n. a flexible plastic tube (25–45 cm long) designed to fit over the shaft of an endoscope. It is used in cases where multiple introductions of the endoscope are required and also as a stiffening device for the endoscope. It can be used with a gastroscope, cholangioscope, enteroscope, or colonoscope (see colonoscopy). An overtube is usually placed over the shaft of an endoscope prior to its insertion; once the endoscope is in the desired place, the overtube is lubricated and slid in position over the shaft. This then makes removal and reinsertion of the endoscope relatively easy and without significant discomfort to the patient. It is commonly used in combination with a gastroscope for removal of ingested foreign bodies from the oesophagus or stomach.
Subjects: Medicine and Health.