Lymphoid hyperplasia narrows the lumen of the appendix, leading to luminal obstruction. Once obstruction occurs, con- tinued mucus secretion and inflammatory exudation increase intraluminal pressure, obstructing lymphatic drainage. Oedema and mucosal ulceration develop with bacterial trans- location to the submucosa. Resolution may occur at this point either spontaneously or in response to antibiotic therapy. If the condition progresses, further distension of the appendix may cause venous obstruction and ischaemia of the appendix wall. With ischaemia, bacterial invasion occurs through the muscularis propria and submucosa, producing acute appendi- citis (Figure 72.7). Finally, ischaemic necrosis of the appen- dix wall produces gangrenous appendicitis, with free bacterial contamination of the peritoneal cavity.