Stones are great for tossing into a stream or using to line your flowerbeds. But they're not so great when they're trapped inside your gallbladder. If you've got pain in the upper part of your belly, a fever, or yellow skin, they could be signs that you've got gallstones.

The stones that form in your gallbladder aren't made of rock. Usually, they're made of cholesterol, a type of fat in your blood. Or, they could be made from a substance called bilirubin, which is processed in your liver. Gallstones can be as small as a grain of sand, or as big as a golf ball.

You're more likely to get gallstones if you're over age 40, or if you have a chronic condition like diabetes, anemia, or cirrhosis of the liver. People who've had weight-loss surgery, or who went on a crash diet and lost weight very quickly can also develop gallstones. Gallstones are more common in women than in men, and they may run in families.

So, how do you know if you have gallstones?

Well, you might not realize it, because often gallstones don't cause any pain. They're often found accidentally during an x-ray or surgery to treat another condition. If the gallstone is very large, though, it may get stuck in one of the tubes, called ducts, which connect to the gallbladder. Then you'll probably feel a sharp or cramping pain in the upper right or middle part of your abdomen. You may also have a fever and feel sick to your stomach.

Your doctor can do an ultrasound, or other scan of the gallbladder area to find out if gallstones are causing your pain. You may also have blood tests to check your liver function and to see if your bilirubin levels are too high.

You may not need to treat gallstones, unless they're causing symptoms. If that's the case, your doctor will recommend treatment which is usually surgery to remove them. Often, this is done with a laparoscopic procedure that removes the gallstone through very small cuts or incisions. Normally, you can go home the same day as your surgery, or the next day. Most people don't need to have their whole gallbladder removed, unless they have complications, like a blocked duct. There is also medicine that can dissolve cholesterol gallstones, but it isn't that effective because it can take two years or more to work, and often the stones form again after you're done taking it.

You can't really prevent gallstones, except by avoiding rapid weight loss or health conditions that can cause gallstones such as obesity, diabetes, or cirrhosis. But if you do get them, gallstones are pretty easy to treat. Most people don't have any symptoms or complications from them, and those who do have symptoms usually recover completely and don't get gallstones again after their surgery. It's important that you call your doctor if you are having abdominal pain, yellow skin or eyes, so you can find out for sure whether you have gallstones, and get them treated.