Home

Online Teaching Files

Literature Search and Reviews

Bulletin Board

Reference Charts and Tables

Recommended Links





 

Likelihood Ratio of Down Syndrome vs Normal Karyotype with use of Nuchal Thickness above Expected Value

 

Change in Nuchal Thickness (mm)

Likelihood Ratio

<0

0.52

0 to <0.5

0.97

0.5 to <1.0

0.95

1.0 to <1.5

1.88

1.5 to <2.0

6.33

>2.0

18.66

 

Expected Nuchal Thickness = 2.8444 - BPD x 0.0513 + BPD(2) x 0.0015

Likelihood Ratio = % Down syndrome / % Normals with given increased change in Nuchal Thickness Value

Risk = Maternal Age Risk x Likelihood Ratio eg 1/270 x 1.88 = 1/144

*Risk may be calculated from multiple sonographic markers by multiplying the likelihood ratios by the maternal age risk eg Maternal Age Risk x Humeral MoM, Nuchal MoM, Hypoplastic 5th Digit MoM, etc

Adapted from:Bahado-Singh R, Deren O, Oz U, Tan A, Hunter D, Copel J, Mahoney MJ. An alternative for women initially declining genetic amniocentesis: Individual Down syndrome odds on the basis of maternal age and multiple ultrasonographic markers. Am J Obstet Gynecol 179:514-9, 1998.

  This is a clickable imagemap, for hyperlinks, see text below.

Ultrasound Educational Press     Go Top
Peter W. Callen, M.D.
Professor of Radiology, Obstetrics, Gynecology and Reproductive Science
University of California Medical Center, San Francisco, California

Home | Teaching Files | Literature | Bulletin Board