Imaging for Suspected Appendicitis - American Family Physician

of-recommendation labels. A ppendicitis remains the most common acute surgical condition of the abdomen. In 1997, more than 260,000 new cases occurred in the United States. The overall lifetime occurrence is approximately 12 percent in men and 25 percent in women.1-3 Because abdominal pain is a common presenting complaint in the outpatient setting, family physicians serve an important role in the rapid diagnosis of acute appendicitis. Accurate and timely diagnosis of acute appendicitis is essential to minimize morbidity. Prompt surgical treatment may reduce the risk of appendix perforation. The case-fatality rate of appendicitis jumps from less than 1 percent in nonperforated cases to 5 percent or higher when perforation occurs.4 The diagnosis of appendicitis traditionally has been based on clinical features found primarily in the patient’s history and physical examination.5 An elevated white blood cell count has a low predictive value for appendicitis because it is present in a number of conditions.6 While the clinical diagnosis of appendicitis may be straightforward in patients with classic signs and symptoms, atypical presentations can result in delays in treatment, unnecessary hospital admissions for observation, and unnecessary surgery. Unnecessary surgery for suspected appendicitis exposes patients to increased risks, morbidity, and expense. In 1997, 261,134 patients underwent nonincidental appendectomies in the United States. However, 39,901 (15.3 percent) of the appendixes removed showed no pathologic features of appendicitis.1 Diagnostic accuracy achieved by history and physical examination has remained at about 80 percent in men and women (men are diagnosed accurately 78 to 92 percent of the time, and women 58 to 85 percent of the time).5 Recently, imaging techniques such as ultrasonography, computed tomogAcute appendicitis is the most common reason for emergency abdominal surgery and must be distinguished from other causes of abdominal pain. Family physicians play a valuable role in the early diagnosis and management of this condition. However, the overall diagnostic accuracy achieved by traditional history, physical examination, and laboratory tests has been approximately 80 percent. The ease and accuracy of diagnosis varies by the patient’s sex and age, and is more difficult in women of childbearing age, children, and elderly persons. If the diagnosis of acute appendicitis is clear from the history and physical examination, prompt surgical referral is warranted. In atypical cases, ultrasonography and computed tomography (CT) may help lower the rate of false-negative appendicitis diagnoses, reduce morbidity from perforation, and lower hospital expenses. Ultrasonography is safe and readily available, with accuracy rates between 71 and 97 percent, although it is highly operator dependent and difficult in patients with a large body habitus. While there is controversy regarding the use of contrast media and which CT technique is best, the accuracy rate of CT scanning is between 93 and 98 percent. Disadvantages of CT include radiation exposure, cost, and possible complications from contrast media. (Am Fam Physician 2005;71:71-8. Copyright© 2005 American Academy of Family Physicians.) Imaging for Suspected Appendicitis