The plain abdominal radiograph in the assessment of constipation

To investigate the value of the plain abdominal radiograph in the assessment of constipation we prospectively studied 30 patients (20 females, 10 males, mean age 48.6 years, range 21-76 years). These patients underwent the following tests: plain abdominal radiograph in supine position, measurement of stool weight (mean of 5 days) and whole gut transit time (20 radioopaque pellets, fluoroscopy of stools). All patients completed a questionnaire regarding their defaecation characteristics (a.o. average defaecation frequency and faecal consistency). The abdominal films were coded and independently scored for the degree of faecal stasis in ascending, transverse, descending colon and rectosigmoid by four gastroenterologists. To each of these parts of the colon a score of 1 (no faeces) to 4 (loaded with faeces) was assigned. The film scores given by the four observers were significantly correlated (p less than 0.001). Significant correlations were found between the radiograph scores and frequency of defaecation, faecal consistency and stool weight. The strength of these correlations were of the same order of magnitude as those between the other subjective and objective defaecation variables. The scores for the left colon (descending colon and rectosigmoid) showed a better correlation with the other defaecation parameters than the scores for the right colon. It is concluded that in the assessment of constipation a simple plain abdominal radiograph is as reliable as measurement of faecal weight or marker transit and can thus be advocated as the first procedure. When an abdominal radiograph is used for this purpose the stasis in the descending and sigmoid colon provides most information.