ultrasound and radiological study of fetal lower limb ossification centers in prolonged pregnancy

ABSTRACT

Twenty subjects with prolonged pregnancy [more than 294 days] and five control full term subjects [280 +/- 3 days] were studied by detailed ultrasound examination of the fetal lower limb ossification centers. The findings were compared to a prenatal X-ray examination of the fetus, a postnatal X-ray of the fetal left hemiskeleton and the postnatal Dubowitz scoring system. The results showed that prenatal radiology predicted the presence or absence of the distal femoral epiphysis [DFE] in 84%, the proximal tibial epiphysis [PTE] in 64%, and the cuboid ossification center [COC] in 50% of instances, while ultrasonography predicted the presence or absence of the DFE and PTE in all studied cases with prolonged pregnancies but failed to predict the presence of the COC in all cases. Compared to the Dubowitz scoring system, ultrasonography was able to predict postmaturity in 20% of the cases, while radiology predicted 10% of the cases only. It was concluded that ultrasound examination of the fetal lower limb ossification centers is a valuable parameter for the determination of fetal age, but cannot be used on its own to determine fetal wellbeing