A physician is evaluating five patients presenting with distinct bleeding or thrombotic profiles across different clinical settings. Match each patient's clinical vignette and initial screening results with the most appropriate targeted laboratory test to establish the definitive diagnosis.
- A 16-year-old girl is evaluated in the primary care clinic for heavy menstrual bleeding since menarche and a recent episode of epistaxis requiring packing. Vital signs are normal. Physical examination shows no petechiae. Initial laboratories reveal a normal platelet count, normal prothrombin time (PT), and a borderline prolonged activated partial thromboplastin time (aPTT).Ristocetin cofactor assay
- A 32-year-old woman is evaluated in the emergency department for a swollen, painful left calf. She has a history of two second-trimester pregnancy losses. Vital signs are normal. Physical examination reveals unilateral lower extremity edema. Initial laboratories reveal a markedly prolonged aPTT that fails to normalize upon a 1:1 mixing study with normal plasma.Dilute Russell viper venom time (dRVVT)
- A 65-year-old man admitted to the intensive care unit for urosepsis acutely develops oozing from his central venous catheter site. Vital signs show hypotension and tachycardia. Physical examination shows diffuse ecchymoses. Initial laboratories reveal a sudden drop in platelet count to , with prolonged PT and aPTT.Fibrinogen and D-dimer levels
- A 24-year-old man presents to the clinic with a swollen, painful right knee after a minor bump. He has a history of recurrent hemarthroses since childhood. Vital signs are normal. Physical examination shows a large right knee effusion. Initial laboratories reveal a normal PT and a prolonged aPTT that fully corrects to the normal range with a 1:1 mixing study.Factor VIII and Factor IX activity levels
- A 45-year-old woman is evaluated in the ambulatory care center for a routine health maintenance examination. She has no complaints and specifically denies bleeding or bruising. Physical examination is unremarkable. Routine laboratories incidentally reveal an isolated platelet count of with a normal peripheral smear and normal PT and aPTT.HIV and Hepatitis C serologies
Cevap
The correct sequence of diagnostic testing maps von Willebrand disease (mucosal bleeding, borderline aPTT) to the ristocetin cofactor assay; Antiphospholipid syndrome (thrombosis, non-correcting aPTT) to dRVVT; DIC (sepsis, global coagulopathy) to fibrinogen and D-dimer; Hemophilia (hemarthroses, correcting aPTT) to Factor VIII/IX activity levels; and newly discovered isolated ITP to HIV and Hepatitis C screening.
Each correct pairing links a distinct clinical presentation and screening laboratory pattern with its gold-standard diagnostic or mandatory secondary screening test. Proper interpretation of mixing studies appropriately separates factor deficiencies (Hemophilia requiring factor assays) from inhibitors (APS requiring dRVVT). Understanding the clinical presentation appropriately distinguishes primary hemostasis defects (vWD requiring ristocetin cofactor) from consumptive emergencies (DIC requiring D-dimer and fibrinogen). Furthermore, it recognizes the high-yield guideline that secondary viral screening (HIV/HCV) must precede a diagnosis of primary ITP.
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Anahtar Kavram
The diagnostic workup of hematologic disorders requires synthesizing the clinical bleeding or thrombotic phenotype with initial screening labs (PT, aPTT, mixing studies) to order precise confirmatory laboratory assays.