Magnetic Endoscope Imaging (MEI) is an optional tool which can be switched on at the beginning of colonoscopy. MEI works by creating an electromagnetic field of very low intensity. By that the position of the endoscope can be displayed virtually on a monitor. The use of MEI has been shown to reduce the formation of loops and to ease the removal of existing loops during the investigation. Furthermore, as loops favour the occurrence of pain when the scope is moved forward, patients who underwent colonoscopy with MEI reported less pain at the end of the procedure.

Sedation is used widely during colonoscopy for it has improved the tolerability of the investigation. Most of the patients demand for sedation. In Germany Propofol is recommended as the first-line sedative when endoscopy it is performed in an outpatient setting. The use of Propofol involves the danger of respiratory complications. One reason for the application of Propofol doses is the occurrence of pain during the investigation. We hypothesized that if MEI is used and if loops can be avoided sufficiently lower Propofol doses would be needed. We therefore planned this prospective controlled trial.

Inclusion Criteria:

• medical indication for colonoscopy
• age >18 years
• written consent given by patient
• investigation under sedation with propofol

Exclusion Criteria:

• application of any other sedative than propofol
• age < 18 years
• pregnant women
• patients denying written consent
• ASA class IV, V and VI
• indication for colonoscopy: emergency (e.g. severe rectal bleeding)
• allergy to propofol
• pre-existing hypotension, bradycardia or hypoxemia
• history of sedation accidents