Gallstones are a fairly common pathology in the developed world. The gallbladder is situated posterior to the liver. The gallbladders role is to store bile for when it needs to be released into the gastrointestinal tract ready for digestion. When bile acid is released from the gallbladder it travels out of the neck of the gallbladder through the cystic duct and into the common bile duct, which is drains the left and right hepatic ducts as well. The pancreatic duct then joins into the common bile duct prior to the release of bile through the sphincter of Oddi, out through the ampulla of Vater into the duodenum. This connection to the duodenum marks the division of the fore gut and the mid gut of the gastrointestinal tract.
There are a few different types of gallstones but they most commonly consist of cholesterol however they may be pigmented due to haemolysis or infection. The formation of gallstones depends on the concentrations of 3 components: cholesterol (increased), decreased lecithin and bile salts. The 5 Fs are commonly used to remember the risk factors for gallstone development; Female, Fat, Fertile, Fair skinned and Forty.
The severity and the effects of gallstones depend on the location and size of the gallstones present. There are a few different terms that are used when it comes to gallstones:
- Cholelithiasis – gallstones within the gallbladder
- Choledocholithaisis – stones in the common bile duct
- Cholecystitis – inflammation of the gallbladder
Classically cholelithiasis symptoms only present in 25% of patients. It is described as a biliary colic pain, a sharp pain that comes in waves in the right upper quadrant of the abdomen. This is accompanied by nausea and vomiting and is usually worse after meals. These features are also seen in choledocholithiasis however due to the gallstone obstructing the bile duct features such as obstructive jaundice, pale stool and dark urine might also be seen. This is because bilirubin is blocked in the common bile duct so leaks out causing yellowing of the skin, very little bilirubin is within the gastrointestinal tract so can no longer colour faeces brown.
Diagnosis of gallstones is done by ultrasound scans, as only 10% of gallstones will appear on a CT scan. There are various techniques for removing gallstones, such as endoscopic retrograde cholangiopancreatography (ERCP). This technique involved an endoscope down the patient’s oesophagus up to the ampulla of Vater and injecting contrast through the sphincter of Oddi and then dilating the duct to better facilitate the transport of bile and gallstones. There are also surgical options after ERCP such as laparoscopic cholecystectomy where the entire gallbladder is removed.