Diagnostic pathways in acute pulmonary embolism: recommendations of the PIOPED II investigators

BACKGROUND Pulmonary embolism (PE) is a potentially fatal disease. Diagnosis is challenging for clinicians because clinical presentation is variable and there is no diagnostic test that combines sufficiently high sensitivity and specificity to be used alone in clinically suspected PE.
AIM OF THE STUDY PIOPED II investigators have formulated recommendations for the diagnostic approach to patients with suspected PE based on randomized trials.
METHODS Diagnostic work-up recommendations were formulated based on the results of the Prospective Investigation of Pulmonary Embolism Diagnosis II and outcomes studies.
RESULTS In many patients that present the combination of low or moderate clinical probability with negative D-dimer PE can be safely excluded. In other patients with suspected PE and positive D-dimer a CT angiography in combination with CT venography is recommended. PIOPED II investigators have also formulated recommendations for patients with suspected PE and allergy to iodinated contrast medium, with impaired renal function, and for women at fertile age and during pregnancy. In patients with discordant findings between clinical assessment and CTA o CTA/CTV, and with segmental or sub-segmental EP, further evaluation may be necessary and the diagnosis should be re-assessed.
DISCUSSION AND CONCLUSIONS PIOPED II recommendations are of particular interest because consider, after the right clinical evaluation necessary for risk stratification of PE, the most recent, sensitive and specific imaging techniques for definitive diagnosis, such as CTA and CTV. D-dimer evaluation is recommended but, however, its low specificity is not underlined. The importance of combining CTA and CTV for a complete evaluation of the deep venous system is stated, but the difficulties of a routinary similar approach are not considered and alternative techniques, like compressive ultrasound and Colour Doppler ultrasound, are not proposed. The study faces also the issue of segmental and sub-segmental embolism, that presents a difficult clinical interpretation: the recommendations are, before starting the therapy, to re-evaluate and confirm the diagnosis, to avoid the risk of overtreatment.