Understanding Urinary Catheters: Uses, Types, Sizing, and What to Expect

If your loved one is being discharged with a urinary catheter, understanding the basics makes home care significantly more manageable. Let’s go over the different types of catheters, why they’re needed, how they are sized, and what family caregivers should watch for once care begins at home.

What are Urinary Catheters?

A urinary catheter is a thin, flexible tube used to collect urine. They are most commonly inserted into the bladder through the urethra (where urine exits the body). Typically, catheters are used when the body can’t drain urine in a controlled manner or at all, which might be because of:

• injury
• surgery
• urinary obstruction
• acute retention
• severely limited mobility
• nerve damage or neurological disorder
• unexplained incontinence
• any condition affecting bladder function

In some cases, urinary catheters are used to instill fluid or medications directly into the bladder rather than drain it. Bladder irrigation, for example, uses a catheter to flush the bladder with fluid to clear blood clots or debris. Likewise, in bladder cancer treatment, a catheter is used to deliver chemotherapy directly into the bladder. 

Most urinary catheters share the same basic components:

• Catheter tubing: the flexible tube that gets inserted into the bladder through the urethra or, in some cases, through the abdominal wall; it is typically made of medical-grade materials such as silicone, latex, or vinyl

• Insertion tip: the last inch of the catheter tubing that enters the bladder itself; the shape of this tip varies by catheter type, including straight, curved, or balloon-tipped
• Drainage eyelets: small holes on the tip that allow urine to flow into the tube and out of the bladder
• Balloon: on an indwelling catheter, the tip has a small balloon that is filled with sterile water to hold the catheter in place for extended periods of time
• Drainage port or connector: the external end of the catheter tubing that can be used as a simple drainage port (for intermittent catheterization) or can be used to connect to the collection bag (for indwelling catheters)
• Collection bag: the bag used to collect urine, which is also called a drainage bag

What are the Different Types of Urinary Catheters?

1. Indwelling Urinary Catheter 

An indwelling catheter, often called a Foley catheter, is a type of catheter that remains in place for extended periods of time. It is held in place in the bladder by a small, water-filled balloon that is inflated after insertion. If it is necessary to remain in place for many months or longer, Foley catheters should be replaced every 30 days to reduce the risk of catheter-associated urinary tract infections (CAUTIs).

There are two different ways a Foley catheter can reach the bladder:

• Urethra: The standard approach is to insert the Foley catheter through the urethra, which is the most common type of indwelling catheter used during a hospital stay.
• Suprapubic: A less common approach is to surgically insert the Foley catheter through a small incision in the lower abdomen, bypassing the urethra entirely. It is used when urethral access is not possible due to injury, obstruction, or anatomy.

While the indwelling catheter is in place, it drains continuously into a collection bag, so you never have to urinate on your own. During the day, more mobile people can use a smaller collection bag that straps around their leg and stays tucked under their clothing. At night, the smaller leg bag is typically swapped for a larger bag to accommodate higher volumes while sleeping.

2. Intermittent Urinary Catheter 

Unlike an indwelling urinary catheter, an intermittent catheter isn’t left in place. It’s inserted on a schedule, typically every four to six hours, to drain the bladder and is then removed immediately. This approach can be used any time the bladder cannot empty fully on its own, regardless of the cause. Regular, intermittent catheterization keeps bladder pressure low, reduces the risk of CAUTIs, and prevents long-term damage to the bladder and kidneys.

You may notice that the process for intermittent catheterization looks a little different at home than it does in a clinical setting. That’s because there are two distinct approaches to how it’s done:

• Aseptic technique is the method healthcare providers use in hospitals and clinical settings. It requires fully sterile equipment designed to eliminate the risk of contamination from the environment.
• Clean technique is the method patients and family caregivers use at home. It focuses on thorough handwashing and careful handling of the catheter to minimize bacterial exposure, rather than eliminate it entirely. 

The clean technique you’ll use at home is still considered safe and appropriate. With proper training, you’ll be able to manage intermittent catheterization on your own. But when that’s not possible (or if you feel like you could use additional education), you can hire a home nurse to assist with this procedure until you feel comfortable and confident to do it yourself.

3. External Urinary Catheter 

An external urinary catheter is a noninvasive approach to managing urinary incontinence that does not involve inserting anything into the body. As a result, the risk of CAUTIs is significantly lower than with indwelling or intermittent catheterization. However, consistent hygiene and proper fit are necessary to minimize prolonged contact with urine that can cause infection or skin irritation and breakdown.

The two most common options for external urinary catheters are:

• Condom catheters fit over the penis, held in place with an adhesive, and connect to a drainage bag. 
• Wicking devices work by drawing urine away from the body through absorbent material connected to a drainage bag. 

External urinary catheters are generally the easiest to manage at home, but they are only appropriate when the bladder is still emptying on its own. If retention is an issue, an indwelling or intermittent catheter is a better choice. 

How are Indwelling and Intermittent Urinary Catheters Sized?

Both indwelling and intermittent urinary catheters are sized using the French (Fr) scale, which measures the outer diameter of the tube. As the number increases, the catheter becomes larger. The scale ranges from 6 Fr, used in pediatrics, to 30 Fr, used in specialized clinical situations such as bladder irrigation or clot drainage. For most adults, a 14 Fr urinary catheter is most commonly used. 

Catheter size can vary based on anatomy, the reason for catheterization, and the care team’s clinical judgment. Using the right catheter size is important because a catheter that is too small may not drain effectively, while one that is too large can cause unnecessary discomfort. 

In addition to size, catheters also come with different tip styles. The two most common are:

• Straight tips are, as the name suggests, straight and smooth. It is also the standard option for catheters. 
• Coudé tips have a slight upward curve at the end, designed to navigate around obstructions in the urethra, such as an enlarged prostate.

Keep in mind that what works for one patient may not be appropriate for another, and neither the size nor the tip style should ever be adjusted without guidance from your care team.  

What to Expect as a Family Caregiver

Once a urinary catheter is in place, urine should drain continuously into the collection bag. Normal urine should be pale yellow to amber in color and relatively clear. The output of most adults ranges roughly from 800 to 2,000 milliliters per day. Output will naturally decrease with dehydration and increase after fluids, so hydration level is always worth considering before assuming something is wrong. 

Managing urinary catheters at home can be challenging, especially if you don’t know what to watch for or what to do if something goes wrong. Here are some things to watch for as you provide care to your loved one: 

• Bypassing the catheter: may be a sign of blockage, bladder spasms, or incorrect sizing
• Little to no output: may be a sign of dehydration or the catheter is kinked, blocked, or dislodged
• Cloudy or dark urine: may be a sign of dehydration, infection, or sediment building up
• Strong or unusual odor: may be a sign of infection
• Blood in the urine: pink-tinged urine after placement is common; bright red urine or visible clots are not
• Fever: may be an early indicator of infection; any fever in someone with a catheter should be reported to the care team

Catheter-associated urinary tract infections are one of the most common complications of catheter use, but also one of the most preventable. While recognizing these red flags is important, the most vital step you can take is learning how to stop infections before they even start.

Getting the Support You Need at Home

Choosing the right type of catheter is a clinical decision made in consultation with your care team and depends on your diagnosis, anatomy, and long-term care goals. If you're navigating catheter care and could use experienced support, Navi Nurses provides concierge nursing services for families in the Phoenix area. Contact us at 480-482-1891 or navinurses.com/contact to learn more.