Third Trimester Ultrasound Scan for Detection of Congenital Abnormalities and Associated Factors, at Abebech Gobena MCH Hospital, a Cross Sectional Study

Abstract Background: Congenital anomaly is a structural or functional anomaly that occurs during intrauterine life. Growing number of evidences suggest that systematic evaluation of the fetal anatomy during 3rd trimester routine scan increases detection of congenital abnormalities that have been missed in earlier scans, occurred late in gestation or progressed from previous findings. Objective: to find out the magnitude of congenital abnormalities and associated factors detected at third trimester ultrasound scan. Methods: This was a facility based cross-sectional study. Data was collected for a sample size of 490 pregnant mother using pre-tested structured questionnaire from the participants and electronic records; by two trained nurses and principal investigator. Ultrasound examinations were done by Maternal Fetal Medicine (MFM) Fellows at third trimester and suspected abnormality cases were confirmed by MFM Consultants. Data entered in to Epi Data version 4.6 & Statistical analysis made through SPSS version 29. Descriptive statistics and tables used to describe the study finding. Analysis was made using chi-square test. P value <0.05 was used to show presence of statistically significant association. Results: During the study period 490 3rd tri ultrasound scans were performed at Y12HMC/AGH. 30 congenital anomalies detected, making the prevalence 6.1%. Of these 30 anomalies 6 of them were diagnosed in the 2nd tri anatomic scan; hence, 1st time detected anomalies during the 3rd tri scan was 4.9%. The commonest organ affected by congenital anomaly detected during 3rd tri scan was Central nervous system (CNS) 9 (30%). The single most common type of congenital anomaly was Urinary Tract Dilation (UTD) 6 (20%). Congenital Pulmonary Airway Malformation (CPAM), skeletal dysplasia, diaphragmatic hernia, multi cystic dysplastic kidney disease, abdominal cyst and cleft lip and palate each contributed for two cases. Ventricular septal defect (VSD), left ventricular hypoplasia, omphalocele, dandy walker malformation and encephalocele each contributed for one anomaly. Not taking folic acid periconception (P value 0.001), medication use during early pregnancy (P value 0.006) and advanced maternal age (P value 0.019) are associated with congenital malformation. Conclusion: high prevalence of 3rd tri congenital anomaly detected in this study; CNS was the commonest organ affected by 3rd tri congenital anomaly. Not using folic acid, medication use early during pregnancy and advanced maternal age are associated with congenital malformations.