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Foley Catheter Size Guide

A Foley catheter is a flexible tube used to drain urine from the bladder. Knowing the range of Foley catheter sizes is critical to ensure the correct size is selected for effective urinary drainage and patient comfort. This guide will cover everything you need to know about Foley catheter sizes, including sizes for males, females, children, and special cases. We also provide a Foley catheter size chart for reference.

What is a Foley Catheter?

A Foley catheter, also known as an indwelling catheter, is inserted into the bladder through the urethra to provide continuous urinary drainage. It is commonly used post-surgery, for urinary retention, or in patients with certain medical conditions that impair normal urination. The original design was created in the 1930s by surgeon Dr. Frederic Foley. This original design was then manufactured by C. R. Bard, who named it after Dr. Foley.

Understanding Foley Catheter Sizes

Foley catheters are sized using the French (Fr) scale, where each unit corresponds to 0.33 millimeters in diameter. The appropriate Foley catheter size ensures comfort and effective drainage without causing trauma to the urethra or bladder.

Foley Catheter Size Chart

For easy identification, Foley catheters are color-coded at the balloon inflation size to indicate their size, however, their size should still be verified. Common Foley catheter sizes range from 6 Fr to 26 Fr, but there are sizes smaller and larger than this common range. See the Foley catheter size chart below.

Foley Catheter Size Chart

Foley Catheter Sizes for Different Demographics

Factors such as the patient's medical condition, anatomy, and the presence of any blockages or strictures determine the appropriate Foley Catheter size and type. The most common sizes used are between 14 Fr and 18 Fr. These sizes balance effective drainage with patient comfort.

Foley Catheter Sizes for Males

Male patients generally use Foley catheter sizes from 14 Fr to 18 Fr. Larger sizes and different types may be necessary for patients with enlarged prostates or other obstructions.

Foley Catheter Sizes for Females

The urethra of the female is shorter, but the diameter is similar between men and women, so the recommended French size is generally the same (between 14 Fr and 18 Fr). In the United States, there is typically no distinction between male and female Foley catheters in terms of sizes. However, smaller length Foley catheters of the same Fr diameter may be common in other countries.

Foley Catheter Sizes for Child

For children and pediatric patients, smaller Foley catheter sizes ranging from 6 Fr to 10 Fr are used. Special considerations must be taken due to the smaller anatomy and increased sensitivity of younger patients.

3-Way Foley Catheter Sizes

A 3-way Foley catheter, used for continuous bladder irrigation, typically comes in sizes 16 Fr to 24 Fr. It has an additional lumen for irrigation fluid, making it slightly larger in diameter.

Foley Catheter Balloon Sizes

The balloon at the tip of the catheter, used to hold it in place inside the bladder, varies in size. Common Foley catheter balloon sizes include 5 ml, 10 ml, and 30 ml. The choice of balloon size depends on the duration of catheterization and patient needs.

Foley Catheter Size Considerations

• Once a catheter is inserted, the elastic tissue in the urethral mucosa will close around the catheter. Therefore, it is important to select the smallest Foley catheter that will effectively drain urine.

• Larger Foley catheters (20+ Fr) are typically used for drainage of blood clots (i.e. hematuria catheters).

• Incorrect sizing can lead to complications such as urethral trauma, bladder spasms, and infection.

• Choosing the right Foley catheter size involves considering patient comfort, the medical condition being treated, and anatomical differences.

Frequently Asked Questions

How to choose Foley catheter size?

To choose a Foley catheter size, consider the patient's age, gender, and condition, referencing the French scale and following your institution’s Foley catheterization guidelines. For reference, the most common Foley catheter size for adults in the United States is 16 Fr.

What are the sizes of Foley catheters?

Foley catheter sizes vary from 6 Fr (2.0 mm) to 26 Fr (8.7 mm), with typical adult sizes between 14 Fr and 18 Fr.

Learn more on the BackTable Urology Podcast

BackTable is a knowledge resource for physicians by physicians. Get practical advice on the Foley Catheter Size Guide and how to build your practice by listening to the BackTable Urology Podcast, reading exclusing BackTable Articles, and following the work of our Contributors.

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