A study published in the February 9, 2011 issue of the New England Journal of Medicine has found that surgery performed on babies prior to birth (in utero) to repair the most serious form of spina bifida, myelomeningocele, was associated with better results than surgery performed after birth for several outcomes. This advancement emphasizes the importance of screening for birth defects early in pregnancy.
Spina bifida is a birth defect in which the bones of the spine and sometimes the skin do not close around the spinal cord. It is the most common type of neural tube defect (NTD), affecting an estimated 1,500 to 2,000 of the babies born in the United States each year. Symptoms and complications of the defect, including mental and physical disabilities, vary from mild to severe.
There are several types of spina bifida, the most serious of which is myelomeningocele, in which the spinal cord protrudes through a gap in the spine. Babies born with this form of spina bifida have a 10% death rate. Those that survive often have excess fluid accumulate around the brain (hydrocephalus) , resulting in brain damage and mental retardation, and damage to the nerves of the legs and lower abdomen, causing paralysis and bowel and bladder malfunction. Currently, surgery is performed within 24 to 48 hours of birth to repair the defect, but it cannot reverse nerve damage that has already occurred. In addition, surgically implanted shunts are often required to drain excess fluid from around the brain.
In a randomized trial of over 150 women, researchers found that surgery performed before the 26th week of pregnancy reduced the risk of death in infants as well as the need for shunts by 12 months of age. Shunts were placed in 40% of babies in the prenatal surgery group compared to 82% in the postnatal surgery group. Prenatal surgery was also associated with improved mental and motor function outcomes at 30 months of age, including an increased likelihood that the child could walk without crutches or other aids.
Findings from this study were positive enough that the trial was stopped early. Now more research is needed on the longer term outcomes following this surgery. Despite the encouraging results, in utero surgery is not without risks, both to the mother and the baby. There was an increased risk of premature birth and associated immature lung development in the newborns in this study. One fifth of the babies in the prenatal surgery group were born with respiratory distress syndrome that likely resulted from being born prematurely. The prenatal surgery was also associated with a higher rate of blood transfusions for the mothers at delivery as well as thinning of the mother's uterine wall, which increased the risk of uterine rupture, requiring that all subsequent deliveries by mothers in the trial be via cesarean section.
To detect spina bifida in developing babies early in a pregnancy, doctors use prenatal screening tests. These include tests for increased levels of alpha-fetoprotein (AFP) in the mothers' blood, often run as part of a quad screen performed in the second trimester, and fetal ultrasound. The quad screen is not specific for spina bifida, but if an elevated level of AFP is detected, it can alert a doctor to perform additional testing such as an ultrasound or amniocentesis. Amniocentesis involves taking a sample of amniotic fluid and testing for elevated AFP levels and/or cholinesterase.
The risk of carrying a baby with spina bifida can be greatly reduced by a woman taking an appropriate amount of folic acid, often included in prenatal vitamins, prior to becoming pregnant and/or early in pregnancy before the neural tube closes by 28 days post conception.
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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
National Institute of Neurological Disorders and Stroke (NINDS). Spina Bifida Fact Sheet. Available online at http://www.ninds.nih.gov/disorders/spina_bifida/detail_spina_bifida.htm through http://www.ninds.nih.gov. Accessed March 2011.
March of Dimes. Spina bifida. Available online at http://www.marchofdimes.com/Baby/birthdefects_spinabifida.html through http://www.marchofdimes.com. Accessed March 2011.
CNN.com. Study: Major benefits for spina bifida surgery in the womb. February 9, 2011. Available online at http://www.cnn.com/2011/HEALTH/02/09/surgery.spina.bifada/index.html through http://www.cnn.com.
ScienceNews. Prenatal Surgery May Be Preferable For Spina Bifida. March 12th, 2011. Available online at http://www.sciencenews.org/view/generic/id/69659/title/Prenatal_surgery_may_be_preferable_for_spina_bifida through http://www.sciencenews.org.
Adzick, N. Scott, et al. A Randomized Trial of Prenatal versus Postnatal Repair of Myelomeningocele. N Engl J Med 2011; 364:993-1004. Available online at http://www.nejm.org/doi/full/10.1056/NEJMoa1014379 through http://www.nejm.org.