N13.0: Hydronephrosis with ureteropelvic junction obstruction

You renal pelvis is distended.

The renal pelvis can become distended if one part of the urinary passages is constricted. The urinary passages consist of the kidneys, the ureters, the bladder and the urethra.

There are normally 2 kidneys in the body. They filter blood and create urine. They thus help to detoxify the body. Furthermore, the kidneys regulate the blood pressure and salt content in the blood, among other things. Each kidney is made up of renal tissue and a renal pelvis. The renal tissue makes up the urine. The urine gathers in the renal pelvis.

The ureter is a thin, muscular tube in the abdomen. There is usually one ureter on each side. The urine flows from the kidney, via the ureter, to the bladder. When you have to pass water, the urine flows from the bladder via the urethra and out.

The passage between your renal pelvis and ureter has become constricted. The narrowing of the ureter is stopping the urine draining from the kidney properly. If the urine cannot drain from the kidneys properly, it builds up there. This can cause the renal pelvis to expand. The renal tissue around the renal pelvis can also become damaged or smaller.