Endoscope-induced colitis: description, probable cause by glutaraldehyde, and prevention.

Six cases of acute, self-limited colitis that occurred after screening flexible sigmoidoscopy were deduced to be iatrogenic, probably caused by glutaraldehyde residues in the endoscopes after disinfection in an automatic disinfecting machine. The concentration of these residues was indirectly estimated by conductivity measurements of electrolyte concentration in the rinse-water tank of the disinfecting machine during and after five cycles and also in fluid remaining on the surface of the endoscopes and in the endoscope channels. After five cycles, residues in both the rinse water and fluid in the endoscope channels contained the equivalent of 0.2% glutaraldehyde. This was the result of a combination of technical and human errors. It can be prevented by changing the rinse water after each cycle, using forced air to dry the instruments, and washing the endoscopes before use. Users of the automatic disinfecting machine should be aware of the potential accumulation of toxic levels of residues that remain in endoscopes after disinfection.