PA20.1-2 | Hemostasis & Bleeding Disorders — Graded Quiz

A 52-year-old woman with advanced cirrhosis presents with haematemesis. Investigations: PT 26 s (INR 2.2), aPTT 58 s, platelets 55,000/µL, fibrinogen 1.4 g/L. You give her 4 units of fresh frozen plasma. Her PT corrects to 18 s but the aPTT remains prolonged at 48 s. After the FFP, her ionised calcium falls to 0.72 mmol/L. Which consequence of the FFP transfusion best explains the persistent aPTT prolongation?

A 3-year-old girl presents with petechiae on her lower limbs after a viral upper respiratory tract infection 2 weeks ago. Platelet count is 11,000/µL. Blood film shows small, sparse platelets and no other abnormalities. PT and aPTT are normal. Her parents are not consanguineous and her CBC prior to the illness was normal. Bone marrow biopsy shows markedly increased megakaryocytes with normal morphology. Which of the following laboratory findings would MOST definitively confirm the immune mechanism of her thrombocytopenia?

A 7-year-old boy with known severe haemophilia A (factor VIII 1% of normal) falls from a bicycle and develops a large haematoma in his right thigh. His mother gives him recombinant factor VIII concentrate at home. Six months later he returns with an unexpectedly poor haemostatic response to factor VIII therapy. Mixing study shows the aPTT does not correct with normal plasma (remains prolonged at 70 s after 1:1 mix). Which investigation will MOST directly characterise the cause of his treatment failure?

During an elective hernia repair, a 58-year-old man's pre-operative work-up reveals: PT 24 s (INR 2.0), aPTT 55 s, platelets 230,000/µL, fibrinogen 2.8 g/L. He takes no anticoagulants and has no liver disease. He is not jaundiced. Urine is dark yellow. He reports no recent dietary change but has been on a broad-spectrum antibiotic (cefoperazone) for 3 weeks for a chest infection. His serum bilirubin is normal, and his liver enzymes are mildly elevated. Which mechanism MOST directly explains his coagulopathy?

A 38-year-old woman delivers her baby at 38 weeks and develops severe postpartum haemorrhage. She receives multiple blood products. Three days later she develops widespread purpura, haemoptysis, haematuria, and worsening renal function. Investigations: platelets 22,000/µL, PT 30 s, aPTT 72 s, fibrinogen 0.6 g/L, D-dimer >20 µg/mL, blood film shows schistocytes. Which finding would MOST reliably distinguish her coagulopathy from that of thrombotic thrombocytopenic purpura (TTP)?

A 16-year-old girl has had recurrent mucosal bleeding since childhood. She now presents with menorrhagia lasting 12 days. Platelet count is 195,000/µL. PT and aPTT are both normal. Platelet aggregation studies show normal aggregation with ristocetin but absent aggregation with ADP, arachidonic acid, and collagen. Electron microscopy of platelets shows absence of dense granules. Which disorder MOST likely explains her platelet function defect?

An 8-year-old boy with severe factor IX deficiency (Christmas disease, factor IX <1%) develops recurrent haemarthroses in his right knee. Plain X-ray shows periarticular osteoporosis and joint-space narrowing. Histologically, the synovium shows haemosiderin deposits, synovial hypertrophy, and pannus formation. Which sequence of events best explains the pathogenesis of haemophilic arthropathy?

A 32-year-old man with chronic kidney disease stage 5 (on haemodialysis) presents with severe epistaxis and oozing from his arteriovenous fistula site. Platelet count is 210,000/µL. PT and aPTT are normal. PFA-100 closure time with collagen/ADP cartridge is markedly prolonged. Which mechanism MOST directly explains his bleeding tendency?

A 28-year-old woman with obstetric antiphospholipid syndrome (APS) is found to have a markedly prolonged aPTT (82 s) on a routine pre-natal screen. Her PT is normal. Platelet count is 140,000/µL. She has no personal history of bleeding. The 1:1 mixing study with normal plasma does NOT correct the aPTT (remains 78 s). Which clinical implication best reflects the paradox in this patient?

A 55-year-old man with metastatic prostate cancer is admitted with bleeding from multiple sites (venepuncture, gums, haematuria). Investigations: platelets 28,000/µL, PT 32 s, aPTT 68 s, fibrinogen 0.7 g/L, D-dimer 18 µg/mL (markedly elevated), schistocytes on film. His oncologist considers initiating heparin therapy to break the DIC cycle. Which statement MOST accurately describes the rationale for heparin in this clinical context?

A 55-year-old man with decompensated liver cirrhosis has: PT 24 s (INR 2.0), aPTT 52 s, platelets 65,000/µL, fibrinogen 1.6 g/L. You administer parenteral vitamin K 10 mg IV. After 24 hours: PT 16 s (INR 1.3), aPTT 40 s. Which factor was MOST responsible for the initial PT prolongation and why did it respond fastest to vitamin K?

A 45-year-old woman undergoes surgery for a ruptured ectopic pregnancy and receives 14 units of PRBC over 4 hours. Her body temperature falls to 34.8°C. Post-operatively: PT 26 s, aPTT 60 s, platelets 38,000/µL, ionised calcium 0.68 mmol/L, fibrinogen 0.9 g/L. D-dimer is 2.8 µg/mL (mildly elevated). Which combination BEST explains the coagulopathy and should guide immediate correction?