Which is why, we made the process easy for you to choose the right catheter. There are several factors included in selecting a urinary catheter-like catheter type, catheter tip, catheter size, and measuring the risk of UTI or urinary tract infections.Catheterization is the process of catheter insertion. Urinary catheters are specifically used to remove or deliver fluids to or from the body, usually entering the bladder. Catheters are made up of silicon, plastic, rubber, or vinyl. They are usually in inches or centimeters, manufactured in widths commonly labeled in French sizes, and lengths.