Sonographic Assessment of the Fetal Thoracic Length (FTL) as a Predictor of Gestational Age (GA) in Nigerian Population

Sa？etak Background: The ultrasound machines used in our locality are programmed with software of non-indigenous normative values; furthermore, as pregnancy advances the accuracy of most biometric parameters in predicting GA varies due to racial morphological difference and error increases, hence the need for this study. Purpose: To determine local (black race) sonographic FTL normative values and to compare the values with that of the Caucasian population. Material and Methods: Women with a singleton pregnancy that was conceived naturally and who met the individual inclusion criteria were recruited consecutively. The Helsinki declaration of 1975 was considered. A prospective cross-sectional study was conducted in the Federal Medical Center Azare, Bauchi. The study involved 253 women from 16 to 38 weeks of gestation. A 2D ultrasound scan was used to measure the FTL (that is from the root of the neck to the diaphragm) at the level of the four-chamber view. Results: Normal values of the FTL were developed and showed a linear and statistically significant correlation with the weeks of gestation (r2= 0.81, P≤0.001). The FTL has a growth rate of 0.182 cm per week. Conclusion: There is no statistically significant difference between the FTL of the population under study (black population) and that of the Caucasian population. Hence, the use of Caucasian FTL on black race is a valid estimate of GA. And the GA predictive equation is; y = 3.61x + 11.95. Where y = gestational age in weeks and x= thoracic length