Should colonoscopy be the first investigation for colonic disease?

SIR,-In the study by Dr D C Lindsay and colleagues the fact that only 36% of barium enema examinations were considered to be complete is disturbing. Could this be related to the preparation technique, in which the barium examination was done immediately after the cleansing enema although this goes against the recommendation that at least one hour should elapse to allow residual water to be resorbed by the colon, thus allowing optimal mucosal coating?' Perhaps it would have been helpful to have had the direct cooperation of a radiologist in this study rather than physicians alone assessing the adequacy ofthe barium enema by reviewing the films and the radiologist's report. The authors stated that patients aged under 40 in whom the expectation of disease was low were excluded from the study, yet patients as young as 19 and 20 years of age were included in both the study groups. It would be interesting to know whether subjective or objective methods were useds to predict the presence or absence of disease. There were 29 patients in whom the barium enema examination was considered incomplete and yet in whom the "exclusion of gross disease was thought to preclude the need for further large bowel investigation." It would be interesting to know whether polyps were considered to be gross disease or to be excluded by an incomplete examination. GRAHAM WILSON