Obesity: Obesity is a major risk factor for gallstones, especially in women. A large clinical study showed that being even moderately overweight increases the risk for developing gallstones. The most likely reason is that obesity tends to reduce the amount of bile salts in bile, resulting in more cholesterol. Obesity also decreases gallbladder emptying.

Estrogen: Excess estrogen from pregnancy, hormone replacement therapy, or birth control pills appears to increase cholesterol levels in bile and decrease gallbladder movement, both of which can lead to gallstones.

Gender: Women between 20 and 60 years of age are twice as likely to develop gallstones as men.

Age: People over age 60 are more likely to develop gallstones than younger people.
 
Cholesterol-lowering drugs: Drugs that lower cholesterol levels in blood actually increase the amount of cholesterol secreted in bile. This in turn can increase the risk of gallstones.

Diabetes: People with diabetes generally have high levels of fatty acids called triglycerides. These fatty acids increase the risk of gallstones.

Rapid weight loss: As the body metabolizes fat during rapid weight loss, it causes the liver to secrete extra cholesterol into bile, which can cause gallstones.
 
Fasting: Fasting decreases gallbladder movement, causing the bile to become over concentrated with cholesterol, which can lead to gallstones.
 

Computed tomography (CT) scan: may show the gallstones or complications.

Cholescintigraphy (HIDA scan): is used to diagnose abnormal contraction of the gallbladder or obstruction. The patient is injected with a radioactive material that is taken up in the gallbladder, which is then stimulated to contract.

Blood tests: Blood tests may be used to look for signs of infection, obstruction, pancreatitis, or jaundice.
Gallstone symptoms are similar to those of heart attack, appendicitis, ulcers, irritable bowel syndrome, hiatal hernia, pancreatitis, and hepatitis. So accurate diagnosis is important.
 

Ultrasound exam:  uses sound waves to create images of organs. Sound waves are sent toward the gallbladder through a handheld device that a technician glides over the abdomen. The sound waves bounce off the gallbladder, liver, and other organs such as a pregnant uterus, and their echoes make electrical impulses that create a picture of the organ on a video monitor. If stones are present, the sound waves will bounce off them, too, showing their location. Ultrasound is the most sensitive and specific test for gallstones.

Magnetic resonance cholangiogram: may diagnose blocked bile ducts.

Endoscopic retrograde cholangiopancreatography (ERCP):  The patient swallows an endoscope -a long, flexible, lighted tube connected to a computer and TV monitor. The doctor guides the endoscope through the stomach and into the small intestine. The doctor then injects a special dye that temporarily stains the ducts in the biliary system. ERCP is used to locate and remove stones in the ducts.