**6. Clinical symptoms of transfusion haemolytic reactions**

Intravascular haemolysis is accompanied by haemoglobinaemia and usually also haemoglobinuria, whereas extravascular haemolysis can only be


#### **Table 3.**

*Initial symptoms of haemolytic transfusion reactions.*

accompanied by anaemia. In both cases, the patient's serum bilirubin increases, but it depends on the degree of haemolysis as well as liver function [1]. Elevated LDH is always observed with intravascular haemolysis, not always with extravascular haemolysis. Reduced haptoglobin levels usually occur in both types of haemolysis. Drop in blood pressure is much more common in patients with intravascular than extravascular haemolysis. Renal failure and DIC are also more commonly associated with intravascular haemolysis. Some patients may experience organ failure such as the pancreas, heart and even multiple organ failure that threatens the patient's life.

In unconscious patients and patients under general anaesthesia, it may be difficult to recognise a haemolytic transfusion reaction, as some symptoms may go unnoticed (e.g. pain and nausea). Pain, which is described as a symptom of haemolytic reactions, is located at the puncture site, back, chest, groin and head. The occurrence of pain in the haemolytic transfusion reaction is not clear. It is probably the result of direct stimulation of nociceptive nerves in perivascular tissue by bradykinin, which, in turn, is released during sudden activation of complement [37]. Clinical manifestations are shown in **Table 3**.
