Fat cannot be dissolved in water, a special system has evolved for its digestion and its absorption through the intestinal wall. Bile is an essential factor in this, since it contains substances that allow fats to be emulsified. It also stimulates the secretion of an enzyme concerned with the breakdown of fats. Bile is secreted by the liver and stored in the gallbladder until needed. When fat is eaten, this stimulates the gallbladder to contract and bile flows down the cystic duct, into the common bile duct and through the ampulla of Vater into the intestine. As well as acting as a storage vessel, the gallbladder concentrates the bile within it by removing water through its wall. Thus, if the gallbladder is removed, although bile still flows into the intestine from the liver, fat digestion may be less efficient because the bile is not concentrated.
The most common disorder of the biliary tract (gallbladder and bile ducts) is gallstones. Why and how gallstones form is not fully understood, but it is thought that in some cases an abnormality in function causes the gallbladder to remove an excessive amount of water from the bile so that some of its constituents can no longer remain in solution. Gallstones occur very frequently in developed countries and may be associated with eating a diet that is high in fat and refined carbohydrates and low in fiber. As many as 10-20 percent of the U.S. population over the age of forty have gallstones, but only in a minority do symptoms occur. If gallstones are found by chance on an X-ray taken for some other reason it is standard practice to leave them alone if they are causing no symptoms, since the risk of developing problems is slightly less than the risk from a major operation. However, if a patient with asymptomatic gallstones is having an abdominal operation for another reason, the gallbladder may be removed at the same time. The problems that gallstones can give rise to are various and include cholecystitis (inflammation of the gallbladder), choledocholithiasis (gallstones in the common bile duct), and cholangitis (infection of the bile ducts), pancreatitis, and gallstone ileus (obstruction of the intestines by a gallstone).
Chronic Cholecystitis (Billary Colic)
The majority of patients with symptoms from their gallstones will suffer from chronic cholecystitis. The attacks are caused by a stone becoming stuck either in the junction of the gallbladder and the bile duct or in the duct itself. The muscle in the wall of both gallbladder and duct contracts in an effort to move the stone and this produces intense pain usually felt under the ribs on the right-hand side of the abdomen. However, the pain may also be felt under the V of the ribs or may extend right across the abdomen and spread around to the back, below the right shoulder blade. The patient may vomit and is usually restless. After several hours, the stone either falls back into the gallbladder or, by virtue of the muscle contractions, is passed down the bile duct and into the intestine. Some patients suffer from a constant dull ache in the upper abdomen and many complain of discomfort and flatulence after eating a fatty meal.
Twenty percent of those who develop gallbladder symptoms suffer from this condition, which most frequently affects women between the ages of twenty and forty. Like chronic cholecystitis, it is caused by a stone becoming jammed either in the junction of the gallbladder and duct or in the duct itself, and many patients have previously suffered from binary colic, indigestion, or flatulence. The pain of acute cholecystitis stems from inflammation that is probably caused at first by the chemicals in the bile. However, a bacterial infection then supervenes in 50 percent or more of cases. The pain comes on suddenly and is severe and constant. It is felt across the right and central parts of the upper abdomen and under the right shoulder blade. The patient usually vomits and is quite ill and feverish. If the common bile duct becomes swollen, slight jaundice may occur as bile from the liver is prevented from passing into the intestine and enters the bloodstream instead.
Cholecystectomy: Removal of the Gallbladder
There are several methods of dealing with gallstones, and the Gastrointestinal Surgeons of the University of Pennsylvania are experts in choosing the correct treatment for an individual patient. When symptoms from gallstones occur, removal of the gallbladder is the best approach in most cases. Currently, the most commonly performed operation is called laparoscopic cholecystectomy - the procedure designed to remove the gallbladder as easily and safely as possible and with the smallest possible incisions. A conventional cholecystectomy involves major abdominal surgery. In some patients who are not fit for surgery, it may be possible to dissolve the stones by giving them chenodeoxycholic acid or ursodeoxycholic acid. These preparations are taken by mouth and are excreted in the bile. However, they will only work if the gallbladder works and if the gallstones are very small and contain very little calcium (making them invisible on a plain X-ray of the abdomen). This treatment is not suitable for women of childbearing age or for those with any form of liver disease. It has the disadvantage that, although 80 percent of stones may be dissolved after six month’s or a year's treatment, they frequently re-form after the medication has stopped. Lithotripsy, in which external shock waves are used to bombard and shatter the stones, is sometimes used but is less successful with gallstones than it is with kidney and ureter stones. Another approach involves injecting into the gallbladder a strong solution that dissolves the cholesterol from which the stones are made. Gallstone disease requires sound judgment and extensive experience to manage properly – experience possessed by the Gastrointestinal Surgeons of the University of Pennsylvania.