Uretero - Pelvic Junction (UPJ) Obstruction

Definition: A blockage of the flow of urine between the kidney and the ureter, the hollow tube that drains the kidney, which results in urine backing up and causing swelling of the kidney, eventually resulting in the loss of kidney function if untreated for a long time.

Anatomy: The kidney has a collecting system that ends in a funnel called the renal or kidney pelvis. The pelvis connects to the ureter. Most often a narrowing between the pelvis and ureter causes the UPJ obstruction.

Diagnostic Tests:

• Renal Ultrasound: This is the least invasive test and can show the resultant swelling of the kidney, however renal swelling may not be due to obstruction

• Intravenous pyelogram (IVP): This test was the classic test used in the past and occasionally is used now. It shows the anatomy of the UPJ. It also shows the resultant swelling as well as providing some functional information and usually defining the anatomy of the distal ureter. This test however is more invasive and exposes the child to some radiation.

• Nuclear renogram: This test provides the least anatomic detail, but the most precise information of renal function. Also, the child is exposed to very little radiation.

• Voiding cystourethrogram (VCUG): This test is necessary to rule out any reflux and is performed on all children that present with an episode of pyelonephritis (infection of the kidney).

• Retrograde uretogram: This test is used in the operating room, prior to the actual surgical repair. It delineates the distal ureteral wall ensuring no other abnormalities and uses very little radiation.

Most often the diagnosis is established with renal ultrasound and nuclear renogram. If the findings on these two tests are unusual, an IVP may be used to supplement the above tests. Sometimes the tests are not conclusive and repeat tests are done several weeks later to show whether improvement or deterioration in swelling and/or renal function occurs over time.

Surgery: A dismembered pyeloplasty is usually done. This entails removing the narrowed segment and reattaching the ureter to the renal pelvis, the funnel shaped drainage area of the kidney. A small drain is usually placed next to the repair, which exits the body below the incision and is removed once it stops draining. A stent (an internal tube) is often placed for 4-6 weeks. The child will usually go home in three to five days.

Follow Up: Assuming no complications, the child will return for an office visit two to three weeks after surgery. A renal ultrasound will be done around four weeks after surgery and a nuclear renogram may be done twelve weeks following surgery. Thereafter a yearly renal ultrasound will be done until the child is fully grown.