Abstract: The present invention is related to a method and apparatus for monitoring the cumulative amount of blood in a blood-containing liquid mixture emanating from a patient during a surgical procedure, or during recovery from a surgical procedure. The apparatus comprises a conduit for withdrawing a liquid mixture comprising blood from the surgical site. The liquid mixture is filtered, after which the blood concentration of the liquid mixture is measured by a first measuring means. The volumetric flow rate of the liquid mixture is also measured by a second measuring means. The liquid mixture blood concentration and flow rate readings are used to electronically calculate the cumulative amount of blood lost by the patient to the liquid mixture. Finally, the cumulative blood loss value is displayed. The liquid mixture is disposed of following the two measurements. A method of using such an apparatus during a surgical procedure and/or during recovery from a surgical procedure is also disclosed.