adj. plainly to be seen or detected: applied to diseases with observable signs and symptoms, as opposed to those whose presence may not be suspected for years despite the fact that they cause insidious damage. An infectious disease becomes overt only at the end of an incubation period.
n. a semirigid plastic tube (25–45 cm long) designed to fit over the shaft of an *endoscope in order to minimize the risk of trauma. It can be used with a *gastroscope, *cholangioscope, *enteroscope, or colonoscope (see colonoscopy). An overtube is 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 into position over the shaft. It is commonly used in combination with a gastroscope for the removal of ingested foreign bodies (especially those with sharp or serrated edges that may cause significant trauma as they are being extracted).... overtube
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