Clinical scenario

A 30 year old woman presents to the emergency department with distressing, left sided pleuritic chest pain. She may have had a pulmonary embolism and you request a D-dimer test. You know the laboratory in your hospital uses the IL D-dimer test and wonder whether a normal result would be sufficiently sensitive to rule out a pulmonary embolus.

Three part question

In a [patient with suspected pulmonary embolus] does a [negative IL D-dimer test] adequately [rule out the diagnosis]?

Search strategy

Medline 1966–04/03 using the OVD interface. ([D-dimer.mp or exp Fibrin Fibrinogen Degredation Products or FDP.mp] AND [IL test.mp] AND [exp Thromboembolism or exp Pulmonary Embolism or pulmonary embol$.mp or PE.mp or pulmonary infarct$.mp or exp venous thromboembolism]).

Search outcome

Six papers were found from the above search. Four were relevant. One further paper was found from hand searching journals and references. These five papers are shown in table 8.

Comments

To date there have been few studies measuring the accuracy of this D-dimer test. Of note, there is almost no research looking in particular at patients presenting with symptoms of PE. The sensitivity of the IL test for ruling out DVT seems to lie somewhere between 90% and 100%. It is worth noting that all of these studies used a comparatively low cut off level and it is worth being aware what the cut off level is in your hospital laboratory.

CLINICAL BOTTOM LINE

The IL D-dimer test alone is not sufficiently sensitive to rule out pulmonary embolus. It must be used in conjunction with another test.