You are a pediatric nurse practitioner seeing a 7-year-old m…
You are a pediatric nurse practitioner seeing a 7-year-old male patient who presents to the emergency department with a swollen right knee following a fall while playing soccer. The mother reports that the child has had similar episodes in the past, often after minor injuries. He has a history of easy bruising and prolonged bleeding after vaccinations. The family history is significant for hemophilia, as the child’s maternal uncle was diagnosed with Hemophilia A. On examination, the child has a painful and swollen right knee with limited range of motion. You suspect hemophilia and decide to order laboratory tests. Which of the following laboratory tests is most useful for diagnosing Hemophilia A in this patient?