Kidney Stones
Stones in the ureter diagnosed at the emergency department
General information
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The kidneys are organs that are found on either side of the spine, just below the rib cage in the back. They filter waste materials out of the blood and pass them out of the body as urine.
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Kidney stones are pebble-like pieces of material that can form in one or both of your kidneys when high levels of certain minerals are in your urine.
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The ureter is the narrow, long tube that connects the kidney to the bladder (see figure on the next page).
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Ureteral stones can take up to 6 weeks to travel between the kidney and the bladder.
What are the chances of passing a stone spontaneously?
Passing a stone spontaneously depends on multiple factors. The most important ones are stone size
and location in the ureter.
Stone size
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Smaller than 5mm: 75% chance of spontaneous passage.
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Between 5-7mm: 30-50% chance of spontaneous passage.
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Greater than 7mm: less than 20% chance of spontaneous passage.
Stone location
Proximal Ureter (closer to the kidney): 20% chance of passing
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If a CT scan is done after a few hours or days, the stone will not have enough time to move to the ureter.
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If CT scan is done several days after pain and the stone is still found near the kidney, this is a signal that the stone may not pass or will take a long time.