The bleeding time test is a diagnostic tool to evaluate platelet function and clotting ability, crucial for identifying bleeding disorders and monitoring therapies.
Frequently Asked Questions
What is the Bleeding Time test and is it still relevant?
Bleeding Time (BT) test measures the time from a small standardised skin puncture to natural clotting (haemostasis). Traditional method (Ivy or Duke): (1) Small superficial cut made with sterile lancet, usually forearm or earlobe; (2) Filter paper touched to bleeding site every 30 seconds; (3) Time to bleeding stop measured. Normal range: 2-9 minutes (varies by method and lab). Modern relevance: BT is largely OBSOLETE for pre-operative screening — replaced by more reliable, standardised tests: (a) Platelet count — should be >100,000/µL for surgery; (b) Prothrombin Time (PT)/INR — measures extrinsic clotting pathway; (c) Activated Partial Thromboplastin Time (aPTT) — measures intrinsic clotting pathway; (d) Fibrinogen level; (e) Platelet Function Assays (PFA-100) — modern replacement for BT for platelet function assessment. Why BT is obsolete: (1) Poor reproducibility between operators and centres; (2) Doesn’t reliably predict surgical bleeding risk; (3) Modern coagulation testing is more informative; (4) Leaves visible scar; (5) Sensitivity/specificity too poor for clinical utility. In India, BT is still ordered at some hospitals due to tradition, not evidence — usually along with modern coagulation tests. American Society of Anesthesiologists (ASA) and Indian Society of Anaesthesiologists no longer recommend routine BT.
When should bleeding time or coagulation tests be done before surgery?
Modern approach: coagulation screening is NOT needed for asymptomatic patients undergoing minor procedures (dental, cataract, minor skin) with no bleeding history. A structured bleeding-history questionnaire is more useful than routine testing — ask about easy bruising, prolonged bleeding after dental extraction or previous surgery, nosebleeds needing medical attention, menorrhagia in women, family history of bleeding disorders, aspirin or anticoagulant use, liver disease, kidney disease. If bleeding history is positive OR high-risk surgery, order platelet count + PT/INR + aPTT + fibrinogen (basic coagulation profile). Additional tests based on findings: vWF antigen and activity (for suspected von Willebrand disease, the most common inherited bleeding disorder), Factor VIII/IX (haemophilia), platelet function tests, thromboelastography (TEG) for complex cases. On aspirin, clopidogrel, or novel anticoagulants (dabigatran, rivaroxaban, apixaban), specific management protocols apply — may need to stop 5-7 days pre-op; consult the treating physician. On warfarin, target INR and consider heparin bridging if high thrombotic risk (mechanical valves, recent stroke). Cardiac, neurosurgery, and major orthopaedic surgery always warrant coagulation screening.
What conditions can prolong bleeding time, and how are they investigated?
Causes of prolonged BT (over 10 minutes typically): thrombocytopenia (low platelet count) — the most common cause; investigate for dengue (endemic in India), immune thrombocytopenia (ITP), leukaemia, aplastic anaemia, viral infections, and drug causes (heparin, quinine, some antibiotics). Platelet function disorders — inherited (Glanzmann thrombasthenia, Bernard-Soulier) or acquired (aspirin — 7-10 days, clopidogrel — 5-7 days, NSAIDs, uraemia in kidney failure). Von Willebrand disease — most common inherited bleeding disorder, often undiagnosed, needs specific vWF testing. Uraemia (chronic kidney disease) — uraemic toxins impair platelet function. Liver disease — reduced coagulation factor synthesis plus thrombocytopenia. Vessel wall disorders — Ehlers-Danlos syndrome, scurvy. Drugs — anticoagulants, some antihypertensives, alcohol excess. Vitamin K deficiency — malnutrition, prolonged antibiotics, malabsorption. Investigation: detailed bleeding history and drug review; CBC with platelet count and smear examination; coagulation panel (PT, aPTT, fibrinogen, thrombin time); liver and kidney function tests; Vitamin K response test (give vit K IM, retest); specific factor assays if an inherited disorder is suspected; platelet function tests (PFA-100 or aggregometry) at specialised centres; vWF panel if inherited bleeding history. Refer to a haematologist for unexplained bleeding disorders.
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