• Level A recommendations. None specified.
• Level B recommendations. In patients with suspected acute appendicitis, use clinical findings (i.e., signs and symptoms) to risk-stratify patients and guide decisions about further testing (e.g., no further testing, laboratory tests, and/or imaging studies), and management (e.g., discharge, observation, and/or surgical consultation).
• Level C recommendations. None specified.

Question 2: In adult patients with suspected acute appendicitis who are undergoing a CT scan, what is the role of contrast? CT with oral and intravenous (IV) contrast is used in many centers, but waiting for oral contrast to transit the small bowel may prolong emergency department stays, lead to allergic reactions, and cause vomiting. This question was chosen by the Clinical Policies Committee to determine if contrast is necessary, and if so, which type of contrast should be recommended. These management recommendations are intended for patients with suspected appendicitis, not patients with non-specific abdominal pain where a number of diagnoses are considered.

• Level A recommendations. None specified.
• Level B recommendations. In adult patients undergoing a CT scan for suspected appendicitis, perform abdominal and pelvic CT scan with or without contrast (intravenous, oral, or rectal). The addition of IV and oral contrast may increase the sensitivity of the CT scan for the diagnosis of appendicitis.
• Level C recommendations. None specified.

Question 3: In children with suspected acute appendicitis who undergo diagnostic imaging, what are the roles of CT and ultrasound in diagnosing acute appendicitis? There are published articles suggesting that the ionizing radiation associated with abdominal/pelvic CTs is associated with a small increase in lifetime risk of cancer in children. Consequently, some centers use ultrasound as the initial radiologic study in selected children. Ultrasound is not as accurate as CT in definitively excluding acute appendicitis, and there are other factors (e.g., patient peritoneal fat distribution, experience of the radiologist) that influence the effectiveness of ultrasound in diagnosing appendicitis. The recommendations for this question balance diagnostic performance and the risks associated with ionizing radiation.

• Level A recommendations. None specified.
• Level B recommendations. 1. In children, use ultrasound to confirm acute appendicitis but not to definitively exclude acute appendicitis. 2. In children, use an abdominal and pelvic CT to confirm or exclude acute appendicitis.
• Level C recommendations. Given the concern over exposing children to ionizing radiation, consider using ultrasound as the initial imaging modality. In cases in which the diagnosis remains uncertain after ultrasound, CT may be performed.

Clinical findings can be used to guide decisions about the need for testing and disposition of the patient with suspected appendicitis. When CT is ordered for suspected appendicitis in adults, it is acceptable to scan with or without contrast, although the addition of IV and oral contrast may increase the sensitivity of the CT scan. Ultrasound can be used to confirm acute appendicitis in children, but not to definitively exclude acute appendicitis. If there is a high pre-test clinical suspicion of appendicitis and the ultrasound is either negative or nondiagnostic, CT may be utilized in children.