Prevalence of Thrombotic Complications in ICU-Treated Patients With Coronavirus Disease 2019 Detected With Systematic CT Scanning

Saeed Mirsadraee, MD, PhD, FRCR, FRCPE; Diana A. Gorog, MD, PhD, FRCP; Ciara F. Mahon, BCh, BAO, MSc, MRCP; Bhavin Rawal, MBBS, FRCR; Thomas R. Semple, FRCR; Edward D. Nicol, MD, FRCP, FRCR; Deepa R. J. Arachchillage, MD, MRCP, FRCPath; Anand Devaraj, MD, FRCR; Susanna Price, PhD, FRCP; Sujal R. Desai, MD, FRCR, FRCP; Carole A. Ridge, FFRRCSI; Suveer Singh, MD, PHD; Simon P. G. Padley, MBBS, FRCR


Crit Care Med. 2021;49(5):804-815. 

In This Article

Abstract and Introduction


Objectives: Severe coronavirus disease 2019 is associated with an extensive pneumonitis and frequent coagulopathy. We sought the true prevalence of thrombotic complications in critically ill patients with severe coronavirus disease 2019 on the ICU, with or without extracorporeal membrane oxygenation.

Design: We undertook a single-center, retrospective analysis of 72 critically ill patients with coronavirus disease 2019-associated acute respiratory distress syndrome admitted to ICU. CT angiography of the thorax, abdomen, and pelvis were performed at admission as per routine institution protocols, with further imaging as clinically indicated. The prevalence of thrombotic complications and the relationship with coagulation parameters, other biomarkers, and survival were evaluated.

Setting: Coronavirus disease 2019 ICUs at a specialist cardiorespiratory center.

Patients: Seventy-two consecutive patients with coronavirus disease 2019 admitted to ICU during the study period (March 19, 2020, to June 23, 2020).

Interventions: None.

Measurements and Main Results: All but one patient received thromboprophylaxis or therapeutic anticoagulation. Among 72 patients (male:female = 74%; mean age: 52 ± 10; 35 on extracorporeal membrane oxygenation), there were 54 thrombotic complications in 42 patients (58%), comprising 34 pulmonary arterial (47%), 15 peripheral venous (21%), and five (7%) systemic arterial thromboses/end-organ embolic complications. In those with pulmonary arterial thromboses, 93% were identified incidentally on first screening CT with only 7% suspected clinically. Biomarkers of coagulation (e.g., D-dimer, fibrinogen level, and activated partial thromboplastin time) or inflammation (WBC count, C-reactive protein) did not discriminate between patients with or without thrombotic complications. Fifty-one patients (76%) survived to discharge; 17 (24%) patients died. Mortality was significantly greater in patients with detectable thrombus (33% vs 10%; p = 0.022).

Conclusions: There is a high prevalence of thrombotic complications, mainly pulmonary, among coronavirus disease 2019 patients admitted to ICU, despite anticoagulation. Detection of thrombus was usually incidental, not predicted by coagulation or inflammatory biomarkers, and associated with increased risk of death. Systematic CT imaging at admission should be considered in all coronavirus disease 2019 patients requiring ICU.


To date, following the first report of coronavirus disease 2019 (COVID-19) in Wuhan in late December 2019, over 60 million people have acquired the disease worldwide. Just over one quarter of symptomatic patients needing hospitalization require intensive care support.[1]

While patients with severe pulmonary infections and the acute respiratory distress syndrome (ARDS) are at risk of thrombosis,[2–6] those with COVID-19 appear to be at particularly high risk, despite thromboprophylaxis.[7] Thrombotic complications in critically ill patients are clinically difficult to detect and may go unrecognized.

Severe COVID-19 pneumonia is characterized by fulminant cytokine release leading to the activation of a coagulation cascade.[8] A prothrombotic state is a recognized feature of severe COVID-19 infection, manifesting as venous and systemic or pulmonary arterial thrombus; however, the true prevalence of detectable (macrovascular) thrombus and associated complications is unknown.[9] While typical pathologic features of ARDS are seen in patients with COVID-19,[1] a recent study reported systemic thrombosis at microvascular level as an additional cause of respiratory failure.[10]

The prevalence of image-diagnosed thrombosis appears higher in COVID-19 than in comparably ill patients with different etiologies. In a recent study, 22% of COVID-19 ICU patients had pulmonary embolism (without systematic imaging) compared with 7.5% in influenza patients, despite similar severity of respiratory disease.[11]

The aim of the present study was to evaluate the true prevalence of vascular thrombotic complications in patients with confirmed COVID-19 admitted to ICU for advanced ventilatory support, including those on extracorporeal membrane oxygenation (ECMO), as apparent on systematic CT imaging.