Four-chamber view of the fetal heart: demonstration related to menstrual age

The four-chamber view of the fetal heart is the most widely used screening examination for the detection of structural cardiac abnormalities during routine fetal ultrasonography. A prospective study of 520 consecutive routine fetal sonograms taken between 13 and 39 weeks of gestational age was performed to determine the frequency of obtaining a satisfactory four-chamber view, focusing on fetuses of less than 19 weeks' menstrual age. Menstrual age was a significant variable in procuring a satisfactory four-chamber view. Visualization of a normal four-chamber view on film progressively increased from five out of 15 (33%) at 14 weeks of menstrual age to 35 out of 38 (92%) at 19 weeks of menstrual age; real-time evaluation improved visualization to six out of 15 (40%) at 14 weeks of menstrual age and to 36 out of 38 (95%) at 19 weeks of menstrual age. Visualization in all fetuses scanned before 19 weeks' menstrual age improved from 62 (on film only) to 75% (real-time and film). Abnormalities on the four-chamber view were demonstrated before 19 weeks of menstrual age in four cases. Although not all serious cardiac defects can be detected, the four-chamber view remains a reliable screening examination of the fetal heart even early in gestation.