The correct answer is choice A, B and E.A D-dimer test is a blood test that measures D-dimer, which is a protein fragment that your body makes when a blood clot dissolves in your body.A positive or elevated D-dimer test result may indicate that you have a blood clotting condition, such as:

• Deep vein thrombosis (DVT): a blood clot that develops in a vein deep in your body, usually in the legs.

• Pulmonary embolism (PE): a blockage in an artery in the lung caused by a blood clot that travels from another part of the body, such as the leg.

• Disseminated intravascular coagulation (DIC): a condition that prevents the blood from clotting normally and causes excessive bleeding or clotting throughout the body.

Choice C and D are wrong because:

• Myocardial infarction (MI): a heart attack caused by a blockage in one of the coronary arteries that supply blood to the heart muscle.A D-dimer test is not used to diagnose MI because other blood tests, such as troponin and CK-MB, are more specific and sensitive for detecting heart muscle damage.

• Stroke: a brain attack caused by a blockage or rupture of a blood vessel in the brain.A D-dimer test is not used to diagnose stroke because other imaging tests, such as CT scan or MRI, are more accurate and reliable for detecting brain damage.

The normal range of D-dimer levels varies depending on the laboratory and the method used, but it is usually less than 0.5 mg/L or 500 ng/mL.However, the normal range may also depend on other factors, such as age, pregnancy, inflammation, infection, trauma, surgery or cancer.

Therefore, a D-dimer test result should always be interpreted in the context of the clinical situation and other test results.

CT pulmonary angiography (CTPA) is the new reference standard for the diagnosis of pulmonary embolism (PE).It is a non-invasive imaging test that uses contrast dye and X-rays to visualize the pulmonary arteries and detect blood clots.

Choice A is wrong because compression ultrasound is used to diagnose deep vein thrombosis (DVT), not PE.However, if a DVT is found in a patient with clinical suspicion for PE, the diagnosis of PE can be accepted without further testing.

Choice C is wrong because ventilation-perfusion scan is an alternative test for PE when CTPA is contraindicated or unavailable.It uses radioactive tracers to measure the airflow and blood flow in the lungs and detect any mismatch that suggests a PE.

Choice D is wrong because chest X-ray cannot diagnose PE directly.

It can only show nonspecific signs of PE such as atelectasis, pleural effusion, or elevated hemidiaphragm.It can also help rule out other causes of chest pain or dyspnea.

Crossing the legs when sitting.

This is because crossing the legs can impair blood circulation and increase the risk of clot formation in the lower extremities.

Choice A is wrong because wearing compression stockings can help prevent deep vein thrombosis by applying pressure to the legs and improving blood flow.

Choice B is wrong because elevating the legs when sitting can also improve blood circulation and reduce swelling and pain in the legs.

Choice C is wrong because drinking plenty of fluids can prevent dehydration and blood viscosity, which are risk factors for deep vein thrombosis.

Normal ranges for blood clotting tests are:

• Prothrombin time (PT): 11 to 13.5 seconds

• International normalized ratio (INR): 0.8 to 1.2

• Activated partial thromboplastin time (aPTT): 25 to 35 seconds

• D-dimer: less than 0.5 mcg/mL

The correct answer is choice A, B and E. A pulmonary embolism (PE) is a blood clot that blocks an artery in the lung and reduces blood flow and oxygen levels.

The common symptoms of PE are:

• Dyspnea(sudden, unexplained shortness of breath)

• Pleuritic chest pain(dull pain that gets worse with deep breathing)

• Hemoptysis(coughing up blood)

Choice C is correct because hemoptysis is a possible symptom of PE, although it is less common than dyspnea and chest pain.Hemoptysis occurs when the blood clot damages the lung tissue and causes bleeding

Choice D is wrong because bradycardia (slow heart rate) is not a typical symptom of PE.In fact, most people with PE have tachycardia (fast heart rate) due to the increased strain on the heart and the reduced oxygen levels

Choice E is correct because hypoxemia (low oxygen levels in the blood) is a common complication of PE.

Hypoxemia can cause pale, clammy or bluish skin, excessive sweating, anxiety, lightheadedness or fainting.Hypoxemia can also worsen the heart strain and lead to heart failure or cardiac arrest

Normal ranges for oxygen saturation are 95% to 100%.Normal ranges for heart rate are 60 to 100 beats per minute

Activated partial thromboplastin time (aPTT) is a test that measures how long it takes for blood to clot.It is used to monitor the effectiveness of heparin therapy, which is an anticoagulant (blood thinner) that prevents the formation of blood clots.Heparin affects one set of clotting factors that are measured by the aPTT test.The normal range of aPTT is 30-40 seconds, but in patients receiving heparin therapy, the range is 1.5-2.5 times the control value in seconds.

Choice A is wrong because prothrombin time (PT) is another test that measures how long it takes for blood to clot, but it is used to monitor the effectiveness of warfarin therapy, which is another anticoagulant that affects a different set of clotting factors than heparin.

Choice B is wrong because international normalized ratio (INR) is a standardized way of reporting the PT results, which are affected by warfarin therapy, not heparin therapy.

Choice D is wrong because platelet count is a test that measures the number of platelets in the blood, which are cells that help with clotting.Platelet count is not affected by heparin therapy and does not reflect its effectiveness.