Lethal gastrointestinal manifestations of COVID-19 infection at autopsy.

COVID-associated acute mesenteric ischaemia is a rare event that has a high mortality rate, particularly in the elderly. Despite gastrointestinal symptoms being relatively common in COVID-19 infections, however, lethal gut complications are often not considered. Two cases with fatal COVID-associated acute mesenteric ischaemia are therefore reported. Case 1: A 74-year-old woman who died following a presentation with diarrhoea and abdominal pain was found at autopsy to have extensive ischaemic changes of her small and large intestines. The superior mesenteric artery and its major branches were widely patent. Histologically acute inflammation and necrosis of the mucosa and intramucosal haemorrhage were found with fibrin thrombi in intramucosal and submucosal vessels. Respiratory viral nucleic acid testing performed on a retronasal swab obtained at autopsy was positive for COVID-19 (SARS-CoV-2). Death was due to multi-organ failure complicating mesenteric ischaemia associated with COVID-19 infection. Case 2: A 94-year-old woman with COVID-19 infection died after developing abdominal pain with melaena and bright red rectal bleeding. At autopsy there was focal transmural acute inflammation of the small intestine with multiple fibrin microthrombi. Death was also due to multi-organ failure complicating mesenteric ischaemia associated with COVID-19 infection. In the absence of obstructive vascular lesions at autopsy in cases of intestinal ischaemia, COVID-19 should be considered with appropriate swabbing and careful histological sampling of the intestine and mesentery to check for microvascular fibrin thrombi.