Specific ultrasonographic features of hypophosphatasia and hypochondrogenesis

Skeletal dysplasia is a rare disease and has numerous classifi cations, so accurate prenatal diagnosis is diffi cult. Hypophosphatasia and hypochondrogenesis, in particular, have a poor prognosis. Therefore, assessment of the prognosis is the key to successful management. We report two cases of hypophosphatasia and hypochondrogenesis detected by ultrasonography. Case 1 : A 24-year-old primigravida was referred to our hospital at 29 weeks due to shortening of the fetal femur. Ultrasonography demonstrated shortening of all long bones. The skull yielded easily to pressure with the probe. The skull, vertebral bodies, and bilateral hands and feet were not detected by 3D-CT. Based on these findings, hypophosphatasia was strongly suspected. The female baby weighed 2436 g and was delivered with an Apgar score of 1(1')/ 1(5'). She died 20 minutes after delivery due to respiratory failure. Her phosphatase value was 5 IU/L. Case 2 : A 31-year-old multigravida was referred to our hospital at 20 weeks due to shortening of the fetal femur. Ultrasonography demonstrated shortening of all long bones. The femur looked like metaphyseal splaying. The skull did not yield easily to pressure with the probe. The thorax was very small. Based on these findings, lethal osteochondrodysplasia was strongly suspected. The patient had an abortion. Accurate assessment of the prognosis is the key to successful management. Therefore, it may be clinically signifi cant to measure all bones and examine them carefully using 3D-CT.