From the Guidelines
Ultrasound of the abdomen is indicated as the first-line imaging study for patients with abnormal liver tests to evaluate for structural causes of liver dysfunction, as recommended by the most recent guidelines 1.
Indications for Ultrasound Abdomen
The examination can detect common causes of abnormal liver tests including:
- Fatty liver disease
- Cirrhosis
- Biliary obstruction
- Gallstones
- Mass lesions such as tumors or cysts Ultrasound is particularly valuable because it is non-invasive, does not use radiation, is relatively inexpensive, and can be performed quickly.
Preparation and Limitations
The test requires minimal preparation, typically just fasting for 6-8 hours before the examination to reduce bowel gas and improve gallbladder visualization. While ultrasound provides excellent anatomical information, it may not detect early parenchymal liver disease or small lesions, so additional imaging (CT, MRI) or liver biopsy may be necessary depending on the clinical scenario and ultrasound findings. Patients should be advised that ultrasound has limitations in obese individuals due to increased attenuation of sound waves through adipose tissue.
Clinical Scenarios
According to the guidelines, ultrasound abdomen is usually appropriate as the initial imaging for patients with abnormal liver functions tests with hepatocellular predominance with mild aminotransferase increase 1. In cases with moderate or severe aminotransferase increase, ultrasound abdomen, US duplex Doppler abdomen, and CT abdomen and pelvis with IV contrast are usually appropriate as the initial imaging 1. For patients with abnormal liver function tests that show cholestatic predominance and elevated ALP, ultrasound abdomen, MRI abdomen without and with IV contrast, and CT abdomen and pelvis with IV contrast are usually appropriate as the initial imaging 1.
From the Research
Indications for Ultrasound Abdomen in Abnormal Liver Tests
- Abnormal liver function tests can be an indication for ultrasound abdomen, as it is a non-invasive and cost-effective first-line investigation 2
- Ultrasonography is often used to evaluate patients with abnormal liver function tests in the emergency department, and can help identify conditions such as biliary ductal dilatation and obstruction 3
- Ultrasound can be used to diagnose common bile duct stones, with a summary sensitivity of 0.73 and specificity of 0.91 4
Diagnostic Accuracy of Ultrasound and Liver Function Tests
- The diagnostic accuracy of ultrasound and liver function tests for common bile duct stones has been evaluated in several studies, with varying results 4
- Liver function tests, such as serum bilirubin and alkaline phosphatase, can also be used to diagnose common bile duct stones, but may have lower sensitivity and specificity than ultrasound 4
- The combination of ultrasound and liver function tests may be more accurate than either test alone, but further studies are needed to determine the diagnostic accuracy of these tests 4
Clinical Applications of Ultrasound Abdomen in Abnormal Liver Tests
- Ultrasound abdomen can be used to evaluate patients with infectious mononucleosis and abnormal liver function tests, but routine assessment of liver function tests and abdominal ultrasound may not be necessary in immunocompetent patients 5
- The initial evaluation of patients with abnormal liver test results should include a review of previous laboratory test results, medical and family histories, substance use, and physical examination, as well as tests such as complete blood cell count, liver transaminase levels, and right upper quadrant abdominal ultrasonography 6
- Additional tests and imaging should be based on patient-specific risk factors and the pattern of abnormal liver test results 6