Obstruction of the appendix lumen in relation to pathogenesis of acute appendicitis

The role of obstruction of the pathogenesis of acute appendicitis was studied by measuring the pressure in the appendix peroperatively in 33 patients undergoing appendectomy because of suspected acute appendicitis. The technique involved insertion of a fine needle via the apex into the lumen of the appendix and measurement of the hydrostatic pressure required to inject a saline solution. In all six patients with gangrenous appendix and in two patients with phlegmonous appendix there were signs of obstruction of the appendix lumen expressed as raised intraluminal pressure. In 19 patients found at operation to have phlegmonous appendix there were no signs of obstruction. The experimental data suggest that obstruction is not an important factor in the causation of acute appendicitis, but may develop as a result of the inflammatory process.