10 doctors weighed in:
I have right flank pain and imaging studies showing mild hydronephrosis on that side (no stones). What could be causing this?
10 doctors weighed in

Dr. Peter Corrado
Family Medicine
6 doctors agree
In brief: Suggests blockage
Despite the lack of stones on imaging this scenario suggests a blockage of the right ureter. It is possible that a stone was passed and time is needed for local dilation to resolve.
There could also be other causes like mass or stricture. If the imaging study was an ultrasound, i would talk to my doctor about further evaluation to claify the cause. Follow up studies will ensure resolution.

In brief: Suggests blockage
Despite the lack of stones on imaging this scenario suggests a blockage of the right ureter. It is possible that a stone was passed and time is needed for local dilation to resolve.
There could also be other causes like mass or stricture. If the imaging study was an ultrasound, i would talk to my doctor about further evaluation to claify the cause. Follow up studies will ensure resolution.
Dr. Peter Corrado
Dr. Peter Corrado
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1 comment
Dr. George Klauber
US can miss small kidney or ureteral stones. Mild hydronephrosis is often of no consequence, however a Mag3 diuretic renal scan can demonstrate presence or absence of any significant blockage causing hydronephrosis. Diuretic, given for test, may also provoke flank pain if due to obstruction.
Dr. George Klauber
Pediatrics - Urology
4 doctors agree
In brief: Possible small stone
Small kidney stone could be missed if imaging was by ultrasound +/- plain abdominal xray.
Spiral ct scan is the gold standard with "slices" 3mm apart. Flank pain could also be due to partial uretero-pelvic junction obstruction (blockage). Pain would tend to increase after consuming lots of fluid. Mild kidney infection and finally hydronephrosis could be "red herring" & pain is musculo-skeletal.

In brief: Possible small stone
Small kidney stone could be missed if imaging was by ultrasound +/- plain abdominal xray.
Spiral ct scan is the gold standard with "slices" 3mm apart. Flank pain could also be due to partial uretero-pelvic junction obstruction (blockage). Pain would tend to increase after consuming lots of fluid. Mild kidney infection and finally hydronephrosis could be "red herring" & pain is musculo-skeletal.
Dr. George Klauber
Dr. George Klauber
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Dr. Reid Blackwelder
Family Medicine
2 doctors agree
In brief: Obstruction mainly
You are right that kidney stones are a common cause of hydronephrosis.
Hydronephrosis is usually from blockages or obstruction of the ureter (the plumbing from the kidney to the bladder), and flank pain fits it. If no stones, then other causes can be masses in the pelvis or abdomin that push on the ureter, or reflux of urine from valves. Needs some follow-up especially of female organs -if a woman.

In brief: Obstruction mainly
You are right that kidney stones are a common cause of hydronephrosis.
Hydronephrosis is usually from blockages or obstruction of the ureter (the plumbing from the kidney to the bladder), and flank pain fits it. If no stones, then other causes can be masses in the pelvis or abdomin that push on the ureter, or reflux of urine from valves. Needs some follow-up especially of female organs -if a woman.
Dr. Reid Blackwelder
Dr. Reid Blackwelder
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2 comments
Dr. Reid Blackwelder
You may have some spasm in that ureter for some reason. Sounds like issues of pelvic mass are much less likely if the CT looked that low. If you have not seen a urologist, it might be worth that consult at this point
Dr. Reid Blackwelder
Glad you are plugged in but that can be challenging as well! Many tests often need more tests, and sometimes with no real answer! Lupus can cause inflammation in lots of places, incluring the kidneys and ureters, bladder, etc. As Dr Corrado suggested a passed stone can also cause swelling. Sorry this is frustrating. Good luck
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