Prenatal diagnosis of diverse chromosome abnormalities in a population of patients identified by triple-marker testing as screen positive for Down syndrome

• Published in: American journal of obstetrics and gynecology 1995-08, Vol.173 (2), p.496-501
• Main Authors: Benn, Peter A., Horne, Donna, Briganti, Susan, Greenstein, Robert M.
• Format: Article
• Language: English
• Subjects: Adult; alpha-Fetoproteins - analysis; Biological and medical sciences; Chorionic Gonadotropin - blood; Chromosome Aberrations - diagnosis; Chromosome Disorders; cytogenetics; Down syndrome; Down Syndrome - diagnosis; Estriol - blood; Female; Fetal Diseases - diagnosis; Gestational Age; Gynecology. Andrology. Obstetrics; Humans; Karyotyping; Management. Prenatal diagnosis; Maternal Age; Medical sciences; Pregnancy; Pregnancy Trimester, Second; Pregnancy. Fetus. Placenta; Prenatal Diagnosis; Prenatal screening; Risk Factors; triple-marker testing; Ultrasonography, Prenatal
• ISSN: 0002-9378; 1097-6868
• DOI: 10.1016/0002-9378(95)90272-4

OBJECTIVE: Our purpose was to determine the incidence of all types of chromosome abnormalities (i.e., trisomy 21 and other abnormalities) in women receiving prenatal chromosome analysis after a Down syndrome screen-positive result by maternal serum triple-marker testing (α-fetoprotein, human chorionic gonadotropin, and unconjugated estriol analyses). STUDY DESIGN: A total of 11,434 patients between 15.0 and 21.9 weeks' gestation received second-trimester Down syndrome risk evaluation by triple-marker testing. By use of a 1:270 midtrimester Down syndrome risk cutoff value, and after ultrasonographic confirmation of gestation age, 677 patients were screen positive for Down syndrome (corrected screen-positive rate 5.92%). Karyotypes were reviewed for 468 (69%) of these patients who received prenatal chromosome analysis. RESULTS: In addition to 12 cases of Down syndrome, 12 other fetal chromosome abnormalities were found (i.e., 5.13% had a chromosome abnormality of some type). Expressed as a proportion of al patients with a corrected Down syndrome screen-positive result, at least 3.69% had a chromosome abnormality. The overall spectrum of abnormal karyotypes (approximately 50% autosomal trisomy, 25% structural and 25% sex chromosome abnormality) appears to be comparable to that seen in patients undergoing amniocentesis because of advanced maternal age. CONCLUSIONS: As is the case for women of advanced maternal age, preamniocentesis counseling for patients with positive triple-marker testing results should reflect the relatively high probability that an abnormality other than Down syndrome may be identified.