Fetal right ventricular (RV) prominence is a known indicator of possible left-sided structural heart disease with a low positive predictive value for aortic coarctation. There is a paucity of data on identifying which fetuses with RV prominence will have postnatal arch obstruction. Our study objectives were to create a clinical prediction tool for coarctation and to describe the diagnostic outcomes of our cohort with fetal RV prominence. We performed a retrospective review of patients referred with fetal RV prominence from January 2009 to October 2015. Recorded fetal echocardiographic variables included gestational age, semilunar and atrioventricular valve dimensions, left and right ventricular mid-cavitary dimensions, foramen ovale and aortic arch flow direction, and isthmal diameter. Postnatal cardiac and non-cardiac diagnoses were documented. We performed descriptive analysis for postnatal outcomes and classification tree analysis to create a clinical prediction tool. Eighty-eight patients were reviewed; 58 (66%) had abnormal postnatal echocardiograms, 45 (51%) had left-sided lesions, including 26 (30%) with coarctation, and 6 (7%) had pulmonary hypertension. Our clinical prediction tool employs gestational age, RV mid-cavitary dimension z-score, and isthmal diameter z-score to predict coarctation with 85% accuracy, 95% confidence interval [75.3, 92.4%]. Our model correctly classified 45/54 non-coarctation and 19/21 coarctation cases, with 90% sensitivity and 83% specificity. Developing an accurate prediction tool for coarctation in cases of fetal RV prominence is an important first step in improving our management of these challenging cases.