A catheter is a tube currently made of silicone, Teflon, or latex, which can be inserted into the body to allow for the passage of fluids or the administration of medical devices. This process may be used to allow urine drainage from the bladder. This is called urinary catheterization. It may be used to drain fluid which has collected in abdominal abscesses. A catheter may also be used to administer intravenous fluids or medication.

For the past three millennia, different forms of the catheter have been used for a variety of medical conditions. It is believed that ancient Egyptians used catheters made of metal pipes to perform urinary catheterization. Syrians once used reeds to make catheters. Many of these catheters were used to study cadavers, in particular to learn about cardiac valve function. The ancient Greeks used metal to form a hollow tube to be used as a catheter.

Claude Bernard, a French physiologist of the 1800s, experimentally inserted a mercury thermometer into the carotid artery of a horse. He then moved it through the aortic valve, which led to the left ventricle. His goal was to measure the blood temperature of the horse and, because he was successful in doing this, physiologists to this day use catheters to observe cardiovascular blood flow.

Another key player in the development of catheterization for the study of cardiac form and function is Adolph Fick of the later 19^th century. His studies have had a major influence on modern day cardiac procedures.

Modern technology has allowed for the evolution of the catheter into a more effective and less evasive medical tool. A variety of polymers are now used to produce catheters, including latex and silicone rubber. Silicone is often used because it does not react to body fluids or most medical fluids.

The medical community is now aware of the possibility of patient infection when using a catheter, which is easy to keep in control with modern-day sterilization. This includes cleansing the area where the catheter will be used, washing hands before use, and using a thin catheter to prevent harming the urethra.

Fortunately, the evolution of the catheter has provided the medical community and patients with a much more sanitary and efficient medical tool. Catheters are now easily accessible to those in need, and may even be purchased discreetly over the Internet. The flexibility and size of individual catheters also make them extremely portable.