Appendicitis and appendectomies, active and reserve components, U.S. Armed Forces, 2002-2011.

Appendicitis is common among young, healthy populations; appendectomy is one of the most common surgical procedures performed in the United States. Among active and reserve component members, there were 31,610 cases of appendicitis and 30,183 appendectomies during 2002 to 2011. The overall incidence rate of appendicitis in the active component was 18.4 per 10,000 person-years (p-yrs). During the period the incidence rates of appendicitis in the active component and counts in the reserve component increased. Active component males reported greater rates of perforated appendicitis (2.6 per 10,000 p-yrs). Active component females had higher rates of incidental appendectomies (2.6 per 10,000 p-yrs). During the period there was a four-fold increase in outpatient appendectomies, a decrease in nonincidental appendectomies without a diagnosis of appendicitis ("negative appendectomies"), and a decrease in inpatient bed days. 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.