Accuracy of Mid-Trimester Ultrasound Scan in Foetal Gender Determination at the University College Hospital, Ibadan Nigeria

Objectives: This study aimed to determine the accuracy of prenatal sonographic gender determination during foetal anomaly ultrasound and the overall sensitivity pattern in our institution. Materials and Methods: A cross-sectional study of 520 consenting pregnant women who presented for foetal anomaly scans within a one-year period in our institution. The diagnostic accuracy of gender determination during the anomaly and delayed scans were determined by comparing the sonographic gender with the birth gender and calculating sensitivity, specificity, positive predictive value and negative predictive value. Data were analyzed using the Statistical Package for Social Sciences (SPSS) version 20. Descriptive statistics, frequencies, Mc-Nemar chi-square test were used at 5% level of significance. Results: The mean maternal age was 31.51 ±5.02years. Of the 520 consenting pregnant women studied, 16(6.0%) women were having twin gestation. Four hundred and ninety-seven (92.7%) genders were determined during foetal anomaly scan. The accuracy of the ultrasonography (US) examination performed by the resident doctors was 98.02% while the accuracy of the scan performed by the consultant radiologists was 100%. Overall, the accuracy of the gender determination on ultrasound was 98.69%. The general specificity and sensitivity of the US were 98.71 % and 98.68% respectively while the positive and negative predictive value were 99.01 % and 98.29% respectively. Conclusion: The accuracy of ultrasound examination in detecting foetal gender during foetal anomaly ultrasound is high with equally high predictive values and therefore it is recommended as a mandatory variable during anomaly scans. There is need for continuous training of resident doctors or operators in lower cadre to improve their competency in foetal gender determination.