Allergic reactions
Blood transfusions can be associated with allergic reactions, ranging in severity from mild skin symptoms to even anaphylaxis.
Mild allergic reaction
Definition
The symptoms of a mild allergic reaction occur during or within 4 hours after the completion of a blood transfusion. The reaction is not life-threatening and responds quickly to symptomatic treatment.
Symptoms
- Urticaria (hives)
- Itching
- Localized swelling
- Mild temperature rise < 38 °C
- Mild shortness of breath
Causes
The transfused product contains unknown factors to which the patient has developed an allergy.
Confirmatory tests
The causes of mild allergic reactions cannot be determined through testing.
Severe allergic reaction or anaphylaxis
Definition
Anaphylaxis refers to a sudden and severe hypersensitivity reaction that can be life-threatening for the patient. Severe anaphylactic-type reactions typically occur immediately at the start of the blood transfusion.
Symptoms
- Bronchospasm
- Severe shortness of breath
- Swelling of the throat
- Drop in blood pressure
- Tachycardia
- Decreased level of consciousness
- Generalized urticaria (hives)
- Angioedema (swelling beneath the skin)
- Abdominal pain
- Nausea
Causes
Usually, the reaction is caused by medication or food components or plasma proteins present in the donor’s plasma. Anaphylaxis can also be caused by antibodies against serum immunoglobulin A (S-IgA) in cases of IgA deficiency. Not all causes of these reactions are known.
Confirmatory tests
An IgA measurement (P-IgA or S-IgA) is performed in the hospital laboratory, primarily from a sample taken before the blood transfusion, and the result is reported to the Blood Safety Office. If the IgA level is below the detection limit of the method, in addition to routine adverse event samples, a 2 ml serum sample is provided to the Blood Safety Office for IgA deficiency investigations.