Sonographic definition of the fetal situs.

The sonographic definition of the fetal situs is of diagnostic importance. However, the current methods that rely on the position of both heart and stomach are not always reliable. Presented are the right-hand rule for transabdominal scanning and the left-hand rule for transvaginal scanning which enable the definition of the fetal situs. The presented rules of thumb enable a definite diagnosis of the fetal situs in all cases and apply for all fetal positions and presentations.