Manual of basic techniques for a health laboratory - libdoc.who.int

298 Manual of basic techniques for a health laboratory9.9.4 ResultsNormal clot retractionThe red clot is well separated and, at the surface, is attached to the sides of the tube(Fig. 9.58). There may be a small deposit of erythrocytes in the bottom of the tube;it should not be more than 5mm thick.Fig. 9.57 LysisAbnormal clot retractionBlood deficient in fibrinogenIf blood is deficient in fibrinogen there is a small red clot at the bottom of the tube,not necessarily attached to the sides of the tube. It is surrounded by sedimentederythrocytes and covered by supernatant (Fig. 9.59).Fig. 9.58 Normal clotretractionBlood deficient in thrombocytesIf blood is deficient in thrombocytes there is a red clot that remains almost completelyattached to the sides of the tube and that will have retracted very little, if atall (Fig. 9.60). Hardly any serum will have exuded.(Examine a Romanowsky-stained thin blood film, using venous blood, see section9.10.)Abnormal plasma proteinsAbnormal plasma proteins cause coagulation of plasma. This appears as a yellowclot — clotted plasma. Beneath it is a poorly retracted red clot (Fig. 9.61).Fig. 9.59 Blood deficient infibrinogenHaemophiliaIf there is no clot at all or a yellow clot that forms very slowly over the deposit oferythrocytes (Fig. 9.62), the cause is a serious clotting factor deficiency such asthat which occurs in haemophilia.Haemophilia is a hereditary haemorrhagic disease affecting males.Report the clot retraction as:—“normal”—“abnormal”, with a description of the clot.Lysis timeA clot normally takes at least 48 hours to dissolve. However, the lysis time may bereduced in certain conditions. For example, in patients with acute fibrinolytic diseasethe clot may dissolve within 1–4 hours.Report the lysis time of the clot in hours.Fig. 9.60 Blood deficientin thrombocytesFig. 9.61 Blood containingabnormal plasmaproteinsFig. 9.62 Haemophilia