Pediatric urologist Ming-Hsien Wang recalls the case of a newborn boy with a peeing problem – no urine output – that wasn’t picked up the first few days of life. Meanwhile, his serum creatinine levels kept going up and up, signaling possible kidney malfunction or even failure. Being born in a community hospital didn’t help, as there was no neonatal intensive care unit (NICU) for close monitoring or nephrology service to consult. He was transferred to the Hopkins Children’s where Wang pinpointed the problem pretty quickly.
“We started the workup and saw on ultrasound signs of urine backup, thickening of the bladder wall, dilated urethra, and hydronephrosis, or swelling of the kidney,” Wang says. “The usual cause in such cases, especially with boys, is posterior urethral valve.”
The condition, Wang explains, is an obstructive membrane in the urethra that occurs in utero exclusively in males with an incidence of between 1/5000 to 1/8000. Posterior urethral valve, or PUV, varies in degree, though severe cases can result in renal failure, respiratory failure from lung underdevelopment as a result of low amniotic fluid volumes, and loss of the fetus in utero. That’s why it’s important, Wang stresses, to detect the disorder early, ideally through prenatal sonogram. If signs of PUV are present, a pediatric urologist can visualize and resect the valve during the first few days of life by utilizing a scope with a camera the size of a pen tip.
“You can see these little translucent flaps of tissue blocking the urethra, which in normal fetal development should never have happened,” Wang says.
In the past, one treatment option was fetal surgery to divert urine from the bladder directly into the amniotic fluid, but the risks to the fetus proved too high. Today, pediatric urologists like Wang first use tubes to drain the bladder as soon as the baby is born, and then once anesthesia is safe – with the endoscopic camera and a tiny scalpel – cut the membrane.
Wang also recommends circumcision at the same time to reduce the risk of infection, which is high for infants with congenital urologic abnormalities. Vesicoureteral reflux, she adds, is also seen in over 90 percent of cases. The take-home message?
“If you have a baby boy with prenatal hydronephrosis, you should get an initial consult with a pediatric urologist, and preferably have the baby delivered at an academic medical center,” Wang says. “A community hospital might not have the equipment needed to drain the bladder, pediatric radiologists to do the imaging studies, a NICU to take care of a baby who needs nephrology management of the kidneys, and if surgery is needed, the availability of a pediatric anesthesiologist.”
How did Wang’s case turn out?
“We did the resection and his creatinine came down,” Wang says. “He had mild hypertension due to the kidney problems but now he’s doing pretty well.”
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