Diagnostic accuracy of anomaly screening ultrasound scan in sex identification of the fetus, at two selected centers in Kampala, Uganda

Abstract

Background: The role of ultrasound scan in obstetric is unquestionably paramount. Over the years the use of ultrasound has evolved to a more sophisticated role such as sex identification. Sex identification remains a contentious topic especially regarding the accuracy of the findings. With WFUMB stand strongly against the non-medical use of ultrasound in which non-medical sex identification is inclusive citing safety of ultrasound waves, several studies have intimated the overwhelming demand for pregnant women to know the sex of their fetus. There are varying opinions regarding the timing to accurately identify the fetal sex. Consensus has been arrived at that diagnostic accuracy of sex identification is hinged on increase in the fetal gestational age. This has created a practice which has led to wrong sex identification either due to very early trimester diagnosis or inadequate skills possessed by the technician. This has far reaching implications to the prospective parents such as cost of purchase of gender specific items as well as psychological disappointment. Objective: This study aimed at identifying the diagnostic accuracy of use of 2D ultrasound scan in sex identification during anomaly screening (18-24 weeks of gestation) in two selected public hospitals. Methods: It was a prospective cohort study where by upon the mother being sent for anomaly ultrasound, sex identification would be carried out on consented participants meeting the inclusion criteria as part of the anomaly screening exercise. A total of204 pregnant women (participants) were enrolled with195 completing the study and 9 participants lost to follow-up. A 2-5 MHz curvilinear transducer on a portable ultrasound machine (2D) was used to identify the sex of the fetus and the presentation of the sex defining characteristics. Actual sex identification at birth was the gold standard.

Data was analyzed using SPSS, calculations of sensitivity, specificity, PPV, NPV and factors associated such as weight of fetus, presentation and amniotic fluid volume were documented and evaluated for any correlation with sex identification findings. The study findings revealed that about 98% of the participants desired to know the fetal sex; the sensitivity and specificity of identifying the male fetus was 99%; Sensitivity and specificity of identifying the female fetus was 97.8% and 99% respectively all calculated at the 95% confidence interval. The male identifying characteristics where predominantly visualization of the scrotum and penis while that of the females was visualization of the three (3) hyperechoic lines depicting the labia folds and clitoris. 98.5% (192) of the fetus were correctly identified while 1.5% (3) were incorrectly identified. The overall accuracy of the study was 98.9% Utility of the findings: The findings will form a basis that will be used in determining the sex of the fetus especially during anomaly screening. The research findings will as well aid the ultrasound sonography practitioners to correctly identify the sex determining characters thus help in alleviating the mother’s frequent requests of knowing the sex of the fetus. 2D ultrasound proved to have over 98 % accuracy in sex identification during anomaly screening period