A retrospective evaluation of second-trimester serum screening for fetal trisomy 18: experience of two laboratories

✍ Scribed by U. Sancken; I. Bartels; F. Louwen; B. Eiben

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 209 KB
• Volume: 19
• Category: Article
• ISSN: 0197-3851
• DOI: 10.1002/(sici)1097-0223(199910)19:10<947::aid-pd674>3.0.co;2-m

✦ Synopsis

A retrospective study on screening methods for fetal trisomy 18 has been carried out in two different laboratories using the serum parameters: total human chorionic gonadotropin (hCG), unconjugated oestriol (uE3), and -fetoprotein (AFP) in different combinations and in single marker protocols. Laboratory A (L A ) utilized a radio-immunoassay to examine 38 fetal trisomy 18 cases and laboratory B (L B ) utilized an enzyme-immunoassay to examine 33 trisomy 18 cases. As unaffected references the whole routine cohorts of each laboratory were used (L A : 29 043; L B : 4264). In both trisomy 18 study groups the median hCG and uE3 multiples of the median (MoM) values were markedly declined (L A : 0.21 MoM, 0.37 MoM; L B : 0.31 MoM, 0.44 MoM). Even after exclusion of trisomy 18 cases with combined neural tube or ventral wall defects the medians of AFP MoM values were only moderately declined (L A : 0.73 MoM; L B : 0.8 MoM). Receiveroperator characteristic (ROC) curves after multivariate discriminance analysis and single marker evaluation demonstrated that the difference of efficiency between a combination of hCG, uE3 and AFP, and a combination of hCG and uE3 is small but that any of these combinations are more efficient than a combination of hCG and AFP or single marker protocols, respectively. At a risk cut-off generating a false-positive rate of one per cent the most effective marker combination detected 31 of 38 (81.6 per cent) affected pregnancies in L A and 25 of 33 (75.8 per cent) in L B . The differences in sensitivity and specificity seem to be due to the different analytical systems being utilized by the two laboratories.