title: Observational study comparing the performance of first-trimester screening protocols for detecting trisomy 21 in a North Indian population.
abstract: OBJECTIVE
  To evaluate first-trimester screening protocols for detecting trisomy 21 in an Indian population.
  
  
  METHODS
  The present prospective study collected data from women with singleton pregnancies and a crown-to-rump length of 45-84 mm who presented at the fetal medicine unit of a tertiary care center in North India between June 1, 2006, and December 31, 2015, for combined first-trimester screening. Maternal age, nuchal translucency, nasal bone, and maternal serum levels of free beta human chorionic gonadotropin and pregnancy-associated plasma protein A were assessed for calculating the risk of trisomy 21. Tricuspid regurgitation and qualitative analysis of ductus venosus data were available from June 2010, and were included where available. Trisomy-21 detection rates were calculated for various screening protocols and were compared.
  
  
  RESULTS
  There were 4523 women screened and 24 records of trisomy 21. Combined screening with maternal age, nuchal translucency, nasal bone, tricuspid regurgitation, and ductus venosus demonstrated optimal detection and false-positive rates of 93.8% and 1.9%, respectively. Screening using only maternal age yielded a detection rate of 37.5%; using fixed nuchal translucency cut-off values of 2.5 and 3 mm resulted in detection rates of 66.7% and 37.5%, respectively.
  
  
  CONCLUSIONS
  Combined first-trimester screening performed well in an Indian population; combining maternal age, nuchal translucency, nasal bone, ductus venosus, and tricuspid regurgitation yielded the most accurate screening.
authors.affiliation: Apollo Centre for Fetal Medicine, Indraprastha Apollo Hospitals, New Delhi, India.
authors.forename: Anita
authors.initials: A
authors.lastname: Kaul
authors.affiliation: Apollo Centre for Fetal Medicine, Indraprastha Apollo Hospitals, New Delhi, India.
authors.forename: Chanchal
authors.initials: C
authors.lastname: Singh
authors.affiliation: Apollo Centre for Fetal Medicine, Indraprastha Apollo Hospitals, New Delhi, India.
authors.forename: Rachna
authors.initials: R
authors.lastname: Gupta
authors.affiliation: Apollo Centre for Fetal Medicine, Indraprastha Apollo Hospitals, New Delhi, India.
authors.forename: Nidhi
authors.initials: N
authors.lastname: Arora
authors.affiliation: Department of Biochemistry, Indraprastha Apollo Hospitals, New Delhi, India.
authors.forename: Abha
authors.initials: A
authors.lastname: Gupta
mesh_terms: D000328:Adult; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood*; D004314:Down Syndrome / Q000175:diagnosis*; D005260:Female; D006801:Humans; D007194:India; D008403:Mass Screening; D008423:Maternal Age; D062145:Maternal Serum Screening Tests; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011266:Pregnancy-Associated Plasma Protein-A / Q000032:analysis*; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D016216:Ultrasonography, Prenatal
chemical_list: D018997:Chorionic Gonadotropin, beta Subunit, Human; D011266:Pregnancy-Associated Plasma Protein-A
keywords: Combined first-trimester screening; Nuchal translucency; Prenatal screening; Trisomy 21; Ultrasonography