Ultrasonographic Evaluation of Foetal Binocular Distance in Second and Third Trimester and its Correlation with Gestational Age

Abstract

Introduction: An accurate assessment of gestational age is vital to the obstetricians in order to come to a decision regarding the time of termination of pregnancy and rout of delivery. Ultrasonography plays an important role in determining gestational age when it cannot be dated from menstrual history. Objective: To find out the role of sonographically measured foetal binocular distance for determination of gestational age in second and third trimester of pregnancy. Methods: This cross sectional observational analytic study was carried out among 100 purposively selected pregnant women between 12 to 40 weeks of gestation according to inclusion and exclusion criteria at Mymensingh Medical College Hospital (MMCH) over a period of 12 months from January 2010 to December 2010. Foetal Binocular Distance (BD) was measured sonographically and gestational age was determined on the basis of Biparietal Diameter (BPD), Femoral length (FL) and an average of these two. These parameters were correlated with gestational age determined according to Last Menstrual Period (LMP). Analysis was done to know the correlation between gestational age and foetal binocular distance. Results: Majority (39.0%) of the respondents were within 21
to 25 years’ age group. Mean age was 24.81±5.02 years. Majority (53.0%) respondent’s height was 150 to 154 cm with a mean of 152.56±3.21cm. Majority (65.0%) were housewife. A strong positive correlation was found between foetal binocular distance and gestational age as predicted by Biparietal Diameter (r=0.99), Femoral Length (r=0.99) and average of Biparietal Diameter & Femoral Length (r=0.99), which was statistically significant (p<0.01). There is a relation between gestational age and mean foetal binocular distance (r=.98, p< 0.01). Conclusion: Measurement of foetal binocular distance by ultrasound is an effective way to detect gestational age during second and third trimester even when some other methods are failed to measure gestational age accurately.