Thoracic Imaging
Gareth Lewis, Hiten Patel, Sachin Modi, Shahid Hussain in On Call Radiology, 2015
It is important to appreciate that radiology only plays one part in the investigation pathway of suspected non-massive pulmonary embolism, which also includes clinical pre-test probability scoring and laboratory D-dimer analysis. The National Institute for Health and Clinical Excellence (NICE) in the UK has published revised guidelines for the investigation and management of pulmonary embolism based on a 2-level Wells Score rather than a 3-level Wells Score (Table 1.5; Figure 1.10, NICE, 2012). D-dimer analysis should be performed only on patients with a low or intermediate pre-test probability of pulmonary embolism; a normal D-dimer test in this scenario has almost a 100% negative predictive value and excludes the diagnosis. A positive result necessitates further radiological investigation to exclude pulmonary embolism; however, false-positive results can be seen secondary to infection, malignancy, pregnancy and recent surgery. D-dimer analysis should generally not be performed in patients with a high pre-test probability, since a false-negative result can occur in over 15% of cases (Stein PD et al., 2007). In stable patients with suspected non-massive pulmonary embolism, treatment in the form of anticoagulation can be started prophylactically prior to radiological confirmation or exclusion. The investigation pathway is different for suspected cases of massive pulmonary embolism, since urgent diagnosis is vital in order to facilitate urgent thrombolytic therapy.
Methodology and Clinical Implementation of Ventilation/Perfusion Tomography for Diagnosis and Follow-up of Pulmonary Embolism and Other Pulmonary Diseases
Michael Ljungberg in Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
Before performing imaging tests, it is recommended to estimate the clinical probability for PE [7]. Usually, a Wells score is applied. The measurement of D-dimer – a breakdown product of cross-linked fibrin clot – is widely used in the investigative workup of patients with suspected venous thromboembolism. However, D-dimer has a low specificity (40%) because a number of conditions, other than venous thromboembolism, may cause it to be elevated: For example, acute myocardial infarction, stroke, inflammation, active cancer, and pregnancy. The specificity declines even further with age and, in the elderly, may reach only 10 per cent [8]. Due to the low predictive value, a positive quantitative D-dimer test does not modify the pre-test probability. A negative quantitative D-dimer test combined with a low clinical probability is associated with a low risk of thromboembolic disease. At moderate to high pre-test clinical probability, D-dimer has no incremental value.
Critical Care and Anaesthesia
Tjun Tang, Elizabeth O'Riordan, Stewart Walsh in Cracking the Intercollegiate General Surgery FRCS Viva, 2020
How will you determine the likelihood that this patient has had a PE?Although PE is not diagnosed by history or physical examination alone, a scoring system (e.g. Wells score) should be used to determine the pre-test probability of PE before further investigations.Wells ScoreClinical probabilityTotal score of 0–1: low probability (∼10%)Total score of 2–6: moderate probability (∼30%)Total score of >6: high probability (∼65%)In this case, the Wells score is 8.5
Pulmonary vascular diseases
Published in Canadian Journal of Respiratory, Critical Care, and Sleep Medicine, 2021
Jason Weatherald, Sanjay Mehta, Andrew M. Hirsch
In the non-COVID patient, progress continues to be made in the use of algorithms combining clinical assessment and D-dimer testing to limit the number of patients requiring chest imaging to rule out significant pulmonary embolism. It has been well established that pulmonary embolism can be ruled out using a low validated clinical pretest probability score (C-PTP), such as the Wells score combined with a D-dimer score less than 500 ng/mL, thus avoiding chest imaging. This combination of findings, however, only occurs in approximately 30% of outpatients presenting to the emergency room with symptoms suggestive of PE. In the Pulmonary Embolism Graduated D-Dimer (PEGeD) study, Kearon et al.28 showed that this algorithm could safely be extended to patients with a combination of a low C-PTP and a D-dimer less than 1000 ng/mL. This resulted in chest imaging being required in only 34% of patients, compared to 52% using standard cutoffs of 500 ng/mL. It should be noted that the higher cutoff of D-dimer 1000 ng/ml only applies to those with a low C-PTP score. In those with a moderate C-PTP score, a D-dimer cutoff of 500 ng/mL still applies, and in those with a high C-PTP score imaging is required in all patients.
Trends and concerns of potentially inappropriate medication use in patients with cardiovascular diseases
Published in Expert Opinion on Drug Safety, 2021
Nina D. Anfinogenova, Irina A. Trubacheva, Sergey V. Popov, Elena V. Efimova, Wladimir Y. Ussov
Computed tomography pulmonary angiography (CTPA) is increasingly used to detect pulmonary embolism (PE). Evidence suggests that pretest probability scores are underemployed whereas CTPA is sometimes overused. The factors of the potential overuse of CTPA were retrospectively investigated at a University Hospital emergency clinic [86]. Patients were assigned to three groups based on the score systems used to assess PE probability: Wells score or revised Geneva score. D-dimer was assessed only in 62.5 and 62.5% patients in the low or intermediate risk group whereas CTPA procedures were inappropriately ordered in 10.5 and 10.7% of patients according to the Wells score and revised Geneva score, respectively. Overall, 16.8% of CTPAs could be avoided based on the use of guideline-recommended risk-stratification algorithms at emergency department [86].
Prevalence and Risk Factors for Pulmonary Embolism in Pediatric Sickle Cell Disease: A National Administrative Database Study
Published in Pediatric Hematology and Oncology, 2023
Natasha Bala, Joseph Stanek, Vilmarie Rodriguez, Anthony Villella
Pulmonary embolism (PE) is a potential life-threatening condition that requires timely diagnosis and management. The incidence of PE in hospitalized pediatric population in the United States (US) has shown an upward trend in recent years with a 200% increase from the year 2001 to 2014.5 The reported higher incidence of PE in children could be attributed to the increased survival of children with complex medical chronic conditions achieved through more aggressive therapies and interventions that posed an increased risk for VTE such as CVL and surgical procedures. Obesity and exposure to hormonal therapy are additional risk factors adding to thrombosis risk. Unlike adults, there is no validated evidence based clinical probability scoring tool applicable to the pediatric age group that can evaluate the risk for a child to have PE. Studies have shown that the Wells score, which is a commonly used validated clinical probability score for evaluating PE in adults, lacks utility in the pediatric population.6,7 This makes the diagnosis of PE reliant on clinical signs, symptoms, and predisposing VTE risk factors for the clinician to initiate the work up of PE in children.
Related Knowledge Centers
- Angiography
- Clinical Prediction Rule
- Computed Tomography Angiography
- Pulmonary Embolism
- Pre- & Post-Test Probability
- Geneva Score
- Ventilation/Perfusion Scan
- Medical Ultrasound
- D-Dimer