The ureteropelvic junction is located where the pelvis of the kidney meets the ureter (the tube that drains urine into the bladder). The term ureteropelvic junction (UPJ)
Obstruction Illustrationobstruction is used to describe a blockage to this area. The obstruction impedes the flow of urine down to the bladder, causing the urine to back up in the kidney and dilate it (hydronephrosis).
Unilateral UPJ obstruction is the most common prenatally detected obstructive disease, often picked up on maternal ultrasounds during pregnancy. Each year, the Division of Urology treats nearly 150 children who have a UPJ obstruction.
Due to the increased use of prenatal imaging, UPJ obstruction may be identified before any symptoms are present. If any dilation (hydronephrosis) is identified, the baby will be monitored throughout the pregnancy and after birth. Once the baby is born further imaging studies may confirm the obstruction. Older children may experience back or flank pain. The pain may be associated with nausea and vomiting. Other symptoms might include bloody urine, a urinary tract infection (often with a fever), or might even be a vague abdominal pain.
UPJ obstruction usually occurs during fetal development. Most of the time, the blockage is caused when the connection between the ureter and the renal pelvis narrows. Typically in older children, UPJ obstruction can also be caused when a blood vessel is in the wrong position, crossing over the ureter and causing constriction. UPJ obstruction can also be due to scar tissue, infection, a benign polyp, or kidney stones.
The overall goal in treating a UPJ obstruction is to preserve renal function. In some children, an ultrasound may show a significant amount of dilation (hydronephrosis) but the kidney functions and drains well. In this situation, we will closely follow your child with repeated imaging studies.
In situations where the kidney function is compromised, surgical intervention is needed. The surgical procedure to correct the obstruction is called a pyeloplasty. The area of obstruction in the ureter is removed, and the normal area is reconnected to the kidney. Drainage tubes may be left in place to allow urine to flow across the surgical area to promote healing.
In young babies, the pyeloplasty is done through a small incision. Minimally invasive surgery (MIS) is an option for children older than 6 months of age. The pyeloplasty can be done either laparoscopically or through a robotic assisted laparoscopic approach. The minimally invasive approach is accomplished through three small incisions, the size of a grain of rice. The advantages are smaller, less visible incisions and a quicker recovery period. The minimally invasive technique is not appropriate for all children. Your healthcare provider will work with you and your family to determine what kind of intervention is best.
Reviewed by: Division of Urology
Date: May 2011