It is not known whether these clots are caused by the coronavirus or by an immune system response.

As the number of sick and dead increases, doctors discover that covid-19, the disease caused by the new coronavirus, it is much more complex than initially thought.

The disease can affect not only the respiratory system of patients but organs such as the liver, kidneys, intestines, heart, and brain.

One of the most worrisome complications is the unusual blood clot formation in many covid-19 patients, including those on anticoagulants.

These clots can reach organs such as the lung, heart, or brain, causing heart attacks or strokes (ACV), with fatal consequences.

A few days ago, doctors at the Mount Sinai hospital chain in New York published studies suggesting that clots, especially in the lungs, play an important role in the most severe cases of covid-19.

The experts also revealed that clots may be related to the incidence of stroke in young patients infected with the coronavirus.

Doctors in several countries report similar problems.

An analysis of 183 covid-19 patients by Chinese scientists revealed that 71% of those who died had clots.

In the Netherlands, a study of 184 covid-19 patients admitted to intensive care found that one third had clots.


In the United States, the main epicenter of the pandemic, where more than a million cases and more than 65,000 deaths have already been confirmed this week, many doctors have already located the clots among the main causes of death in patients with covid-19, behind severe acute respiratory syndrome (SARS).

Although clot formation is not uncommon in critically ill patients, clinicians are surprised at the magnitude of the problem in coronavirus cases.

This is very different from what we are used to seeing in intensive care units, ”surgeon Craig Coopersmith, an intensive care specialist and professor at Emory University School of Medicine in Atlanta, told BBC Brazil.

“We are very used to having severe ICU patients, ventilator patients, with multiple organ failure,” he describes.

“But what is very different about covid-19 is that we are seeing a much greater clot burden and many more patients are dying from those clots.”

Coronavirus can affect not only the respiratory system of patients, but also several other organs, such as the liver, kidneys, intestines, heart, and brain. (Photo: .)

World phenomenon

Coopersmith says that clot formation in covid-19 patients began to get his attention about a month ago.

Exchanging messages with other intensive care doctors in the network of 10 university hospitals in the state of Georgia, he realized that they were all observing the same phenomenon.

“It is clearly something that is happening across the country and around the world.”, details.

According to doctors, blood clots in the legs are seen more frequently than normal in patients with covid-19.

These clots can break loose and migrate to the lungs. Depending on the size of the clot, the pulmonary circulation can be completely interrupted and cause death.

Dr. Gregory Piazza, a specialist in cardiovascular medicine at Brigham and Women’s Hospital in Boston and a professor at Harvard University School of Medicine, tells BBC Brazil that he also began to observe clot formation mainly in patients with covid- 19 who were in intensive care, in serious condition and with respirators.

“We are finding clots in the legs, what we call deep vein thrombosis, many clots in the lungs, what we call pulmonary embolism,” describes Piazza, who is conducting a study of cardiovascular complications of covid-19, focusing on investigating the frequency of these clots.

According to Piazza, Many of the covid-19 patients who die suddenly are believed to have been victims of pulmonary embolism.

Blood clots can cause multiple conditions in a patient. Even lead to death. (Photo: .)

Amputations, heart attacks and strokes

But they have also been seen clots in other parts of the patient’s body.

“In some cases, we see the formation of large clots in the arteries,” explains Piazza.

“It can be in the arteries of the heart, causing a heart attack, in the arteries of the brain, causing a stroke, or sometimes in the arteries of the extremities, which can cause the patient’s arms and legs are at risk and creates the possibility of an amputation being necessary“, it states.

One of the cases that recently attracted attention in the United States was that of actor Nick Cordero, 41, who was hospitalized after contracting the coronavirus and had his right leg amputated after complications related to clot formation.

“We are also seeing many healthy patients suffering from strokes“Lung disease specialist Hooman Poor, a professor at the Icahn School of Medicine, the academic arm of the Mount Sinai hospital system in New York, assures BBC Brazil.

Last week, doctors at that hospital released details about 5 coronavirus-infected patients who suffered a stroke.

They had between 33 and 49 years, well below the common age group in these cases, and had only mild symptoms or no signs of covid-19.

Some did not know they were infected or realized they were having a stroke, and did not ask for help for fear of infection in the hospital.

Coronavirus may be causing abnormal clot formation in patients. (Photo: .)

Dialysis machines clogged

Many of the patients who had clot problems were taking blood-thinning medications, which doctors say makes the image even more unusual.

One of the observed phenomena is that of dialysis machines, used to filter impurities from the blood, blocked by clots.

Coopersmith says that about 20% of covid-19 patients have kidney failure and need dialysis.

“We were seeing a lot of cases of dialysis machine clogging. So we switched to a different type of anticoagulant, the type with which clot formation is never seen, “he says.

“But we were still seeing the machines blocked, three times a day, which is something totally different from what we are used to,” he describes.

Doctors have also reported the presence of large amounts of micro clots in the lungs of patients with covid-19.


Still there is no consensus on what is causing clots in covid-19 patients. “Right now, there is a lot of speculation,” says Coopersmith.

He says there are multiple factors that must be present for blood to clot and that the body constantly seeks a delicate balance between clotting and bleeding.

“What we know so far is that this is very unbalanced in covid-19 patients. And there are several reports on why this happens, but each report is different, “he says.

It is not known whether the clots are caused by the coronavirus or by an immune system response to fight the virus. In addition, many of the patients are immobilized, which also increases the risk of clotting.

According to Poor of the Mount Sinai hospital, it is not yet known if the clots are just a side effect of what is happening to patients or if they are causing organ failure.

“We don’t know if there is a process that is causing damage to the lungs and then some patients are also experiencing clot formation, or if clots play a bigger role,” says Poor.

There is a high probability that, in many cases, the clots are causing organ failure. But we don’t know the percentage of cases. “

According to doctors, clots in the legs are seen more often than normal in patients with covid-19. (Photo: EPA)

Some hospitals administer anticoagulants to all hospitalized patients with covid-19.

But experts warn that this type of treatment requires a lot of care since it can increase the risk of bleeding and emphasize that more studies are needed.

Coopersmith notes that the pandemic is only a few months old and much remains to be discovered about the coronavirus. “We are learning a little more every day,” he concludes.