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Imaging in Gallstones (Cholelithiasis)

Practice Essentials

Gallstones (cholelithiasis) are solid calculi formed by precipitation of supersaturated bile composed of cholesterol monohydrate crystals or by “black pigment” of polymerized calcium bilirubinate. In the United States, more than 80% of gallstones contain cholesterol as their major component.In Asia, pigmented stones predominate, although studies have shown an increase in cholesterol stones in the Far East. Gallstones are present in 10-20% of the population in developed countries. The incidence increases with age and is higher in women. About 80% of carriers are asymptomatic, and most remain asymptomatic throughout life.
 Potentially life-threatening complications of gallstones include acute cholecystitis, obstructive cholangitis and gallstone pancreatitis.

The characteristic symptoms of gallstones are episodic attacks of severe pain in the right upper abdominal quadrant (biliary colic) for at least 15-30 minutes, with radiation to the right back or shoulder and a positive reaction to analgesics. Most attacks resolve spontaneously. The following are all highly suggestive of gallstones: irregular periodicity of pain; onset of pain after meals, during the evening, or at night; pain awakening the patient from sleep; and pain duration of more than an hour. Acute cholecystitis should be suspected in a patient with fever, severe pain located in the right upper abdominal quadrant lasting for several hours, and right upper abdominal pain and tenderness on palpation (Murphy’s sign).

Preferred examination

Ultrasonography is the procedure of choice in suspected gallbladder or biliary disease; it is the most sensitive, specific, noninvasive, and inexpensive test for the detection of gallstones. Current high-resolution, real-time US can identify gallstones as small as 2 mm, with a sensitivity greater than 95%. Moreover, it is simple, rapid, and safe in pregnancy, and it does not expose the patient to harmful radiation or intravenous contrast. An added advantage is that it can be performed by skilled practitioners at the bedside.
 False negatives may occur on ultrasonograms when small stones are in the presence of biliary sludge. Inadequate visualization of the gallbladder may occur in obese patients or patients with abdominal wounds.

Although cholescintigraphy is recognized to have a higher sensitivity and specificity, US remains the initial test of choice for imaging patients with suspected AC. Among its disadvantages are longer study time, ionizing radiation, and findings limited to the  hepatobiliary tract.

Radiography of the abdomen is of limited value for evaluating right upper quadrant pain. Although abdominal radiographs performed for initial evaluation may identify gallstones, they are not sufficient for establishing diagnoses of AC.

Only 74-79% of gallstones are identified in patients with computed tomography (CT) scanning. CT is not a screening tool for uncomplicated cholelithiasis.

Magnetic resonance imaging (MRI) is not a screening tool. Stones may be incidental findings on abdominal MRI.

(See the images below.)

Cholelithiasis. Ultrasound image obtained with a 4

Cholelithiasis. Ultrasound image obtained with a 4-MHz transducer demonstrates a stone in the gallbladder neck with typical acoustic shadow.

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Cholelithiasis. A noncalcified filling defect is p

Cholelithiasis. A noncalcified filling defect is present in the gallbladder on this contrast-enhanced CT. Ultrasound examination confirmed a mobile stone and excluded the other possible diagnoses of polyp or tumor.

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Cholelithiasis. Multiple tiny gallstones appear as

Cholelithiasis. Multiple tiny gallstones appear as signal void-filling defects in the gallbladder on this T1-weighted spoiled gradient-echo sequence.

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Each type of stone has a particular pathophysiology and specific set of risk factors that alter the equilibrium and solubility of the components of bile. Biliary microlithiasis refers to the presence of gallbladder calculi smaller than 2 mm, which is too small to be detected by current imaging techniques.

Although it originally referred to ultrasonographic findings of echogenic, nonshadowing, microscopic material within the gallbladder, the term biliary sludge currently indicates a precipitate of microcrystals occurring in bile with high mucous content. Sludge may contain microliths. Milk of calcium bile, a calcium carbonate precipitate opaque on plain radiographs, may coexist with cholelithiasis.


The ACR guidelines for evaluation of right upper quadrant pain include the following

Ultrasonography (US) is preferred as the initial imaging study for right upper quadrant pain, with supplemental cholescintigraphy performed when US results are equivocal.

If US shows gallstones, cholescintigraphy should be performed to exculde other sources of pain.

When fever is present and acute cholecystitis (AC) is suspected, the diagnosis should be confirmed or excluded using US and/or cholescintigraphy. 

CT or MRI may be performed in equivocal cases and to identify complications of AC.

MRI is the preferred test for pregnant patients with right upper quadrant pain when US is inconclusive.

The European Association for the Study of the Liver (EASL) guidelines recommend that abdominal ultrasonography be used as the primary diagnostic imaging tool for suspected gallstones. In the case of strong clinical suspicion and negative abdominal ultrasound, endoscopic ultrasound or MRI may be performed. CT scanning should be performed if acute cholecystitis is suspected.

The Japanese Society of Gastroenterology guidelines recommend the following stepwise algorithm for the diagnosis of cholelithiasis

Step 1: History and physical examination.

Step 2: Blood tests, ultrasonography, and abdominal radiograph.

Step 3: For cases that are undefined: CT and/or magnetic resonance cholangiopancreatography (MRCP), and drip infusion cholangiography associated CT

Step 4: For cases still to be diagnosed: endoscopic retrograde cholangiopancreatography (ERCP), endoscopic ultrasonography, intraductal ultrasonography, and percutaneous transhepatic cholangiography 

For excellent patient education resources, see eMedicineHealth’s Digestive Disorders Center and Cholesterol Center. Also, visit eMedicineHealth’s patient education article Gallstones.

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