This is a gallbladder. Specifically this is my gallbladder (lovely, isn’t it?) after it was removed laparoscopically this past February and as is routine, sent for pathology. As you can see, there was a lot going on in my gallbladder at the time. While gallbladder disease and surgical treatment is pretty much routine medicine, I thought this was a good example to illustrate that the pathophysiology behind it can be varied in nature.
The simple explanation for what causes gallbladder disease is an over concentration or saturation of a particular substance. What causes the saturation is not always known and there are a couple of substances involved. When it comes to explaining to my patients the concept of concentration, I like to describe to them a very simple example. I use the example of putting sugar into water or iced tea. I remind them that when you put in a little sugar, it dissolves very easily but if you put in too much, the sugar precipitates out and you can see it. In much the same way, this is what happens with gallstones.
- Pigment stones (1): Pigment stones are composed of Bilirubin, which is the result of the breakdown of red blood cells. Certain conditions cause the liver to make too much bilirubin such as cirrhosis, biliary tract infections, and some blood dyscrasias. Again, the end result is a hyper concentration of, in this case, bilirubin that precipitation out. Pigment stones make up about 20% of gallstones, are black or brown in color, and have smoother (but not completely smooth) edges than their cholesterol counterparts.
- Cholesterol stones (2): Your liver excretes cholesterol and normally the bile in your gallbladder can dissolve this. However, in some people, the liver excretes more cholesterol than the bile can handle. The cholesterol eventually precipitates out, crystallizes, and eventually forms a stone or stones. These stones are typically yellow in color with jagged edges and account for about 80% of gallstones. Of note, one does not need to have high cholesterol for this to occur.
- Impaired Emptying: Sometimes, the saturation of cholesterol and/or bilirubin can be due to impaired emptying of the gallbladder and not increased excretion / production from the liver. Impaired emptying can be due to pathology of the smooth muscles and epithelial cells of the gallbladder wall, contractile dyscoordination of the gallbladder wall and cystic duct, cystic duct resistance, and gallbladder polyps near the opening of the cystic duct. The net result is a slower and/or irregular emptying of bile. The longer the bile pools in the gallbladder without moving, the more risk of bilirubin or cholesterol precipitating out. This can lead to stones or gallbladder sludge.
- Sludge: This is a mixture of particulate solids that have precipitated from bile. Such sediment consists of cholesterol crystals, calcium bilirubinate pigment, and other calcium salts. The precipitates cause the bile to become thicker, more viscous in nature but not yet concentrated enough to form stones. Many patients may be asymptomatic but some may develop biliary colic symptoms as is seen with gallstones.
- Polyps (present but not seen in the picture): These are growths that arise from the inner wall of the gallbladder. About 95% of polyps are benign in nature with cancer’s being rare. In addition, a majority cause no symptoms and in most cases are monitored with serial ultrasounds to make sure they don’t increase to a size concerning for malignancy. Sometimes, the polyp can arise near the opening of the cystic duct (as in my case) and cause an outflow obstruction leading to sludge and/or stone formation resulting in biliary colic symptoms.