Hematopathology III: Bleeding Disorders Flashcards
(39 cards)
What are hemorrhagic diatheses?
Disorders characterized by abnormal bleeding, either spontaneously or after trauma/surgery
What 3 main factors control bleeding?
Integrity of the blood vessel wall
Platelet function
Clotting cascade (to form fibrin mesh)
What does a bleeding time test measure?
The time it takes for a small skin cut to stop bleeding — a clinical test of platelet function
What is the normal platelet count?
150,000–450,000/μL
What does Prothrombin Time (PT) test?
Measures the extrinsic and common clotting pathways
Uses tissue thromboplastin and calcium (Ca²⁺)
What does Partial Thromboplastin Time (PTT) test?
Measures the intrinsic and common clotting pathways
Uses kaolin, phospholipid, and calcium (Ca²⁺)
What does “increased fragility of vessels” refer to?
condition where blood vessels are more prone to rupture, leading to bleeding into the skin, despite normal platelet and clotting function
What are common causes of increased vessel fragility?
- Vitamin C deficiency (Scurvy) – weakens collagen in vessel walls
- Chronic glucocorticoid use – causes vessel wall thinning
- Systemic amyloidosis – deposits in vessels weaken their structure
- Ehlers-Danlos syndrome – genetic connective tissue disorder affecting collagen
- Infections and hypersensitivity vasculitis – inflammation damages vessel walls
What symptoms are seen in patients with fragile blood vessels?
Petechiae (small pinpoint bleeding) and ecchymoses (larger bruises)
What are the lab findings in increased vessel fragility?
Normal PT (prothrombin time)
Normal PTT (partial thromboplastin time)
Normal platelet count
→ Because the issue is with the blood vessels, not the clotting system or platelets
What are the two types of platelet disorders?
- Quantitative – Low platelet count (thrombocytopenia)
- Qualitative – Platelets don’t work properly
What causes thrombocytopenia (low platelet count)?
mostly due to decreased production and increased destruction from
- drugs
- infections
- aplastic anemia
- metastases
- leukemias
- autoimmune (e.g., idiopathic thrombocytopenic purpura)
What are qualitative platelet disorders?
- Acquired: uremia, myeloproliferative neoplasms (MPN)
- Inherited: Bernard-Soulier syndrome, Glanzmann’s thrombasthenia
What is Bernard-Soulier syndrome?
GPIb-V-IX glycoprotein defect/missing → adhesion problem
What is Glanzmann’s thrombasthenia?
GPIIb-IIIa glycoproteins defect/missing → aggregation problem
What are common symptoms of platelet disorders?
- Petechiae (small red spots), ecchymoses (bruises)
- Easy bruising
- Epistaxis (nosebleeds)
- Menorrhagia (heavy menstrual bleeding)
- Excessive bleeding from minor trauma
What are the lab findings in platelet disorders?
- Normal PT and PTT
- Prolonged bleeding time (due to impaired platelet plug formation)
What are coagulation disorders?
Disorders affecting the clotting cascade, leading to impaired fibrin clot formation
What lab findings are typical of coagulation disorders?
Prolonged PT, PTT, or both — depending on which factor(s) are deficient
What are the main types of coagulation disorders?
Acquired:
- Vitamin K deficiency (affects prothrombin (II), VII, IX, X)
- Liver disease (↓ synthesis of clotting factors)
Hereditary:
- Factor VIII deficiency (Hemophilia A)
- Other congenital factor deficiencies
What are typical symptoms of coagulation disorders?
- Normal bleeding time, but impaired clot formation
- Petechiae are usually absent
- Massive bleeding after surgery or trauma
- Internal hemorrhage including: Intramuscular bleeds, Joint bleeds (hemarthroses)
What is Hemophilia A?
most common genetic bleeding disorder caused by a deficiency or dysfunction of clotting factor VIII, leading to serious bleeding
What is the genetic pattern of Hemophilia A?
- X-linked recessive
- Affects mostly males but homozygous females can also be affected
- 30% of cases occur without a family history (spontaneous mutations)
When does severe bleeding occur in Hemophilia A?
When factor VIII levels fall below 1% of normal because of either:
- Quantitative: Not enough factor VIII
- Qualitative: Factor VIII is present but doesn’t function properly
