Which condition involves swelling of the kidney due to backup of urine?

• A. Irritable Bowel Syndrome
• B. Hernia
• C. Gastritis
• D. Hydronephrosis

Answer: (D)

The main concept tested is hydronephrosis, which is swelling of the kidney caused by backup of urine. When the urinary tract is obstructed, urine can’t drain properly, and pressure builds in the kidney, dilating the renal pelvis and calyces. This back-pressure can occur from stones, ureteral strictures, tumors, or other blockages, and it may produce flank pain or be found on imaging. The other conditions listed are unrelated to urine flow and kidney swelling: irritable bowel syndrome involves the gut, a hernia is a protrusion through the abdominal wall, and gastritis is inflammation of the stomach lining. Hydronephrosis is diagnosed with imaging such as ultrasound or CT and treated by relieving the obstruction to protect kidney function.