleaned thoroughly twice a day with water and unscented, pH-neutral washing lotion.During cleaning, incrustations and mucus are removed from the leakage site with sterile disposable compresses. The urethra is always “wiped away” so as not to rub bacteria into the entry point. In uncircumcised men, the foreskin has to be pushed forward again after cleaning.

To ensure that the urine can flow out optimally, you should neither kink nor pull on the catheter tube. Always store the collection bag below the level of the bladder, otherwise there is a risk that the urine will run back through the catheter tube.

With a urinary catheter lying down, you should make sure to drink at least 1.5 liters of fluid. To prevent germs, you can also acidify the urine a little by drinking cranberry or lingonberry juice instead of water.

If the doctor wants to remove the transurethral urinary catheter, he uses a syringe at the end of the catheter tube to drain the distilled water from the small balloon and pulls the catheter out through the urethra. An anesthetic is not necessary for this. To remove the suprapubic urinary catheter, the doctor pulls the sutures and removes the catheter tube.

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