Catheter
Long, thin rubber/plastic tube that can be placed into a blood vessel to deliver contrast media for angiographies, or other drugs or miniaturised instruments to almost any part of the body. Other types of catheters are used to drain fluids (urine, puss) from body cavities. Catheters often have special shapes to facilitate positioning of the catheter in the target artery. Most catheters will have a cross-section of 1.2 - 3 mm (4 - 10 F) but thinner and thicker diameters are used. To position the catheter a guide wire is used. Catheters are regarded as a foreign body in the blood stream. The body will therefore try to isolate it, initially by covering the catheter with fibrin. Various methods of coating catheters have been developed to delay or avoid this process. Blood will flow backwards into the catheter during catheterisation. This blood can clot if left inside the catheter too long and should be removed by frequent flushing of the catheter.
GE Healthcare Glossary