Origin of acute appendicitis: fecal retention in colonic reservoirs: a case control study.

BACKGROUND

Appendicitis is encountered predominantly in Western, industrialized countries. Animal experiments and clinical studies have suggested an obstructive fecalith as a cause of acute appendicitis. It was hypothesized that patients with acute appendicitis would have a longer colonic transit time and more fecal retention reservoirs (coprostasis) than healthy control persons, thus favoring the occurrence of a fecalith in the appendix.

METHODS

Sixty-eight patients scheduled for appendectomy were included in this approved study. Before surgery, a plain abdominal radiograph was taken; at surgery, the degree of inflammation of the appendix was recorded, along with the presence or absence of a fecalith. Six weeks postoperatively, the patients underwent a colonic transit study. A cohort of 44 control persons over 18 years of age was selected at random to undergo the same marker study as the patients. The parameters studied were the number of radiopaque markers (h), the fecal retention or load (score 0-3) in the right, left, and distal colonic segments, and the number of fecaliths.

RESULTS

Twelve patients were excluded; i.e., 56 patients and 44 controls were eligible for most analyses. In the patient group, statistically significant correlations were found between fecal loading scores and the number of markers (transit time) both overall and within the left and distal colonic segments (all p < 0.05). In the control subjects, there was significance with regard to the distal segment. The median colon transit time was 25.0 h (range 1-107 h) in patients with appendicitis compared with 19.0 h (range 0-71 h) in controls (p = NS). The transit time was longer in the right, left, and distal colon in patients than in control subjects, although not to a statistically significant extent. The total and segmental fecal loads in the colon did not differ significantly between patients and controls. A fecalith occurred in 49.0% of the patients and was in most cases associated with a gangrenous or perforated appendix. If a fecalith was not found, this correlated to a significant extent with a high fecal loading score in the left colon (p = 0.04).

CONCLUSIONS

An obstructive fecalith occurred in one-half of the patients with acute appendicitis. The appendicitis patients had a colonic transit time similar to that in healthy controls. Furthermore, there was no difference in colonic fecal loading between patients and controls. In consequence, the occurrence of a fecalith could not be attributed to delayed colonic transit or fecal loading. However, we discovered greater amounts of feces in the colon of both patients and controls than would have been expected physiologically, and the role of these fecal reservoirs has yet to be understood.