As a man, this is hard for me to think about, let alone write. Doctors in California recently surgically removed a stone the size of an ostrich egg from a man's bladder.
After having a hard time going to the washroom for over three days he finally checked himself into a hospital to see what was going on. When the scans came back, doctors were sure the machine was broken. There were two stones inside the man, one smaller one blocking a tube, and then the monster sitting heavy in the bladder. Once removed, the stone weighed a whopping 1.7 pounds.
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This was a special case, and the average person does not have to worry about getting a bladder stone this big. The man in question had survived cancer by having his bladder removed and a new one created using intestine. This had left him more susceptible to stones in general. Here is a picture of your common bladder stone.
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If you want to avoid this situation yourself all you have to do is drink water and stay hydrated, so that the crystals that form these stones don't get a chance to do so.