First-trimester screening with nasal bone in twins

• Published in: American journal of obstetrics and gynecology 2008-09, Vol.199 (3), p.283.e1-283.e3
• Main Authors: Cleary-Goldman, Jane, MD, Rebarber, Andrei, MD, Krantz, David, MA, Hallahan, Terrence, PhD, Saltzman, Daniel, MD
• Format: Article
• Language: English
• Subjects: Adult; Biological and medical sciences; Chorionic Gonadotropin, beta Subunit, Human - blood; Down Syndrome - diagnosis; Down Syndrome - diagnostic imaging; Down syndrome screening; Female; Gynecology. Andrology. Obstetrics; Humans; Maternal Age; Medical sciences; nasal bone; Nuchal Translucency Measurement; Obstetrics and Gynecology; Pregnancy; Pregnancy Trimester, First; Pregnancy-Associated Plasma Protein-A - analysis; Retrospective Studies; twin pregnancy; Twins
• ISSN: 0002-9378; 1097-6868
• DOI: 10.1016/j.ajog.2008.07.010

Objective The purpose of this study was to evaluate the Down syndrome detection rate at a 5% screen positive rate in first-trimester screening for twins. Study Design This was a retrospective study from August 2005 to July 2007 of twins who underwent first-trimester screening with nuchal translucency, nasal bone, pregnancy-associated plasma protein-A, and free β-hCG. Risks were calculated on the basis of the Fetal Medicine Foundation twin algorithm. The model simulated distributions of unaffected and affected cases at 12 weeks of gestation. Results Two thousand ninety-four twin pregnancies (4188 fetuses) met the inclusion criteria. The addition of nasal bone to nuchal translucency, pregnancy-associated plasma protein-A, and free β-hCG increased the Down syndrome detection rate from 79-89% at a 5% screen-positive rate. Conclusion In twins, first-trimester screening with nasal bone is valuable. The improved Down syndrome detection rate can help these high-risk patients with the decision-making process of whether to pursue invasive testing with its associated pregnancy loss risk.