Present case demonstrates osteogenesis imperfecta type III, diagnosed by two dimensional sonography in a fetus at 24th weeks of gestation upon admission for second trimester ultrasound scan. Her first antenatal visit and ultrasound examination was performed at 15+5 weeks of gestation; normal growth and development of fetal morphometry was detected and no structural anomalies were observed. However, at 24th weeks of gestational age, we detected a fetus with bilateral femoral fractures and mild thoracal dysplasia. According to these features, the diagnosis was considered as osteogenesis imperfecta and medical legal abortion was performed after decision of family and taken informed consent. In post-mortem physical examination, moderate shortening of femur limbs and deformed ribs were detected. X-ray study of fetus confirmed the diagnosis of OI type III by demonstrating the bilateral femoral fractures, beaded ribs, normal bone mineralization of calvaria and upper extremities.
Consequently, an early second trimester detailed ultrasound of the limb bones should be performed to all pregnant women with or without at risk for congenital skeletal abnormalities and prenatal diagnosis should be made before 24th weeks of gestation. This requires a participation of both sonologist and geneticist in a team in order to achieve a specific genetic diagnosis.