Page 354 - Essential Haematology
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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).
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