Gallstones Explained

Physical Examination In patients with known gallstones;the doctor can often diagnose acute cholecystitis (gallbladder inflammation) based on classic symptoms (e.g., constant and severe pain in the upper right quadrant of the abdomen). Imaging techniques, however, are necessary to confirm such a diagnosis. There is usually no tenderness in chronic cholecystitis.

Laboratory Tests
Blood tests are usually normal in people with simple biliary colic or chronic cholecystitis. The following abnormalities may indicate gallstones or complications:

The enzyme alkaline phosphatase and bilirubin are usually elevated in acute cholecystitis, and especially choledocholithiasis (common bile duct stones). Bilirubin is the orange-yellow pigment found in bile. High levels cause jaundice, which gives the skin a yellowish tone.
Liver enzymes known as aspartate aminotransferase (AST) and alanine aminotransferase (ALT) are elevated when common bile duct stones are present. A threefold or more increase in ALT strongly suggests pancreatitis

A high white blood cell count is a common finding in many (but not all) patients with cholecystitis.

Diagnosing Choledocholithiasis
General Guidelines. Common duct stones (choledocholithiasis) may be detected at one of several points:

When the patient complains of gallbladder symptoms. At the same time that gallstones are diagnosed. (Common duct stones often accompany gallstones.) During or after performing surgery to remove the gallbladder for gallstones (cholecystectomy).

If the doctor only suspects common duct stones, however, identifying them is problematic. It requires blood tests, imaging tests, invasive procedures, or some combination that serve both for detection and possibly removal.

Laboratory Tests. Evidence that may suggest common bile duct stones includes dark urine, jaundice, or pancreatitis. In such cases, the doctor may perform certain blood tests. Elevated levels of the following suggest the presence of common duct stones:

Alkaline phosphatase (ALP). Elevated levels of this enzyme are typically the first signs of common bile duct stones. Bilirubin (the orange-yellow pigment found in bile). Bilirubin levels increase after alkaline phosphatase rises. Liver enzymes known as aspartate aminotransferase (AST) and alanine aminotransferase (ALT). These enzymes may temporarily spike if the stone passes into the small intestine.

A number of techniques, particularly endoscopic retrograde cholangiopancreatography (ERCP), endoscopic ultrasound (EUS) and magnetic resonance cholangiography (MRC), are proving to be equally effective for detecting common bile duct stones. Only ERCP, however, allows removal of the stones, but it is invasive. A National Institutes of Health expert panel has endorsed the use of ERCP as a diagnostic technique for patients who are clearly ill with symptoms of gallstones. For patients who are not as sick, the panel recommended noninvasive imaging techniques.

Imaging Techniques
Ultrasound. Ultrasound is a simple, rapid, and noninvasive imaging technique. It is the diagnostic method most frequently used to detect gallstones and is the method of choice for detecting acute cholecystitis. The patient must not eat for six or more hours before the test, which takes only about 15 minutes. During the procedure, the doctor can check the liver, bile ducts, and pancreas and quickly scan the gallbladder wall for thickening (characteristic of cholecystitis).

Ultrasound detects gallstones as small as 2 mm in diameter with an accuracy of 90% to 95%. Some experts recommend that if an ultrasound does not detect stones, but gallstones are still strongly suspected, the test should be repeated.

Air in the gallbladder wall may indicate gangrene.

Ultrasound does not appear to be very useful for identifying cholecystitis in symptomatic patients who do not have gallstones. In one study, ultrasound detected some gallbladder abnormalities, no matter what the cause of the abdominal pain. In only a few cases, however, were the symptoms actually caused by cholecystitis.

Ultrasound is also not as useful for common bile duct stones and cannot image the cystic duct. (Nevertheless, normal ultrasound results along with normal bilirubin and liver enzyme tests are very accurate indications that there are no stones in the common bile duct.)

An ultrasound variation called endoscopic ultrasound (EUS) is accurate and useful for patients with an intermediate risk for common bile ducts stones. Its accuracy is comparable to endoscopic retrograde cholangiopancreatography (ERCP), the standard for diagnosing stones in the common bile duct. However, if common duct stones are detected they cannot be removed. It is useful then when common bile duct stones are suspected but the patient is not clearly ill.

X-Rays. Standard x-rays of the abdomen may detect calcified gallstones and gas. Variations include oral cholecystography or cholangiography.

In oral cholecystography the patient takes a tablet containing a dye the night before the test. The dye fills the gallbladder and x-rays are used to take images of it the next day. It has been available since 1924 but has largely been replaced by ultrasound. It is more sensitive than standard x-rays, however, and may be useful in some cases for determining the structural and functional status of the gallbladder, often before nonsurgical procedures.

Cholangiography uses a dye injected into the bile duct and x-ray to view the common bile duct. It is typically used during operations to provide a clear image of the biliary tract.

Cholescintigraphy (Also Called Gallbladder Radionuclide Scan). Cholescintigraphy, a nuclear imaging technique, is more sensitive than ultrasound for diagnosing acute cholecystitis. It is noninvasive but can take 1 to 2 hours and even longer. The procedure involves the following steps:

A tiny amount of a radioactive dye is injected intravenously. This material is excreted into bile. The patient lies on a table under a scanning camera, which detects gamma rays emitted by the dye as it passes from the liver into the gallbladder. The test can take up to 2 hours, since each image takes about a minute and they are taken every 5 to 15 minutes.

If the dye does not enter the gallbladder, the cystic duct is obstructed thereby indicating acute cholecystitis. The scan cannot identify individual gallstones or chronic cholecystitis. Occasionally the scan gives false positive results. (In other words, it appears to detect acute cholecystitis in people who do not have the condition.) Such results are most likely in alcoholic patients with liver disease or patients who are fasting or receiving all nutrients intravenously.

Endoscopic Retrograde Cholangiopancreatography(ERCP). Endoscopic retrograde cholangiopancreatography (ERCP) has been the gold standard for detecting common bile duct stones, particularly because they can be removed during the procedure. However, it is invasive and carries a risk for complications. With the advent of noninvasive imaging techniques, it is now generally limited to patients who have a high likelihood of common bile ducts stones and so would need them removed.

Computed Tomography. Computed tomographic (CT) scans may be a valuable additional imaging technique if the doctor suspects complicating features, such as perforation, common duct stones, or other problems such as cancer in the pancreas or gallbladder. Helical, or spiral, CT scanning is advanced technique that shortens the time and obtains clearer images. With this process, the patient lies on a table that moves while a donut-like, low-radiation x-ray tube rotates around him or her.

Magnetic Resonance Imaging (MRI). MRIs may be very useful for detecting common bile duct stones, particularly a specific MRI technique called magnetic resonance cholangiography (MRC). It employs MRI and cholangiography, in which a dye is injected into the bile duct and x-rays are used to view the duct. MRC is extremely sensitive in detecting biliary tract cancer. This imaging procedure is very expensive, however, and may not detect very small stones or chronic infections in the pancreas or bile duct. As with EUS, it is most likely to be useful in a small subset of patients and would not eliminate the need for ERCP in most patients.

Virtual Endoscopy. Virtual endoscopy is an investigative technique that uses data from CT and MRI scans to generate a three-dimensional internal view of various body structures. The images resemble those used in endoscopy but the procedure is noninvasive. It one study it was able to detect smaller stones in the common bile duct than MRI. At this time it is still experimental. View an in-depth explanation of the Gallbladder and why a Gallstone forms. See the inter-workings of the Gall Bladder and formation of a Gall Stone.

Gallbladder Stone Formation