Accuracy Of Ultrasound Prediction Of Fetal Maturity By Ossification Center Of Long Bones in The Cases Of Elective Cesarean Section At 38 Week Gestation

Fetal lung maturity can be assessed by biochemical analysis of amniotic fluid, but it carries the potential for serious complications of amniocentesis .Efforts have been made to use prenatal diagnostic ultrasonography as a means of evaluating lung maturity. Ultrasonography, a non invasive and widely available method, would be more acceptable.
Objective: The aim of this study is to determine accuracy of sonographic prediction of fetal maturity by ossification center of long bone(femur ,tibia and humerus) ,to determine most accurate one in estimation of gestational age(GA) at 38 weeks to do elective cesarean section and evaluate if gestational age by obstetric ultrasound is corresponding to evaluation by neonatology specialist. Methods: The study was conducted on 200 pregnant woman were delivered by elective cesarean section in General Monof and AL-Zahraa University Hospitals in the period from Februrary2017 to August2017.
All the mother where subjected to full history, examination(general-local),ultrasound examination for detection of(GA) by fetal biometry ,visualize and measure proximal ossification center of (tibia, humerus) and distal(femur).Then reassessment of (GA)and fetal maturity after delivery by neonatology specialist .We have 2 groups (mature &immature) fetus according to(GA) of neonates , Apgar Score and the need of the neonates to NICU. Results: We studied prospectively 200 pregnant women scheduled for elective cesarean section at 38 wks gestation and compared the sonographic
epiphyseal findings with the results showing after delivery. we found 187 mature fetus with mean age (38)wks and 13 immature fetus with mean age(36 wks ) admitted in NICU. Immature group having distal femur epiphysis(DFE) (13/13) and proximal tibia epiphseal (PTE) ossification present in (12/13cases)but absent in(1/13)case while Proximal ossification center of humerus (PHE) was absent in (0/13) immature fetus but(PHE) was present in 168 and absent in19 mature
fetus. While ossification center of femur and tibia present(187/187) mature fetus. Using cut off point of size distal Epiphyseal Ossification Center(EOC) of femur ( 6.25mm) or more as good predictor of fetal maturity with sensitivity of 86.1% & specificity of 70.4%&area under the curve0.878.While cut off point of size proximal (EOC) of tibia(< 5.05mm) predict fetal immature with sensitivity of 76.5% & specificity of 61.5%&area under the curve of 0.790. While cut off point of size of proximal (EOC) of humerus between mature& immature groups at 38 weeks gestation was found < (1mm) is immature with sensitivity of 90% & specificity of 100%&area under the curve of 0.949. And best cut off points of total size (EOC) of femur, tibia& humerus between mature& immature groups was found< (14.05mm) in immature fetus with sensitivity of 85% & specificity of 70.2%&area under the curve of 0.850. (EOC) of humerus was present in 168 mature fetus but absent in 32 fetus(19)mature &(13) fetus immature so can use the presence of(EOC) of humerus as a best ultrasonographic sign for fetal maturity at(>38)gestation but its absence not indicate fetal immaturity because it was absent in 19 case of mature fetus ,so can depends on size of distal (EOC) of femur >( 6.25mm) and total size of(EOC) of 3 long bones >14mm , as tool for estimating of fetal maturity in the absence(EOC) of humerus. Conclusion: Confirmation of fetal maturity obtained by fetal biometry and ultrasound visualization and measurement of size of the epiphyseal ossification centers of long bones (femur-tibia-humerus) can be used as a tool for estimation of fetal maturity at 38 wks before elective cesarean section.