Second trimester diagnosis of thanatophoric dysplasia.

Thanatophoric dysplasia is one of the most common skeletal dysplasia, with an incidence from 1:6,400 to 1:100,000 births. While the etiology is unknown, either autosomal recessive or polygenic transmission with 0.2% recurrence risk had been suggested. It is a lethal disorder characterized by extremely short ribs, tubular bones and macrocephaly. Death is often secondary to pulmonary hypoplasia caused by the small thoracic cavity. We present a fetus with shortening of four limbs, typical thanatophoric dwarfism, diagnosed by sonography at the 25th week of gestation. The second trimester diagnosis by ultrasound was crucial, because it gave an alternative option of pregnancy termination when the affected fetus was discovered.