Background. Anticoagulant therapy is recommended as basic medical treatment for COVID-19 patients with risk factors. At the same time, it is accompanied by a large number of hemorrhagic complications. Massive bleeding into abdominal and chest walls soft tissues as well as retroperitoneal space significantly worsens the course of underlying disease.

Objective: to assess the prognostic value of specific CT signs and their correlation with angiography data for the diagnosis of ongoing bleeding into soft tissues in COVID-19 patients.

Material and methods. A retrospective study was conducted, in which multi-slice computed tomography (MSCT) and angiography data were assessed and compared in 60 COVID-19 patients with spontaneous bleeding into chest and abdominal wall soft tissues as well as retroperitoneal space. A retrospective analysis of MSCT was carried out to identify symptoms specific to coagulopathic bleeding into soft tissues: contrast agent extravasation, hematocrit effect, and signal flare phenomenon.

Results. Contrast agent extravasation identified by MSCT was confirmed in 57 (95%) patients. More often (39 (68.4%) patients), extravasation was detected in MSCT arterial phase. In MSCT venous phase it was noted in 17 (29.8%) cases, in delayed phase – in 1 (1.8%) patient. With native MSCT, hematoma contained clots and fluid level (hematocrit effect) in 43 (71.7%) patients, in 17 (28.3%) patients it had a homogeneous structure. With intravenous contrast, in 39 (90.7%) cases with fluid level the signal flare phenomenon was established, which was more often detected in the arterial phase (33 (84.6%) cases). Extravasation was detected on angiography in 27 (45%) patients; they underwent therapeutic embolization. In another 15 patients preventive embolization was performed. When extravasation into hematoma without fluid level on MSCT (13 cases), extravasation on angiography was detected in 4 (30.8%) patients. In the presence of extravasation into hematoma with fluid level, but without signal flare phenomenon (4 patients) it was noted on angiography in 1 case. In the presence of all three signs (extravasation, hematocrit effect, and signal flare phenomenon – 39 patients), the incidence of extravasation on angiography was the highest – 56.4% (p = 0.028), and patients more often required therapeutic embolization.

Conclusion. Detection of extravasation, fluid level and signal flare phenomenon on MSCT in the structure of spontaneous hematoma in COVID-19 patients corresponded to ongoing bleeding and more often required embolization than in isolated extravasation. 

Metformin is a sugar-lowering drug that is actively used in long-term therapy of type 2 diabetes mellitus (DM2). The safety of metformin for different groups of DM2 patients is currently well studied. However, the drug is contraindicated for patients with severe renal impairment and should be used with caution in cases of moderate renal impairment. Since contrast agents as well as metformin are excreted by kidneys, patients with reduced renal function taking metformin require special attention due to the risk of lactic acidosis, a life-threatening condition resulting from functional renal failure and accumulation of metformin in tissues. Numerous studies have shown that the risk of lactic acidosis is relatively low and in most cases is not associated with metformin therapy per se, but rather with comorbidities. Initial versions of clinical recommendations related to the use of contrast agents strictly limited the use of metformin before and after examination, but as data on lactate acidosis and possible causes of this condition expanded, the recommendations gradually became less strict. For emergency contrast studies, they are currently unchanged, but data are gradually accumulating on the safety of continuing metformin in these clinical situations. There is no consensus among contrast manufacturers on whether and in what regimen metformin should be interrupted during contrast studies as well as on a number of other related issues. The best strategy for clinicians is to check the instructions for each specific drug before use. 

In recent years, the frequency of contrast-enhanced radiological studies has increased significantly, and the issues of their selection and rational use do not lose their relevance. These methodological recommendations represent a complete up-to-date guide for using contrast agents (CA) in radiology. Types of currently used CA in computed tomography, magnetic resonance imaging, and ultrasound examinations are described. Safety rules for injection of each CA type are systematized, the principles of dosing and possible side effects are explained. In addition, it is important to highlight the issues of interactions between CA and other drugs that patient might take, in particular, the possible deterioration of renal function when using CA in diabetes mellitus patients taking metformin. It should be noted that these recommendations have undergone significant changes in recent years. Also questionnaire templates for patients prior to the contrast-enhanced study are given in the supplements. The methodological guidelines are based on current publications of international experts on CA use in radiology as well as on the data of two major guidelines: American College of Radiologists (ACR) Guidelines (2023) and European Society of Urogenital Radiology (ESUR) Safety Recommendations (2018, version 10). Thus, the information presented is validated, which provides grounds for its application in real clinical practice. The guidelines will be actualized as new scientific evidence becomes available, but to date they appear to be the most relevant.