Gastrointestinal and hepatic manifestations of COVID-19: A comprehensive review

The severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) that causes coronavirus disease-2019 (COVID-19) is a global pandemic, manifested by an infectious pneumonia. Although patients primarily present with fever, cough and dyspnea, some patients also develop gastrointestinal (GI) and hepatic manifestations. The most common GI symptoms reported are diarrhea, nausea, vomiting, and abdominal discomfort. Liver chemistry abnormalities are common and include elevation of aspartate transferase, alanine transferase, and total bilirubin. Studies have shown that SARS-CoV-2 infects the GI tract via its viral receptor angiotensin converting enzyme II, which is expressed on enterocytes of the ileum and colon. Viral RNA has also been isolated from stool specimens of COVID-19 patients, which raised the concern for fecal-oral transmission in addition to droplet transmission. Although indirect evidence has suggested possible fecal-oral transmission of SARS-CoV-2, more effort is needed to establish the role of the fecal-oral transmission route. Further research will help elucidate the association between patients with underlying GI diseases, such as chronic liver disease and inflammatory bowel disease, and severity of COVID-19. In this review, we summarize the data on GI involvement to date, as well as the impact of COVID-19 on underlying GI diseases.