BILIARY Dr. John Powell, Christiana Care Health System INDICATIONS: • • • •
Right upper quadrant, epigastric or flank pain Concern for gallstones Jaundice Pancreatitis
KEY QUESTIONS: • •
Are there gallstones? Are there signs of cholecystitis?
TECHNIQUE: • •
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A low frequency transducer (2-5 MHz) is ideal for assessment of the gallbladder. Identify the portal triad or main lobar fissure and trace to an anechoic structure, the gallbladder (Figure 1). o Place probe in a sagittal plane in the epigastrium, then sweep transducer along the right costal margin. The indicator should initially be directed towards the patient’s head. After visualizing the gallbladder, the transducer may need to be slightly rotated to obtain true sagittal and transverse views. Scan the entire gallbladder in two planes. o Identify any pericholecystic fluid or gallstones. o If a gallstone is in the gallbladder neck, roll the patient to ensure mobility. Measure the gallbladder wall thickness in the anterior field (transverse or sagittal) (Figures 2 and 3). Identify the common bile duct. o Measure the internal diameter, i.e. inner wall to inner wall (Figure 4). Assess for a sonographic Murphy’s sign. Do this by identifying the gallbladder and placing it in the center of the screen, then applying pressure directly with the transducer onto the region of the gallbladder. Reproduction of exquisite pain is considered positive.
BILIARY Dr. John Powell, Christiana Care Health System
Figure 1. Gallbladder Connected to Portal Triad via Main Lobar Fissure (MLF)
Figure 2. Gallbladder Anterior Wall Measurement, Sagittal View
BILIARY Dr. John Powell, Christiana Care Health System
Figure 3. Gallbladder Anterior Wall Measurement, Transverse View
Figure 4. Common Bile Duct (CBD), Sagittal View
MEASUREMENTS:
BILIARY Dr. John Powell, Christiana Care Health System • •
GB wall thickness: <3 mm is normal. CBD: usually <6 mm is normal although some sources use 3 mm as normal with the addition of 1 mm per decade of life; s/p cholecystectomy the CBD can be considered normal up to 10 mm.
PEARLS AND PITFALLS: • • •
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Be sure to measure the anterior wall. Posterior acoustic enhancement falsely increases the posterior wall measurement. Gallstones display acoustic shadowing, tend to locate in a dependent region, and move with gravity. Sonographic criteria for acute cholecystitis include: -thickened anterior gallbladder wall (>3 mm) -pericholecystic fluid -sonographic Murphy’s sign -gallbladder hydrops (transverse measurement >4 cm) Improve difficult images: o Sit the patient upright between 45 and 60 degrees. o Roll the patient to the left lateral decubitus position. o Have the patient take a deep breath and hold it when possible. Consider bedside aorta scan if elderly and abdominal / flank pain.