Thursday, June 26, 2014

Some facts about gallstones

Gallstone disease, or cholelithiasis, is often thought to be a major affliction in modern society. However, gallstones must have been known to humans for many years, since they have been found in the gallbladders of Egyptian mummies dating back to 1000 BC! Today, this disease is a worldwide medical problem, although its prevalence varies depending on the geographical region.

How do gallstones form, and why? The liver secretes bile - a greenish-brown, bitter fluid that is discharged into the digestive tract (into the duodenum, to be precise) and helps emulsify the fats in food, so that they can be digested more easily. Bile is composed of water (92%), bile salts (6%), the pigment bilirubin, tiny amounts of cholesterol and mineral salts. When an imbalance in the chemical constituents of bile causes one or more of the components to precipitate, hardened crystalline deposits form. They can be as small as a grain of sand or as large as a golf ball. (Ouch!)

Gallstones are composed mainly of cholesterol, bilirubin, and calcium salts, with smaller amounts of protein and other materials. There are three types of gallstones:
(1) Pure cholesterol stones, which contain at least 90% cholesterol.
(2) Pigment stones, either brown or black, which contain at least 90% bilirubin.
(3) Mixed composition stones, which contain varying proportions of cholesterol, bilirubin and other substances such as calcium carbonate, calcium phosphate and calcium palmitate.

In Western societies and in Pakistan more than 70% of gallstones are composed primarily of cholesterol, either pure or mixed with pigment. Cholesterol gallstones form when the cholesterol concentration in bile exceeds the ability of bile to hold it in solution, so that crystals form and grow as stones.

Below, you can admire some beautiful specimens of gallstones taken out from the gallbladders of various unfortunate people.

Specimen A) shows a group of gallstones retrieved from a single patient. They all have a similar size and look pretty much the same. B) A cross section of gallstone (GS 1) and C) a cross section of gallstone (GS 4) reveal a heterogeneous appearance throughout a single gallstone. D) 4 gallstones from 4 different patients have different sizes, shapes and colors. (Image from: Marshall et al. 2014)

Gallstones are becoming increasingly common. They are seen in all age groups, but the incidence increases with age; about a quarter of women over 60 years will develop them. The good news is that in most cases gallstones do not cause symptoms. Only 10% and 20% will eventually become symptomatic within 5 years and 20 years of diagnosis. However, the bad news is that cholelithiasis can have severe consequences: acute cholecystitis (inflammation of the gallbladder) or obstruction of the bile ducts, which can lead to ascending cholangitis (infection of the bile duct) or acute pancreatitis, both of which are life-threatening medical conditions.

And how can gallstones be treated?

Cholesterol gallstones can sometimes be dissolved by oral ursodeoxycholic acid, but it may be necessary for the patient to take this medication for up to two years. Gallstones may recur, however, once the drug is stopped. Obstruction of the common bile duct with gallstones can sometimes be relieved by an endoscopic surgical intervention. Gallstones can also be broken up using a procedure called extracorporeal shock wave lithotripsy (often simply called "lithotripsy"): briefly, ultrasonic shock waves are directed onto the stones to break them into tiny pieces. These bits are then passed safely in the feces. However, this form of treatment is suitable only when there is a small number of gallstones. 

Surgical removal of the gallbladder, known as a cholecystectomy, has a 99% chance of eliminating the recurrence of cholelithiasis. Surgery is only recommended in symptomatic patients. There are two surgical options for cholecystectomy: open surgery via an abdominal incision below the lower right ribs or a laparoscopic cholecystectomy, performed via small puncture holes for a camera and instruments. The laparoscopic procedure is much less invasive - patients are often released home on the same day, or after a one-night hospital stay, and can resume normal activity after a week or so, whereas the open procedure typically requires 3-5 days of hospitalization and a much longer recovery period afterwards.

Had enough? I'll serve you one more juicy fact about gallstones: recent studies show that in chronic carriers of the disease-causing bacterium Salmonella typhi, which causes typhoid fever, the microorganism grows in biofilms on the surface of - yes, you've guessed in - gallstones in the gallbladder.

By the way - if you're interested in the anatomy of the liver, bile ducts and gallbladder, there's a very cool free interactive tool online that shows 3D images of various parts of the human body. It's called Human Body Maps and you'll find it under the link . You can look inside different layers of the body, rotate the images to get a 360-degree view, and when you mouse over various body areas, descriptions appear.

Check out this interactive map of the gallbladder:

Have fun!


Marshall JM, Flechtner AD, La Perle KM, Gunn JS. (2014) Visualization of Extracellular Matrix Components within Sectioned Salmonella Biofilms on the Surface of Human Gallstones. PLoS One. 9(2): e89243. Published online 2014 February 14.

Njeze GE. (2013) Gallstones. Niger J Surg. 19(2): 49–55.

Wikipedia: Gallstone

1 comment:

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