Previous studies have shown that the family members of children with acute appendicitis are more likely than others to have themselves had acute appendicitis. A study in South Carolina (Michael WL Gauderer and colleagues.

) has confirmed this family susceptibility and provided more precise data.

Between April 1996 and July 2000 a total of 166 children (aged 2–19 years) underwent appendicectomy and appendicitis was confirmed histologically in 155. They were compared with 117 children with acute abdominal pain who did not undergo appendicectomy (abdominal pain controls) and 141 children who presented with other conditions without abdominal pain (other condition controls). A history of acute appendicitis in one or both parents was obtained for 36% of the children with appendicitis, 21% of abdominal pain controls, and 14% of other condition controls. The odds ratios for a positive parental history were 2.0 and 3.0 for the appendicitis group compared with the two control groups respectively. Thirteen patients had a sibling who had had acute appendicitis, nine in the appendicitis group and two each in the other two groups (odds ratios again 2.0 and 3.0).

Children with appendicitis were two or three times more likely than hospital controls to have a parent or sibling who had had appendicitis.