Kidneys can swell due to a blockage in the urinary tract, according to Healthline. The condition is called hydronephrosis, and it usually only affects one kidney. It occurs frequently in babies but also occurs in about 1 percent of adults.
Kidney stones, blood clots and scarring are some conditions that can block a ureter so that urine is unable to pass. The urine backs up into the kidney and causes swelling, explains Healthline. Tumors in the ureter and congenital birth defects can also cause such blockages.
Symptoms of hydronephrosis include the need to urinate frequently and urgently, painful urination, urinary tract infection and fever, states MedlinePlus. Nausea and vomiting, flank pain, and a mass in the abdomen are other possible symptoms.
To treat hydronephrosis, a doctor may insert a stent to allow urine to drain into the bladder, notes MedlinePlus. Alternatively, he may insert a tube that causes urine to drain into a bag. If infection is present, antibiotics are necessary. If a kidney stone, scarring or a blood clot is causing the blockage, surgical intervention may be necessary, adds Healthline.
Prompt treatment of hydronephrosis is critical to prevent permanent kidney damage, emphasizes MedlinePlus. In addition, untreated urinary tract infections that may arise from hydronephrosis can lead to serious conditions, such as kidney infection or blood poisoning.