Response to Letter

TO THE EDITOR: In the paper by Aslinia et al. (1), Table 1 shows a significant increase in the use of thinner colonoscopes during the 6-yr period. This may be due to their greater use on female patients whose distal colons can be difficult to navigate. Use of thinner colonoscopes, which can help navigate these difficult distal colons, may also explain the increasing completion rate over the study period. However, a new problem proximally may be encountered. Our study examining predictors of difficult colonoscopies performed with an adult colonoscope observed that predictive factors for female patients included older age, diverticulosis, and a low body mass index (BMI) (2). We also retrospectively studied 2,000 patients, and observed that when using the adult scope, female patients were more likely to have incomplete colonoscopies arrested in the distal colon (3). This was especially pronounced in thinner female patients (BMI <25). Marshall et al. compared the adult versus pediatric colonoscope in women with hysterectomies (4). They observed that while the use of the adult colonoscope was associated with incomplete colonoscopies halted in the distal colons of female patients, the pediatric colonoscope was associated with a higher rate of completion. Unfortunately the greater flexibility of a thinner colonoscope is associated with greater looping due to the loss of column strength compared with a thicker colonoscope (5). Aslinia et al. observed that women were more likely than men to have the incomplete colonoscopy terminated in the sigmoid colon, but there are no data regarding 6-yr trends. We suspect that due to the greater use of thinner colonoscopes, the percentage of procedures terminated in the distal versus the proximal colon decreased in their female patients during the 6-yr period. Our clinical experience is that women who are thin, older, have diverticular disease, or a combination of these factors, can be difficult to perform colonoscopy with an adult colonoscope. A thinner scope is beneficial in the distal colon, but a redundant colon can cause problems proximally. Whereas the watershed area for colonoscopy in female patients in the past has been the distal colon, the new challenging portion of the colon is the proximal portion. Olympus (Tokyo, Japan) has developed a tapered, prototype colonoscope that combines the distal flexibility of a pediatric colonoscope with the proximal column strength of the adult colonoscope. Our recent data demonstrate a decrease in looping as well as a diminished time required for cecal intubation when using this prototype as compared with the pediatric variable stiffness colonoscope (6).