Gallstones are hardened deposits of digestive fluid that form in your gallbladder. To diagnose them, doctors typically start with an abdominal ultrasound, which is a painless imaging test that can detect stones with high accuracy. If the ultrasound is unclear or more details are needed, your doctor may order blood tests, a CT scan, or a specialized scan called a HIDA scan.
What are gallstones and who gets them?
Gallstones are solid particles that form in the gallbladder, a small organ under your liver that stores bile. Bile helps digest fat. When bile contains too much cholesterol or bilirubin, it can harden into stones.
There are two main types: cholesterol stones (most common) and pigment stones. Cholesterol stones are often yellow-green and form when bile has too much cholesterol. Pigment stones are dark and form when bilirubin levels are high, which can happen with liver disease or blood disorders.
Anyone can get gallstones, but certain factors raise the risk. Women are more likely than men, especially during pregnancy or with hormone therapy. Age over 40, obesity, rapid weight loss, and a family history of gallstones also increase the odds. People with diabetes or cirrhosis have higher rates as well.
Many people with gallstones never have symptoms. These are called silent gallstones and usually do not need treatment. Problems arise when a stone blocks one of the ducts that carry bile from the gallbladder or liver.
What symptoms might lead your doctor to suspect gallstones?
When gallstones cause symptoms, the most common is pain in the upper right part of your abdomen. This pain, called biliary colic, often comes on suddenly after a fatty meal and may last from 30 minutes to a few hours. The pain can also radiate to your back or right shoulder blade.
Other symptoms include nausea, vomiting, bloating, and indigestion. If a stone blocks a bile duct, you may develop jaundice — yellowing of the skin and whites of the eyes. Dark urine, light-colored stools, and fever with chills can signal a more serious infection or inflammation of the gallbladder (cholecystitis) or pancreas (pancreatitis).
If you have these symptoms, your doctor will take a medical history, do a physical exam, and order tests. The exam may include pressing on your upper right abdomen to check for tenderness or a sign called Murphy’s sign — when you breathe in and the doctor presses that area and you feel sharp pain.
How To Diagnose Gallstones? The main tests
The first and most common test for gallstones is an abdominal ultrasound. This is a quick, non-invasive imaging test that uses sound waves to create pictures of your internal organs. Ultrasound can detect gallstones with high accuracy — research suggests it identifies stones in 95% of cases or more.
During the test, you lie on a table while a technician moves a handheld device (transducer) over your abdomen. A gel on your skin helps the sound waves travel. You may feel slight pressure but no pain. The entire test takes about 30 minutes.
Ultrasound can show the size, number, and location of stones. It can also reveal a thickened gallbladder wall or fluid around the gallbladder, which indicate inflammation. The test is safe for pregnant women and people who cannot undergo other imaging.
If the ultrasound is negative but your symptoms strongly suggest gallstones, your doctor may order additional tests. These include blood work and other imaging methods.
What does an ultrasound look for in detail?
Ultrasound is good at finding stones as small as 2 to 3 millimeters. Stones appear as bright echoes with a shadow behind them. The technician will scan the gallbladder in different positions — lying flat, on your left side, or sitting up — to get the best view.
The test also checks the common bile duct. If the duct is widened (dilated), it may mean a stone is stuck there. This is important because a blocked bile duct can cause serious complications like jaundice or pancreatitis.
Sometimes a stone is present but the ultrasound does not see it clearly — for example, if it is very small or located in a hard-to-see part of the duct. That is when other tests become useful.
Additional imaging tests for gallstones
If ultrasound is unclear or your doctor suspects a stone in the bile duct, they may order a computed tomography (CT) scan. CT uses X-rays to create detailed cross-sectional images. It can detect gallstones that contain calcium, but it misses many cholesterol stones. For that reason, ultrasound is preferred for initial diagnosis.
Magnetic resonance imaging (MRI) with a technique called magnetic resonance cholangiopancreatography (MRCP) provides very detailed images of the bile ducts, gallbladder, and pancreas. MRCP is especially good at finding stones in the common bile duct. It does not use radiation and is often done when ultrasound results are unclear or when symptoms suggest a duct blockage.
Another test is a HIDA scan (hepatobiliary iminodiacetic acid scan). You receive a small amount of radioactive tracer through an IV. The tracer travels through your liver and into the bile ducts and gallbladder. A camera takes images to see how well your gallbladder fills and empties. This test helps diagnose gallbladder dysfunction even if no stones are seen.
Endoscopic ultrasound (EUS) is a more invasive option. A thin, flexible tube with an ultrasound probe on the tip is passed through your mouth into your stomach and upper intestine. It gives very clear images of the bile duct and can find small stones missed by other tests. EUS is often done before a therapeutic procedure called ERCP.
Blood tests and gallstone diagnosis
Blood tests alone cannot diagnose gallstones, but they provide important clues. Your doctor will order a complete blood count (CBC) to check for infection. Liver function tests (LFTs) measure enzymes like ALT, AST, alkaline phosphatase, and bilirubin. Elevated levels may indicate a blocked bile duct.
Amylase and lipase levels check for pancreatitis, which gallstones can cause. If these enzymes are high, your doctor will look for a stone in the bile duct or where the bile duct meets the pancreatic duct.
Blood tests help your doctor decide whether urgent treatment is needed. They also guide the choice of further imaging.
What happens if gallstones are found?
If you have silent gallstones — no symptoms — treatment is usually not needed. Your doctor may recommend a “watch and wait” approach because the risk of developing symptoms is low (about 2% per year).
If you have symptoms, the standard treatment is surgical removal of the gallbladder, called cholecystectomy. This is most often done laparoscopically (through small incisions) and recovery takes about one to two weeks. Without a gallbladder, bile flows directly from your liver to your small intestine, and most people digest food normally.
In some cases, if a stone is blocking the bile duct, a procedure called endoscopic retrograde cholangiopancreatography (ERCP) can remove it. During ERCP, a doctor passes a thin tube through your mouth into your small intestine, then uses a tiny balloon or basket to pull the stone out. This does not remove the gallbladder, so you may still need surgery later.
Medications are rarely used for gallstones. Ursodeoxycholic acid can dissolve small cholesterol stones, but it takes months to work and stones often return after stopping. It is mainly reserved for people who cannot have surgery.
How to prepare for a gallstone diagnosis
If you think you might have gallstones, start by seeing your primary care doctor. Be ready to describe your symptoms: when the pain started, where it is, what brings it on, and how long it lasts. Mention any fatty meals before episodes. Also list your medical history and any medications you take.
Your doctor may ask you to fast for 4 to 6 hours before an ultrasound, because food can cause the gallbladder to contract and make it harder to see stones. For a HIDA scan or MRCP, you may need to fast longer. Follow your doctor’s specific instructions.
No special preparation is needed for a CT scan or blood tests, though for some scans you may be asked to drink contrast material. Always tell your doctor if you are pregnant, have allergies (especially to contrast dye), or have kidney problems.
Key points to remember
Ultrasound is the main test for diagnosing gallstones. It is safe, accurate, and widely available. If your symptoms are severe — such as high fever, jaundice, or intense abdominal pain — seek emergency care right away. These could be signs of a blocked duct, infection, or pancreatitis, which require immediate treatment.
Most people with gallstones do not need treatment unless they cause symptoms. If you have symptoms, surgery is the most effective option. Imaging and blood tests guide the decision. Talk with your doctor about which tests are right for you.
Frequently Asked Questions
Can gallstones be seen on a CT scan?
Yes, but CT scan is less sensitive than ultrasound for cholesterol stones, which are the most common type.
What blood tests show gallstones?
Blood tests do not show stones directly, but elevated liver enzymes or bilirubin can suggest a blocked bile duct.
Is a HIDA scan painful?
No, a HIDA scan is painless. You receive an IV line and lie still while a camera takes images.
How long does an abdominal ultrasound take?
An abdominal ultrasound usually takes about 30 minutes and is completely painless.
