Gallstones are small stones that form within the gallbladder. The stones form from concentrated bile in the bile duct. Most stones are made of cholesterol.
These may be completely asymptomatic. They can also cause pain and lead to complications, such as acute cholecystitis, acute cholangitis and pancreatitis.
Gallstones blocking the drainage of the pancreas (i.e. the pancreatic duct) result in pancreatitis.
The right hepatic duct and left hepatic duct leave the liver and join together to become the common hepatic duct. The cystic duct from the gallbladder joins the common hepatic duct halfway along. The pancreatic duct from the pancreas joins with the common hepatic duct further along. When the common bile duct and the pancreatic duct join they become the ampulla of Vater, which then opens into the duodenum. The sphincter of Oddi is a ring of muscle surrounding the ampulla of Vater that controls the flow of bile and pancreatic secretions into the duodenum.
There are some key definitions that are helpful to be familiar with relating to the gallbladder and gallstones:
- Cholestasis: blockage to the flow of bile
- Cholelithiasis: gallstone(s) are present
- Choledocholithiasis: gallstone(s) in the bile duct
- Biliary colic: intermittent right upper quadrant pain caused by gallstones irritating bile ducts
- Cholecystitis: inflammation of the gallbladder
- Cholangitis: inflammation of the bile ducts
- Gallbladder empyema: pus in the gallbladder
- Cholecystectomy: surgical removal of the gallbladder
- Cholecystostomy: inserting a drain into the gallbladder
Risk Factors (4 Fs)
The risk factors for gallstones can be remembered with the four F’s mnemonic:
- F – Fat
- F – Fair
- F – Female
- F – Forty
Patients with gallstones may be completely asymptomatic.
The typical symptom of gallstones is biliary colic. Biliary colic is caused by stones temporarily obstructing drainage of the gallbladder. It may get lodged at the neck of the gallbladder or in the cystic duct, then when it falls back into the gallbladder the symptoms resolve. It causes symptoms of:
- Severe, colicky epigastric or right upper quadrant pain
- Often triggered by meals (particularly high fat meals)
- Lasting between 30 minutes and 8 hours
- May be associated with nausea and vomiting
Alternatively, patients may present with a complication of gallstones, such as:
- Acute cholecystitis
- Acute cholangitis
- Obstructive jaundice (if the stone blocks the ducts)
TOM TIP: Fat entering the digestive system causes cholecystokinin (CCK) secretion from the duodenum. CCK triggers contraction of the gallbladder, which leads to biliary colic. Patients with gallstones and biliary colic are advised to avoid fatty foods to prevent CCK release and gallbladder contraction. Exams may test this mechanism, so it is worth remembering.
Liver Function Tests
Bilirubin normally drains from the liver, through the bile ducts and into the intestines. Raised bilirubin (jaundice) with pale stools and dark urine represents an obstruction to flow within the biliary system. Obstruction may be caused by a gallstone in the bile duct or an external mass pressing on the bile ducts (e.g., cholangiocarcinoma or tumour of the head of the pancreas).
Alkaline phosphatase (ALP) is a non-specific marker. It is an enzyme originating in the liver, biliary system and bone, and abnormal results can indicate liver or bone problems. It is often raised in pregnancy due to production by the placenta.
A raised ALP is consistent with biliary obstruction in presence of right upper quadrant pain and/or jaundice.
Raised alkaline phosphatase can also be caused by liver or bone malignancy, primary biliary cirrhosis, Paget’s disease of the bone and many other things.
Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) are enzymes produced in the liver. They are helpful as markers of hepatocellular injury (damage to the liver cells).
In patients with cholestasis (e.g., due to gallstones), ALT and AST can increase slightly, with a higher rise in ALP (“an obstructive picture”).
If ALT and AST are high compared with the ALP level, this is more indicative of a problem inside the liver with hepatocellular injury (“a hepatitic picture”).
An ultrasound scan is a useful first-line investigation for symptoms of gallstone disease, for example, abdominal pain, right upper quadrant pain and jaundice. It is the most sensitive initial imaging test for gallstones (CT scans are not good at identifying gallstones or biliary disease).
Ultrasound is limited by the patient’s weight, gaseous bowel obstructing the view and discomfort from the probe.
Ultrasound can be helpful in identifying:
- Gallstones in the gallbladder
- Gallstones in the ducts
- Bile duct dilatation (normally less than 6mm diameter)
- Acute cholecystitis (thickened gallbladder wall, stones or sludge in gallbladder and fluid around the gallbladder)
- The pancreas and pancreatic duct
Magnetic Resonance Cholangio-Pancreatography
A magnetic resonance cholangio-pancreatography (MRCP) is an MRI scan with a specific protocol that produces a detailed image of the biliary system. It is very sensitive and specific for biliary tree disease, such as stones in the bile duct and malignancy.
MRCP is used in a number of scenarios for gaining a detailed picture of the biliary system, such as identifying biliary strictures or congenital abnormalities.
With gallstone disease, MRCP is typically used to investigate further if the ultrasound scan does not show stones in the duct, but there is bile duct dilatation or raised bilirubin suggestive of obstruction.
Endoscopic Retrograde Cholangio-Pancreatography
An endoscopic retrograde cholangio-pancreatography (ERCP) involves inserting an endoscope down the oesophagus, past the stomach, to the duodenum and the opening of the common bile duct (the sphincter of Oddi). This gives the operator access to the biliary system.
The main indication for ERCP is to clear stones in the bile ducts.
ERCP allows the operator to:
- Inject contrast and take x-rays to visualise the biliary system and diagnose pathology (e.g., stones or strictures)
- Perform a sphincterotomy on the sphincter of Oddi if it is dysfunctional (blocking flow)
- Clear stones from the ducts
- Insert stents to improve bile duct drainage (e.g., with strictures or tumours)
- Take biopsies of tumours
Key complications of ERCP are:
- Excessive bleeding
- Cholangitis (infection in the bile ducts)
CT scans are less useful for looking at the biliary system and for gallstones. They may be used to look for differential diagnoses (e.g., pancreatic head tumour) and complications such as perforation and abscesses.
Asymptomatic patients with gallstones may be treated conservatively, with no intervention required.
Patients with symptoms or complications of gallstones are treated with cholecystectomy, which is surgical removal of the gallbladder (provided they are fit for surgery).
Cholecystectomy involves surgical removal of the gallbladder. It is indicated where patients are symptomatic of gallstones, or the gallstones are leading to complications (e.g., acute cholecystitis). Stones in the bile ducts can be removed before (by ERCP) or during surgery.
Laparoscopic cholecystectomy (keyhole surgery) is preferred to open cholecystectomy (with a right subcostal “Kocher” incision), as it has less complications and a faster recovery.
Complications of cholecystectomy include:
- Bleeding, infection, pain and scars
- Damage to the bile duct including leakage and strictures
- Stones left in the bile duct
- Damage to the bowel, blood vessels or other organs
- Anaesthetic risks
- Venous thromboembolism (deep vein thrombosis or pulmonary embolism)
- Post-cholecystectomy syndrome
Post-cholecystectomy syndrome involves a group of non-specific symptoms that can occur after a cholecystectomy. They may be attributed to changes in the bile flow after removal of the gallbladder. Symptoms often improve with time. Symptoms include:
- Epigastric or right upper quadrant pain and discomfort
- Intolerance of fatty foods
Last updated May 2021