Catheterization is a medical procedure in which a thin, flexible tube called a catheter is inserted into the body to drain fluid, deliver medication, or diagnose a condition. The two most common types are urinary catheterization, which drains urine from the bladder, and cardiac catheterization, which allows doctors to examine and treat heart problems. While the word sounds intimidating, most catheterization procedures are routine, low-risk, and performed millions of times each year.
Urinary Catheterization
A urinary catheter is a thin rubber or plastic tube placed into the bladder to drain urine when you can’t empty your bladder on your own. This might happen after surgery, during a hospital stay when you’re immobilized, or because of a condition that blocks or weakens normal urination. There are three main approaches, and which one you get depends on how long drainage is needed and your specific medical situation.
An intermittent catheter is the simplest type. It’s a single-channel tube inserted through the urethra, used to empty the bladder, and then removed right away. People who need this type typically use it several times a day on a schedule. It carries the lowest infection risk of the three options because it doesn’t stay in the body between uses.
An indwelling catheter, most commonly called a Foley catheter, stays in place for continuous drainage. It enters through the urethra and has two internal channels: one that drains urine into a collection bag, and another that inflates a small balloon inside the bladder to hold the catheter in position. Foley catheters should be changed about once a month. Some patients need a three-way version that allows fluid to be flushed through the bladder while still draining.
A suprapubic catheter is a third option. Instead of going through the urethra, it enters the bladder through a small incision in the lower abdomen. Placement requires a minor surgical procedure, but suprapubic catheters tend to be more comfortable for long-term use, especially for men. They’re easier to change, interfere less with sexual activity, and are generally preferred by people who use wheelchairs. They also carry a somewhat lower risk of urinary tract infections compared to urethral catheters when drainage is needed for more than five days.
Cardiac Catheterization
Cardiac catheterization is a very different procedure that shares only the concept of threading a thin tube into the body. In this case, a catheter is guided through a blood vessel, usually in the wrist or groin, and advanced to the heart. It serves both as a diagnostic tool and, in many cases, a way to treat problems at the same time.
On the diagnostic side, cardiac catheterization lets doctors measure blood pressure and oxygen levels inside the heart’s chambers, take small tissue samples for biopsy, and inject a contrast dye that makes blood vessels visible on X-ray (a process called angiography). It’s often used to confirm or clarify results from other imaging tests like echocardiograms or cardiac CT scans, and to evaluate patients before heart surgery or transplant. Conditions it can help diagnose include coronary artery disease, heart valve problems, heart muscle disease, and irregular heart rhythms.
On the treatment side, doctors can perform several interventions through the same catheter. The most common is opening a narrowed or blocked coronary artery using a tiny balloon (angioplasty), often followed by placing a small mesh tube called a stent to keep the artery open. They can also widen narrowed heart valves, treat certain abnormal heart rhythms by destroying small areas of misfiring tissue, and repair some congenital heart defects.
What the Procedures Feel Like
For urinary catheterization, the insertion involves brief discomfort or a pressure sensation as the tube passes through the urethra. A numbing gel or lubricant is applied beforehand to reduce pain. Once in place, a Foley catheter can cause an ongoing urge to urinate, but this usually fades. For suprapubic placement, local anesthesia numbs the incision site on the abdomen.
Cardiac catheterization is more involved but still not considered surgery. You’re typically awake but sedated. Local anesthetic numbs the insertion site at the wrist or groin, and sedatives help you relax throughout the procedure. You may feel pressure when the catheter is inserted, and a brief warm, flushing sensation when contrast dye is injected. The procedure usually takes 30 minutes to an hour for diagnostic purposes, though interventional procedures like stent placement can take longer.
Risks and Complications
The most common risk with urinary catheters is infection. Catheter-associated urinary tract infections are among the most frequent hospital-acquired infections. In intensive care settings, roughly 9 out of every 100 patients with a catheter develop one. The risk increases the longer the catheter stays in place, which is why doctors aim to remove them as soon as they’re no longer needed. Intermittent catheterization and suprapubic catheters both carry lower infection rates than standard indwelling urethral catheters for longer-term use.
Cardiac catheterization is remarkably safe for a procedure that involves the heart. The risk of a major complication during a diagnostic procedure is less than 1%, and the mortality risk is about 0.05%, or roughly 1 in 2,000. The most common issue is a reaction to contrast dye, which occurs in up to 1% of patients and is usually mild. Kidney stress from the dye is more common, affecting roughly 7% of patients undergoing coronary intervention, particularly those with pre-existing kidney problems. Stroke risk is low at 0.05% to 0.1% for diagnostic procedures. When access is through the wrist, there’s about a 5% chance of temporary blockage in the artery used for insertion, though this rarely causes lasting problems.
Preparation and Recovery
Urinary catheterization requires little preparation. If you’re having a suprapubic catheter placed, you may receive instructions similar to those for minor surgery. For routine Foley or intermittent catheter placement, no special prep is needed on your part.
Cardiac catheterization traditionally requires fasting beforehand, though the specifics vary. Some hospitals ask you to stop eating and drinking at midnight the night before, while others allow clear liquids up to two hours prior. The fasting requirement comes from older surgical guidelines about preventing vomiting during procedures, and practices are gradually shifting as newer evidence suggests strict fasting may not be necessary for most catheterization patients. Your care team will give you specific instructions, including whether to adjust any medications you take.
After urinary catheter removal, the bladder and urethra need a couple of days to regain normal strength. During that time, you shouldn’t strain to urinate. Pelvic floor exercises, started about three days after removal, help rebuild bladder control. Some temporary leaking or urgency is normal.
Recovery from cardiac catheterization is typically quick. If the catheter was inserted at the groin, you’ll need to lie flat for several hours afterward to prevent bleeding at the puncture site. Wrist access allows you to sit up sooner. Most people go home the same day or the next morning and can return to normal activities within a few days, though heavy lifting is usually restricted for about a week. A small bruise at the insertion site is common and resolves on its own.