Unfortunately, kidney stones are rarely easy. Sure there are times when a patient has a very small stone that passes into the bladder and urinates it out. But that is far less common than the usual routine. The ESWL procedure tries to make passing the fragments as painless as possible, and as you can imagine, the smaller the fragments, the less the pain.
Kidney stones are all made within the kidneys and then at some point pass down the long tube called the ureter. The ureter is the tube that connects the kidneys to the bladder. Each kidney routinely has only one ureter. Some people can be born with two ureters per kidney, but this is rare and a topic for another day.
As the stones travel down the ureter, this is routinely where the pain starts. Think about a small pea traveling down a straw that opens and closes but then gets stuck in the straw. OK, that’s very similar to what happens to stones. So, the smaller the size of the pea fragments, the less pain involved.
ESWL is the least invasive approach, but in order for it to be successful, the patient needs to drink plenty of fluids afterward to pass the fragments. Occasionally, these fragments can get stuck in the ureter, causing more pain. The more fluids a patient drinks, the more the ureter stays open and the better chance for the fragments to pass into the bladder. Once in the bladder, the fragments will pass during normal urination.
Bladder stones are a completely different animal and primarily occur because the bladder can’t empty completely, not because the kidney stones get stuck in the bladder.