[Role of "subtle" ultrasonographic signs during antenatal screening for trisomy 21 during the second trimester of pregnancy: meta-analysis and CPDPN protocol of the Grenoble University Hospital].
OBJECTIVE
A meta-analysis about subtle ultrasonographic signs in second trimester of pregnancy.


METHODS
196 articles dealing with the subject--from 1985 to July 2002--were studied. Data on the 11 reported signs were collected from 92 theoretically and/or statistically valid studies. Then, the studies were selected according to several criteria: isolated characteristic, defined thresholds, calculable sensitivity and specificity. After checking for homogeneity, a likelihood ratio was calculated for some of the signs.


RESULTS
This meta-analysis of the second trimester ultrasonographic signs of Down's syndrome enabled us to estimate the likelihood ratio (LHR) of six signs. At 22 weeks'gestation (WG) these signs are: pyelectasis equal to or greater than 5 mm; nuchal fold thickness equal to or greater than 6 mm; persistence of choroid plexus cysts; shortness of the femur and humerus below the tenth percentile; hyperechogenic bowe; and nasal bone length less than 2.5 mm.


CONCLUSIONS
These validated ultrasonographic signs are independent of nuchal translucency thickness at 12 WG and of maternal serum biochemistry. This allows to calculate a combinate risk for nuchal translucency, maternal serum biochemistry and second trimester ultrasonographic signs when they are validated.
Viossat
P
P
Centre Pluridisciplinaire de Diagnostic Prénatal, CHU de Grenoble, BP 217, 38043 Grenoble Cedex 09.
Cans
C
C
Marchal-André
D
D
Althuser
M
M
Tomasella
T
T
Pons
J-C
JC
Jouk
P-S
PS
D002831:Choroid Plexus / Q000000981:diagnostic imaging / Q000196:embryology; D004314:Down Syndrome / Q000000981:diagnostic imaging*; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000196:embryology; D005865:Gestational Age; D006801:Humans; D006811:Humerus / Q000000981:diagnostic imaging / Q000196:embryology; D009295:Nasal Bone / Q000000981:diagnostic imaging / Q000196:embryology; D009333:Neck / Q000000981:diagnostic imaging / Q000196:embryology; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D016216:Ultrasonography, Prenatal