Measurement of the Great Vessels in the Mediastinum Could Help Distinguish True From False-Positive Coarctation of the Aorta in the Third Trimester

Abstract

OBJECTIVE: We investigated the utility of analyzing prenatal mediastinal measures of the great arteries in distinguishing true coarctation of the aorta (CoA) from false-positive CoA. METHODS: All fetuses in this study had suspicion of CoA based on the presence of right-left heart disproportion. We defined 3 study groups: group 1, true fetal CoA; group 2, false-positive fetal CoA with a narrow aortic arch; and group 3, false-positive fetal CoA without a narrow aortic arch. RESULTS: In group 1, the mean mediastinal pulmonary artery (PA) to ascending aorta (Ao) diameter ratio +/- SD was 2.03 +/- 0.48, and in group 2, the ratio was 1.60 +/- 0.23. The difference was statistically significant (P = .0018, t test). In group 3, the mean PA:Ao ratio was 1.35 +/- 0.14. The difference between groups 1 and 3 was statistically significant (P = .0002, t test). In our study group, for a PA:Ao ratio of 1.60, sensitivity was 83.0%; specificity, 85.0%; positive predictive value, 62.5%; and negative predictive value, 94.0%. CONCLUSIONS: In the third trimester, the main PA:Ao ratio as measured in the fetal mediastinum can be a helpful tool in distinguishing true CoA requiring neonatal cardiac surgery from false-positive CoA and simple disproportion requiring medical attention but no surgery in the first month of postnatal life.