RECOGNITION OF A FETAL SUBDIAPHRAGMATIC VENOUS VESTIBULUM ESSENTIAL FOR FETAL VENOUS DOPPLER ASSESSMENT

Ultrasonic visualization of the human fetal subdiaphragmatic area demonstrated anatomical relationships, different from descriptions in the literature. Four human fetal postmortem specimens at 18, 26, 28, and 34 wk of gestation were examined to ascertain morphologic details of intra- and perihepatic vasculature. Drawings of these dissected preparations were compared with ultrasonic images from the same region. With both methods the presence of a venous vestibulum immediately proximate to the diaphragm could be demonstrated. The abdominal inferior vena cava ends in a funnel-like structure, which also contains the orifices of the hepatic veins, the ductus venosus, and a phrenic vein. A considerable variability in Doppler flow recordings could result from blood propelling out of these various vessels into the vestibulum. It is, therefore, suggested that information on blood-flow velocities in venous hepatic vessels should be obtained more distally in the separate vessels and not at the entrance into the right atrium.