Q5 LONG ANSWER 10M ★ High-yield

Describe the approach to a patient with a bleeding disorder. Interpret the coagulation screening tests and classify the causes of thrombocytopenia.

Pathology · 2nd Professional — Para-Clinical

Component	Role	Disorders
Vessel wall	Vasoconstriction; provides collagen and von Willebrand factor	Scurvy, senile purpura, Henoch–Schonlein purpura, hereditary haemorrhagic telangiectasia, steroid purpura
Platelets	Primary haemostatic plug	Thrombocytopenia; defects of function
Coagulation factors	Fibrin stabilisation of the plug	Haemophilia, von Willebrand disease, liver disease, vitamin K deficiency, DIC

Feature	Platelet / vessel disorder	Coagulation disorder
Onset after injury	Immediate	Delayed, hours later
Site	Superficial — skin and mucous membranes	Deep — joints, muscles, retroperitoneum
Characteristic lesion	Petechiae and purpura; epistaxis, gum bleeding, menorrhagia	Haemarthrosis and muscle haematoma
Petechiae	Typical	Rare
Bleeding after minor cuts	Persistent oozing	Minimal
Family history	Usually absent	Often present (X-linked in haemophilia)
Sex	Both	Males in haemophilia
Example	ITP	Haemophilia

CLINICAL PEARL

The history usually tells you which system has failed before any test is done.
Immediate, superficial, mucocutaneous bleeding is a platelet or vessel problem
delayed, deep bleeding into joints and muscles is a coagulation problem. Taking that history properly directs the whole investigation and avoids ordering everything at once.

Test	Measures	Normal
Platelet count	Number of platelets	1.5–4 lakh/mm3
Bleeding time	Platelet number and function, and vessel wall	2–7 minutes
Prothrombin time (PT/INR)	Extrinsic and common pathway — factors VII, X, V, II, I	11–16 seconds
Activated partial thromboplastin time (aPTT)	Intrinsic and common pathway — XII, XI, IX, VIII, X, V, II, I	25–40 seconds
Thrombin time	Fibrinogen to fibrin conversion	10–15 seconds
Fibrinogen and D-dimer	Consumption and fibrinolysis	—

PT	APTT	Platelets	Diagnosis
Prolonged	Normal	Normal	Factor VII deficiency; early warfarin or vitamin K deficiency; early liver disease
Normal	Prolonged	Normal	Haemophilia A (VIII) or B (IX); von willebrand disease; heparin; lupus anticoagulant
Prolonged	Prolonged	Normal	Vitamin K deficiency; liver disease; common pathway defect
Prolonged	Prolonged	Low	DIC; massive transfusion; severe liver disease
Normal	Normal	Low	ITP; hypersplenism; marrow failure
Normal	Normal	Normal	Vessel wall disorder, or a platelet function defect (check bleeding time)

Mechanism	Causes
Decreased production	Aplastic anaemia, leukaemia, marrow infiltration, megaloblastic anaemia, alcohol, cytotoxic drugs, radiation
Increased destruction — immune	ITP; SLE; CLL and lymphoma; drugs (heparin, quinine, sulphonamides); post-transfusion purpura; HIV
Increased destruction — non-immune	DIC, thrombotic thrombocytopenic purpura, haemolytic uraemic syndrome, dengue and other viral infections, malaria, sepsis
Sequestration	Hypersplenism from any cause of splenomegaly
Dilutional	Massive transfusion
Spurious	PSEUDOthrombocytopenia from EDTA-induced clumping — always check the film before acting

In India, dengue is a very common cause of acute thrombocytopenia, and the count often falls dramatically before recovering spontaneously
Spontaneous bleeding is unusual above 20,000/mm3, and serious bleeding above 10,000, unless platelet function is also impaired

Feature	Vitamin K deficiency	Liver disease
Factors affected	II, VII, IX, X and proteins C and S only	All factors except VIII and von Willebrand factor
Factor VIII	Normal	Normal or raised — it is made by endothelium, not hepatocytes
Factor V	Normal	Low
Response to vitamin K	Corrects	Little or no correction
Causes	Newborn (haemorrhagic disease), obstructive jaundice, malabsorption, prolonged antibiotics, warfarin	Cirrhosis, acute hepatic failure

Factor V distinguishes them — it is made in the liver but is not vitamin K dependent, so it is normal in vitamin K deficiency and low in liver disease

A careful history is the most valuable investigation — family history, drugs, response to previous surgery and dental extraction, and the pattern of bleeding
Vitamin K at birth prevents haemorrhagic disease of the newborn, and is among the most cost-effective interventions in medicine
Platelet transfusion is given for bleeding or before a procedure, not for a number alone; it is contraindicated in thrombotic thrombocytopenic purpura, where it fuels the thrombosis
Always examine the film in unexplained thrombocytopenia — it excludes clumping, and may show schistocytes, blasts or malarial parasites
A prolonged aPTT that corrects on mixing with normal plasma indicates a factor deficiency; one that does not correct indicates an inhibitor, such as a lupus anticoagulant or an acquired factor VIII antibody
Aspirin and NSAIDs must be stopped before surgery in any patient with a bleeding tendency, and should never be used for fever in suspected dengue

All questions in Haematology II: Leukaemias, Lymphomas & Haemostasis