Sono-fetal tibial length evaluation as a predictor of gestational age: A case of Nigerian population

Background: Accurate pregnancy dating is essential for guiding patients about the option of termination of pregnancy or in analysis of biochemical serum screening test and to ensure adequate management of pregnant women with the intention to reduce maternal morbidity and mortality, especially when considering the best parameter for estimating gestational age, it is important that the structure has little biological variation, and can be measured with high degree of reproducibility. This study was designed to evaluate the use of fetal tibia length as a tool for the estimation of gestational age among the Nigerian population. Materials and Methods: This was a cross-sectional study, which involved 215 pregnant women selected using convenient sampling technique based on the inclusion criteria in a single private diagnostic centre in Port Harcourt. Ultrasound scan was done on each subject and fetal biometric parameters (Biparietal diameter, femur length and tibial length) and gestational age were assessed and documented. Data obtained were analyzed using descriptive and inferential statistics. Results: The majority (n = 12) of the pregnant women had gestational age of 25 weeks. The mean values for BPD, FL and TL of those with 17th week GA were 36.70±1 0.35, 23.65±0.7 and 22.28±1.42 as the least mean values while the highest mean values were identified in patients that had 41 weeks of GA, which were 95.20±0.00, 79.40±0.00 and 58.00±0.00 for BPD, FL and TL respectively. There were no statistically significance mean differences between BPD (t = 225.17, p = 0.001), FL (t = 100.84, p = 0.001) and TL (t = -33.38, p = 0.001) and the estimated gestational age of 17 weeks. Conclusion: The fetal tibial length (FTL) increases with advancing gestational age in apparently healthy fetus. The FTL can be strongly use as a tool for the prediction of fetal gestational age, where other parameters cannot be evaluated.