Sonographic assessment of the fetal palpebral fissure slant--an additional tool in the prenatal diagnosis of syndromes.

Several syndromes and aneuploidies are associated with ocular abnormalities including up- and down-slanting palpebral fissures. We describes a technique for the sonographic assessment of the fetal palpebral fissure slant which was used in 70 normal pregnancies from 14 to 36 weeks of gestation. In a frontal view of the fetal face, the inferior angle between the palpebral fissure and the midline of the skull was determined. The median angle was 89 degrees, with a range from 87 degrees to 90 degrees. In selected cases, sonographic assessment of the fetal palpebral fissure slant may be a helpful additional tool in the prenatal diagnosis of syndromes, as demonstrated in a fetus with Seckel syndrome associated with downslanting palpebral fissures and in a fetus with Down's syndrome associated with upslanting palpebral fissures.