The genetic sonogram: Experience with isolated ultrasound soft markers in 1463 high-risk pregnancies

Abstract

Objective: The aim of this study has been to report our prospective experience with the prenatal ultrasound detection of soft markers for trisomy 21 in high-risk population undergoing cytogenetic amniocentesis. Methods: Women referred to our unit for amniocentesis because of advanced maternal age. Second-trimester abnormal biochemistry and first-trimester screening based on nuchal translucency and maternal serum biochemistry were included in the study. We evaluated the presence or absence of the following ultrasound soft markers in every case: nuchal fold, pyelectasis, short femur, short humerus, echogenic bowel, golf ball and choroid plexus cysts. Sensitivity, specificity and likelihood ratios were calculated. Pregnancies affected with chromosomal abnormalities other than trisomy 21 were therefore excluded as well as those with major foetal anomalies detected by means of ultrasound. Results: The likelihood ratios for individual soft markers were: nuchal fold 132, renal pyelectasis 5, short femur 2.1, short humerus 3.6, echogenic bowel 11, golf ball 3.9, choroid plexus cysts 3.7. Conclusions: We confirm that foetuses with trisomy 21 have a higher prevalence of soft markers than those with normal karyotype. However, the so-called genetic sonogram has a high false-positive rate and a low sensitivity. In high-risk population, the use of the genetic sonogram could reduce the a priori risk of carrying a foetus with trisomy 21. © Copyright 2004, CIC Edizioni Internazionali, Rome.