Microvascular Thrombosis in the Bowel: Is There a Covid Connection?

Brenda F. Johnson, MSN

The past two years have changed our world in many ways. We have seen unsuspecting patients, family, and friends get sick, and sometimes die from Covid. The long-term effects of this virus have yet to be seen.

With my job in the GI lab, I am able to observe some trends associated with GI diseases and conditions. I have noticed during colonoscopies that ICU Covid patients often suffer from fragile colon mucosa that bleeds very easily. It turns out that Covid does have a multitude of effects on the GI tract.

The gastrointestinal tract and its ability to do the myriad of functions that it does, is at risk in Covid patients, especially in the acutely ill. From hydration to waste elimination, the GI tract is vital to our survival. Complications such as intolerance to tube feedings, an ileus, to bowel ischemia can be found in 3 out of 4 patients who are critically ill with Covid¹.

Symptoms often begin with diarrhea, abdominal pain, or nausea: diarrhea being the most popular symptom². These GI issues can escalate alongside the respiratory issues and become life threatening. In almost two-thirds of the critically ill, liver transaminases become elevated³. Other organs that can also become inflamed are the gallbladder, and pancreas⁴. Acute colonic pseudo-obstruction described as severe distension from gas with no obstruction has been seen⁵. However, this could be from the length of the illness, rather than Covid.

Mesenteric ischemia has been reported in about 4% of the critically ill Covid patients⁶. Nausea, vomiting, and abdominal pain from lack of blood flow to the small bowel could require surgery. These patients are not able to report how they feel due to the fact that they are ventilated, and sedated. So I suspect that conditions such as these can become serious before they are noticed. The fact that these patients are on so many medications, prolonged ventilation, and ECMO, can lead to a watershed of acute conditions.

In some patients, however, mesenteric ischemia develops even though their mesenteric vessels were patent⁷. Kaafarani tells us that the thrombosis may be implicated in the small intestinal vessels, rather than the larger ones⁸. Surgeons have been able to examine the bowel more closely during an operation for a resection. This observation has revealed some unusual things.

One of the observations is well-defined patchy areas of yellow discoloration of the bowel wall⁹. Another finding is that the mucosa can sometimes have considerable ulcerations and inflammation along the entire wall of the colon¹⁰. "Fibrin microthrombi were occasionally noted in the capillaries underlying areas of necrosis,” which alludes to the idea of blood clots on a micro level¹¹.

There are several other reasons that these critically ill patients can develop mesenteric ischemia apart from Covid. Medications and metabolic or blood flow issues are a few other rationales. However, mesenteric ischemia along with the above mentioned anomalies point to a Covid connection. Complications of the GI tract in a Covid patient have been proven to be connected, and as more data is gathered, we will be able to definitely draw an association to the more serious symptoms.

There are some statistical relationships seen in ICU Covid patients. A large percentage of the severe cases are male, in fact 66.5% are men according to El Moheb et al.¹². Out of 313 patients, over 72% had one or more GI symptoms¹³. And as can be expected, a large percentage had either a rectal tube, nasogastric tube, and/or a gastrostomy tube¹⁴.

These patients are very sick, and having tubes in every orifice only sets them up for further problems. They are more prone to infections, bleeding, and medication or feeding intolerances. As these patients are studied further, hopefully, future patients will benefit and some of these problems will be prevented. These patients are not good candidates for major surgery, so prevention of bowel ischemia is vital.

Although doctors aren't sure yet of the entire pathophysiology of these occurrences, knowing that they exist will help in identifying them earlier and possibly prevent surgery or death of these patients. Have you had a Covid patient that had a bowel resection for ischemia? If so, how did they do?

References/Resources

^{1,2; 12-14}Gastrointestinal Complications in Critically Ill Patients With COVID-19

^3-11COVID-19: Gastrointestinal symptoms and complications

Microvascular Thrombosis in the Bowel: Is There a Covid Connection?

About Brenda F. Johnson, MSN

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