Role of Ultrasonogram in Detection of Congenital Anomalies and Prevalence of Anomalies in High-risk Pregnancies

Introduction: In any antenatal population, about 2-3% of the foetus are affected by congenital anomalies it is mainly due to intrinsic genetic pathology and abnormal embryogenesis during the early gestational period. Objective: To categorize the type of major congenital anomalies in routine second and third trimester ultrasonogram (USG) and its association with high-risk pregnancy. Methods: This is a cross-sectional study carried out in the Department of Obstetrics and Gynaecology at Government Theni Medical College and Hospital, Tamil Nadu. The study population includes about 6250 antenatal mothers in the second and third trimester, who were subjected to USG by expert radiologists and the ultrasound findings were analysed on a statistical basis in structured data collection form. Results: About 6250 antenatal mothers of the 2nd and 3rd trimester were subjected to USG out of which 122 mothers were found to have an anomalous foetus. (1) The antenatal prevalence of congenital anomalies was 1.95%, (2) The mean gestational age and mean maternal age at diagnosis was 24 weeks (Standard deviation [SD] +/- 5.15) and 28.5 years (SD +/- 6.10), respectively. Central nervous system was the most common system affected out of which maximum anomaly was anencephaly. Conclusion: USG is a cost-effective, non-invasive and sensitive tool in detecting the congenital anomalies antenatally in the hands of an experienced radiologist. Besides the first-trimester USG, the second trimester scan is mandatory in detecting anomaly in the growing foetus, as the majority of congenital anomalies are detected between 20 and 22 weeks of pregnancy.