- Diseases, Disorders & Conditions
Gallbladder Problems: Gallstones
What Is the Gallbladder?
The gallbladder can be found on the right side of the abdomen just below the liver. It is a small, pear-shaped organ that stores bile.
Bile is a digestive enzyme that is excreted into the small intestines after a meal to help dissolve fats. It is made up of several components including bile salts, bile pigments like bilirubin, cholesterol, phospholipids (like lecithin), and proteins. The liver can produce and secrete up to 1200 milliliters of bile per day.
When the gallbladder contains stones, the condition is known as cholelithiasis, which comes from the Greek chol (meaning bile), lith (meaning stone) and iasis (meaning process).
Sometimes stones can get caught in the biliary tract, which is also known as the biliary tree. This tract is the pathway taken by the bile secreted from the liver to the small intestines. The presence of stones in this pathway is termed choledocholithiasis.
Types of Gallstones
Gallstones vary widely when it comes to their size and shape. There can be one huge stone in the gallbladder, or there can be many small stones the size of a grain of sand. There are three types of gallstones that can form in the gallbladder and each form for different reasons. The three types of stones are:
- Cholesterol stones
- Pigment stones
- Mixed Stones
Bile is comprised of bile salts, acids and cholesterol. The bile salts and acids are usually enough to break down the cholesterol; however, in those with gallbladder disease this is not the case.
In these people, the cholesterol is left to sit in the gallbladder and solidify because the bile itself does not contain enough bile salts to break it down.
This isn’t always the case, however. Sometimes the gallbladder doesn’t empty frequently enough or contract completely enough to squeeze out any excess bile. The little bit that remains can solidify into gallstones.
Pigment stones are made from a combination of calcium salts and bilirubin. Bilirubin is the end result of the liver breaking down hemoglobin (red blood cells). These stones are typically seen in developing countries and can be the result of several different risk factors including:
- Hemolytic anemias (like sickle-cell disease or hereditary spherocytosis)
- Biliary tract infections
- Prolonged use of proton-pump inhibitors
- Erythropoietic protoporphyria (EPP)
This type of stone is typically made up of anywhere from 20 to 80 percent cholesterol and bile pigments such as calcium carbonate, palmitate phosphate and bilirubin. Because mixed stones contain a fair amount of calcium, they can easily be seen on x-rays.
Gallstones are typically diagnosed using ultrasonography. An ultrasound uses sound waves at a high frequency to produce an image. The waves are projected through a probe called a transducer. In the case of the gallbladder, there are two ways to perform an ultrasound.
This type of ultrasound is performed using a transducer on the abdomen, similar to an ultrasound performed on a pregnant woman.
This test can diagnose gallstones and also detect a thickened wall of the gallbladder caused by cholecystitis; an enlarged gallbladder and bile duct caused by an obstruction; and pancreatitis.
There are drawbacks to transabdominal ultrasonography. This type of ultrasound is unable to detect stones that are smaller than four to five centimeters, and it is unable to detect a stone in the bile duct.
If performed during a gallbladder attack, transabdominal ultrasonography will not be able to detect the gallstones. However, it is painless, poses little risk to the patient and is inexpensive to perform. It is the most common test used to diagnose gallstones.
This version of ultrasonography uses an endoscope, which is a long flexible tube-like instrument that slides down the patient’s esophagus into the duodenum (the initial portion of the intestines). The patient is sedated intravenously for the test.
Because the transducer is in such close proximity to the gallbladder, common bile duct and pancreas, the images received are much more detailed making it easier to spot smaller stones. This form of ultrasound does pose more risk to the patient, mainly because of the intravenous sedation. There is also the possibility of the endoscope perforating the intestines.
Endoscopic Retrograde Cholangiopancreatography or ERCP
ERCP uses two diagnostic testing procedures, endoscopy and fluoroscopy, to diagnose and treat problems in the biliary and pancreatic ductwork.
The patient is sedated for the procedure, and the endoscope slides down the patient’s esophagus to the duodenum. A dye is then injected via a cannula (a small plastic catheter that is passed through a channel in the endoscope) into both the pancreas and biliary tree making them visible on an x-ray.
With this procedure, small gallstones trapped in the common and hepatic bile ducts can be removed (if need be) possibly alleviating the need for more invasive surgery in the future.
There are other diagnostic tests that can be used to diagnose gallstones, such as:
Magnetic Resonance Cholangiopancreatography (MRCP)
This test uses an MRI machine to look at all the structures related to the gallbladder. MRCP is actually quite sensitive and can detect stones in the bile ducts as well as the gallbladder. This test has replaced the ERCP to some extent because there is no risk to the patient since the procedure is not invasive and the patient doesn’t have to be sedated.
Cholescintigraphy (HIDA scan)
This test involves injecting the patient with a radioactive dye and taking “pictures” with a device that is similar to a Geiger counter. The test has the advantage of detecting bile leaks and fistulas as well as blockages caused by stones. This test can also be used to study the contraction of the gallbladder as it empties.
This is one test that is hardly ever used and can be very unpleasant. A thin tube (with several holes at the end of it) is inserted into the patient’s nostril and guided down into the duodenum.
Once there, a synthetic hormone that causes the gallbladder to empty (called cholecystokinin) is injected intravenously. The bile released is vacuumed through the tube and then examined by a microscope for any particles of pigment or cholesterol. There is little risk to the patient; however, as stated earlier, it can be very uncomfortable.
Oral Cholecystogram (OCG)
The OCG finds approximately 95 percent of all gallstones. The patient takes iodine orally for one to two days after which time x-rays of the abdomen are taken. However, the ducts cannot be seen with this procedure. The IVC, or intravenous cholecystogram, is the same as the OCG with one exception. The iodine is injected intravenously instead of taken orally.
Complications of Gallstones
Gallstones can cause quite a few complications including:
- Ascending cholangitis
Choledocholithiasis is the term used to describe gallstones that have moved from the gallbladder to the ducts of the biliary tract.
It can sometimes lead to obstruction of the biliary tree, which can cause cholecystitis, an infection of the bile ducts and / or the gallbladder itself.
Choledocholithiasis can also lead to cholangitis, an infection in the bile found in the common bile duct and both the hepatic and intrahepatic ducts.
The infection comes from the intestines and spreads through the ducts after they are blocked by a gallstone. It can lead to an abscess of the liver or even sepsis. Someone with cholangitis will usually become very sick and develop a very high fever and chills.
The gallbladder can become gangrenous when inflammation (caused by cholecystitis) cuts off the blood flow to the gallbladder. The lack of blood causes death to the tissue that makes up the wall of the gallbladder, which substantially weakens the wall.
This weakening can lead to the gallbladder rupturing allowing any infection to spread throughout the body, a condition known as sepsis.
The common bile duct is surrounded by the pancreas as it enters into the intestines. Digestive juices are drained from the pancreas through the pancreatic duct, which is joined to the common bile duct at a junction known as the ampulla of Vater (also called the hepatopancreatic ampulla).
If a gallstone blocks the pancreatic duct just before the ampulla of Vater, the fluid draining from the pancreas is obstructed and the result is pancreatitis, or inflammation of the pancreas.
When the ducts are obstructed for long periods of time, jaundice can occur. Jaundice is the result of too much bilirubin in the bloodstream, which creates the characteristic yellowing of the skin and whites of the eyes.
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