Question: Hello,
I came down with pain in the abdomen and lower back. Went to emergency and the doctor suspected kidney stone.
Subsequently, they did a CT scan and found a 4mm stone in the left ureter very close to the ureterovesical junction. The pain subsided significantly in the next few hours and I went home. I used a strainer to try and catch the stone, but was not able to. The CT scan clearly showed the stone, but the report and the scan showed no other obstruction or sone in either of the kidneys. The left kidney showed a little bit of nephrohydrosis on the left kidney, but the doctor said that was because of the blockage by the stone in the ureter.

3 days later, I saw my urlogist and becuase I was largely symptom free except for mild discomfort, he asked me to do an ultrasound to see if we could see any major dialation of the kidney. The result of the Ultra sound from the radiologist said -
"Both kidneys are normal in size, contour and echotexture. Right kidney measures 9.7 cm in length, and left kidney measures
9.9 cm in length. There is a 5 mm echogenic focus in the midpole of the right kidney. There is a 4 mm echogenic focus in
the midpole of the left kidney. There is an additional 7 mm echogenic focus in the upper pole of the left kidney. Findings are
consistent with bilateral nephrolithiasis. There is no hydronephrosis. "

Based on this, my urologis said I must have passed the stone since it was only 4mm.

one week later I started experiencing pain when I went to pass the urine. Pain was while I started the stream and the stream was also very weak. There was no abdomen pain or back pain classic in kidney stone.
On Saturday, I finally and actually passed the stone, and all the pain and discomfort magically disappeared.

While this was a good outcome, I am concerned about the disparity between the CT Scan and Ultrasound. I am told that the CT Scan is the gold standard and much more accurate than the ultrasound when trying to identify kidney stones.
The Ultrasound and CT scan were done 3 days apart.
My questions are -
1. Based on the CT Scan report that there was no other stone except for the one in the Ureter(which I passed), is it safe to assume that the Ultrasound report is more of a false positive and that I dont have any more stones?
2. Is it common to see something in an Ultrasound and then do a CT scan to confirm?

Appreciate the response and guidance.