[Value of ultrasonic diagnosis of fetal malformations in the detection of chromosomal abnormalities].

We report 118 foetal karyotypes studied on the basis of ultrasonographic warning signs which appeared in pregnancies with no significant risk of chromosomal abnormalities, judging from the personal and familial histories. Foetal karyotyping was performed either in amniotic fluid (AF) or in foetal blood. The ultrasonographic warning signs fell into 3 categories: (1) intrauterine growth retardation (IUGR) which was harmonious and below the 5th percentile, without foetal malformation at ultrasonography and without maternal cause (doppler examination, normal Pourcelot's index): 30 cases (24.4%). IUGR was isolated in 22 cases and associated in 8 cases with abnormal amounts of amniotic fluid: oligoamnios 6, hydramnios 2; (2) Isolated abnormality of AF volume: 22 cases (18.8%); hydramnios 19 and oligoamnios 3; (3) Foetal malformations in 66 cases (56%), including 16 central nervous system malformations, 4 cystic hygromas, 10 urinary tract malformations, 9 foetal effusions, 9 abdominal wall abnormalities, 7 gastrointestinal malformations, 5 malformations of the limb and 3 cardiac malformations. The mothers' mean age was 27.5 +/- 4.5 years; the mean term of pregnancy at the time of foetal karyotyping was 28 +/- 6.5 AW. In 51% of the cases the ultrasonographic warning sign was discovered after 29 AW. Among the 118 foetal karyotypes studied, 12 chromosomal abnormalities (10.6%) were detected. During the same period, 712 foetal karyotypes were studied in women aged 38 or more and 18 chromosomal abnormalities (2.53%) were detected. This study confirms that more chromosomal abnormalities can be detected by ultrasonographic warning signs than by relying on the mother's age which is the most frequent reason for foetal karyotype studies. Ultrasonography performed during the second trimester of pregnancy is of value to evaluate foetal growth and the amount of AF and to investigate for possible foetal malformations.