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The measurement of forces exerted during colonoscopy
M N Appleyard1, C A Mosse, T N Mills
1Department of Medical Physics, University College London, Royal London Hospital, London, UK.
Background:
The widely varying forces used at colonoscopy have not been measured. An electronic device was designed to measure the forces exerted by the clinician on the endoscope during colonoscopy.
Methods:
The device featured a handle designed in the shape of a hinged split cylinder that could be locked around the endoscope but readily moved up and down the insertion tube as the colonoscopy proceeded. This cylinder contained strain-gauges arranged so that the forces transmitted could be accurately measured. The device recorded the torque forces in addition to the push and pull forces exerted during diagnostic colonoscopy.
Results:
In a series of 21 colonoscopies in 20 patients: peak pushing force = 4.4 kg, pulling force = -1.8 kg, anti-clockwise torque = 1.0 Newton meters, clockwise torque = 0.8 Newton meters. Percentage time force greater than 1 kg = 5%. Peak anal insertion force = 1.8 kg.
Conclusions:
These measurements represent the first accurate measurements of the forces exerted during colonoscopy. Reducing the force during colonoscopy is likely to diminish pain and reduce the risk of perforation. A knowledge of these forces may also help with the design of new instruments and models for teaching or research.