In medicine, a catheter is a tube that can be inserted into a body cavity duct or vessel. Catheters thereby allow drainage or injection of fluids or access by surgical instruments. The process of inserting a catheter is catheterization. In most uses a catheter is a thin, flexible tube: a "soft" catheter; in some uses, it is a larger, solid tube: a "hard" catheter.

The ancient Egyptians are reported to have fashioned catheters from papyrus, and the ancient Greeks from reeds. A flexible urinary catheter was invented by Benjamin Franklin for the use of his brother.

Placement of a catheter into a particular part of the body may allow:

• draining urine from the urinary bladder as in urinary catheterization, i.e. Foley catheter or even when the urethra is damaged as in suprapubic catheterisation. By comparison, a Texas catheter is not inserted into the urethra, but connects to the penis via a condom-like envelope with a drainage tube at its tip.
• drainage of fluid collections, e.g. an abdominal abscess
• administration of intravenous fluids, medication or parenteral nutrition
• angioplasty, angiography, balloon septostomy, balloon sinuplasty
• direct measurement of blood pressure in an artery or vein
• direct measurement of intracranial pressure
• administration of anaesthetic medication into the epidural space, the subarachnoid space, or around a major nerve bundle such as the brachial plexus

A central venous catheter is a conduit for giving drugs or fluids into a large-bore catheter positioned either in a vein near the heart or just inside the atrium. A Swan-Ganz catheter is a special type of catheter placed into the pulmonary artery for measuring pressures in the heart.

See also

• cannula
• stent
• french catheter scale chart
• urinary catheterization

medical equipment

Katheter | Catéter | Cathéter | צנתר | Katheter | カテーテル | Kateter | Katetri | Kateter