Fetal echocardiograms (F-echo) are recommended in all pregnancies when the fetus has Down syndrome (DS) even if there was a prior obstetric scan (OB-scan) that was normal. The utility of a screening F-echo in this high-risk population when an OB-scan is normal is unknown. Goal of this study was to evaluate if any diagnosis of a critical congenital heart disease (CHD) was missed in a fetus with DS who had a normal OB-scan. Secondary goal was to determine if any CHD was missed postnatally when an OB-scan was read as normal. Retrospective chart review of all fetuses that had a F-echo whose indication was DS between 1/1/2010 to 6/30/2022 was performed. Fetuses were included if they had an OB-scan that was read as normal and had a F-echo. Postnatal transthoracic echocardiogram (pTTE) was reviewed when available. Critical CHD was defined as CHD requiring catheterization or surgical intervention < 1 month of age. One hundred twenty-two F-echo on fetuses with DS were evaluated, of which 48 met inclusion criteria. OB-scan was performed at 20.4 ± 4.5 weeks gestational age and F-echo was performed at 24.0 ± 4.6 weeks gestational age. No patient with a normal OB-scan had a diagnosis of a critical CHD by F-echo (n = 48, negative predictive value = 100%). Evaluating those patients that had an OB-scan and a pTTE (n = 38), 14 patients were diagnosed with CHD (muscular ventricular septal defect (VSD) n = 5, perimembraneous VSD n = 3, secundum atrial septal defect (ASD) n = 2, primum ASD n = 1, transitional atrioventricular septal defect (AVSD) n = 2, and aortic valve abnormality n = 1; negative predictive value = 63.2%). F-echo correctly diagnosed 4 of the 14 missed OB-scan CHD (perimembraneous VSD n = 2, muscular VSD n = 1, and transitional AVSD n = 1). Critical CHD was not missed with a normal OB-scan in this high-risk population. F-echo also missed the majority of CHD when an OB-scan was read as normal. The cost/benefit of screening F-echo in fetuses with DS should be evaluated if a normal OB-scan has been performed, considering all these patients would have a pTTE performed per guidelines.