What is the size of a Foley catheter for men?

• A. 16-18
• B. 14-16
• C. 18-20
• D. 12-14

Answer: (A)

Foley catheter sizing in adult men centers on balancing drainage efficiency with minimizing urethral trauma. Catheter size is given in French units, where 1 French is about 0.33 mm in outer diameter. For adult men, a range of 16 to 18 French provides enough lumen to allow reliable urine drainage and reduce clogging, while keeping the size small enough to minimize irritative trauma to the urethra. A smaller size (like 12–14 Fr) can occlude more easily and may require more effort to drain, increasing obstruction risk. A larger size (like 18–20 Fr) raises the chance of urethral injury, discomfort, and tissue trauma unless there is a specific indication such as heavy bleeding or the need for irrigation. Therefore, 16–18 Fr is the standard choice for routine adult male catheterization.