1/19. When considering whether a patient is at risk of bleeding before a procedure/surgery or if a patient is bleeding and you want to assess if there are any 'correctable' clotting abnormalities, a thorough approach is needed to ensure all factors are identified.
2/19. The patient might have a PT of 19 seconds but this will probably make little/no difference in terms of bleeding risk, but the clopidogrel they have continued to take without telling the nurses/medical staff really will. I.e the coagulation screen isn't the whole picture..
3/19. The 3 main elements are platelets, fibrinogen and clotting factors.
Platelet function depends on platelet number and function. Count can be reduced by many causes. Major surgery can occur with a platelet count of 50x10^9 or more (BSH guidelines. Note neurosurgery >100)
Platelet function depends on platelet number and function. Count can be reduced by many causes. Major surgery can occur with a platelet count of 50x10^9 or more (BSH guidelines. Note neurosurgery >100)
4/19. This emphasises that platelets can be relatively low against the reference range e.g 62, where lower end of normal range is 150, without a major bleeding risk. Platelet function can be impaired by medications, uraemia, liver dysfunction.
5/19. Fibrinogen is often raised in inflammation (a normal finding) but can be reduced in patients with severe liver disease/critically ill patients- when this is combined with thrombocytopenia, prolonged PT or APTT (APTT more predictive) and raised D-Dimers, this suggests DIC.
6/19. Other rare causes for low fibrinogen are the inherited hypofibrinogenaemias. There can also be dysfunction, even if the absolute number is not particularly low e.g 1.3g/L, therefore in any patient with fibrinogen disorder, discuss with haematology pre-procedure.
7/19. Finally the coag screen. The PT is often abnormal in unwell patients. This is because clotting factors are consumed in unwell patients and FVII (main element in the extrinsic pathway/PT @KateMusgrave)has shortest half life of the clotting factors and is 'used up' first
8/19. Unwell patients often also synthesize less vitamin K dependent factors, or are nutritionally vitamin K deplete. However a PT up to 20 is unlikely to be associated with a significant bleeding phenotype. There is also little in terms of treatment options for it.
9/19. FFP will not 'correct' a PT of 20 seconds or less, therefore FFP for a PT of 17 will be very unlikely to reduce the bleeding risk, and instead expose the patient to a blood product and a further 1L of fluid (for an average adult).
10/19. In cases of life-threatening bleeding or where a bleed would have significant consequences (e.g intracranial bleed) then prothrombin complex concentrate (e.g beriplex) could be considered. This does however have a small thrombosis risk, and not an insignificant cost.
11/19. A prolonged APTT is more likely to be associated with a true underlying bleeding disorder, but can be due to a lupus anticoagulant, which is actually clinically procoagulant. If pre-op coag testing performed, do so early to allow lupus anticoag testing and factor levels
12/19 In summary if planning a procedure & thinking about bleeding;1) Bleeding history from pt-this is the most useful predictor of bleeding risk. e.g Pt. may have a PT of 17s, but had teeth pulled out the week before with no bleeding-you can be fairly sure PT is not significant
13/19. 2) Diligent medication review
3) Routine coagulation screen not recommended pre-op as does not improve outcomes. See below for some of the evidence of how the coagulation screen is only really beneficial in a patient with a bleeding history/family bleeding history
3) Routine coagulation screen not recommended pre-op as does not improve outcomes. See below for some of the evidence of how the coagulation screen is only really beneficial in a patient with a bleeding history/family bleeding history
14/19. British Journal anaesthesia (academic.oup.com/bja/article/10…); only test coag screen if family history/personal hx bleeding disorder or if acute severe illness like sepsis or liver failure.
15/19. From Royal College of Physicians of Edinburgh (rcpe.ac.uk/sites/default/…) - 'poor performance' of PT and APTT of predicting bleeding in populations with low incidence of bleeding disorders (most of the UK)
16/19. From NICE pre-op testing guidance (nice.org.uk/guidance/ng45/…) Haemostatic tests not advised before minor surgery, or intermediate/major with ASA 1/2. If ASA 3/4 + major surgery only consider if liver disease.
17/19. Paper from neurosurgical journal about >1100 patients in NZ/Aus (ncbi.nlm.nih.gov/pubmed/30876935) Pre-op testing only identified unexpected, clinically significant coag screen abnorm in 0.5% pts. These were all long APTT, none were corrected, and none of those pts had 🔼bleeding
18/19. Authors advise a screening questionnaire and testing only if relevant indicator e.g history bleeding/family history.
19/19. So...the coag screen is only really useful if a patient has bleeding phenotype. Otherwise it picks up clinically insignificant changes which can cause harm to the pt by delaying procedures/exposing to blood products. All this info and more on the Buku Haematology App 👍
