There are several causes for hydronephrosis. Obstruction at the outlet of the bladder will cause hydronephrosis of both kidneys, because in this case the back pressure is applied equally to both. Obstruction may be from a urinary stone, a tumor, a blood clot, inflammatory narrowing or external pressure from any cause, including an abnormally placed artery to the kidney. One of the most common causes is enlargement of the prostate gland. Obstruction in one ureter, as from a stone, will affect only the kidney on that side.
I would suggest a referral to a urologist for further evaluation of the prostate to ensure it isn't causing the hydronephrosis.
Followup with your personal physician is essential.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.
My friend has had many double kidney infections. She was just told that she has and enlarged left kidney and it was failing. We are looking for information about how it happens, what to do, & what she is looking at as treatment?