Medical Q&As

Kidney stone - size?

I am a 53-year-old man and had gall bladder surgery four weeks ago. At the same time an 8 mm kidney stone was found to be blocking my left kidney. The kidney was infected, a stent was inserted and the stone was pushed back up inside until it can be treated. I have further infection in the kidney and my doctor put me on antibiotics for this. Is an 8 mm stone large, does it continue to grow until it is removed and are there any long-term infection problems associated with leaving the stent in place?

As a general rule of thumb a kidney stone (within the kidney), greater than 1 cm in size, will rarely pass from the kidney into the ureter. Therefore such stones cannot be ignored and need to be treated, since it is extremely unlikely that they could be passed spontaneously. If the stone is lodged in the ureter, which is the tube connecting the kidney to the bladder, there is a good chance of it being passed spontaneously if it is less than 4 mm in diameter. However stones greater than 8 mm in diameter are unlikely to be passed. Your question suggests that your kidney stone has been dislodged from the ureter back into the kidney and given its size it is unlikely that it will be passed spontaneously. Kidney stones can continue to grow but their rate of growth is slow and there should not be a significant increase in the size of your stone while you await further treatment. Some stones can be of much greater size than the one lodged in your left kidney. However the crucial issue is the size of the stone in relation to the diameter of the ureter. If the stone is 8 mm or more in diameter it is unlikely that it will pass. You continue to be at risk of further urinary infections until such time as the stone is dealt with. The possibility also exists of developing further stones in the future therefore it is important to establish if you have any predisposing risk factors for stone formation in order to prevent such recurrences.