Digestive health

Studies show Covid-19 can infect and harm digestive organs


The new coronavirus isn't just attacking the lungs: New research shows it's causing harm to the gastrointestinal tract, especially in more advanced cases of Covid-19.

A variety of imaging scans performed on hospitalised Covid-19 patients showed bowel abnormalities, according to a study published online on 11 May in Radiology. Many of the effects were severe and linked with clots and impairment of blood flow.

"Some findings were typical of bowel ischaemia, or dying bowel, and in those who had surgery we saw small vessel clots beside areas of dead bowel," said study lead author Dr Rajesh Bhayana, who works in the department of radiology at Massachusetts General Hospital in Boston.

"Patients in the ICU can have bowel ischaemia for other reasons, but we know Covid-19 can lead to clotting and small vessel injury, so bowel might also be affected by this," Bhayana explained in a journal news release.

Multisystem involvement

One expert unconnected to the new study said the findings aren't surprising.

"Our emerging understanding of Covid-19 has found the disease to have multisystem involvement including the nervous, cardiac, vascular [excess clotting] and finally the digestive systems, among others," said Dr Sherif Andrawes. He directs endoscopy in the division of gastroenterology and haematology at Staten Island University in New York City.

"It seems that this disease is intricate, in the sense that it can involve multiorgan systems, rather than being a disease of the respiratory system solely," Andrawes said.

In fact, a study published online on 13 May in the journal Science Immunology has found evidence that SARS-CoV-2, the virus behind Covid-19, can infect the human digestive system.

Researchers led by Siyuan Ding of Washington University School of Medicine in St. Louis, said their findings "highlight the intestine as a potential site of SARS-CoV-2 replication, which may contribute to local and systemic illness and overall disease progression".

That seems to be borne out by the Boston study.

Preliminary study

That research included 412 Covid-19 patients who were hospitalised between 27 March and 10 April. They averaged 57 years of age, and 134 of them underwent abdominal imaging, including 137 radiographs, 44 ultrasounds, 42 CT scans, and one MRI.

Abnormalities of the bowel wall (intestines and colon) were detected on 31% of CT scans and were more common among patients in intensive care than in other patients, the findings showed.

Bowel abnormalities included thickening and ischaemia – restricted blood flow due to a clot. Surgery was conducted in four patients with bowel abnormalities detected on scans, and it revealed an unusual yellow discolouration of the bowel in three patients, plus bowel infarction ("dead bowel," caused by reduction in blood supply) in two.

The researchers said possible explanations for bowel abnormalities in Covid-19 patients include direct infection by the new coronavirus; clots arising in small vessels that supply the bowel with blood; or what's known as "nonocclusive mesenteric ischaemia" – a condition caused by inadequate blood supply to the intestines.

"Our study is preliminary, and more work is needed to understand the cause of bowel findings in these patients," Bhayana cautioned in a journal news release.

For his part, Andrawes agreed that severe gastrointestinal symptoms are appearing in some Covid-19 patients.

Life-threatening bowel issues

"Patients with predominantly respiratory symptoms may also have mild symptoms of nausea, vomiting and diarrhoea," he said. But in the new study, "a subgroup of Covid-19 patients was found to have more involvement of the gastrointestinal tract with intense symptoms of nausea, vomiting and diarrhoea leading to dehydration and less severe upper respiratory symptoms," Andrawes said, and their stool also tested positive for traces of the new coronavirus.

In some cases of Covid-19, gastrointestinal issues may even arise before the respiratory tract is affected.

So, "patients with new-onset of digestive symptoms after possible contact with Covid-19 or connection with a Covid-19 case should be investigated for Covid-19 illness, even in the absence of the more common upper respiratory symptoms of cough, fever and shortness of breath," Andrawes advised.

Dr David Bernstein is chief of hepatology at the Northwell Health's Sandra Atlas Bass Center for Liver Diseases in Manhasset, New York. Reading over the new study, he said that it's "concerning" that patients are developing life-threatening bowel issues, probably due to clots within the bowel that are cutting off the organ's blood supply.

This should "remind Covid-19 health care providers about the critical use of anticoagulant therapy early on in the disease, in an effort to prevent life-threatening complications such as bowel ischaemia and pulmonary embolism [clots]," Bernstein said.

Image credit: Getty Images

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