Due to the lack of specific clinical manifestations of PE, there is a high rate of misdiagnosis in various departments at home and abroad, with the United States showing a misdiagnosis rate of 67–73% and China around 80%. clinical symptoms of PE are more common with dyspnea, chest pain and cough, and other symptoms include palpitations, hemoptysis, anxiety, or fear, sweating and syncope. Mild cases may be asymptomatic, and severe cases may die suddenly. Multiple recurrent small pulmonary embolisms can cause chronic pulmonary heart disease. It is worth noting that the typical triad of PE (dyspnea, chest pain, hemoptysis) is less than 1/3. The presence of unexplained dyspnea, chest pain, syncope, etc. should be considered as a possible PE. Signs: accelerated respiration, accelerated heart rate, hyperactive second pulmonary artery sound, cyanosis lower limb edema, hypotension, jugular venous anger, pleural friction sound, etc. Surgical procedures are one of the high-risk factors for pulmonary embolism. Some data show that the incidence of pulmonary embolism after surgery is 5 – 10%, and most of them are sudden death type, acute cardiogenic shock type and acute pulmonary heart disease type, and the mortality rate is extremely high, and the mortality rate is high because the patient has a variety of occurrence factors after surgery: postoperative patients have vascular injury, slow blood flow in bed, and enhanced coagulation 1, surgical trauma to changes in blood rheology: intraoperative, tension and anxiety, the body is in a state of stress; After surgery, coagulation function is enhanced for trauma repair; and the smooth muscle of the vein wall under anesthesia exposes the collagen fibers by stretching the endothelial cells. All these make the blood in a state of hypercoagulation. Easy to lead to thrombosis. 2, surgery time and position, long time lying operating table lower limb venous flap prone to stasis thrombosis nest, which leads to lower limb venous thrombosis. 3, long-term bed rest after surgery leads to weakening of the lower extremity veins through muscle pump reflux, plus the lower extremity has abundant venous sinuses prone to blood stagnation to form thrombosis [8]. It usually occurs 3 – 4 days after surgery, once the patient is found to have progressive shortness of breath, dyspnea, syncope, chest pain, cold sweat, fear, and convulsions after surgery. The clinician must think of PE to make a diagnosis quickly in order to save the patient’s life. Diagnosis: Most of the patients with pulmonary embolism have precipitating factors: such as lower limb and pelvic vein thrombosis or thrombophlebitis, long-term bed rest or inactivity (air travel, car travel) chronic cardiopulmonary disorders, surgery, trauma, malignancy, obesity, blood disorders, advanced age, pregnancy oral contraceptives, etc. Because the onset of pulmonary embolism is closely related to susceptibility factors, patients with the above susceptibility factors who have unnamed causes Patients with these factors should be aware of the possibility of pulmonary embolism if they experience dyspnea, chest pain, and syncope. Pay attention to distinguish dyspnea as exertional dyspnea, chest pain as pleuritic pain, and syncope as pulmonary origin. Goldhaber [9] suggested that the differential diagnoses of PE are AMI, pneumonia, congestive heart failure and dilated cardiomyopathy in that order. It must be noted that the first easy misdiagnosis of coronary heart disease complicating heart failure is left heart failure, while PE presents with exertional shortness of breath, with right heart failure predominating. The ECG changes of pulmonary embolism are non-specific, non-diagnostic but valuable. The pathological basis of the ECG changes of pulmonary embolism is the sudden blockage of pulmonary artery causing sudden increase in pulmonary artery pressure, acute right ventricular load increase and right heart dilatation response in the early changes of chest lead T-wave inversion on ECG, (68-75%) and have good correlation with pulmonary embolism, so the common ECG changes are SIQIIITIII (S-wave deepening >1.5 mm in the first lead, q-wave and T-wave inversion in the third lead); T,V1-2T inversion in the right precordial leads and leads II, III, and AVF; cis-clockwise transposition to V5; complete or incomplete right bundle branch block. Sometimes only V1, V3R, V5R waves are stuttered and frustrated. In one study, 68% of 80 patients with PE had ECG changes with T-wave inversions in one or more leads. In conclusion, the presence of S1QIIITIII changes, sinus tachycardia without other explanations, T-wave inversion and ST-segment downward shift, rightward deviation of the QRS axis, complete or incomplete right bundle branch block, pulmonary P waves, and arrhythmias are especially important for clinicians with acute pulmonary embolism, as a double-edged sword can help to diagnose pulmonary embolism, while the opposite can misdiagnose other heart diseases. Blood gas analysis: most of them have hypoxemia, only a few have partial pressure of oxygen >10.7KPa(80mmHg), when partial pressure of oxygen >12KPa(90mmHg), it is not like to have obvious pulmonary embolism, partial pressure of carbon dioxide is reduced, PH is increased, hypoxemia combined with clinical should highly support pE, but normal blood gas cannot exclude pulmonary embolism. X-ray plain film may be normal, but there are many changes, such as regional pulmonary blood flow reduction or uneven distribution of pulmonary blood; lung volume reduction; elevation of the affected diaphragm; for pulmonary shadow with or without hemoptysis, or with pleural effusion, the possibility of pulmonary infarction should be considered in the differential diagnosis. UCG: non-invasive bedside operation, has been reported: the diagnosis of acute PE sensitivity 93%, specificity 80% There are direct or indirect signs, the former has embolism of the main pulmonary artery and its left and right branches; the latter is the right ventricular enlargement, left septal shift left ventricle becomes smaller in the “D” shape, right ventricular motion is reduced, pulmonary artery widening, tricuspid regurgitation and increased pulmonary artery pressure, etc. UCG if there are typical segmental Ventricular wall motion abnormalities often indicate AMI with important differential diagnostic value. Peripheral vascular ultrasonography can detect larger DVT formation in the lower extremities. The use of lower extremity ultrasound as the initial clinical DVT examination in patients with suspected PTE can reduce the need for pulmonary imaging. Bedside UCG is the most important and useful tool in emergency situations for diagnosis and to assist in treatment decisions. Serum D-dimer assay: Abnormally high plasma D-dimer has a sensitivity of more than 90% for pulmonary embolism, <500ug/L strongly suggests the absence of acute pulmonary embolism and has a diagnostic value for exclusion. In a trial, 444 patients with suspected PE were excluded from the diagnosis of PE by serum D-dimer measurement in 159 cases. No PE occurred in any of the patients at three months of follow-up. Because physical examination is normal in half of the patients, further determination is often required by the following methods: conventional venography, vascular ultrasound Doppler, and proximal enhanced CT or MRI of the lower limb veins are considered the gold standard for the diagnosis of pulmonary embolism, but not all hospitals have the equipment for PAA, and the limited experience of radiologists and clinicians consider it an invasive test, which limits the application of PAA. The advent of CT pulmonary angiography has brought a technological revolution in the diagnosis of pulmonary embolism and has made it possible to schedule emergency examinations in some hospitals.CTPA can directly demonstrate intravascular thrombus and also show secondary effects such as wedge shadows or characteristic right ventricular changes such as acute right ventricular dilatation and septal shift. CTPA is now gradually being recommended as the pulmonary impact study of choice for PTE. It has been suggested that a high-quality negative CTPA examination does not require further testing or treatment for PTE In hemodynamically unstable patients, the combined use of rapid, noninvasive bedside examinations can greatly improve the accuracy of the diagnosis of pulmonary embolism. (UCG, ECG, blood gas analysis, and thrombolytic dimer should be performed as soon as possible.) If the combined results of the above tests suggest a definite or high probability of pulmonary embolism, immediate thrombolysis should be performed. If the result is low, spiral CT or CTPA should be performed immediately to exclude the diagnosis if the result is negative, and thrombolysis should be performed immediately if the result is positive.