Background: Since the first use of sonography, most fetal dwarfism has been detectable prenatally. The correct differentiation of the subtype of dwarfism is difficult at times. Dyssegmental dysplasia is probably an exception to these subtypes because the vertebral disorganization and occipital encephalocele at times permits prenatal diagnosis.
Case: A 34-year-old woman, gravida 3, para 1, elective abortion 1 for dwarfism, was referred at 27 weeks' gestation for cystic hygroma. Further sonographic findings included: cystic hygroma with massive ascites, micromelia, occipital encephalocele, spinal disorganization and hydramnios. The fetus and both parents appeared to have a normal karyotype. Later the pregnancy was terminated with vaginal delivery. The fetus had micromelia, camptomelia, cystic hygroma, a flat face, short neck, short trunk, narrow thorax with protuberant abdomen, scoliosis and clubfeet.
Conclusion: Sonography is effective in prenatal diagnosis of dyssegmental dysplasia. With sonography, diagnosis of dyssegmental dysplasia becomes possible as early as the first trimester.