"In this congenital condition, more than one ureter, the tube from the kidney to the bladder, drains a different pole of the kidney," he said. In Angel's case, one of the ureters in each kidney remained free of damage.
Angel's deformity likely occurred during her development in utero when tissue masses split during the evolution of the kidneys, said Becker, who was not involved in her treatment. The condition can be related to a number of different syndromes.
Becker speculated that when doctors discovered the functional ureters during surgery, they "left everything in there and let the kidneys keep working and do their thing."
Kidney disease is relative rare in children; adults are about 20 times more likely to have problems and the risk increases with age.
In the general population, slightly more than 30 people in every 100,000 develop kidney failure each year. But in children, aged 19 and under, the annual rate is only one or two new cases per 100,000 children, according to the National Kidney and Urologic Disease Information Clearing House (NKUDIC), which is part of the National Institutes of Health.
Boys are more susceptible than girls to have kidney failure due to birth defects and other hereditary diseases. African Americans in their late teens are three times more likely than Caucasians in the same age group to develop kidney failure.
"When children develop kidney failure, not only do they have the same set of co-morbidity conditions that adults get, they are more at risk on how it takes a toll in their lifetime," said Becker.
The kidneys also regulate blood pressure, balance chemicals like sodium and potassium, and make hormones to help bones grow and keep the blood healthy by making new red blood cells.
Children with kidney disease are especially at risk for growth disturbances. Becker cited the "classic example" of such an illness in Tiny Tim, the sickly character from Charles Dickens novel, "A Christmas Carol."
"The kidneys don't work well and they don't develop muscular-skeletally and it affects their ability to function," he said.
When kidney failure occurs, doctors are more apt to recommend an organ transplant, rather than dialysis, according to Becker.
In children aged 1 to 5, the transplant success rate is nearly 80 percent for five years and 63 percent for 10 years. In children 6 to 11 years, that rate is about the same for five years and drops closer to adult rates at 50 percent over 10 years.
"Dialysis for a child is very complex," he said. "Even with the ability to give growth hormone, it's a very time-consuming and personally intensive treatment that requires a huge commitment of the family and child to be successful."