This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Souter, V. L. Articles by Luthy, D. A. Search for Related Content PubMed PubMed Citation Articles by Souter, V. L. Articles by Luthy, D. A.

Correlation of Second-Trimester Sonographic and Biochemical Markers

Center for Perinatal Studies, Swedish Medical Center, Seattle, Washington USA (A.Z., F.L., D.A.L.); Banner Good Samaritan Medical Center, Phoenix, Arizona USA (V.L.S.); Banner Desert Medical Center, Mesa, Arizona USA (D.A.N.); Division of Human Genetics, Department of Genetics and Developmental Biology, University of Connecticut, Farmington, Connecticut USA (P.A.B.); Cytogenetics, Dynagene/Laboratory Corporation of America, Seattle, Washington USA (A.Z., F.L.); and Center for Perinatal Studies and Pediatrix Medical Group of Washington, Seattle, Washington USA (D.A.L.).

Address correspondence and reprint requests to David A. Nyberg, MD, Antepartum Ultrasound, Banner Desert Medical Center, 1400 S Dobson Rd, Mesa, AZ 85202 USA. E-mail: nyberg{at}u.washington.edu.

Objectives. To investigate correlations between sonographic soft markers and biochemical markers (human chorionic gonadotrophin, -fetoprotein, and estriol) for Down syndrome in the second trimester of pregnancy. Methods. A total of 2183 women with apparently normal singleton fetuses who underwent second-trimester sonography (14–22 weeks) and maternal serum biochemical testing (triple test) were identified. Seven sonographic markers were recorded: nuchal fold thickness, humerus length, femur length, renal pyelectasis, hyperechoic bowel, echogenic intracardiac focus, and choroid plexus cysts. Results. Weak negative but statistically significant correlations were observed between human chorionic gonadotropin (multiples of the median) and both femur length (multiples of the median; Spearman = -0.073; P < .01) and humerus length (multiples of the median; Spearman = -0.083; P < .01). No other correlations significant at the 1% level were observed between femur length (multiples of the median) or humerus length (multiples of the median) and the biochemical markers. There were no significant correlations between nuchal fold thickness and any of the 3 biochemical markers. At the 5% (P < .05) level, the median human chorionic gonadotropin level (multiples of the median) was lower when an echogenic intracardiac focus was detected. Hyperechoic bowel also tended to be associated with higher median human chorionic gonadotropin (multiples of the median) and -fetoprotein (multiples of the median) levels (P < .05). Conclusions. We found that sonographic and biochemical markers for trisomy 21 are largely independent in unaffected pregnancies. For accurate risk estimation, correlations in both affected and unaffected pregnancies need to be considered. No or minimal correlation between sonographic markers and serum screening tests indicates that they can be used as independent modifiers of the maternal age–specific risk for Down syndrome.

Key Words: Down syndrome • sonographic markers • soft markers • triple test

Abbreviations: AFP, -fetoprotein • BPD, biparietal diameter • EIF, echogenic intracardiac focus • FL, femur length • hCG, human chorionic gonadotropin • HL, humerus length • MOM, multiples of the median • NF, nuchal fold