P14.70: Routine assessment of amniotic fluid alpha‐fetoprotein in second trimester genetic amniocentesis to detect fetal neural tube defects

Abstract

The main aim of the study was to evaluate the clinical usefulness of routine assessment of amniotic fluid alpha-fetoprotein (AF-AFP) in second trimester genetic amniocentesis, to detect fetal neural tube defects (NTD). A secondary aim was to survey the routine for analyses of AF-AFP in obstetric clinics in Sweden today. This is a retrospective study. The studied population included all 1919 pregnant women, from the county hospitals of Norrköping and Jönköping, who underwent second trimester genetic amniocentesis, during the years 1993–2003. Indications for the genetic amniocentesis were elevated maternal age (> 35 years old) or increased anxiety for chromosomal defects of the expected baby. A questionnaire concerning policy and experience of AF-AFP analyses was sent to all obstetric clinics in Sweden who performed genetic amniocentesis in 2003. Of the 1811 analysis of AF-AFP, eight cases had increased values (0.4%) and five of them were false positive (63%). Of the three true positive cases, one had clinical relevance. In the other two cases the detection of NTD was of subordinate importance; one fetus had trisomy 18 and the other pregnancy was a missed abortion at the ultrasound check-up. In Sweden 91% (39/43) of the obstetric clinics perform routine assessment of AF-AFP at second trimester genetic amniocentesis, but according to the answers in the questionnaire only 8% of the clinics regarded the analyses useful in clinical practice. During 2003 about 8000 genetic amniocentesis were made in Sweden. We concluded that routine assessment of AF-AFP in second trimester genetic amniocentesis does not appear to be justified. The clinical usefulness seems to be limited, and the result of AF-AFP more often creates parental anxiety.