<prompt> The gold standard for diagnosis of pulmonary embolismChest X-rayPulmonary angiographyVentilation perfusion scintiscanCECT  <response>: Pulmonary embolism The risk factors for pulmonary embolism are the risk factors for thrombi formation within the venous circulation.The most common site for DVT: Calf veinsMost common source of pulmonary emboli: proximal vein of lower extremity femoropopliteal and iliac veinCalf venous thrombosis is itself associated with a low risk for embolism but when the thrombosis progresses proximally to involve the larger veins then the risk factors become very highClinical featuresFactors for clinical assessment of pulmonary embolismSymptoms: dyspnoea MC, chest pain, hemoptysis, coughSigns: tachypnoea MC, fever, unilateral leg swelling, wheeze, pleural friction rubClinical signs and symptoms of DVTAn alternative diagnosis is less likely than pulmonary embolismHea rate 100minImmobilization or previous surgery in 4 weeksPrevious DVTPEHemoptysisMalignancy on treatment, treatment in past 6 monthsECG changesDiagnosisFeatures suggesting acute right hea strain on ECG occur relatively infrequently, these include :Acute right axis detionP pulmonaleRight bundle branch blockInveed T wavesST segment changeECG changes highly predictive but found in 12 pts S wave in lead IQ wave in lead IIInveed T wave in lead III S1Q3T3S wave in lead I, II, and III S1S2S3D-dimer is an excellent screening test for the diagnosis of PE Best investigation when there is clinical suspicion of PE: Multidetector Contrast CTLung scanning is now a second line diagnostic test for PE.Pulmonary angiography is the gold standard for the diagnosis of PE ECG changesDiagnosisFeatures suggesting acute right hea strain on ECG occur relatively infrequently, these include :Acute right axis detionP pulmonaleRight bundle branch blockInveed T wavesST segment changeECG changes highly predictive but found in 12 pts S wave in lead IQ wave in lead IIInveed T wave in lead III S1Q3T3S wave in lead I, II, and III S1S2S3D-dimer is an excellent screening test for the diagnosis of PE Best investigation when there is clinical suspicion of PE: Multidetector Contrast CTLung scanning is now a second line diagnostic test for PE.Pulmonary angiography is the gold standard for the diagnosis of PE Refer: Harrisons Principle of Internal Medicine, 18thedition, pg no- 2174 