May also be called: Unilateral Hydronephrosis; Bilateral Hydronephrosis; Urinary
Obstruction; Swollen Kidneys
Hydronephrosis (hi-dro-ne-FRO-sis) is when one or both kidneys
become enlarged because the flow of urine (pee) is backed up or blocked.
More to Know
Normally, urine flows from the kidneys to the bladder through thin tubes called
ureters. But some conditions and obstructions in the urinary tract can block the normal
flow of urine or reverse the urine flow. This can cause a buildup of urine in the
kidney, leading to hydronephrosis, or swelling of the kidneys. Hydronephrosis can
sometimes be diagnosed before a baby is born on prenatal
Hydronephrosis may lead to a urinary tract infection or cause pain in the abdomen.
The two main causes of hydronephrosis include blockage of urine flow (which can occur
at different points in the urinary tract) and urine reflux (a reversal of urine flow).
Keep in Mind
Many times, hydronephrosis resolves on its own without treatment. However, if treatment
is needed, most causes of hydronephrosis can be resolved with medications or minor
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