Utility of Ultrasound in the Initial Evaluation of Adult Patients with Suspected Appendicitis

Clinical Policy Statement
Utilization of ultrasound (US) as the initial imaging screening tool for appendicitis in adults can reduce the need for computer tomography (CT) and exposure to ionizing radiation.

Acute appendicitis continues to be the most frequent cause of acute abdominal emergency in the United States. However, the diagnosis of appendicitis is challenging. As a result, it is common to obtain preoperative imaging to confirm the diagnosis. Current literature indicates that abdominal computed tomography (CT) is superior to ultrasound (US) for diagnosing acute appendicitis.(1) Despite its reported superiority, abdominal CT exposes a predominantly young population with this disease to iodizing radiation. Additional complications and undesirable consequences of abdominal CT include allergic reactions, acute kidney injury from intravenous contrast, delays due to the administration of oral contrast, and higher costs. In contrast to abdominal CT, US provides imaging that is free of radiation exposure, eliminates the need for intravenous or oral contrast, and allows results to be obtained expeditiously. Importantly, the diagnostic capability of US is operator-dependent; thus, results can be affected by the location of the appendix, overlying bowel and the presence of peritoneal signs.(2) Patients with a high BMI are thought to be poor candidates for ultrasound.(13) It is difficult to validate this assumption as those patients with high BMI are routinely excluded from these studies. While US is the standard initial imaging modality of choice for pediatric patients with suspected appendicitis(1), the utility of US in the adult patient with suspected appendicitis is less clear.

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