Editing Nursing Skills and Procedures (section)

=== Indications and anatomy ===
A straight or intermittent catheter drains the bladder once, obtains a sterile specimen, or measures residual urine. An indwelling Foley catheter provides continuous drainage for acute urinary retention, bladder outlet obstruction, accurate output measurement in critical illness, perioperative need, and comfort in end of life care. Indwelling catheters are not appropriate for incontinence alone or for staff convenience, because every catheter day increases catheter-associated urinary tract infection risk. A condom or external catheter is the safer alternative for male incontinence, and external female pouch devices exist as well.

The female urethra is about 3 to 4 cm long. The male urethra is about 18 to 20 cm and curves, which is why the penis is held perpendicular to the body with gentle traction during insertion.