[Ultrasonography's role in prenatal diagnosis: The nuchal fold].

Two cases of nuchal fold abnormalities diagnosed by transvaginal ultrasonography are presented: nuchal edema at 10 weeks (fold = 5.5 mm) of normal size at 13 weeks (fold = 2.6 mm) and cystic hygroma colli associated with omphalocel in a women with a 24-week arrested pregnancy terminated by spontaneous abortion. Genetic tests done in the second case showed a karyotype 45XO. The etiopathogenesis of nuchal skin fold abnormalities--edema and cystic hygroma colli is discussed. The importance of ultrasound screening during pregnancy is emphasized, the detection rate of genetic abnormalities depending on both the quality of the ultrasound equipment and examiners skills. Ultrasound examination at 10 and 20 weeks--ultrasound marker (nuchal fold, LF ratio and DBP/FL ratio)--together with the triple test (AFP, HCG and E3) in the mathematical model used for detecting the risk of genetic defects may represent an alternative to amniocentesis and trophoblast biopsy when this is impracticable or rejected by the patient.