PA H10 | Hemostasis & Bleeding Disorders — Practice Quiz

A 35-year-old woman presents with prolonged bleeding after a dental extraction. Her platelet count is 220 × 10⁹/L. Prothrombin time (PT) is normal. Activated partial thromboplastin time (aPTT) is prolonged. A 1:1 mixing study with normal plasma corrects the aPTT to normal. Which factor deficiency is most consistent with these findings?

A 9-year-old boy is brought to the emergency department after a fall from a bicycle. He has a large haemarthrosis of the right knee and deep muscle haematomas. His older brother had a similar episode last year. Platelet count and PT are normal; aPTT is prolonged. Which inheritance pattern and coagulation arm is most likely affected?

A 28-year-old woman presents with menorrhagia since menarche and easy bruising. She reports that her gums bleed for 20 minutes after brushing. Platelet count is 180 × 10⁹/L, PT is normal, and aPTT is mildly prolonged. Ristocetin cofactor activity is markedly reduced. What is the most likely diagnosis?

A 6-year-old girl has had nosebleeds since age 2, multiple episodes of prolonged bleeding from minor cuts, and no joint bleeds. Her platelet count is 12 × 10⁹/L. Blood film shows no platelet clumps and normal platelet morphology. PT and aPTT are normal. Bone marrow biopsy shows increased megakaryocytes. Which diagnosis is most likely?

A 45-year-old woman presents with confusion, fever, purpuric rash, and oliguria. Blood film shows numerous schistocytes. Platelet count is 18 × 10⁹/L. PT and aPTT are normal. Lactate dehydrogenase is markedly elevated. Which mechanism best explains her thrombocytopenia?

A 7-year-old boy is referred because of repeated episodes of petechiae on his lower limbs and prolonged bleeding from cuts. Peripheral blood film shows giant platelets. Platelet count is 40 × 10⁹/L. Ristocetin-induced platelet agglutination is absent. PT and aPTT are normal. Which protein is most likely deficient?

A surgeon preparing a patient for elective cholecystectomy notices that the PT is prolonged (INR 2.1) while the aPTT is normal and platelet count is 260 × 10⁹/L. The patient is otherwise well and takes no anticoagulants. Which vitamin-K-dependent factor has the shortest half-life and would be depleted first in vitamin K deficiency?

CLINICAL VIGNETTE: A 32-year-old primigravida at 36 weeks gestation develops abruptio placentae and is transferred to the ICU. She begins oozing from IV sites and her gums. Investigations: platelets 35 × 10⁹/L; PT 28 s (control 12 s); aPTT 68 s (control 32 s); fibrinogen 0.8 g/L (normal >2 g/L); D-dimer markedly elevated; blood film shows schistocytes. Which best describes the underlying pathophysiology?

CLINICAL VIGNETTE: A 55-year-old man with decompensated cirrhosis presents with haematemesis. Investigations show: PT 22 s (INR 1.9), aPTT 55 s, platelets 60 × 10⁹/L, fibrinogen 1.6 g/L, D-dimer mildly elevated. Which feature best distinguishes this coagulopathy from DIC?

A 24-year-old man with known Haemophilia A undergoes a mixing study: his aPTT is 78 s (normal <38 s), and after 1:1 mixing with normal plasma his aPTT corrects to 36 s. A second patient with systemic lupus erythematosus has an aPTT of 72 s; after mixing with normal plasma the aPTT remains prolonged at 65 s. Which best explains the different mixing study results?

CLINICAL VIGNETTE: A 4-year-old boy presents with gingival bleeding and easy bruising for 3 weeks following a febrile illness. Platelet count is 22 × 10⁹/L. PT and aPTT are normal. Peripheral blood film shows no schistocytes and normal platelet morphology (small platelets). Direct antiglobulin test is negative. Which first-line management is most appropriate?

A 14-year-old girl presents with heavy menstrual bleeding since menarche. Platelet aggregation studies show absent aggregation with ADP, collagen, and arachidonic acid, but normal agglutination with ristocetin. Platelet count is 240 × 10⁹/L and platelet morphology is normal. Which protein is deficient?

A 65-year-old man develops septicaemia following bowel perforation. Over 48 hours, progressive bleeding from wounds and catheter sites is noted. Investigations: PT 34 s, aPTT 72 s, platelets 28 × 10⁹/L, fibrinogen 0.5 g/L, D-dimer >10 µg/mL (markedly elevated), blood film shows schistocytes. Which single test result best distinguishes this coagulopathy from vitamin K deficiency?

A 19-year-old man presents with spontaneous haemarthrosis of the left ankle and a deep thigh haematoma. His sister is a known carrier of haemophilia. Platelet count, PT, and bleeding time are normal. aPTT is prolonged; mixing study corrects. Specific factor assays show Factor IX activity at 2% of normal. Which statement correctly describes this condition?