Liver Ultrasonography (Liver Echography, Liver Ultrasound)
Norm of Liver Ultrasonography (Liver Echography, Liver Ultrasound)
Liver is of proper size, shape, and position and with a homogeneous soft echo pattern. Image indicates normal relationship to adjacent anatomic structures. Negative for intrahepatic duct dilatation, abscess, cyst, hematoma, or tumor.
Usage of Liver Ultrasonography (Liver Echography, Liver Ultrasound)
Determine the cause of jaundice; differentiate between obstructive and nonobstructive jaundice; detect cirrhosis, hepatic abscess, cyst, hematoma, and tumors; differentiate cysts and abscesses from tumors; examine the shape and structure of intrahepatic ducts; visualize pleural effusion; evaluate hepatic hemodynamic flow balance; evaluate ascites; and monitor hepatic metastasis response to cancer therapy. Used before and after placement of a transjugular intrahepatic portosystemic shunt (TIPS). May be used before a liver biopsy or can help differentiate the constitution of abnormalities identified during hepatobiliary nuclear medicine scanning. It is useful with liver scanning to define the “cold spots.” Serial scans may be used to determine the volume of the liver. Not reliable in detecting metastasis, especially when a client's liver is high and primarily under the rib cage. Without contrast, this procedure is a less sensitive alternative to hepatic dye imaging tests for clients with allergy to radiographic dyes. Advancements in contrast agents have led to contrast-enhanced ultrasound imaging that is comparable to CT and MRI results.
Description of Liver Ultrasonography (Liver Echography, Liver Ultrasound)
With or without contrast enhancement, this procedure provides an evaluation of the liver, intrahepatic duct structure, and ancillary areas of the gallbladder and diaphragm. It creates an oscilloscopic picture from the echoes of high-frequency sound waves, which pass over the right upper quadrant of the abdomen (acoustic imaging). A computer converts the time required for the ultrasonic beam to be reflected back to the transducer from differing densities of tissue to an electrical impulse. This impulse is displayed on an oscilloscopic screen to create a three-dimensional picture of the liver. Hepatitis and fatty liver may be indicated by hepatomegaly. Fatty infiltration also causes brighter-than-normal echoes, with decreased amount of vascular structures. Hepatic fibrosis is demonstrated by a smaller-than-normal liver size and inhomogeneity of the liver tissue. Cysts appear sonolucent with borders that are easily defined, and they have an echo-free nature. Abscesses may contain internal echoes. Malignant neoplasm (such as adenocarcinoma and other primary liver tumors) may appear as a diffusely distorted parenchymal area, where homogeneity of tissue would be expected. The image pattern, which is produced by malignant neoplasms, is called a “bull's-eye.” This is attributable to the dense central echo pattern that is surrounded by the less echo-producing halo.
Professional Considerations of Liver Ultrasonography (Liver Echography, Liver Ultrasound)
Consent form NOT required.
Preparation
- This test should be performed before intestinal barium tests or after the barium is cleared from the system.
- Obtain ultrasonic gel or paste.
- See Client and Family Teaching.
Procedure
- The client is positioned supine in bed or on a procedure table.
- The right upper quadrant of the abdomen is covered with ultrasonic gel, and a lubricated transducer is passed slowly over the area along the transverse plane at intervals 1 cm apart with the client in deep inspiration. This is followed by longitudinal scanning in 0.5- to 2-cm increments, moving from the umbilicus to the xiphoid process, with the transducer angled so that the sound waves pass under the rib cage. The client may be changed to a left lateral decubitus position to obtain lateral views of the liver by coronal scanning. If the client is dehydrated, he or she may be asked to expand the abdomen to enhance the smoothness of the anterior abdominal wall. The final views taken are right anterior oblique.
- Photographs are taken of the oscilloscopic display.
- The procedure takes less than 30 minutes.
Postprocedure Care
- Remove the lubricant from the skin.
Client and Family Teaching
- Fast from food and fluids, and refrain from tobacco smoking overnight before the test.
- The procedure is painless and carries no risk.
- Wear a gown during the test.
Factors That Affect Results
- Dehydration interferes with adequate contrast between the organs and body fluids.
- Intestinal barium, gas, or food obscures results by preventing proper transmission and deflection of the high-frequency sound waves.
- Fatty liver causes scattering in the attenuation of the ultrasonic beam.
- The more abdominal fat present, the greater is the attenuation (reduction in sound-wave amplitude and intensity), which interferes with the clarity of the picture.
- Lung tissue may interfere with visualization of the liver dome in transverse views.
- Rib artifacts may obscure images of the right lobe of the liver.
