Maximum surgical blood ordering schedule MSBOS

A system of tailoring blood requirements to particular elective surgical procedures, including—importantly—procedures which do not usually require blood cover.

• The ABO group and Rh (D) type of the patient is determined on duplicate samples, and the serum screened for significant RBC ('atypical') antibodies. If there are no antibodies, the serum is kept available ('saved') for a determined period (usually a week)—this is the 'Group, Screen and Save' (G&S) procedure.

• If there are no atypical antibodies, and the planned surgery is likely to need peri-operative transfusion, the required number of red cell units are matched by routine tests, labelled and set aside in an accessible refrigerator. Storage conditions must meet certain standards (continuous recording of appropriate temperature, alarms, etc).

• If more blood is required than anticipated, extra units must be readily available. If the need is urgent, suitable arrangements—such as rapid matching (using the 'saved' serum) and despatch procedures—must enable the timely supply of blood.

• If there are atypical antibodies, which may occur in up to 10% patients, their specificity must be determined and, if clinically significant, sufficient (extra) red cell units lacking the relevant antigen provided and matched by detailed techniques. (These are often referred to as 'phe-notyped red cells'.)

• If there is no 'MSBOS' more units must be matched than are usually required for transfusion, in order to give rapid access if extra blood is needed. Matched 'bespoke' blood is therefore unavailable for other patients for the 2-3 days set aside.

• A good MSBOS gives better access to blood stocks and enables more efficient use, in particular of O Rh(D) -ve blood. There is no good reason for regarding O Rh(D) -ve blood as a 'universal' donation type. It can be antigenic; and it is a precious resource, being available from <8% of the population.

• The surgical team must be confident in the system, and the blood bank staff committed to 'minimal barriers'. The cross-match: transfusion

646 ratio of a blood bank may well become lower than 2 (i.e. overall <2 units matched for every unit transfused) which is an indication of efficient practices. It could even be nearer to 1 than to 2.

• MSBOS schedules will vary between hospitals—depending on demographic factors, general layout, access to the blood bank refrigerators, types of surgery etc.

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