How to Perform Liver Ultrasound: a Practical Guide for Clinicians

Abstract

Liver ultrasound is important for screening of hepatocellular carcinoma, hepatitis virus associated chronic hepatitis, and cirrhosis. It is also useful for diagnosis and follow-up of diffuse and focal liver diseases. Liver ultrasound is noninvasive and has no risk of radiation, so we can safely apply it on children and pregnant women. In this article, we discuss how to perform liver ultrasound for better imaging. The liver is the largest organ in abdomen, difficult to examine by one image on a screen, so it is essential that the examiner scan liver systemically. For a better examination, we should keep in mind the followings: 1) Overnight fasting or fasting for 6 hours is necessary prior to an examination. 2) Use a convex probe (2-5 MHz) and, if needed, a linear probe (7-12 MHz). 3) Couinaud's 8-segment anatomy is useful for localizing hepatic lesions. 4) Subcostal, intercostal, longitudinal, and transverse scans are necessary for each segment and vascular structures. 5) It is necessary to understand characteristic ultrasound findings of benign and malignant tumors when a lesion mass is found. 6) If ultrasound examination is done incompletely due to bowel gas or severe obesity, consider abdominal CT or MRI for further evaluation. 7) Changing the patient's position is sometimes necessary.