Colonoscopy aided by magnetic 3D imaging: is the technique sufficiently sensitive to detect differences between men and women?

Colonoscopy tends to be more difficult to perform in women. Women also experience more pain during flexible sigmoidoscopy, and the mean insertion distance of the instrument is less than in men. The 'Bladen system', first described in 1993, is a non-radiological method of continuously visualising the path of the endoscope using magnetic drive coils under the patient and a chain of sensors up the biopsy channel of the instrument. In 1998, results were published that used a novel computer graphics system (the 'RMR system'), in which a much more realistic endoscope could be produced using the stored positional data from the Bladen system. The RMR computer graphics system has been further refined to enable measurement of the anatomical lengths of different parts of the large intestine to an accuracy of greater than 5mm. The system is used to analyse the results obtained in 232 patients undergoing a total colonoscopy. In women, the colonoscope tends to form loops in the sigmoid colon more readily than in men (p < 0.05). When the first 50cm of the endoscope are inserted for the first time, the tip passes either up to or beyond the splenic flexure in 40/116, or 34.5%, of males, compared with 24/117, or 20.5%, of females (p = 0.0137). It is demonstrated that women have longer transverse colons than men, and the differences are especially apparent when a stiffening tube is used to splint the left side of the colon (p < 0.0001). The possible relevance of these observations to biomedical engineers and those manufacturing and assessing prototype endoscopes is discussed.