Appendicitis was first described and teported by Reginald H. Fitz [1] at llie 1886 meeting of the Association of American Physicians. Appendicitis is the most frequent cause of acute abdominal pain requiring surgical intervention in the Western world, and appendectomy is the most common abdominal operation performed on an emergency basis annually in this country [2, 3]. The current annual incidence of acute appendicitis is one case per 1,000 population in the United States and 86 cases per every 100,000 persons worldwide [4, 5]. Furthermore, missed appendicitis is one of the most common causes of successful malpractice claims against physicians [6-8].
Despite continued advances in clinical medicine, the diagnosis of acute appendicitis often remains elusive, with as many as 12-30% of patients undergoing unnecessary appendectomy [9]. The classic clinical triad of migrating abdominal pain, right lower quadrant tenderness, and leukocytosis is absent in up to 50% of patients [10]. The currently accepted negative laparotomy rate is 10-15%, but negative laparotomy rates can be much higher in women of child-bearing age [11, 12]. The physicians goal is to expeditiously and accurately confirm or exclude the diagnosis of acute appendicitis while minimizing diagnostic delays and hospital costs. Mortality and morbidity rates for removal of a normal appendix are 0.14% and 4.6%, respectively, but increase to 0.24% and 6.1% for acute appendicitis and to 1.7% and 19% for perforated appendicitis [13]. Prevention of appendiceal perforation mandates diagnosis in a timely fashion.
Clinical assessment remains an essential and critical part of the initial evaluation of patients with suspected acute appendicitis. However, advances in radiology have made preoperative noninvasive imaging an important diagnostic adjunct to clinical evaluation. Toward that end, radiology is now commonly used for elucidation of the cause of acute abdominal pain. The diagnosis or exclusion of acute appendicitis is greatly facilitated by accurate identification of the inflamed or normal appendix. In addition, radiology can often determine alternate conditions as the cause of the patients pain when the appendix is normal. Graded compression sonography and MDCT are currently the preferred primary imaging methods throughout the world for evaluating the appendix in patients with right lower quadrant pain who are suspected of having appendicitis.
The technique of graded compression sonography, introduced by Puylacrt [14] in the mid 1980s, has substantially aided sonographic identification of the appendix. The advantages of sonography are that it is widely available, relatively inexpensive, and noninvasive, and, most important, that it poses no ionizing radiation risk to the patient. This latter advantage is significant when evaluating pregnant patients. In addition, radiation is an important concern in pediatric and young adult patients, who are up to 10 times more sensitive to the effects of ionizing radiation than middle-aged and elderly adults. Important limitations of sonography are that it is operator-dependent, it can be difficult to perform in patients with severe abdominal pain or in patients with large amounts of bowel gas, and it can be limited in muscular or obese patients. The limited ability of sonography to adequately penetrate the abdomen in obese patients has contributed to its lack of widespread use in North America and parts of Europe.