The normal pattern of pulmonary venous flow on pulsed Doppler examination of the human fetus.

The pattern of pulmonary venous flow was studied in 52 normal fetuses between 16 weeks gestation and term. A characteristic flow profile was defined. This was similar to that described in the child and adult and different from the pattern of flow in the systemic veins described in the fetus. The velocity of flow increased with gestation and was not influenced by heart rate. The velocity-time integral showed that systolic flow was 2.0 +/- 0.3 times the flow in diastole. Pulsed Doppler echocardiography demonstrates a distinctive pattern of pulmonary venous blood flow that reflects left atrial hemodynamics.