Delicate fetal surgery performed in the womb can prevent or minimize the disabling complications of a birth defect called spina bifida, in which the newborn's spinal cord does not fully form or, in the worst cases, grows exposed outside the baby’s back. The deformity has meant life in a wheelchair for many children. But the pioneering surgical procedure promises to help spina-bifida children avert that fate and lead more normal lives.
The fetal surgery has been undergoing human clinical trials with a team of doctors, led by Scott Adzick, chief surgeon at Children’s Hospital of Philadelphia, in the eastern U.S. state of Pennsylvania. The delicate procedure they have been perfecting involves lifting the womb containing the fetus out of the mother at between 20 and 26 weeks of pregnancy, and operating on the fetus to repair the deformed spinal cord.
Katherine Mulligan of Cincinnati, Ohio underwent the procedure at Children's Hospital when she was pregnant with her son Sean, who is now 10. She says before the procedure, her son’s prognosis was bleak. "A doctor [had] told us he would be in a wheelchair, we would have bowel and bladder problems, he would need a shunt due to hydrocephalus (water on the brain). And today, he plays basketball, baseball, soccer, tennis, swimming, does it all. We still cannot get over how lucky we were. Our life would be very, very different if it weren't for [Children’s Hospital of Philadelphia] and fetal surgery," she said.
Spurred on by the success of cases like the Mulligan's, surgeon Scott Adzick led teams of investigators at CHOP, at Vanderbilt University in Tennessee and at the University of California-San Francisco, through 183 surgeries during the past eight years, on pregnant women whose fetuses had the severest form of spina bifida, called myelomeningocele.
Women who underwent the prenatal surgery were delivered by Caesarean section at 37 weeks. The outcomes for their babies were compared to the health of infants who were delivered by C-section at 37 weeks, and had their spines surgically repaired within 24 hours of delivery.
Among children who were examined at one year after birth and again at 30 months, Adzick says those who had the surgery in utero fared significantly better than newborns who had the repair procedure done after delivery. "Although the ability to walk depends upon the spina bifida lesion somewhat, at 30 months of age children in the prenatal repair group were much more likely to walk independently; 42 percent compared to children in the post-natal repair group, [only] 21 percent," he said.
Also, at one year, twice as many children in the post-natal surgery group required a shunt, or valve, to relieve pressure from fluid accumulations on the brain, compared to children who had their spines repaired in the womb.
Because of its success, the eight-year trial was stopped early at the end of 2010 and Adzick and other surgeons were given permission to perform the fetal operation routinely.
Adzick believes infants who underwent prenatal surgery fared better because he says the womb can be as toxic as it is nurturing to a fetus with spina bifida. "You have this exposed, unprotected spinal cord, even in utero, [brushing] up against the walls of the womb or the walls of the uterus which causes trauma as well. So, by doing the operation before birth, you are protecting it. You are putting tissue layers between the developing spinal cord and the inter-uterine environment," he said.
Adzick adds that the amniotic fluid inside the womb - in which the developing fetus is floating - contains fetal urine, which can be corrosive to the exposed spinal cord.
Researchers now want to see if they can identify which babies would benefit the most from prenatal surgery by looking at the leg movements of the fetus. Adzick says researchers also want to develop a plastic material they can inject into the womb to patch the exposed spinal cord lesion of a fetus with spinal bifida.
The surgeons hope their success with in-utero spina bifida repairs will help to broaden the application of fetal surgery to other serious, and more life-threatening fetal birth defects.
A study describing the delicate fetal surgery is published this week in the New England Journal of Medicine.
