Fetal heart assessment in the first trimester of pregnancy: influence of crown-rump length and maternal body mass index

OBJECTIVE: To evaluate the influence of the crown-rump length and body mass index on sonographic evaluation of the fetal heart using abdominal and vaginal routes in the first trimester of pregnancy. METHODS: We conducted a cross-sectional study with 57 pregnant women between 12-14 weeks (CRL≤ 84 mm). We evaluated the following fetal cardiac plans using the abdominal and vaginal routes: four-chamber view, right ventricle outflow tract, left ventricle outflow tract and aortic arch. We used the B-mode, color Doppler and four-dimensional ultrasonography (spatio-temporal image correlation). To evaluate the influence of crown-rump length and body mass index in the assessment of fetal cardiac planes, we used the t test unpaired. RESULTS: There were no statistically significant differences in the rates of success and failure between abdominal and vaginal routes in relation to body mass index, however, there was a higher failure rate in vaginal assessment using B mode associated with color Doppler (P<0.01). CONCLUSION: The crown-rump length and body mass index had no interference in fetal cardiac assessment in the first trimester of pregnancy.