Duplex Collecting System

In children with a duplex collecting system, also known as ureteral duplication, a kidney has two ureters (tubes that carry urine from the kidney to the bladder) rather than one.

  • Children with this condition often also have a ureterocele, an enlargement of the portion of the ureter closest to the bladder due to the ureter opening being very tiny. This obstructs urine flow into the bladder, causing urine to back up the ureter toward the kidney.
  • In a duplex collecting system, the ureter with the ureterocele generally drains the top half of the kidney, while the other ureter drains the lower half. The ureter with the ureterocele may enter the bladder lower than the other ureter, which may cause a backflow of urine (reflux) into the higher ureter.
  • A duplex collecting system can result in frequent urinary tract infections, backflow of urine into the kidney, and sometimes kidney damage.

Richard Lee, MD — Urologist

What causes ureteral duplication?

Ureteral duplication is much more common in girls than in boys. No one knows the cause of ureteral duplication; however, some cases have been reported in siblings, suggesting a genetic component.

What are the symptoms of ureteral duplication?

How Boston Children’s approaches a duplex collecting system

A duplex collecting system and ureterocele are generally treated in tandem. Treatment of the ureterocele often depends on the size of the constriction and how well the kidney that the ureter drains is functioning.