Application of Gastrointestinal Tract Ultrasound in Emergency and Critical Medicine
Journal of Medical Ultrasound
Acute abdominal pain is one of the most common complaints in the emergency department  and can present a diagnostic challenge. Ultrasound (US) is one of the common diagnostic modalities used for evaluation of acute abdominal pain, especially in cases involving the gastrointestinal (GI) tract, such as appendicitis. Point-ofcare US is mainly used in emergency and critical care applications to determine whether there is a need for surgery or further inpatient treatment. For example, when
... xample, when patients complain of right upper quadrant pain, physicians should exclude acute cholecystitis or biliary obstruction and determine whether surgery/interventional treatment is needed. This article primarily focuses on the use of US to diagnose the most common acute GI disorders in emergency medicine. GI tract: Normal structure Assessment of the normal GI tract should involve examination of the GI tract layers and intestinal thickness, size, blood flow, and peristalsis. GI tract layers The normal GI tract consists of five layers (Figure 1) , and each layer has a different echogenicity on US. The five layers are (1) the interface between the lumen and mucosa, which is hyperechoic; (2) the mucosa, which is hypoechoic; (3) the submucosa, which is hyperechoic; (4) the muscular layer, which is hypoechoic; and (5) the serosa, which is hyperechoic. Thickness of the intestines The thickness of the intestines from the serosa to the interface is usually less than 3e4 mm (<5e6 mm in the case of the stomach). A high-frequency US probe (i.e., 5 MHz) is recommended when performing thickness measurements.