Hydronephrosis is swelling of one or both kidneys. It happens when urine can't drain from a kidney and builds up in the kidney as a result. The condition can be due to a blockage in the tubes that drain urine from the kidneys. It also can happen due to a difference present at birth that prevents urine from draining properly. In some people, hydronephrosis causes kidney damage over time.
Hydronephrosis can happen at any age. The condition often causes no symptoms. People who get symptoms may have side and back pain, painful urination, vomiting and fever. Healthcare professionals have various ways to spot hydronephrosis. Tests to find the condition can be done during infancy or sometimes before a baby is born.
Treatment for hydronephrosis depends on the condition's cause. Some people need medicine or surgery to feel better and prevent kidney damage. Mild hydronephrosis sometimes goes away on its own over time.