Urinary catheterization

1. What is urinary catheterization?

Urinary catheterization consists of inserting a catheter into the bladder in order to allow drainage of urine or bladder contents.

Access can be achieved by two main routes: through the urethra (urethral catheterization) or through the abdominal wall (suprapubic catheter).

The urethral catheter can be inserted temporarily to empty the bladder and removed immediately, or it can be left in place and connected to a drainage system.

2. Anatomy we need to remember

To perform catheterization correctly, it is essential to understand the anatomical differences between the male and female urethra.

Female urethra

It is relatively short and nearly straight. The urethral meatus is located in the vulvar vestibule, below the clitoris and above the vaginal introitus. For this reason, female catheterization is usually technically easier. However, difficulties may arise due to:

• obesity;
• edema;
• anatomical abnormalities;
• prior surgery;
• genital atrophy;
• difficulty identifying the meatus.

Male urethra

It is considerably longer and has several segments:

meatus → penile urethra → bulbar urethra → membranous urethra → prostatic urethra → bladder

Male anatomy explains why catheterization can be more difficult, particularly in the presence of:

• prostatic hyperplasia;
• urethral stricture;
• prior urethral surgery;
• prior instrumentation;
• urethral trauma;
• anatomical abnormalities.

3. Why is a urinary catheter placed?

The most common indications include:

• Urinary retention: acute or chronic.
• Lower urinary tract obstruction: for example, prostatic hyperplasia, certain urethral strictures, or other obstructive causes.
• Accurate measurement of urine output: especially in critically ill patients when urinary balance changes therapeutic decisions.
• Surgery: it may be used in certain procedures to keep the bladder empty, monitor urine output, protect or monitor the urinary tract, and facilitate certain urologic surgeries.
• Significant hematuria: it may be necessary to evacuate clots, maintain bladder drainage, and perform bladder irrigation.
• Intravesical treatments: in certain situations it allows medication to be administered into the bladder.
• Selected prolonged immobilization: for example, certain polytrauma patients.
• Palliative care: when it significantly improves patient comfort.

Guidelines insist that an indwelling catheter should be placed only when there is a justified indication.

4. When should we not place a catheter "as a routine"?

A catheter should not be placed simply:

• "because the patient is hospitalized";
• for the convenience of the team;
• to keep the patient from going to the bathroom;
• as routine treatment of incontinence;
• without evaluating alternatives.

Duration also matters.

Reducing the use and duration of catheters is one of the main measures to prevent catheter-associated infection.

5. Types of catheters

There are many designs. For the medical student, there are a few that must be recognized.

Foley catheter

It is the classic indwelling urinary catheter. It has a balloon near the distal end that, once correctly positioned inside the bladder, is inflated to keep the catheter from coming out.

Two-way. It has one channel for urinary drainage and one channel for the balloon. It is the usual catheter when we need continuous bladder drainage.

6. Three-way catheter

It has:

1. urinary drainage;
2. balloon;
3. irrigation.

It is used especially when we need continuous bladder irrigation. A classic example is hematuria with clot formation: irrigation reduces the risk of catheter obstruction by clots and maintains bladder drainage.

7. Nélaton catheter

It is a straight catheter without a retention balloon. It is used for:

• intermittent catheterization;
• one-time bladder emptying;
• certain diagnostic or therapeutic procedures.

It is inserted, the bladder is emptied, and the catheter is then removed.

8. Tiemann / Coudé catheter

It has a curved distal tip. It can be useful in certain male patients in whom catheterization is difficult.

9. What does "French" mean?

The external caliber of catheters is usually expressed in French (Fr), also called Charrière (Ch).

The relationship is: 1 Fr = approximately 0.33 mm of external diameter. Therefore: diameter in mm ≈ Fr / 3.

10. Which size should be chosen?

The general principle is to use the smallest caliber that allows adequate drainage. This helps reduce urethral and bladder trauma.

In an adult with clear urine, sizes of approximately 14–16 Fr are usually used, depending on the patient and the clinical situation.

When there is significant hematuria, clots, or a need for washout, larger catheters may be required, often three-way.

11. The balloon

The Foley has a balloon designed to keep the catheter inside the bladder. The inflation volume depends on the catheter used, and the manufacturer's instructions must be followed.

12. Necessary equipment

Before starting, we must prepare all the equipment. We will usually need:

• appropriate catheter;
• gloves;
• drape;
• material for periurethral hygiene/antisepsis according to protocol;
• lubricant;
• syringe for the balloon;
• fluid indicated by the manufacturer for the balloon;
• collection bag;
• securement material.

In the acute care hospital, insertion of an indwelling catheter must be performed using aseptic technique and sterile equipment.

13. Patient preparation

Before performing the procedure:

1. Confirm the indication.
2. Correctly identify the patient.
3. Explain what we are going to do.
4. Preserve their privacy.
5. Position them correctly.
6. Perform hand hygiene.
7. Prepare the equipment.
8. Perform the appropriate aseptic technique.

Explaining beforehand reduces anxiety and facilitates cooperation.

14. Male urinary catheterization

Step 1. Position

Patient in the supine position. Expose only the area necessary for the procedure.

Step 2. Preparation

Perform hand hygiene, prepare the drape and equipment.

Step 3. Exposure

If the patient is not circumcised, carefully retract the foreskin to visualize the meatus.

Step 4. Periurethral cleansing

Perform it following the institutional protocol.

Step 5. Lubrication

Adequate lubrication reduces pain, friction, and urethral trauma.

Step 6. Penis position

Hold the penis and align it appropriately to facilitate passage of the catheter.

Step 7. Insertion

Insert the catheter gently. Do not force it. If significant resistance appears: stop and reassess.

Step 8. Reaching the bladder

The appearance of urine indicates that the drainage end has reached the bladder, but in men sufficient insertion must be ensured before inflating the balloon. A safe practice is to advance the catheter adequately until you are certain the balloon is intravesical before inflating it.

Step 9. Balloon

Inflate it with the volume indicated for that catheter.

Step 10. Gentle traction

Once inflated, gently withdraw until you feel the balloon rest against the bladder neck.

Step 11. Connection

Connect to the closed drainage system.

Step 12. Replacing the foreskin

15. Female urinary catheterization

The technique shares the same principles of indication, asepsis, lubrication, atraumatic insertion, correct intravesical positioning, and safe balloon inflation.

The patient is usually placed in the supine position with adequate exposure of the perineum. The labia are carefully separated to identify:

clitoris → urethral meatus → vaginal introitus

Periurethral preparation is performed and the catheter is gently inserted until urine is obtained. Correct intravesical position is then ensured before inflating the balloon.

16. What happens if the catheter enters the vagina?

It is a common mistake during training.

17. What if no urine comes out?

Do not immediately assume that "the catheter is wrong." Think about:

• empty bladder;
• catheter not yet intravesical;
• lumen obstruction;
• kinking;
• incorrect position;
• significant anuria/oliguria.

18. Difficult male catheterization

Catheterization can be difficult because of:

• prostatic hyperplasia;
• urethral stricture;
• prior urethral surgery;
• prior instrumentation;
• trauma;
• prior false passage;
• altered anatomy.

The most dangerous mistake is turning a difficult catheterization into a traumatic one.

19. What to do if the catheter will not pass?

The student should remember this sequence:

1. Stop.
2. Do not force it.
3. Review technique and position.
4. Ensure good lubrication.
5. Consider whether there is an obstruction or anatomical abnormality.
6. Ask for help.

In trained hands, other strategies may be used, including:

• Coudé/Tiemann catheters;
• guidewires;
• flexible cystoscopy;
• endoscopic techniques;
• suprapubic access in selected cases.

20. Suspected urethral injury

This is one of the most important concepts of the chapter. In certain traumas, a urethral injury may be present. We should suspect it especially in the presence of:

• significant pelvic/perineal trauma;
• blood at the urethral meatus;
• marked difficulty with catheterization in a trauma setting;
• other findings consistent with urethral injury.

Suspected urethral trauma is a relative contraindication to urethral catheterization in the EAUN guideline.

21. Urethral false passage

It occurs when the instrument creates a track outside the normal urethral lumen. It can occur due to:

• excessive force;
• multiple attempts;
• stricture;
• altered anatomy;
• traumatic instrumentation.

It can manifest as pain, urethral bleeding, resistance, inability to advance, or increasing difficulty in subsequent attempts.

22. Hematuria and clots

A patient with significant gross hematuria can develop clots inside the bladder. These can cause urinary retention due to clots. The patient may present with:

• suprapubic pain;
• intense urge to urinate;
• decreased or absent drainage;
• hematuria;
• bladder distension.

23. Three-way catheter and bladder irrigation

In certain patients with significant hematuria, a three-way catheter is used. Its channels allow:

irrigation inflow → bladder → outflow of urine + irrigation

The goal is to keep the catheter patent and prevent the accumulation of clots.

24. Manual irrigation

When clots are present, it may be necessary to perform manual irrigation through an appropriate catheter and under the corresponding indication/training. The goal is to:

• mobilize clots;
• restore patency;
• allow drainage.

It must not be done violently.

25. Intermittent catheterization

It consists of inserting a catheter, emptying the bladder, and removing it. It may be preferable to an indwelling catheter in certain situations of bladder emptying dysfunction. It is common in patients with:

• neurogenic bladder;
• certain functional disorders;
• selected chronic retention.

In patients who require chronic intermittent catheterization outside the acute care hospital, a clean technique may be used, depending on the context and training.

26. Suprapubic catheter

It is a catheter that enters the bladder through the abdominal wall, bypassing the urethra. It may be considered in situations such as:

• inability to drain via the urethra;
• certain strictures or obstructions;
• urethral/pelvic trauma;
• complications of prolonged urethral catheterization;
• selected situations requiring prolonged drainage.

It is not simply "another Foley." Its placement is a procedure that requires proper indication, technique, and anatomical evaluation.

27. The collection bag

After correctly placing a catheter, care of the system is essential. The bag must be kept below the level of the bladder. This promotes gravity drainage. It must never rest on the floor. In addition:

• avoid kinking;
• avoid traction;
• keep the flow free;
• keep the system closed.

These measures are part of the core recommendations for preventing complications and infection.

28. Catheter securement

An indwelling catheter must be properly secured. The goal is to avoid traction, excessive movement, urethral trauma, and discomfort. The CDC recommends properly securing indwelling catheters to prevent movement and urethral traction.

29. Catheter-associated urinary tract infection

Catheter-associated urinary tract infection —often called CAUTI— is one of the most important complications. The risk increases especially with the duration of catheterization.

How can the risk be reduced? Prevention begins before the catheter is placed:

1. Have a real indication.
2. Proper placement technique.
3. Maintain a closed system.
4. Maintain free urine flow.
5. Bag below the bladder.
6. Avoid unnecessary disconnections.
7. Remove the catheter as soon as it is no longer needed.

30. Should antibiotics be given because of a catheter?

Not routinely. The presence of an indwelling catheter alone does not justify routinely administering systemic prophylactic antibiotics.

Unnecessary use promotes adverse effects, selection of antimicrobial resistance, and unnecessary treatments. The CDC advises against routine systemic antimicrobials simply to prevent CAUTI, except for specific clinical indications.

31. How to collect a urine sample from a catheterized patient?

32. Should the catheter be changed every "X" days?

There is no universal rule that indicates changing all indwelling catheters at a fixed interval regardless of context. The CDC recommends that replacement be based on clinical indications, such as:

• obstruction;
• infection in situations where appropriate;
• compromise of the closed system;
• other clinical needs.

33. A catheter that does not drain

It is a common problem. Before changing it immediately, think systematically:

1. Does the bladder actually contain urine?
2. Is the tubing kinked?
3. Is the bag correctly positioned?
4. Is the catheter obstructed?
5. Are there clots?
6. Is the catheter malpositioned?
7. Is there oliguria or anuria?
8. Does the patient have pain or bladder distension?

34. Pain with the catheter

It may be due to:

• traction;
• poor securement;
• incorrect position;
• malpositioned balloon;
• obstruction;
• bladder spasms;
• infection;
• trauma.

Severe pain immediately after inflating the balloon should make you think of a balloon inflated in the wrong position.

35. Urine around the catheter

Leakage of urine alongside the catheter may be due to:

• obstruction;
• bladder spasms;
• constipation;
• traction;
• drainage problems;
• inadequate caliber or position.

36. Complications of catheterization

The main ones include:

• Infectious: bacteriuria, urinary tract infection, ascending infectious complications.
• Traumatic: urethrorrhagia, hematuria, false passage, urethral injury.
• Mechanical: obstruction, kinking, displacement, accidental removal.
• Related to prolonged use: urethral trauma, encrustation, obstruction, discomfort, other urinary tract complications.

37. Accidental removal with the balloon inflated

It can cause urethral injury and bleeding. We must not blindly reinsert the same catheter or assume that no injury occurred. We must:

• evaluate the patient;
• assess the bleeding;
• consider urethral injury;
• request urologic evaluation when appropriate.

38. Catheter removal

Before removing it, we must confirm that the indication no longer exists. The balloon is completely deflated before gently withdrawing the catheter. Afterward we should observe:

• whether the patient recovers spontaneous voiding;
• time to voiding;
• symptoms;
• voided volume when appropriate;
• postvoid residual if indicated.

39. Trial without catheter

In certain patients, the catheter is removed to check whether they can urinate spontaneously again. We then assess:

Did they void? → How much? → Do they have symptoms? → Is there a significant postvoid residual?

Ultrasound/bladder scanner can be very useful to assess bladder volume without performing an unnecessary repeat catheterization. The CDC specifically contemplates the use of bladder ultrasound as a strategy to reduce unnecessary catheterizations.

Patient who is not urinating

1. Is the bladder full?

History + exam + bladder scan/ultrasound when available.

2. Distended bladder

Think of urinary retention.

3. Is there a contraindication or suspicion of urethral injury?

• No: consider urethral catheterization.
• Yes / doubt: do not make traumatic attempts → request evaluation.

4. If catheterization is performed

Atraumatic technique + lubrication + appropriate catheter.

5. Does it pass easily?

• Yes: confirm position → balloon → closed system → securement.
• No: do not force → reassess / ask for help.