In those who have low risk, age less than 50, heart rate less than 100 beats per minute, oxygen level more than 94% on room air, and no leg swelling, coughing up of blood, surgery or trauma in the last four weeks, previous blood clots, or estrogen use, further testing is not typically needed.In situations with more high risk individuals, further testing is needed. A CT pulmonary angiogram (CTPA) is the preferred method for diagnosis of a pulmonary embolism due to its easy administration and accuracy. Although a CTPA is preferred, there are also other tests that can be done. For example, a proximal lower limb compression ultrasound (CUS) can be used. This is a test which is primarily used as a confirmatory test, meaning it confirms a previous analysis showing the presence or suspected presence of a pulmonary embolism. According to a cross-sectional study, CUS tests have a sensitivity of 41% and specificity of 96%.If there are concerns this is followed by testing to determine a likelihood of being able to confirm a diagnosis by imaging, followed by imaging if other tests have shown that there is a likelihood of a PE diagnosis.The diagnosis of PE is based primarily on validated clinical criteria combined with selective testing because the typical clinical presentation (shortness of breath, chest pain) cannot be definitively differentiated from other causes of chest pain and shortness of breath.
The typical cut off is 500 μg/L, although this varies based on the assay. However, in those over the age of 50, changing the cut-off value to the persons age multiplied by 10 μg/L (accounting for assay which has been used) is recommended as it decreases the number of falsely positive tests without missing any additional cases of PE.When a PE is being suspected, several blood tests are done in order to exclude important secondary causes of PE. This includes a full blood count, clotting status (PT, aPTT, TT), and some screening tests (erythrocyte sedimentation rate, kidney function, liver enzymes, electrolytes). If one of these is abnormal, further investigations might be warranted to the issue.Troponin levels are increased in between 16 and 47% with pulmonary embolism. Imaging
In typical people who are not known to be at high risk of PE, imaging is helpful to confirm or exclude a diagnosis of PE after simpler first-line tests are used. Medical societies recommend tests such as the D-dimer to first provide supporting evidence for the need for imaging, and imaging would be done if other tests confirmed a moderate or high probability of finding evidence to support a diagnosis of PE.CT pulmonary angiography is the recommended first line diagnostic imaging test in most people.Ultrasound of the legs can confirm the presence of a PE but cannot rule it out. CT pulmonary angiography
CT pulmonary angiography (CTPA) is a pulmonary angiogram obtained using computed tomography (CT) with radiocontrast rather than right heart catheterization.