Routine measurement of amniotic fluid alpha-fetoprotein and acetylcholinesterase: the need for a reevaluation

Abstract

The objective of the study was to evaluate whether the current screening regimen of measuring amniotic fluid alpha-fetoprotein (AF-AFP) at the time of amniocentesis and reflex acetylcholinesterase testing vs ultrasound alone to detect neural tube and ventral wall defects offers improved diagnostic accuracy and cost benefit. A retrospective chart review on all patients who had amniocentesis performed at 1 center over the past 11 years was performed. Those with an elevated AF-AFP were compared with those whose AF-AFP was within normal limits. Ultrasound findings and outcomes were reviewed in all cases to assess whether neural tube defects (NTDs) or ventral wall defects (VWDs) were missed by AF-AFP or ultrasound screening. A cost-benefit analysis was then performed. Of 6232 women who underwent amniocentesis between January 2002 and December 2012, 81 had an elevated AF-AFP with or without a positive acetylcholinesterase (AChE). Of these 81 women, 13 had NTDs and 5 had VWDs. The sensitivity of the detailed ultrasound was 100% in detecting NTDs and VWDs, whereas that of the AF-AFP ranged from 22% to 77%, with the inclusion of AChE. The total expenditure for AF-AFP in our sample set (n = 6232 amniocentesis at $76.00 per AF-AFP) was $473,632, and all NTDs and VWDs were detected by ultrasound. Translated to a national laboratory (>42,447 samples/year), the cost savings in 2011 alone would be $3,225,972. Given the accuracy of high-resolution ultrasound in the detection of both NTDs and VWDs, measuring AF-AFP and AChE as a reflex-screening test is not a cost-effective approach.