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PA20.1-2 | Hemostasis & Bleeding Disorders — PBL Case

CLINICAL SETTING

Meena, a 28-year-old primigravida at 34 weeks gestation, is admitted to the obstetrics ward of a district general hospital in Pune with sudden-onset severe abdominal pain and vaginal bleeding. The obstetrician confirms placental abruption and performs emergency caesarean section. During the procedure, the anaesthetist notices oozing from the incision edges that is difficult to control, and blood dripping from the IV cannula site that does not stop despite local pressure. In the recovery room, the nurse flags multiple petechiae on Meena's chest and arms, and Meena passes a small amount of dark red urine. Her BP falls to 88/58 mmHg. The pathology resident on call is asked to urgently interpret a blood sample. The immediate impression: this is not a single-system bleeding disorder — something has consumed the clotting machinery itself.

Trigger 1: Initial Presentation — Recognising the Pattern

The pathology resident reviews the clinical history: a young obstetric patient, emergency caesarean for placental abruption, simultaneous bleeding from the surgical wound, IV cannula site, and mucous membranes — multiple sites at once. This is the defining red flag. Emergency CBC and coagulation screen: • Hb 8.2 g/dL (was 11.4 g/dL at 30 weeks) • Platelets: 38 × 10⁹/L • Peripheral blood film: several fragmented erythrocytes (schistocytes, helmet cells) • PT: 28 s (control 12 s) • aPTT: 72 s (control 32 s) • Fibrinogen: 0.7 g/L (reference >2.0 g/L) • D-dimer: markedly elevated (>8 µg/mL)

DISCUSSION POINTS

  • What is the single unifying diagnosis that explains simultaneous thrombocytopenia, prolonged PT and aPTT, low fibrinogen, elevated D-dimer, and schistocytes on the film? Describe the pathophysiological mechanism in three steps.
  • Why does placental abruption trigger this syndrome? What is released from the placenta that initiates the coagulation catastrophe?
  • Using the two-axis framework (primary vs secondary haemostasis failure), explain why Meena's bleeding cannot be explained by a simple platelet disorder or a simple coagulation factor deficiency alone.
  • Distinguish D-dimer from FDPs (fibrinogen/fibrin degradation products) — what does D-dimer specifically indicate, and why is it more diagnostically specific in this context?
Click to reveal Trigger 2: Investigations — Confirming the Mechanism (discuss previous trigger first!)

Trigger 2: Investigations — Confirming the Mechanism

The obstetrics team calls in the haematologist. She orders a 'DIC panel' and asks for the peripheral film to be reviewed personally. Her finding: 12 schistocytes per 100 RBCs. She also notes that the activated partial thromboplastin time (aPTT) is prolonged but NOT corrected on a 1:1 mixing study. Additional results: • Factor V: markedly reduced (12% of normal) • Factor VIII: reduced (28% of normal) • Antithrombin III: reduced (45% of normal) • Repeat fibrinogen 1 hour later: now 0.4 g/L — falling despite empirical FFP infusion Meena's mother, anxious at the bedside, asks: 'My sister also bled like this once — is this a family disease?'

DISCUSSION POINTS

  • The mixing study did not correct the prolonged aPTT. What does this indicate — factor deficiency, factor inhibitor, or both? In the context of DIC, why does the mixing study fail to correct?
  • Interpret the pattern of factor levels: factor V is markedly reduced but factor VIII is only mildly reduced. In DIC, which clotting factors are consumed early and which are consumed late? Why is factor VIII relatively preserved in early DIC (hint: think about vWF and factor VIII binding)?
  • Meena's mother asks if this is hereditary. How would you reassure her? What inherited coagulation disorder causes a prolonged aPTT that does correct on mixing, and how is its clinical presentation completely different from Meena's acute illness?
  • What is the single most important first-line intervention in DIC management and why? If the trigger is not addressed, why will replacing clotting factors and platelets fail to stop the bleeding?
Click to reveal Trigger 3: Diagnosis & Management — DIC vs Its Mimics (discuss previous trigger first!)

Trigger 3: Diagnosis & Management — DIC vs Its Mimics

Meena stabilises after delivery of the placenta, FFP, cryoprecipitate, and platelet transfusion. Forty-eight hours post-operatively, her laboratory parameters trend toward recovery: fibrinogen 1.8 g/L, platelets 95 × 10⁹/L, PT normalising. The following week, the haematologist is called to review another patient on the surgical ward: a 55-year-old man with decompensated alcoholic liver cirrhosis and haematemesis. His investigations: PT 22 s, aPTT 52 s, platelets 48 × 10⁹/L, fibrinogen 1.4 g/L, D-dimer mildly elevated (2.1 µg/mL). She asks the interns: 'This looks like DIC — but is it? What one result tells you the difference?'

DISCUSSION POINTS

  • Compare Meena's acute DIC laboratory picture with the cirrhosis patient's coagulopathy. What single test result best distinguishes DIC from liver disease coagulopathy? (Hint: think about which factor requires NO vitamin K and is made only by the liver.)
  • Construct the three-way comparison table for acute DIC, vitamin K deficiency, and liver disease across these parameters: platelet count, PT, aPTT, fibrinogen, D-dimer, factor V, and factor VIII.
  • Meena's condition improved when the placenta was delivered. Describe the pathological basis of 'chronic compensated DIC' as seen in patients with retained dead fetus or mucinous carcinoma — why do platelets and fibrinogen remain near-normal despite ongoing activation?
  • If Meena had developed DIC from gram-negative sepsis instead of placental abruption, which cytokine-driven cellular pathway would have triggered the coagulation cascade, and which specific NACO-mandated blood screening test safeguards future patients from transfusion-transmitted sepsis?

Group Task Assignments

Group 1: Normal haemostasis — pathway to pathology

  • Draw the cell-based model of coagulation showing initiation (tissue factor + factor VII on fibroblasts), amplification (platelet surface), and propagation (tenase + prothrombinase). Identify where thrombin acts as a master amplifier.
  • Map each laboratory test (PT, aPTT, TT, fibrinogen, D-dimer) to the specific pathway segment it measures, and predict which tests will be abnormal in DIC, haemophilia A, and vitamin K deficiency.

Competencies: PA20.1

Group 2: Platelet and vascular bleeding disorders

  • Compare ITP (immune thrombocytopenic purpura) and TTP (thrombotic thrombocytopenic purpura): pathogenesis, peripheral blood film, PT/aPTT, marrow findings, and key management difference. Create a side-by-side table.
  • Explain why the marrow biopsy in ITP shows increased megakaryocytes and why this finding excludes aplastic anaemia as the cause of thrombocytopenia.

Competencies: PA20.1, PA20.2

Group 3: DIC — mechanism, triggers, laboratory panel

  • List the major triggers of DIC categorised by mechanism (tissue factor release vs contact activation), with at least two Indian clinical examples in each category.
  • Construct the DIC laboratory panel and explain the mechanistic basis for each abnormal result: why are platelets consumed? Why does fibrinogen fall? Why does D-dimer rise? Why do PT and aPTT both prolong?

Competencies: PA20.2

Group 4: Three-way comparison: DIC vs Vitamin K deficiency vs Liver disease

  • Build the three-way comparison table (DIC / Vitamin K deficiency / Liver disease) across: platelet count, PT, aPTT, fibrinogen, D-dimer, factor V, factor VIII. Identify the single most discriminating test for each comparison pair.
  • Explain the 'warfarin paradox at initiation' — why do patients sometimes develop thrombosis when first started on warfarin despite its anticoagulant intent? Link this to the half-lives of protein C and pro-coagulant factors.

Competencies: PA20.2

Group 5: Haemophilia and von Willebrand disease — differential

  • Tabulate haemophilia A, haemophilia B, and von Willebrand disease type 1 and type 3 using: inheritance, affected factor/protein, PT, aPTT, bleeding time/PFA, specific confirmatory test, and DDAVP responsiveness.
  • Explain the dual function of vWF in haemostasis — why does severe vWD type 3 cause a mixed picture of primary and secondary haemostasis failure?

Competencies: PA20.1

Learning Issues

Research these questions and bring your findings to the discussion.

  1. [PA20.1] What are the sequential steps of normal haemostasis (vascular, primary, secondary, fibrinolysis), and how do defects in each step produce distinct clinical bleeding patterns and laboratory abnormalities in conditions such as ITP, haemophilia A, haemophilia B, von Willebrand disease, and vascular purpuras?
  2. [PA20.2] What is the pathogenesis of DIC, what are its major triggers (including obstetric and septic causes common in India), what is the complete laboratory diagnostic panel, and how does DIC differ from vitamin K deficiency and liver disease coagulopathy in both mechanism and laboratory pattern?