AFP testing is expensive, now largely obsolete.(Obstetrics)

MIAMI BEACH -- Maternal serum [alpha]-fetoprotein is no longer an effective or cost-effective second-trimester screen for neural tube defects in an era when women routinely undergo first-trimester Down syndrome screening and subsequent ultrasound, Dr. Todd J. Rosen said at the annual meeting of the Society for Maternal-Fetal Medicine.

Before ultrasound was commonplace--back in the 1970s and 1980s-women got an [alpha]-fetoprotein (AFP) test for spina bifida and anencephaly. "Now more and more women are screening for Down syndrome in the first trimester, and it is routine for women to do an ultrasound screen as well," said Dr. Rosen of the division of maternal-fetal medicine, Columbia University, New York. Dr. Rosen and his associates assessed clinical and cost effectiveness of AFP testing for U.S. women who had a first-trimester Down syndrome risk assessment and second-trimester ultrasound examination. They used a decision analysis model that assumed ultrasound provides 100% detection of anencephaly and 92% detection of spina bifida (the lowest percentage reported in the literature). To put AFP testing in the most favorable light, the model assumed a 92% detection rate for spina bifida (the highest in the literature) with a 3% false-positive rate.

The model predicted an estimated 4,000 neural tube defects among the approximate 4 million births in the United States in 2003. ...