Send Feedback

Print

Mobile

 Back

CDHB

Diagnosis of Pulmonary Embolism (PE)

If the patient is pregnant, see Investigations for Suspected PE in Pregnancy.

Clinical Features and Causes of PE

• Suspect PE if central chest pain, dyspnoea, hypoxia, collapse/shock, raised JVP, tachycardia, or arrhythmia are present. If PE has progressed to infarction, then haemoptysis, pleuritic chest pain, and pleural effusion may occur.

Causes

• Surgery, immobilization including travel, oestrogen therapy (combined oral contraceptive pill, hormone replacement therapy), malignancy, pregnancy and puerperium, polycythaemia, thrombocytosis.
• Check for family history of VTE.
• Thrombophilia testing is not required for the majority of patients with DVT/PE. If the patient is under 45 years, consider activated protein C resistance (Factor V Leiden), anti-thrombin III deficiency, protein C or protein S deficiencies, prothrombin gene mutation, or antiphospholipid antibody syndrome. These tests should be taken before treatment is started.

Risk Assessment for PE

Reference: Le Gal et al. Ann. Int. Med. 2006; 144: 165-171.

Note: It is essential to work out the pre-test probability for PE and write this in the patient's notes.

Investigations for Suspected PE

• All patients with suspected PE should have their pre-test probability assessed using the Revised Geneva Scoring system and have blood taken for a D-dimer assessment.
• Patients with signs of right ventricular dysfunction should have urgent investigations with a CTPA and/or echo, as they may benefit from thrombolytic therapy using the standard tPA protocol.
• Out of normal working hours, and if it is clinically safe to delay establishing the diagnosis, consider anticoagulation overnight and investigate the following morning.

Action to take when results are available

Note: D-dimer levels may be above the quoted upper limit in otherwise normal elderly patients (>60 years).

If the D-dimer is negative and:

• the patient has a low or intermediate pre-test probability, a clinically significant PE can be excluded.
• the patient has a high pre-test probability, consider CTPA or VQ scans.

If the D-dimer is positive:

• If the CXR is normal, VQ scanning or CTPA scanning should be considered. VQ scanning has fewer potential side effects than CTPA scanning, and may be preferred if renal function is impaired, in iodine allergy, and for young women. A VQ scan could also be considered if CTPA is equivocal or indeterminate for technical reasons. In pregnancy, see Investigations for Suspected PE in Pregnancy.
• Patients with a low/intermediate pre-test probability and a negative CTPA or normal VQ scan: excludes clinically significant PE.
• Patients with a low/intermediate pre-test probability and an intermediate probability VQ: investigate further with CTPA scanning.
• Patients with a low/intermediate pre-test probability and a positive CTPA and/or high probability VQ: treat with anticoagulation.
• Patients with a high pre-test probability and a negative CTPA may require further investigations with USS of leg veins or VQ scanning. The higher the D-dimer, the more likely it is that patients have a PE.
• Patients with a high pre-test probability and a positive CTPA and/or high or intermediate probability VQ: treat with anticoagulation.

ACCP Antithrombotic Guidelines 9th edition. Chest 2012; 141:7S-47S.

Investigations for Suspected PE in Pregnancy

• When a pregnant woman presents with chest pain and/or dyspnoea, the possibility of pulmonary embolism (PE) is always considered. The established risk equations such as the Wells score and the Revised Geneva score have not been validated for use in pregnancy.
• The American Thoracic Society (Leung et al) and an Australasian group representing the Society of Obstetric Medicine of Australia and New Zealand and the Australasian Society of Thrombosis and Haemostasis (McLintock et al) have published recommendations which we have reviewed in producing this CDHB guideline.
• The use of CTPA is associated with a significant radiation dose to the maternal breasts and, because of the altered haemodynamic environment in pregnancy, the rate of technically inadequate or non-diagnostic scans is increased. It is therefore desirable to make use of other diagnostic modalities where this is possible. The attached flow diagram has been developed in discussion with Obstetric Physicians, the Radiology Service, and the Department of Nuclear Medicine.
• In contrast to the above guidelines, we have chosen to use the D-dimer assay in the work-up. The rationale for avoiding its use is the fact that D-dimer levels go up in normal pregnancy. However, it is not always significantly elevated, and despite occasional reports of false negative results, a normal D-dimer level makes the diagnosis of PE very unlikely.
• A chest X-ray is often required to look for other possible diagnoses such as pneumonia or pneumothorax, and involves minimal radiation to both mother and fetus.
• While a perfusion-only lung scan is often all that is required, a ventilation/perfusion (VQ) scan minimally increases the radiation dose and may be opted for at the discretion of the Nuclear Medicine Department.

  

References:

Leung AN, Bull TM, Jaeschke R et al. An Official American Thoracic Society/Society of Thoracic Radiology Clinical Practice Guideline: Evaluation of Suspected Pulmonary Embolism In Pregnancy. American Journal of Respiratory and Critical Care Medicine 2011;184(10):1200-1208.

McLintock C, Brighton T, Chunilal S et al. Recommendations for the diagnosis and treatment of deep venous thrombosis and pulmonary embolism in pregnancy and the postpartum period. Aust NZ J Obstet Gynaecol 2012;52(1):14-22.

Topic Code: 38598