Distinguishing right from left: a standardized technique for fetal echocardiography.

Improved echocardiographic equipment and increasing experience have led to accurate and reliable prenatal diagnosis of congenital defects and arrhythmias. However, without a standard convention for acquisition and presentation of fetal images, distinguishing the right side of the fetus from the left side can be difficult and confusing. This article proposes a standard method of image acquisition and presentation that allows confident determination of the fetal right/left axis by easily identified anatomic landmarks. This technique provides a reliable determination of the fetal right/left axis regardless of fetal position (i.e., face up, face down, facing left, or facing right), in both real time and retrospective review. Only after the fetal right/left axis has been determined can accurate diagnoses of fetal atrial and visceral situs, base-apex axis, and cardiac segmental anatomy be made.