A comparison of noninvasive methods for early detection of hemorrhage: Inferior vena cava ultrasonography and spectrophotometric hemoglobin levels.

Objectives: Blood hemoglobin concentration measurements using a spectrophotometric method (SpHb), and inferior vena cava ultrasonography (IVC-US) are noninvasive methods used to follow-up hemorrhages. We compared their efficacy using voluntary blood donation as a model of moderate (approx. 500 mL) blood loss.