INTRODUCTION: In recent years we have observed various consequences of systemic hyperinflammation associated with COVID-19, including pericardium and pleura involvement. From 2020 to 2022 an increase in the incidence of effusion into the pleural and pericardial cavities was noted in the numerous of breast MRI studies, which could potentially be associated with the COVID-19 pandemic.OBJECTIVE: To objectify this impression a comparative study was planned, which aimed to analyze the occurrence of pleural and pericardial effusion in groups of patients in 2022 compared with a matched group in 2019 and to describe the structures of the identified changes.MATERIALS AND METHODS: Тhe database of breast MRI studies during 2019 and 2022 was processed, data from 220 women were selected, indicating as a complaint for breast pain at a mammologist’s appointment and COVID-19 transferred in the group 2022. The telephone questionnaire of the 2022nd year patients were conducted about the presence of common symptoms of inflammation. Statistic: Statistical analysis was carried out using the program Statistica 13.5.0.17 TIBCO Inc. Quantitative parameters are presented as median, 5th-95th percentiles. A 2-tailed t-test was used to compare quantitative parameters. Binary data correlations were carried out using a contingency table. RESULTS: Age included 46 [33–66] years old. MRI was performed 105 [21–198] days after COVID-19. In the 2022 group, at the time of survey, 36% had general inflammatory symptoms in addition to chest pain. In 2022 vs 2019 increase the chance of encountering a pleural effusion (OR 5 [3–8]), the volume of effusion (5 [2–11] mm vs 2 [2–5] mm), incidence of pericardial (OR 31 [11–89]) and combined effusion (OR 11 [4–28]). The detection and the size of effusion of any localization didn’t correlate with age. Patients with breast implants during the pandemic years turned to a mammologist after 29 [8–44] months, before the pandemic — after 40 [19–56] months after surgery and tended to more frequent detection of effusion of all localizations and an increase in the volume of seromas. In the majority of MRI protocols, the effusion was not described.DISCUSSION: Our study will help to increase the doctors literacy about the frequency and manifestations of serositis associated with COVID-19 in a group of young, non-comorbid women who had a mild infection on an outpatient basis. The barriers to describing a small effusion on an MRI are its probability in physiological conditions, the absence of specific symptoms at the patient and none request from the attending physician. Considering the possibility that effusion into serous cavities may be a sign of pathology that led to chest pain will allow diagnosticians to describe it even with a small amount and will give the attending physician a support for a differential diagnosis. Findings in patients with breast implants confirm the connection of changes with an infectious trigger, and that there is some initial tension of the immune system, which, with additional external provocation, results in a brighter response.CONCLUSIONS: Effusion into the pleural cavity or pericardium is a common finding in patients who have undergone COVID19, which may reflect systemic inflammatory syndrome and cause chest pain.