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Gallbladder and Biliary System Ultrasonography

Norm of Gallbladder and Biliary System Ultrasonography

Gallbladder

Appearance

Sonolucent; free of sludge or stones

Location

Anterior to the right kidney, lateral to the pancreas and duodenum

Shape

Circular on transverse scans

Pear shaped on longitudinal scans

7–10 cm long and 2–3 cm wide with a capacity of 30–50 mL

Walls

Sharply defined and smooth, 1–2 mm thick
Cystic Duct

Appearance

Not sonolucent because of lumen; Heister's valves visible

Shape

Serpentine
Common Bile Duct

Shape

Linear; internal diameter <6 mm
Hepatic Duct

Lumen

Internal diameter <4 mm

 

Usage of Gallbladder and Biliary System Ultrasonography

Diagnosis of cholelithiasis and cholecystitis and differential diagnosis of the cause of jaundice (obstructive versus nonobstructive). Useful in adults with hereditary spherocytosis and those with Gilbert syndrome.

 

Description of Gallbladder and Biliary System Ultrasonography

Evaluation of the gallbladder, cystic duct, and common bile duct by the creation of an oscilloscopic picture from the echoes of high-frequency sound waves passing over these areas. The time required for the ultrasonic beam to be reflected back to the transducer from differing densities of tissue is converted by a computer to an electrical impulse displayed on an oscilloscopic screen to create a three-dimensional picture of the gallbladder and biliary duct system. This noninvasive test has replaced oral cholecystography for evaluation of the biliary system. The presence of sludge causes low-level echoes in the interior of the gallbladder. Acute cholecystitis causes the walls to appear thickened and sonolucent because of edema. Cholelithiasis is demonstrated by a dilated interior, with shadows present. Biliary tree gas causes shadows. Polyps appear as sharply defined masses, whereas carcinoma appears as a poorly defined mass. In obstructive jaundice, dilatation of the gallbladder and biliary duct system is detected.

 

Professional Considerations of Gallbladder and Biliary System Ultrasonography

Consent form NOT required.


Risks
If sincalide is given: infection.
Contraindications
Administration of sincalide is contraindicated in pregnancy and in children.

 

Preparation

  1. See Client and Family Teaching.
  2. Some scans may require intravenous access.

 

Procedure

  1. The client is positioned supine and instructed to hold his or her breath during the scans.
  2. A lubricated transducer is passed slowly over the right upper quadrant of the abdomen with transverse scans (moving from the midline to the right side) taken every 1 cm from the xiphoid process to the right subcostal area.
  3. As the gallbladder borders are identified, they are marked on the client's skin.
  4. Longitudinal and oblique scans are then taken every 5 mm between the marked borders of the gallbladder.
  5. The client is then turned to a steep, left lateral decubitus position, and the scan is repeated from the right costal margin.
  6. The client may then be positioned upright to observe for movement of suspected stones away from the walls of the gallbladder or cystic duct.
  7. If contractility of the gallbladder is to be evaluated, intravenous sincalide may be injected or a fatty meal may be ingested, and the scan is repeated in 30 minutes.
  8. Photographs are taken of the oscilloscopic display.

 

Postprocedure Care

  1. Remove the lubricant from the skin.
  2. Resume previous diet.

 

Client and Family Teaching

  1. Consume a diet free of fat the day before the test.
  2. Fast for 8–12 hours before the ultrasonography, but drink plenty of fluids.
  3. It is important to lie as motionless as possible during the ultrasonography.

 

Factors That Affect Results

  1. Gallstones appear as shadows when well mixed with bile, but if the gallbladder is full of stones, shadows are difficult to detect.
  2. Sincalide may cause nausea. Movement during nausea may interfere with results.
  3. Dehydration interferes with adequate contrast between organs and body fluids.
  4. Very small stones (<1–2 mm) in the gallbladder must be differentiated from polyps by repositioning of the client. The stones will move downward with gravity, whereas polyps will remain stable.
  5. 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.

 

Other Data

  1. Gallbladder cancer cannot usually be diagnosed by sonography.