The 'question mark' sign as a new ultrasound marker of tetralogy of Fallot in the fetus

Abstract

Objective: To describe a new ultrasonographic marker, the 'question-mark' sign, to assist in the diagnosis of tetralogy of Fallot (TOF) in the fetus, and to evaluate its prevalence in TOF as compared with other cardiac defects. Methods A prospective evaluation over a 5-year period of a consecutive series of 3998 pregnant women undergoing fetal echocardiography from 12 to 40 weeks' gestation due to high risk for congenital heart disease (CHD). Standard echocardiographic planes with color Doppler assessment and evaluation of the whole aortic arch, from the left ventricular outflow tract to the descending aorta in the axial upper mediastinum views, were performed. The question-mark sign corresponded with an enlarged and dilated ascending aorta and aortic arch in the three-vessel view of the upper fetal mediastinum. The frequency of this sign was evaluated in cases with TOF and in other cases of cardiac defects, as well as in fetuses with normal cardiac scans in this series. Results CHD was diagnosed in a total of 447 (11.2%) fetuses at a median gestational age of 24 (range, 12-40) weeks. Forty-two of the 447 (9.4%) had TOF, of which 29 cases (69.0%) had classical TOF (pulmonary stenosis), nine (21.4%) pulmonary atresia and four (9.5%) absent pulmonary valve syndrome. A question-mark sign was observed in 16/29 (55.2%) cases of classical TOF and in 8/9 (88.9%) cases of TOF with pulmonary atresia. The sign was never observed in any of the cases of TOF with a right-sided aortic arch. Likewise, the sign was observed in 1/405 (0.2%) cases with other cardiac anomalies (a fetus with a complex cardiac defect) and in none of the fetuses with normal hearts. Conclusions The finding of an enlarged aorta with a question-mark shape should raise a strong suspicion of tetralogy of Fallot, in particular the variant with pulmonary atresia. This sign may be useful in screening considering that prenatal diagnosis of TOF by routine ultrasonography remains a challenge. Copyright © 2010 ISUOG. Published by John Wiley & Sons, Ltd.