Ureteropelvic junction obstruction; UP junction obstruction; Obstruction of the ureteropelvic junction
Definition of UPJ obstruction
Ureteropelvic junction (UPJ) obstruction is a blockage in the area that connects the renal pelvis (part of the kidney) to one of the tubes (ureters) that move urine to the bladder.
Causes, incidence, and risk factors
UPJ obstruction generally occurs when a baby is still growing in the womb. This is called a congenital condition (present from birth). Most of the time, the blockage is caused when the connection between the ureter and the renal pelvis narrows. This causes urine to build up, damaging the kidney.
There may not be any symptoms. When symptoms occur, they may include:
Signs and tests
An ultrasound during pregnancy may show kidney problems in the unborn baby.
Surgery to correct the blockage allows urine to flow normally. Open (invasive) surgery is usually performed in infants. Adults may be treated with less-invasive procedures. These procedures involve much smaller surgical cuts than open surgery, and may include:
Early diagnosis and treatment of UPJ obstruction may help preserve future kidney function. UPJ obstruction diagnosed before birth or early after birth may actually improve on its own.
Linda Vorvick, MD, Family Physician, Seattle Site Coordinator, Lecturer, Pathophysiology, MEDEX Northwest Division of Physician Assistant Studies, University of Washington School of Medicine; Louis S. Liou, MD, PhD, Assistant Professor of Urology, Department of Surgery, Boston University School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc. – 2/9/2009