Approach to diagnosis of VTE

Clinical diagnosis of venous thromboembolism (VTE) (ie deep vein thrombosis [DVT] or pulmonary embolism [PE]) is difficult, and objective testing must be performed to confirm the diagnosis, ideally before or as soon as possible after starting treatment.

Clinical prediction tools can help to determine if there is a need for diagnostic imaging studies (eg compression ultrasound for diagnosis of DVT). If the tool predicts that DVT or PE is unlikely and the patient has a negative D-dimer test result, diagnostic imaging may not be neededTran, 2019. Examples of clinical prediction tools are:

• Wells Criteria for DVT
• PE clinical prediction tools:
  • Wells Criteria for PE and Revised Geneva Score for PE—these are the most well-validated tools for PE, but are for outpatient or emergency department use, and are not applicable to hospitalised patients
  • Pulmonary Embolism Rule-out Criteria (PERC) rule—for patients younger than 50 years with a low estimated rate of PE (less than 15%, which is seen in most Australian emergency departments)Tran, 2019
  • YEARS algorithm for PE—for haemodynamically stable patients 18 years or older
  • pregnancy adapted YEARS algorithm for PEvan der Pol, 2019—at the time of writing, data are limited to support the use of this tool.

A single negative compression ultrasound can exclude DVTTran, 2019. Compression ultrasound is also used for the diagnosis of superficial vein thrombosis; see Superficial vein thrombosis for more information.

Computed tomography pulmonary angiography (CTPA) or a ventilation perfusion isotope (V/Q) lung scan are the imaging modalities used to investigate PE. CTPA is the preferred option for most patients, if available. If minimal radiation exposure is desired (eg pregnant patients), consider using a V/Q scan. See Thoracic imaging for more informationBates, 2018Tran, 2019.

Cardiac troponin is used to stratify the risk of death in patients presenting with suspected PE and chest pain; check cardiac troponin concentration on admissionKonstantinides, 2020Tran, 2019.