Appendicitis and appendectomies among non-service member beneficiaries of the Military Health System, 2002-2011.

Among non-service member beneficiaries of the Military Health System, there were 79,820 cases of appendicitis and 98,385 appendectomies during 2002 to 2011; from the fi rst to last year of the period, the annual number of appendicitis cases increased by 61.1 percent. Perforated acute appendicitis occurred in one quarter of all cases; the proportion of perforated cases was higher among males (30.2%) than females (23.3%). The annual number of total appendectomies decreased during the period; however, outpatient appendectomies increased 5-fold. Th e proportion of inpatient appendectomies that were incidental was greater in females (15.6%) than males (8.8%). During the period, the number of nonincidental appendectomies that were not associated with diagnoses of appendicitis ("negative appendectomies") decreased by 65 percent, and the mean number of inpatient bed days per appendicitis case decreased by one day (21.1%). The findings likely reflect more frequent uses of and advances in diagnostic imaging to detect and characterize appendicitis and a shift in surgical treatment to the outpatient setting with increasing use of laparoscopy for appendectomies.