In a large series of 3,799 patients with suspected acute appendicitis, Cundy et al [26] showed 92% visualization of the appendix with 95.5% accuracy, 97% sensitivity, and 95% specificity for the diagnosis of acute appendicitis. As an initial imaging modality for suspected acute appendicitis, US has been shown to have high diagnostic accuracy and to reduce or obviate the need for further imaging without increased complications or unacceptable increases in length of stay [22,26-28]. An important limitation of US is its low sensitivity in the diagnosis of perforated appendicitis [2]. This should be taken in consideration if nonoperative management is considered. CT CT has high sensitivity (~94%) and specificity (~95%) for the diagnosis of acute appendicitis [29]. If the appendix is not visualized, the negative predictive value is similar to a CT with normal visualized appendix [51]. Studies in both children and adults have allowed optimization of CT technique for the diagnosis of acute appendicitis. There is debate about the usefulness of oral contrast because some studies showed no significant increased accuracy, longer time to examination completion, and increased rates of patient emesis [30-32]. Rectal contrast does not increase accuracy compared to CT with intravenous (IV) contrast only [33]. Most CT examinations for appendicitis are performed with standard technique and coverage for imaging the abdomen and pelvis. Some centers have had success decreasing CT exposure parameters without compromising diagnostic performance [34,35] for acute appendicitis. Other retrospective studies in both adult and pediatric populations have shown that a focused CT from L2 or L3 or based on height-adjusted distance from the umbilicus through the pubis symphysis is sufficient to diagnose acute appendicitis and identify most alternative diagnoses [36,37]. There are no studies that compare unenhanced and contrast-enhanced CT for diagnosis of acute appendicitis.
Suspected Appendicitis Child. In a large series of 3,799 patients with suspected acute appendicitis, Cundy et al [26] showed 92% visualization of the appendix with 95.5% accuracy, 97% sensitivity, and 95% specificity for the diagnosis of acute appendicitis. As an initial imaging modality for suspected acute appendicitis, US has been shown to have high diagnostic accuracy and to reduce or obviate the need for further imaging without increased complications or unacceptable increases in length of stay [22,26-28]. An important limitation of US is its low sensitivity in the diagnosis of perforated appendicitis [2]. This should be taken in consideration if nonoperative management is considered. CT CT has high sensitivity (~94%) and specificity (~95%) for the diagnosis of acute appendicitis [29]. If the appendix is not visualized, the negative predictive value is similar to a CT with normal visualized appendix [51]. Studies in both children and adults have allowed optimization of CT technique for the diagnosis of acute appendicitis. There is debate about the usefulness of oral contrast because some studies showed no significant increased accuracy, longer time to examination completion, and increased rates of patient emesis [30-32]. Rectal contrast does not increase accuracy compared to CT with intravenous (IV) contrast only [33]. Most CT examinations for appendicitis are performed with standard technique and coverage for imaging the abdomen and pelvis. Some centers have had success decreasing CT exposure parameters without compromising diagnostic performance [34,35] for acute appendicitis. Other retrospective studies in both adult and pediatric populations have shown that a focused CT from L2 or L3 or based on height-adjusted distance from the umbilicus through the pubis symphysis is sufficient to diagnose acute appendicitis and identify most alternative diagnoses [36,37]. There are no studies that compare unenhanced and contrast-enhanced CT for diagnosis of acute appendicitis.