Abstract
Background: Trisomy 21, caused by the presence of an extra chromosome 21, results in Down syndrome (DS). Maternal biochemical markers and prenatal sonographic findings are valuable for assessing the risk of Trisomy 21, although they are not definitive for diagnosis. Case Presentation: The biochemical markers evaluated included Inhibin A, β-hCG, and alpha-fetoprotein (AFP). Elevated Inhibin A and β-hCG levels and reduced AFP levels are associated with an increased risk of Trisomy 21. Sonographic findings, including an echogenic cardiac focus and mild renal pelvicalyceal prominence, may represent normal variants but can be associated with a slightly increased risk of chromosomal abnormalities. In the present case, the combination of these sonographic findings and abnormal serum marker levels raised suspicion of Trisomy 21 or other fetal conditions. Genetic counselling was advised, with further diagnostic evaluation by amniocentesis or chorionic villus sampling (CVS). Conclusion: The combined interpretation of maternal serum biochemical markers and prenatal sonographic findings may assist in identifying pregnancies at increased risk of Trisomy 21 and guide the need for further diagnostic evaluation.