Association of combined first-trimester screen and noninvasive prenatal testing on diagnostic procedures

Obstet Gynecol. 2014 Jun;123(6):1303-1310. doi: 10.1097/AOG.0000000000000275.


Objective: To describe the changes over a 9-year period in the number and rate of diagnostic testing after the introduction of the combined first-trimester screen and subsequent noninvasive prenatal testing.

Methods: The number of prenatal screening and diagnostic tests was recorded over a 9-year period from billing records. Three time intervals were considered: 1) 20 months before a combined first-trimester screen was offered; 2) 72 months after a combined first-trimester screen was offered; and 3) 16 months after noninvasive prenatal testing introduction. Prenatal testing was compared per year, per time interval, and per 100 morphologic ultrasonograms to account for fluctuations in patient number.

Results: A total of 15,418 prenatal tests was recorded during the study period, consisting of 9,780 combined first-trimester screen, 1,265 noninvasive prenatal testing, 608 chorionic villus sampling (CVS), and 3,765 amniocenteses. Combined first-trimester screen peaked at 1,836 in 2009-2010 but declined by 48.1% after noninvasive prenatal testing was introduced. Combined first-trimester screen per 100 morphologic ultrasonograms also significantly decreased (P<.05) after noninvasive prenatal testing introduction. Chorionic villus sampling peaked after combined first-trimester screen introduction in 2007-2008 with 100 procedures, representing an 81.8% increase from prefirst-trimester screen. After the introduction of noninvasive prenatal testing, CVS declined by 68.6% during 2012-2013. Chorionic villus sampling per 100 morphologic ultrasonograms followed the same trend. Amniocentesis declined every year of the study period (78.8% overall), including 60.3% after combined first-trimester screen and a further 46.7% after noninvasive prenatal testing. Monthly amniocentesis procedures per 100 morphologic ultrasonograms significantly decreased (P<.05) after introduction of a combined first-trimester screen and noninvasive prenatal testing.

Conclusion: The introduction of combined first-trimester screen was associated with an increase in CVS and a decrease in amniocentesis testing. Noninvasive prenatal testing was associated with a subsequent decrease in CVS and further decrease in amniocentesis. LEVEL OF EVIEDENCE: III.

MeSH terms

  • Amniocentesis / statistics & numerical data*
  • Aneuploidy
  • Chorionic Villi Sampling / statistics & numerical data*
  • Down Syndrome / diagnosis*
  • Female
  • Humans
  • Pregnancy
  • Pregnancy Trimester, First
  • Prenatal Diagnosis / trends*
  • Retrospective Studies
  • Ultrasonography, Prenatal / statistics & numerical data*