A health care provider will usually order an ultrasound exam to diagnose gallstones. Other imaging tests may also be used.
                
- Ultrasound exam. Ultrasound uses a device, called a transducer, that bounces safe, painless sound waves off organs to create an image of their structure. A specially trained technician performs the procedure in a health care providers offi ce, outpatient center, or hospital, and a radiologista doctor who specializes in medical imaginginterprets the images. Anesthesia is not needed. If gallstones are present, they will be visible in the image. Ultrasound is the most accurate method to detect gallstones.  - Computerized tomography (CT) scan. A CT scan is an x ray that produces pictures of the body. A CT scan may include the injection of a special dye, called contrast medium. CT scans use a combination of x rays and computer technology to create three-dimensional (3-D) images. CT scans require the person to lie on a table that slides into a tunnel-shaped device where the x rays are taken. An x-ray technician performs the procedure in an outpatient center or hospital, and a radiologist interprets the images. Anesthesia is not needed. CT scans can show gallstones or complications, such as infection and blockage of the gallbladder or bile ducts. However, CT scans can miss gallstones that are present.  - Magnetic resonance imaging (MRI). MRI machines use radio waves and magnets to produce detailed pictures of the bodys internal organs and soft tissues without using x rays. A specially trained technician performs the procedure in an outpatient center or hospital, and a radiologist interprets the images. Anesthesia is not needed, though people with a fear of confi ned spaces may receive light sedation. An MRI may include the injection of contrast medium. With most MRI machines, the person lies on a table that slides into a tunnel-shaped device that may be open ended or closed at one end; some newer machines allow the person to lie in a more open space. MRIs can show gallstones in the ducts of the biliary system.  - Cholescintigraphy. Cholescintigraphyalso called a hydroxyl iminodiacetic acid scan, HIDA scan, or hepatobiliary scanuses an unharmful radioactive material to produce pictures of the biliary system. In cholescintigraphy, the person lies on an exam table and a health care provider injects a small amount of unharmful radioactive material into a vein in the persons arm. The health care provider may also inject a substance that causes the gallbladder to contract. A special camera takes pictures of the radioactive material as it moves through the biliary system. A specially trained technician performs the procedure in an outpatient center or hospital, and a radiologist interprets the images. Anesthesia is not needed. Cholescintigraphy is used to diagnose abnormal contractions of the gallbladder or obstruction of the bile ducts.   - Endoscopic retrograde cholangiopancreatography (ERCP). ERCP uses an x ray to look into the bile and pancreatic ducts. After lightly sedating the person, the health care provider inserts an endoscopea small,  flexible tube with a light and a camera on the endthrough the mouth into the duodenum and bile ducts. The endoscope is connected to a computer and video monitor. The health care provider injects contrast medium through the tube into the bile ducts, which makes the ducts show up on the monitor. The health care provider performs the procedure in an outpatient center or hospital. ERCP helps the health care provider locate the affected bile duct and the gallstone. The stone is captured in a tiny basket attached to the endoscope and removed. This test is more invasive than other tests and is used selectively.
                
Health care providers also use blood tests to look for signs of infection or in flammation of the bile ducts, gallbladder, pancreas, or liver. A blood test involves drawing blood at a health care providers offi ce or commercial facility and sending the sample to a lab for analysis.
                
Gallstone symptoms may be similar to those of other conditions, such as appendicitis, ulcers, pancreatitis, and gastroesophageal refl ux disease.
                
Sometimes, silent gallstones are found when a person does not have any symptoms. For example, a health care provider may notice gallstones when performing ultrasound for a different reason.