Hydronephrosis is caused when urine flow is obstructed in the ureter (the tubes that drain urine from the kidneys to the bladder), thus leading to a back-up of urine which causes the kidneys to swell. The condition generally occurs as the result of, or along with, another disease or condition (such as vesicoureteric reflux or kidney stones). Nausea, vomiting, fever, urinary tract infections, swelling of the abdomen and painful urination are common symptoms associated with hydronephrosis. A round of antibiotics will typically cure the condition. For those suffering from a higher, more severe grade of hydronephrosis, surgical treatment is typically required.