What is UPJ Obstruction?

A ureteropelvic junction (UPJ) obstruction is a blockage which prevents fluid from draining out of the renal pelvis to the ureter, the tube which carries urine away to the bladder so that it can be expressed. The renal pelvis essentially acts like a funnel for urine, and when it is blocked, urine can back up into the kidney, causing kidney damage. This condition most commonly occurs as a congenital abnormality caused by malformations during fetal development, although it can also have extrinsic causes.

Patients with a UPJ obstruction can experience abdominal swelling and tenderness, bloody urine, and reduced urine production. This condition is often diagnosed during a prenatal ultrasound, in which the malformation can be clearly visualized and addressed shortly after birth. In cases where the cause is extrinsic, as in the instance of an obstruction caused by scarring, a kidney stone, or an infection, a UPJ obstruction may be diagnosed in response to blood tests indicating abnormal kidney function, followed by an ultrasound to assess kidney health.

If a UPJ obstruction is mild, it may be left alone and allowed to resolve on itself. The patient may be given medications to eliminate infection or to break up a kidney stone, and the patient will be checked in a follow up appointment to see if the UPJ has cleared. More serious obstructions like total blockages and obstructions which do not resolve will require surgery. Surgery can include placement of a stent to temporarily drain the kidney until the site has healed.

Surgery for a UPJ obstruction can take a number of forms, with some procedures being more invasive than others. The choice of surgery is usually dictated by the cause of the obstruction, the patient's general health, and the surgeon's preference. Recovery times vary, and generally include monitoring to check urinary output, and follow up care to confirm that the obstruction has been successfully removed.

People who have had kidney surgery are at increased risk for developing a UPJ obstruction, and they should seek the attention of a urologist if they develop any of the symptoms. The same holds true for patients with a history of kidney stones. A UPJ obstruction can also occur as a result of physical trauma, one of the many reasons why an evaluation should be conducted after a car accident, serious fall, or fight, even if a patient feels fine. A medical exam can also reveal issues like internal bleeding which could cause severe complications.