In patients hospitalized with coronavirus disease 2019 (COVID-19), thrombi in segmental pulmonary arteries are common and are located in opacitated lung segments, which may suggest local clot formation, according to the results of a retrospective study published in Respiratory Medicine.

Respiratory failure is a common complication in hospitalized patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and is frequently complicated by pulmonary embolism in segmental pulmonary arteries. The distribution of pulmonary embolism with regard to lung parenchymal opacifications has not been investigated; therefore, researchers in Germany investigated whether pulmonary embolism manifestations are limited to lung segments affected by COVID-19-pneumonia.

Of 22 patients with severe COVID-19 treated between March 8 and April 15, 2020 in the hospital intensive care unit (ICU), 16 (age, 60.4±10.2 years) underwent computed tomography (CT) and a total of 288 lung segments were analyzed. Thrombi were detectable in 56.3% (9 of 16) patients with 4.4±2.9 segments occluded per patient, and 13.9% (40 of 288) segments were affected in the whole cohort. The researchers noted that patients with thrombi had significantly worse segmental opacifications on CT (P <.05) and that all thrombi were located in opacitated segments. There was no correlation between D-dimer level and number of occluded segmental arteries.

There were several limitations in this study, including that the data were from a small patient collective, and because only patients from the ICU were included, these findings cannot be extrapolated to patients with mild to moderate COVID-19-pneumonia. Therefore, these data can only be considered hypothesis generating.

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“Thrombi in segmental pulmonary arteries are common in COVID-19,” The study authors concluded. “All segments occluded by thrombus were opacitated and no pulmonary embolus was detectable located in a segment without opacitation. This might suggest local clot formation.”


Müller-Peltzer K, Krauss T, Benndorf M, et al. Pulmonary artery thrombi are co-located with opacifications in SARS-CoV2 induced ARDS. Respir Med. Published online September 10, 2020. doi:10.1016/j.rmed.2020.106135