Nuttall et al developed a standing blood order equation for patients undergoing a total hip arthroplasty, but the concept should apply to other surgical patients requiring blood. This is both is cost effective and allows for better use of blood product inventory. The authors are from the Mayo Clinic in Rochester, Minnesota.

standing blood order equation =

= (hemoglobin loss expected related to a surgical procedure in g/dL) – ((preoperative hemoglobin in g/dL) – (minimum acceptable hemoglobin for the patient))



• Each unit of packed red blood cells effects a change in hemoglobin of 1 g/dL.

• For patients undergoing total hip arthroplasty, the expected hemoglobin loss was 3.7 +/- 1.7 g/dL for a primary arthroplasty and 4.8 +/- 2.4 g/dL for a revision arthroplasty.


If the equation gives a value < 0.5, then a type and screen is ordered.


If the equation gives a value >= 0.5, then a type and cross is ordered for a number of units equal to the equation value rounded to the nearest whole number.

To read more or access our algorithms and calculators, please log in or register.