Flexural and torsional rigidity of colonoscopes at room and body temperatures

A series of experiments have been conducted to determine the flexural and torsional rigidity of an Olympus colonoscope CF-140S and torsional rigidity of a Pentax colonoscope EC-3870 and the dependency of these properties on temperature and on the presence of loops. Along the length of the colonoscope, the flexural rigidity of the Olympus colonoscope varied between 260 and 400Ncm2 and the torsional rigidity varied between 68 and 88Ncm2/deg, with an average of 76Ncm2/deg for tests involving 0.86Nm of anticlockwise torque. Results show a significant decrease of 10 per cent in torsional rigidity between clockwise and anticlockwise torque. For the Pentax colonoscope flexural rigidity was not tested; its torsional rigidity varied between 34 and 76Ncm2/deg, with an average of 46Ncm2/deg for tests involving 0.43Nm of anticlockwise torque. An increase in temperature of the Olympus colonoscope from 24 to 37 uC reduced the flexural rigidity by an average of 17 per cent and torsional rigidity by an average of 7 per cent. A right-handed loop caused a significant increase in flexural rigidity, but other looping configurations had no significant influence.