Role of second-trimester genetic sonography after Down syndrome screening.
OBJECTIVE
To estimate the effectiveness of second-trimester genetic sonography in modifying Down syndrome screening test results.


METHODS
The First and Second Trimester Evaluation of Risk (FASTER) aneuploidy screening trial participants were studied from 13 centers where a 15- to 23-week genetic sonogram was performed in the same center. Midtrimester Down syndrome risks were estimated for five screening test policies: first-trimester combined, second-trimester quadruple, and testing sequentially by integrated, stepwise, or contingent protocols. The maternal age-specific risk and the screening test risk were modified using likelihood ratios derived from the ultrasound findings. Separate likelihood ratios were obtained for the presence or absence of at least one major fetal structural malformation and for each "soft" sonographic marker statistically significant at the P<.005 level. Detection and false-positive rate were calculated for the genetic sonogram alone and for each test before and after risk modification.


RESULTS
A total of 7,842 pregnancies were studied, including 59 with Down syndrome. Major malformations and 8 of the 18 soft markers evaluated were highly significant. The detection rate for a 5% false-positive rate for the genetic sonogram alone was 69%; the detection rate increased from 81% to 90% with the combined test, from 81% to 90% with the quadruple test, from 93% to 98% with the integrated test, from 97% to 98% with the stepwise test, and from 95% to 97% with the contingent test. The stepwise and contingent use of the genetic sonogram after first-trimester screening both yielded a 90% detection rate.


CONCLUSIONS
Genetic sonography can increase detection rates substantially for combined and quadruple tests and more modestly for sequential protocols. Substituting sonography for quadruple markers in sequential screening was not useful.


METHODS
II.
Aagaard-Tillery
Kjersti M
KM
From the University of Utah, Salt Lake City, Utah; Royal College of Surgeons in Ireland, Dublin, Ireland; Swedish Medical Center, Seattle, Washington; University of California, San Francisco, California; Columbia University, New York, New York; DM-STAT, Malden, Massachusetts; William Beaumont Hospital, Royal Oak, Michigan; University of Texas Medical Branch at Galveston, Texas; Mount Sinai Medical Center, New York, New York; Albert Einstein College of Medicine, Bronx, New York; University of Colorado Health Sciences Center, Denver, Colorado; Tufts University, Boston, Massachusetts; NYU Medical Center, New York, New York; Brown University, Providence, Rhode Island; and University of North Carolina at Chapel Hill, North Carolina.
Malone
Fergal D
FD
Nyberg
David A
DA
Porter
T Flint
TF
Cuckle
Howard S
HS
Fuchs
Karin
K
Sullivan
Lisa
L
Comstock
Christine H
CH
Saade
George R
GR
Eddleman
Keith
K
Gross
Susan
S
Dugoff
Lorraine
L
Craigo
Sabrina D
SD
Timor-Tritsch
Ilan E
IE
Carr
Stephen R
SR
Wolfe
Honor M
HM
Bianchi
Diana W
DW
D'Alton
Mary E
ME
D000328:Adult; D004314:Down Syndrome / Q000175:diagnosis / Q000000981:diagnostic imaging*; D005260:Female; D005820:Genetic Testing; D006801:Humans; D011247:Pregnancy; D011446:Prospective Studies; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D016216:Ultrasonography, Prenatal; D055815:Young Adult