Radiologist Questions Kidney Stones

My X-ray showed a 3mm stone in the right kidney however it was not seen in the following x-ray. Why did this happen?

I took an X-ray one week back which showed a 3 mm stone in the right side kidney. Before the treatment started, a follow up X-ray was taken at the hospital and the stone was not to be seen. What could have happened?

12 Answers

At 3mm it is possible that it passed in your urine with minimal symptoms, or that has been obscured by overlying structures, which is also common.
It most likely was excreted through the ureter and bladder
You probably passed the stone. You should be checked for nanobacterial infection. See

It might have gotten dissolved...

Not all types of the kidney stones are visible by plain X-ray. Almost all types of stones could be seen by CT. Location and very small size could make the stone invisible in a plain X-ray as well.
Dear Sir or Madam,

Scenario 1: You probably passed the stone during the week, which elapsed between the 2 X-rays, which would be good news, specially if you are no longer in pain.

Scenario 2: If you are still in pain, you may still have the kidney stone, although there might be other shadows obscuring the right kidney on X-ray that prevent the radiologist from seeing the stone on X-ray. If you are still in pain, you might need a CT of the abdomen and pelvis without intravenous contrast (the ultimate test) to determine whether you have a stone in your right kidney or not. This is the best test to check whether you have a stone or not.

Best regards,
Without seeing the X-rays (presumably plain films as opposed to CT), possibilities include an artifact (not really a stone, but an abnormality on the film, skin or tissue adjacent to the kidney that changed in position or was no longer present when the second X-ray was taken), or passing of the stone before the second film was obtained.
The first stone may have either passed or the initial finding could be artifact. Also, it could have not been seen on second film. If you're symptomatic, get a CT.
3mm stones are quite small and can travel down the ureters to the bladder and out through the urethra without causing obstruction and may do so with little to no pain. It's quite possible that in the time between the first and second studies the stone was passed.
CT is much more sensitive than plain X-ray. Certain kinds of small stones can be missed on plain X-ray. CT is much better at detecting small stones.
Dr. Reed
Frequently we can see things on CT that we cannot see on plain film. This has to do with the density and type of the stone.
It's probably a uric acid stone and too small to see on an X-ray.