Determine if only an US examination practiced by a highly-trained specialist is as effective as the current golden test to detect congenital alterations in the 1st trimester of pregnancy. A retrospective study. 1022 genetic screenings made on patients between 11–14.4wks of pregnancy. Highly-trained US specialist searched in each patient. The risk calculation was practiced with a 4proprisca program. The decision of practicing a genetic amniocentesis was solely based on the US examination and not at the final risk given by the combined exam. The golden pattern was made on every patient to determine follow up of a healthy new-born or a genetic alteration. With in all the patients with altered biochemical tests an uterine artery Doppler was performed between wk22–24. The rate of intrauterine growth restriction and severe preeclampsia was made before 32 weeks. The rate of the detection of genetic alterations was based only on US testing in 100%. The amniocentesis revealed 3:t21, 1:t13 and 1:t22. 128 amniocentesis were avoided based on the decision of practicing them only by abnormal US. Of the 145 cases presenting an abnormal biochemistry, 10% presented an ip in abnormal uterine arteries presented an ip in abnormal uterine arteries. Of the patients with abnormal biochemistry plus more ip in abnormal uterine arteries, 90% presented preeclampsia or severe preeclampsia before week 32 or a IUGR. Contrary to this, only 1.2% of the patients with normal biochemistry plus ip of the normal uterine arteries presented preeclampsia before wk32 or severe IUGR. In expert hands, the US examination with the 4 main markers for chromosomal alterations is at least as effective as the combined test. The biochemical examinations PAPP-A, an abnormal free B-HCG plus an abnormal uterine artery ip between wk 22–24 predicts in a great way the risks of preeclampsia and/or severe IUGR.