Visual comparative colorimetry. A practical method of estimating operative blood loss.

To the editor, most anesthesiologists estimate blood loss by rough visual assessment, by noting its effects on cardiovascular parameters, by weighing of swabs, by substraction of fluids used in surgical irrigation from blood in suction reservoir, either by laboratory estimation or by trusting their experiences and instinct. I describe here a simple and practical method of estimating operative blood loss (OBL). It is based on colour comparison of two solutions containing blood using simple equipments readily available in and operating room, without the need to know the patients’ initial Hb or Hct or depend on laboratory results.