Page 354 - Essential Haematology

340 / Chapter 25 Bleeding disorders

Massive t ransfusion s yndrome

Platelets are unstable in blood stored at 4 ° C and the
platelet count rapidly falls in blood stored for more
than 24 hours. Patients transfused with massive
amounts of stored blood (more than 10 units over
a 24 - hour period) frequently show abnormal clot-
ting and thrombocytopenia. These should be cor-

rected by the use of platelet transfusions and FFP.

(a) Disorders of p latelet f unction
Disorders of platelet function are suspected in
patients who show skin and mucosal haemorrhage
despite a normal platelet count and normal levels
of VWF. These disorders may be hereditary or

acquired.

Hereditary d isorders
Rare inherited disorders may produce defects at
each of the different phases of the platelet reactions

leading to the formation of the haemostatic platelet
plug.
(b)

Figure 25.8 Thrombotic thrombocytopenic purpura. Thrombasthenia (Glanzmann ’ s d isease)
(a) Platelet thrombus in a small cardiac vessel with
minor endothelial and infl ammatory reaction. This autosomal recessive disorder leads to failure of

(Courtesy of Dr J.E. McLaughlin.) (b) Peripheral blood primary platelet aggregation because of a defi ciency
fi lm showing red cell fragmentation.

Splenic pool
30% 60%

90%

Circulating platelets
70% 10–40%

Figure 25.9 The platelet distribution between the circulation and spleen in normal individuals (left), and in
patients with moderate or massive splenomegaly (right).