Contrast agent pooling sign
Citation, DOI & article data
The contrast agent pooling sign is characterized by dense intravenous iodinated contrast media pooling and layering in veins such as the inferior vena cava (most commonly), renal, hepatic, mesenteric, splenic, lumbar veins, or within the parenchyma of the liver and/or kidney.
Occasionally the distinctive appearance may also be visible in the superior vena cava, right atrium, right ventricle, coronary sinus, great cardiac vein, azygos vein, and/or hemiazygos vein. Since positive CT contrast agents have a higher density than blood, they may pool and accumulate in the dependent part of the venous system in patients with cardiogenic shock and imminent circulatory collapse 1.
Treatment and prognosis
This sign may be observed in patients with diverse underlying conditions including aortic dissection, hypovolemic shock due to trauma or bleeding, pulmonary embolism, myocardial infarction, diastolic dysfunction, constrictive pericarditis, large pleural or pericardial effusions, cerebral hemorrhage, and septic shock.
According to the original retrospective study a positive contrast agent pooling sign on CT has an accuracy of 85.94% in predicting cardiac arrest within 1 hour. Moreover, none of the patients with a positive contrast agent pooling sign survived hospitalization, and all experienced cardiac arrest within 8 hours after the scan. Thus, the sign is considered a red flag for imminent death, and poor prognosis 1.
History and etymology
The dependent pooling of contrast media in the context of cardiac arrest was first described in the English language in 2002; although this article cites a German language case report from 2000, which summarizes similar findings due to a cardiac arrest whilst a patient underwent CT 2. The German article does not cite any earlier reports demonstrating such a finding 3.
- 1. Lee Y, Chen J, Chen P et al. Contrast Agent Pooling (C.A.P.) Sign and Imminent Cardiac Arrest: A Retrospective Study. BMC Emerg Med. 2022;22(1):77. doi:10.1186/s12873-022-00634-4 - Pubmed
- 2. Tsai P, Chen J, Huang J, Shen W. Dependent Pooling: A Contrast-Enhanced Sign of Cardiac Arrest During CT. AJR Am J Roentgenol. 2002;178(5):1095-9. doi:10.2214/ajr.178.5.1781095 - Pubmed
- 3. Stöger A, Münsterer B, Schinnerl A. [Acute Heart Arrest in Spiral CT]. Rofo. 2000;172(5):490-1. doi:10.1055/s-2000-672 - Pubmed
- 4. Roth C, Sneider M, Bogot N, Todd M, Cronin P. Dependent Venous Contrast Pooling and Layering: A Sign of Imminent Cardiogenic Shock. AJR Am J Roentgenol. 2006;186(4):1116-9. doi:10.2214/ajr.04.1850 - Pubmed