Few bodily functions are as misunderstood as blood clots. While most people have heard about blood clots in the heart or brain causing serious issues or even death, fewer realize that blood clotting is something every healthy body does automatically under some circumstances. “Blood clotting is important to help us stop bleeding or to heal areas of injury,” says Dr. Shaline Rao, a cardiologist at NYU Langone Hospital, Long Island.
It occurs when the blood clots (often called coagulation) to seal a wound in order to stop blood from leaving the body after a cut or other injury. In fact, “your blood not being able to effectively clot is a high-risk disease,” says Rao.
The danger of blood clotting, she explains, is when a clot forms at the wrong time, in the wrong place or becomes dislodged and ends up blocking blood, oxygen or nutrients from getting to a vital organ.
Here are some of the conditions and dangers associated with such blood clots and how they can become serious and even life-threatening.
What is a blood clot?
Blood clots begin forming when a blood vessel is damaged and nearby cell fragments (called platelets) begin clumping together and adhering to a protein in the blood known as fibrin, explains Dr. Fadi Elias Shamoun, a cardiologist and vascular medicine specialist at Mayo Clinic. This combining of platelets and fibrin “forms a mesh-like structure that traps blood cells,” he says. This thickening not only slows down blood loss, but also seals the wound and provides a sort of scaffolding for tissue repair. Once that repair has taken place and healing has occurred, the body breaks down and dissolves the blood clot.
“This is usually a well-regulated, efficient and localized process,” explains Dr. Doris Chan, a cardiologist at NYU Langone Hospital in Brooklyn. “However, the cycle can become disordered or disrupted and overall dysfunctional.”
Indeed, sometimes blood clots don’t dissolve – or they form on the inside of vessels without an obvious injury. Such clots form in the body’s circulatory system in veins or arteries, which are responsible for transporting blood throughout the body and to vital organs.
A blood clot that forms in a vein is called a thrombosis. It’s a formation that can restrict blood flow and cause pain and swelling in the area as blood builds up behind it. Blood clotting in a major vein in one’s leg is known as deep vein thrombosis, or DVT, and sometimes appears in the arms, pelvis or other areas, according to the American Society of Hematology.
Sometimes, that buildup can cause the clot to become dislodged, which is called an embolism. A pulmonary embolism is a clot that travels through the heart and becomes lodged in the lungs. “This can lead to severe symptoms and in some cases be life-threatening,” says Shamoun. Blockage can also occur in a brain artery (called a brain embolism), or in an artery in the heart (called a coronary embolism or arterial embolism).
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What causes blood clots?
Several factors can cause your blood to clot, with the most common one also being the least worrisome. “Blood clots that form near a site of injury are usually not concerning,” says Chan.
But clots that don’t dissolve or that form abnormally are worrisome. Some of the reasons such formation may occur include stickier than normal platelets due to inhaling cigarette smoke, there being damage to the inner lining of a blood vessel wall or from a condition known as hypercoagulability, “which is an increase in the tendency of the blood to clot such as with cancer or pregnancy,” says Shamoun.
Sometimes infections can irritate blood vessel walls as well, “which can trigger clotting,” says Rao; and “during long car and plane rides, we sometimes see inappropriate clot formation due to inactivity.”
Obesity, aging, a recent surgery, genetic predispositions, hormonal treatments and autoimmune conditions like antiphospholipid syndrome can all also increase your risk of developing an abnormal blood clot, says Chan. “Some medications can also have a pro-clot formation side effect,” adds Rao.
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Why are blood clots serious?
Abnormal blood clots can be serious when they “obstruct blood flow carrying oxygen and nutrients to vital organs,” says Shamoun. For instance, a clot blocking blood flow to the brain can cause a stroke, which can lead to disability, brain damage and even death.
When a clot blocks an artery that’s responsible for circulating blood to the heart, it can damage heart tissue and cause a heart attack. And when an embolism blocks blood flow to the lungs, it can cause severe breathing problems and death.
Other forms of blood clots include renal vein thrombosis, which can cause kidney damage or kidney failure; and mesenteric ischemia, which is a clot within intestinal arteries that can lead to severe abdominal pain and digestive issues.
There are many ways to prevent blood clots, according to the National Blood Clot Alliance, including being aware of your risk factors and discussing them with a medical provider.
This article originally appeared on USA TODAY: What causes blood clots?
