Dots are not clots: the over-diagnosis and over-treatment of PE

Abstract

The purpose of this work is to question the conventional theory that all pulmonary emboli (PE) are abnormal, and to test the hypothesis that small peripheral PE are a function of life. Most radiologists report any filling defect, independent of size, as clinically significant PE when detected in the pulmonary arteries. We sought to reinforce the theory that small dots in the pulmonary arteries are not clinically significant clots in the conventional setting. The necessity for anticoagulation should be balanced against the risk of bleeding. This retrospective HIPAA-compliant study was approved by the institutional review board; informed consent was not required. All patients diagnosed with PE by 16-slice or 64-slice multidetector computed tomography (CT) over a 6-month period who also had a lower extremity venous ultrasound (US) performed within 7 days of CT were identified. The study group included 26 women and 24 men (mean, 56 years; range, 21-90 years). The locations of the PE were plotted on a pulmonary arterial diagram, and width of the most proximal clot for each patient was measured. Of 1,273 consecutive CT studies, 101 were positive (7.9%) and 50 patients underwent lower extremity US. Thirty-three (66%) patients had PE in the central pulmonary arteries, of which 19 (58%) had deep vein thrombosis (DVT). Seventeen (34%) patients had peripheral PE; DVT was detected in 0 (0%) patients. The peripheral clots measured 1.0-3.8 mm (mean, 2.5 mm). These clots appeared focal and rounded with a "dot-like" appearance. Peripheral, focal filling defects in the pulmonary arteries, which we termed "dots," are not traditional embolic clots, are not associated with detectable lower-extremity clot load, and may represent "normal" embolic activity originating from the lower extremity venous valves. We suggest that more in-depth understanding about small peripheral PE is needed. The necessity of conventional anticoagulation should be critically reviewed in patients with subsegmental PE and minimal clot burden.

Changing trends in venous thromboembolism‐related imaging in Western Australian teaching hospitals, 2002–2010

“…Indeed, technological advances in both CTPA and VQS have permitted detection of small, clinically insignificant emboli in low‐risk patients 21 . It has been suggested that many of the small clots seen in the pulmonary arteries during CTPA are physiological, with the lung capillary beds trapping and dissolving emboli by endogenous fibrinolysis, thereby protecting the systemic circulation 22 . In addition to unnecessary irradiation, the overdiagnosis of clinically insignificant PE is almost certainly associated with unnecessary complications of anticoagulant therapy, 9 although we did not assess this in our study.…”

Pulmonary Embolism Diagnosis and Mortality With Pulmonary CT Angiography Versus Ventilation-Perfusion Scintigraphy: Evidence of Overdiagnosis With CT?

“…Engleke et al [30] found no difference between the 1-year survival rate of patients with small PE on CT images that were missed, and therefore not treated, and the survival rate of patients with PE that was diagnosed and treated. Suh et al [31] described a series of patients with PE who underwent pulmonary CTA and lower extremity ultrasound. They found that 58% of the patients with central PE had lower extremity deep venous thrombosis, in contrast to none of the patients with small peripheral emboli.…”

Faut-il traiter les embolies pulmonaires sous-segmentaires ?

“…On retrouve moins de thrombose veineuse profonde en association avec une EPSS qu'en présence d'une embolie proximale (0-3,3 % vs 43,8-58 %) [2,26]. Ces patients sont plus souvent asymptomatiques et ont moins fréquemment une probabilité clinique pré-test élevée [2,9].…”

“…Aucun événement thrombo-embolique n'a été rapporté à 3 mois chez 65 patients avec EPSS non anticoagulés [3]. Néanmoins, la majorité des patients avec un diagnostic d'EPSS sont traités, ce qui correspond à une augmentation d'environ 5 % du nombre de patients sous anticoagulant lorsque le test de référence utilisé pour le diagnostic d'embolie pulmonaire est un scanner multibarrette [4,26]. Certains auteurs sible que le patient avec une EPSS isolée, asymptomatique ou de découverte fortuite, présente un mécanisme physiopathologique et un pronostic différents du patient avec une clinique suggestive d'embolie pulmonaire et un scanner démontrant une ou plusieurs EPSS.…”