Pulmonary embolismBMJ 2010; 340 doi: https://doi.org/10.1136/bmj.c1421 (Published 13 April 2010) Cite this as: BMJ 2010;340:c1421
All rapid responses
Pulmonary embolism is a frequently missed but treatable condition.
It was therefore with great interest that we read Meyer and colleagues’
review of its diagnosis and management. Whilst we agree that dyspnoea,
tachypnoea or chest pain are present in most cases of pulmonary embolism
(97% in one case series), it is our experience that syncope is an under
-recognised mode of presentation, especially in older age groups. In a
classic review of 132 consecutive cases of pulmonary embolism diagnosed by
pulmonary angiography, syncope was the initial or predominant presenting
feature in 13% of cases . Timmons et al. have reported an incidence of
syncope of 24% in patients over the age of 65 presenting with pulmonary
embolism, compared to just 3% in patients under 65 . Syncope has been
called the ‘forgotten sign’ of pulmonary embolism [4 ]. We should consider
pulmonary embolism in our differential diagnosis when patients present to
the emergency department with syncope.
1. Miniati M, Prediletto R, Formichi B et al. Accuracy of clinical
assessment in the diagnosis of pulmonary embolism. Am J Respir Crit Care
Med 1999; 159: 864–71.
2. Thames MD, Alpert JS, Dalen JE. Syncope in patients with pulmonary
embolism. JAMA. 1977 Dec 5;238(23):2509-11.
3. Timmons S, Kingston M, Hussain M, Kelly H, Liston R. Pulmonary
embolism: differences in presentation between older and younger patients.
Age and Ageing 2003; 32:601-605.
4. Varon J, Fromm RE Jr. Syncope: the forgotten sign of pulmonary
embolism. J Emerg Med. 1998 Jan-Feb;16(1):117-8.
Competing interests: No competing interests
Meyer and colleagues highlighted the problem of easily missed
diagnosis of pulmonary embolism. At the same time, the contrary of an
increased number of diagnoses of unsuspected PE also has become a nemesis.
This is related to high number of radiological investigations for
suspected diagnoses especially occult malignancies. The improved quality
of multi detecter scanning methods (MDCT) and increased access to CT scans
compound the problem .
Incidental PE has been noted in upto 5% of patients scanned for a
variety of indications including trauma and malignancy evaluation [2, 3].
Very often these patients have no symptoms which may be attributable to
PE. In some patients however, the emboli could cause symptoms like fatigue
which are otherwise very common in the oncology patients. The difficulty
arises for the physician in the decision making process of further
management of these emboli. In the absence of any symptoms how relevant
are these emboli?
Two studies looked at this retrospectively. Eyer and colleagues found
of the 192 patients with sub-segmental PE, one-third did not receive
anticoagulation . None of these patients had recurrent venous
thromboembolism or mortality related to the clots. Another retrospective
study of untreated sub-segmental emboli, where the diagnosis was missed
also did not have any increase in mortality related to PE . It was
reassuring that these patients had favorable short-term outcome without
therapeutic anticoagulation at one-year follow-up.
Prospective studies on this front are urgently required before a
definitive conclusion can be made. Although the need for anticoagulant
treatment of major pulmonary emboli (saddle thrombi or major pulmonary
artery thrombi) detected on these unsuspected scans is without a doubt,
whether small peripheral emboli needs blood thinning agents is a difficult
conundrum. This is especially so when some experts consider lungs is
considered as filter for small emboli . Sub-segmental emboli is even
more of a contentious issue and Goodman`s suggestions of holding off
anticoagulation in patients with normal cardiopulmonary reserve and absent
lower limb deep vein thrombosis takes some guts and lots of experience to
be followed .
1. Desai SR. Unsuspected pulmonary embolism on CT scanning: yet
another headache for clinicians? Thorax. 2007; 62: 470-2.
2. Gladish GW, Choe DH, Marom EM, et al. Incidental pulmonary emboli in
oncology patients: prevalence, CT evaluation, and natural history.
Radiology 2006; 240: 246–255.
3. O'Connell CL, Boswell WD, Duddalwar V, et al. Unsuspected pulmonary
emboli in cancer patients: clinical correlates and relevance. J Clin Oncol
2006; 24: 4928–4932
4. Eyer BA, Goodman LR, Washington L. Clinicians’response to radiologists’
reports of isolated subsegmental pulmonary embolism or inconclusive
interpretation of pulmonary embolism using MDCT. AJR Am J Roentgenol 2005;
5. Engelke C, Rummeny EJ, Marten K. Pulmonary embolism at multi-detector
row CT of chest: one year survival of treated and untreated
patients.Radiology 2006; 239: 563–75
6. Goodman LR. Small pulmonary emboli: what do we know? Radiology 2005;
Competing interests: No competing interests
Meyer et al highlight that D-dimer measurement forms a valuable
component in the assessment of suspected pulmonary thromboembolism
(PTE) (1). However vigilance is required in clinical practice to ensure
dimers are not used inappropriately as a ‘blanket screening tool’ for PTE.
D-dimers are produced when fibrin clots are degraded and, as
the authors, are highly sensitive in excluding PTE in the context of a low
moderate clinical pre-test probability. However, D-dimers can be elevated
a number of other common clinical situations, including liver disease,
pregnancy, recent trauma or surgery, cancer and in the presence of
inflammatory markers (2-4). Unfortunately these factors are often not
considered when ordering or interpreting these tests and physicians often
feel compelled to act on a positive D-dimer result (5). Such
use of D-dimers may result in increases in imaging (and subsequent
radiation exposure), decreased positive diagnostic yield on imaging, and
potentially unnecessary anti-coagulation of patients.
We recently audited the introduction of D-dimers for the assessment
suspected PTE in out-patients attending our unit. Over a 3-month period,
assessed whether D-dimers had been used appropriately (i.e. in low-
moderate clinical probability cases and in the absence of potential causes
false positive D-dimer) and the impact on patient management. We found
the introduction of D-dimers facilitated direct discharges from the
emergency department in 21% of the audit cohort, reduced use of CTPA
imaging by 50%, and significantly increased the positive diagnostic yield
CTPA to 23%. However, D-dimers were used inappropriately in 13.4% (n=13)
of cases. The most common reason for ‘inappropriate use’ were in
where patients had elevated inflammatory indices, the majority of which
had abnormal admission chest x-rays. In such cases the proportion with a
false-positive D-dimer was significantly higher than in the rest of the
The British Thoracic Society guidelines for the management of
recommend that before a D-dimer is requested the patient must have: 1) a
good quality chest x-ray, 2) an assessment by an experienced middle-grade
doctor to allow alternative diagnoses to be considered, and 3) a clinical
probability assessment completed (6-7). Such thorough assessment
facilitates the use of D-dimers only in situations where they are likely
advance the diagnostic process.
Pulmonary thromboembolism is an extremely important diagnosis and a D
dimer assay can be an extremely useful test – but it should be used
judiciously in the context of wise clinical assessment.
1) Meyer G, Roy PM, Gilberg S, Perrier A. Easily Missed? Pulmonary
Embolism. BMJ 2010; 340:974-976.
2) Castro D, Pe´rez-Rodrı ´guez E, Montaner L, et al. Diagnostic
value of D
dimer in pulmonary embolism and pneumonia. Respiration 2001; 68:371-75
3) Perrier A. D-dimer for suspected pulmonary embolism: whom should
test? Chest 2004; 125:807-9
4) Mountain D, Jacobs I, Haig A. The VIDAS D-dimer test for venous
thromboembolism: a prospective surveillance study shows maintenance of
sensitivity and specificity when used in normal clinical practice. Am J
Med 2007; 25:464–71.
5) Jones P, Elangbam B, Williams N. Inappropriate use and
D-dimer testing in the emergency department: an unexpected adverse effect
of meeting the ‘4-h target’. Emerg Med J 2010; 27:43-47
6) The British Thoracic Society Standards of Care Committee,
Embolism Guideline Development Group; BTS Guidelines for the Management
of Suspected Acute Pulmonary Embolism, 2003; Thorax 2003; 48:470-484
7) The British Thoracic Society Standards of Care Committee,
Embolism Guideline Development Group; D-dimer in Suspected Pulmonary
Embolism – A statement from the British Thoracic Society Standards of Care
Committee December 2006; www.brit-thoracic.org.uk/clinical-
Competing interests: No competing interests