Sonographic prenatal diagnosis of heterozygous achondroplasia: a case report.

A case of heterozygous achondroplasia diagnosed prenatally by sonographic examination at third trimester, demonstrating a large head, frontal bossing, low nasal bridge, shortening of the long bones (rhizomelic form), was presented and confirmed by neonatal physical examination and radiograph. Sonography has become the most sensitive and accurate method for detection of this abnormality. It displays the fetal biometry without distortion and permits accurate prenatal diagnosis. However, the prenatal diagnosis of this abnormality is very difficult until the third trimester of pregnancy.