Appropriate diagnosis of bleeding disorders needs to follow algorithm of clinical evaluation, screening test for coagulation disorders and planning further tests as per results of screening. Those haemostatic screening tests include platelet count & morphology, bleeding time (BT), prothrombin time (PT), activated partial thromboplastin time (APTT) and sometimes thrombin time (TT). It is generally practiced to diagnose common coagulation disorders, Haemophilia A and B, by assessment of factor VIII and FIX respectively, as next step to basic haemostatic screening. FVIII & FIX assessment are widely available facility in major cities of Bangladesh. But, when rare bleeding disorders are encountered, respective factor assessment facilities are hardly available. However, it is worth noting that to identify a certain coagulation disorder it is not necessary to have the specific factor assessment facility. Keeping the physiology of haemostasis in mind, all coagulation abnormalities can be identified by observing the correction of an abnormal basic coagulation test or clotting time, after mixing the patient’s plasma sample with plasma or serum with ‘known property’. This approach is called ‘correction test’ or ‘mixing test’ of clotting. These plasma or serum with ‘known property’ are pooled normal plasma (PNP) adsorbed plasma, aged serum, FVIII deficient plasma (from severe haemophilia A patient), FIX deficient plasma (from severe haemophilia B patient) etc. By observing either correction or no correction of an abnormal clotting time (mostly APTT) give precise information about the step of defect (factor deficiency) in coagulation pathway. This algorithm also informs whether the defect is due to deficiency of a factor or inhibitor against coagulation factor.
So, logistic facility of basic clotting tests is sufficient to solve almost all coagulation problem. What we need are availing and preserving various plasma and serum sample of known property to be used as ‘reagents’, and most importantly, applying knowledge and skill of haemostasis properly. Even for quantification of clotting factors, besides FVIII & IX, and quantification of inhibitor, it is not needed to have much more additional equipment and reagents but basic coagulation laboratory facilities.
Correspondence: Professor Akhil Ranjan Biswas, Department of Haematology, Mymensingh Medical College, Mymensingh.