The Prevalence of Gastrointestinal Bleeding in COVID-19 Patients: A Systematic Review and Meta-Analysis.

: Severe acute respiratory syndrome coronavirus 2 caused the coronavirus disease of 2019 (COVID-19), which rapidly became a pandemic, claiming millions of lives. Apart from the main manifestations of this infection concerning the respiratory tract, such as pneumonia, there are also many manifestations from the gastrointestinal tract. Of these, bleeding from the gastrointestinal tract is a significant complication quite dangerous for life. This bleeding is divided into upper and lower, and the primary pathophysiological mechanism is the entering of the virus into the host cells through the Angiotensin-converting enzyme 2 receptors. Also, other comorbidities and the medication of corticosteroids and anticoagulants are considered to favor the occurrence of gastrointestinal bleeding (GIB). : This systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and the studies were searched in two different databases (Scopus and PubMed) from November 2019 until February 2023. All studies that reported GIB events among COVID-19 patients were included. : 33 studies were selected and reviewed to estimate the prevalence of GIB. A total of 134,905 patients with COVID-19 were included in these studies, and there were 1458 episodes of GIB. The prevalence of GIB, in these 33 studies, ranges from 0.47% to 19%. This range of prevalence is justified by the characteristics of the COVID-19 patients. These characteristics are the severity of COVID-19, anticoagulant and other drug treatments, the selection of only patients with gastrointestinal manifestations, etc. The pooled prevalence of gastrointestinal bleeding was estimated to be 3.05%, rising to 6.2% when only anticoagulant patients were included. : GIB in COVID-19 patients is not a rare finding, and its appropriate and immediate treatment is necessary as it can be life-threatening. The most common clinical findings are melena and hematemesis, which characterize upper GIB. Treatment can be conservative; however, endoscopic management of bleeding with embolization is deemed necessary in some cases.