Sentinel event

ABO incompatibility

The transfusion of ABO incompatible product(s) resulting in an acute haemolytic transfusion reaction. Generally major ABO red blood cell mismatches result in significant morbidity or mortality, but minor incompatibilities may be innocuous and not result in harm. Incompatible platelet and plasma transfusions may or may not result in haemolysis and harm.

Haemolytic transfusion reactions (HTR) are clinically suspected if one or more of the following is present in a temporal association with transfusion:

• fever and a variety of other symptoms (including dyspnoea, hypotension, tachycardia, flank or back pain)
• inadequate rise in post‑transfusion Hb level
• drop in Hb level (≥2 g/dl within 24 hours)
• rise in LDH (≥50% within 24 hours)
• rise in bilirubin, haemoglobinuria or decrease in haptoglobin levels.

It should be noted that adverse events attributed to transfusion of ABO incompatible products are included in the Incorrect Blood Component Transfused (IBCT) category. Such events could equally be described as acute haemolytic transfusion reactions (AHTR), but the key failure is IBCT. Transfusion of ABO incompatible products to a patient is considered a 'sentinel event' and is also subject to other reporting channels outside the National Haemovigilance Program.