I have 'sludge' in my gallbladder. Will it need removing?

I've been getting pain in the upper part of my tummy, especially after eating, which has been going on for months. I tried taking antacids, which didn't help, and eventually my doctor arranged a scan, which showed I had 'sludge' in my gallbladder. What is this, and how does it differ from gallstones? And what's the best way of treating it? Will I need to have my gallbladder removed?

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The gallbladder is a small pear-shaped sac that lies just underneath the liver in the upper right side of the abdomen. It stores bile, which is then emptied into the small intestine after you eat a meal, to help digest food.

If the gallbladder doesn't empty completely, particles in the bile, such as calcium salts and also cholesterol, can remain in it, and lead to a collection of sludge like material.