Negative appendectomy: a 10-year review of a nationally representative sample

Appendectomy remains one of the most common emergency surgical procedures encountered throughout the United States. With improvements in diagnostic techniques, the efficiency of diagnosis has increased over the years. However, the entity of negative appendectomies still poses a dilemma because these are associated with unnecessary risks and costs to both patients and institutions. This study was conducted to show current statistics and trends in negative appendectomy rates in the United States.

A retrospective analysis was conducted using data from the National Inpatient Sample from 1998 to 2007. Adult patients (>18 y) having undergone appendectomies were identified by the appropriate International Classification of Diseases 9th revision codes. Patients with incidental appendectomy and those with appendiceal pathologies, also identified by relevant International Classification of Diseases 9th revision codes, were excluded. The remaining patients represent those who underwent an appendectomy without appendiceal disease. The patients then were stratified according to sex, women were classified further into younger (18-45 y) and older (>45 y) based on child-bearing age. The primary diagnoses subsequently were categorized by sex to identify the most common conditions mistaken for appendiceal disease in the 2 groups.

Between 1998 and 2007, there were 475,651 cases of appendectomy that were isolated. Of these, 56,252 were negative appendectomies (11.83%). There was a consistent decrease in the negative appendectomy rates from 14.7% in 1998 to 8.47% in 2007. Women accounted for 71.6% of cases of negative appendectomy, and men accounted for 28.4%. The mortality rate was 1.07%, men were associated with a higher rate of mortality (1.93% vs .74%; P < .001). Ovarian cyst was the most common diagnosis mistaken for appendicitis in younger women, whereas malignant disease of the ovary was the most common condition mistaken for appendiceal disease in women ages 45 and older. The most common misdiagnosis in men was diverticulitis of the colon.

There has been a consistent decline in the rates of negative appendectomy. This trend may be attributed to better diagnostics. Gynecologic conditions involving the ovary are the most common to be misdiagnosed as appendiceal disease in women.