Prospective first-trimester screening for trisomy 21 in 30,564 pregnancies

Am J Obstet Gynecol. 2005 Jun;192(6):1761-7. doi: 10.1016/j.ajog.2005.03.021.

Abstract

Objective: This study was undertaken to evaluate the performance of a 1-stop clinic for first-trimester assessment of risk (OSCAR) for trisomy 21 by a combination of maternal age, fetal nuchal translucency (NT) thickness, and maternal serum-free ss- human chorionic gonadotrophin (hCG) and pregnancy-associated plasma protein-A (PAPP-A).

Study design: OSCAR was carried out in 30,564 pregnancies at 11 to 13 + 6 weeks. Patient-specific risks for trisomy 21 and detection and false-positive rates were calculated.

Results: The median maternal age was 34 (range 15-49) years. Chromosomal abnormalities were identified in 330 pregnancies, including 196 cases of trisomy 21. The estimated risk for trisomy 21 was 1 in 300 or greater in 7.5% of the normal pregnancies, in 93.4% of those with trisomy 21 and in 88.8% of those with other chromosomal defects.

Conclusion: The most effective method of screening for chromosomal defects is by first-trimester fetal NT and maternal serum biochemistry.

Publication types

  • Evaluation Study

MeSH terms

  • Adolescent
  • Adult
  • Chorionic Gonadotropin, beta Subunit, Human / blood
  • Down Syndrome / blood
  • Down Syndrome / diagnosis*
  • Down Syndrome / diagnostic imaging
  • Down Syndrome / epidemiology
  • False Positive Reactions
  • Female
  • Humans
  • London / epidemiology
  • Maternal Age
  • Middle Aged
  • Neck / diagnostic imaging
  • Neck / embryology
  • Predictive Value of Tests
  • Pregnancy
  • Pregnancy Trimester, First
  • Pregnancy-Associated Plasma Protein-A / metabolism
  • Prenatal Diagnosis*
  • Prospective Studies
  • Ultrasonography

Substances

  • Chorionic Gonadotropin, beta Subunit, Human
  • Pregnancy-Associated Plasma Protein-A