A 28-year-old woman presents with a 6-month history of menorrhagia and spontaneous bruising. Coagulation studies show: PT 12 s (normal), aPTT 38 s (prolonged), platelet count 180 × 10⁹/L, bleeding time normal. Which of the following is NOT consistent with a diagnosis of Factor VIII deficiency?

Question

Accepted Answer

B. Prolonged bleeding time with normal platelet count. ## Diagnosis: Factor VIII Deficiency (Hemophilia A)

### Coagulation Profile in Factor VIII Deficiency

| Test | Expected Result | Reasoning |
|------|-----------------|----------|
| PT | Normal | Extrinsic pathway intact (Factor VII) |
| aPTT | Prolonged | Intrinsic pathway defect (Factor VIII) |
| Bleeding time | Normal | Platelet function and von Willebrand factor normal |
| Platelet count | Normal | No thrombocytopenia |
| Mixing study | Corrects aPTT | Factor deficiency, not inhibitor |

**Key Point:** Bleeding time is a test of **primary hemostasis** (platelet plug formation) and is normal in all coagulation factor deficiencies. It is prolonged only in disorders of platelets (count or function) or von Willebrand disease.

**High-Yield:** The triad of prolonged aPTT + normal PT + normal bleeding time = intrinsic pathway defect (Factor VIII, IX, XI, or XII deficiency).

**Clinical Pearl:** Factor VIII deficiency is X-linked recessive; affected males present with hemarthrosis, muscle hematomas, and mucosal bleeding. Carrier females may have mild symptoms due to lyonization.

**Mnemonic:** **BLEED** for bleeding time abnormality: **B**lood platelets, **L**ow count, **E**ndothelial (von Willebrand), **E**nzyme (platelet dysfunction), **D**isorders of primary hemostasis.

### Why Bleeding Time is NOT Prolonged in Factor VIII Deficiency

Bleeding time depends on:
1. Platelet count (≥100 × 10⁹/L required)
2. Platelet function (adhesion, aggregation, secretion)
3. von Willebrand factor (bridges platelets to collagen)

Factor VIII is a **secondary hemostasis** cofactor — it amplifies thrombin generation but does NOT participate in platelet adhesion or aggregation. Therefore, bleeding time remains normal.

**Warning:** A prolonged bleeding time in a patient with suspected hemophilia should prompt investigation for concurrent von Willebrand disease or platelet disorder, not acceptance as part of hemophilia.

Answer

A. Normal prothrombin time

Answer

C. Positive family history in maternal uncles

Answer

D. Correction of aPTT after mixing study with normal plasma

A 28-year-old woman presents with a 6-month history of menorrhagia and spontaneous bruising. Coagulation studies show: PT 12 s (normal), aPTT 38 s (prolonged), platelet count 180 × 10⁹/L, bleeding time normal. Which of the following is NOT consistent with a diagnosis of Factor VIII deficiency?

Explanation

Practice similar questions