Thrombosis

Thrombosis is when a blood clot forms inside a blood vessel, stopping blood from flowing properly through the body. When a blood vessel gets hurt, the body makes clots to stop the bleeding. These clots are made from tiny parts in the blood called platelets and a substance called fibrin.

Sometimes, clots can form even when there is no injury. If a clot breaks apart and starts moving in the body, it is called an embolus. This can be very dangerous because the clot can block blood flow to important parts of the body, leading to serious problems like a stroke or a heart attack.

Thrombosis can happen in both veins (venous thrombosis) and arteries (arterial thrombosis). In veins, it often causes a clot in the leg, known as deep vein thrombosis (deep vein thrombosis). In arteries, it can cut off blood to tissues, causing damage. Pieces of these clots can break off and travel to other parts of the body, which can lead to even more serious issues like a pulmonary embolism in the lungs (pulmonary embolism).

Signs and symptoms

Thrombosis, the formation of a blood clot inside a blood vessel, shows different signs based on where the clot forms.

Arterial thrombosis

Arterial thrombosis happens when a clot forms in an artery, often after a fatty buildup in the artery wall breaks open. These clots can move and affect other parts of the body. A common cause is irregular heart rhythms that make clot formation easier.

Stroke

Main article: Stroke

A stroke happens when blood flow to the brain is disturbed, often because of a clot. In thrombotic stroke, a clot usually forms around fatty buildup in the arteries. The symptoms can appear slowly because the blockage builds up over time.

Myocardial infarction

Main article: Myocardial infarction

A heart attack occurs when a clot blocks a artery to the heart, reducing oxygen supply to the heart muscle. This can be very serious and needs quick medical help.

Limb ischemia

A clot can also form in the arms or legs, causing serious problems with blood flow.

Venous thrombosis

Main article: Venous thrombosis

Deep vein thrombosis

Main article: Deep vein thrombosis

Deep vein thrombosis (DVT) is when a clot forms in a deep vein, usually in the legs. Signs include swelling, pain, and redness in the affected area.

Paget-Schroetter disease

Main article: Paget-Schroetter disease

Paget-Schroetter disease is a type of clot in an arm vein, often noticed after heavy exercise. It usually affects young, healthy people, and men more often than women.

Budd-Chiari syndrome

Main article: Budd-Chiari syndrome

Budd-Chiari syndrome happens when a vein in the liver gets blocked. This can cause abdominal pain, swelling in the abdomen, and an enlarged liver.

Portal vein thrombosis

Main article: Portal vein thrombosis

Portal vein thrombosis affects the vein that carries blood to the liver, often due to other health issues. It can reduce blood flow to the liver.

Renal vein thrombosis

Main article: Renal vein thrombosis

Renal vein thrombosis blocks the vein that drains blood from the kidney, which can reduce drainage from the kidney.

Cerebral venous sinus thrombosis

Main article: Cerebral venous sinus thrombosis

Cerebral venous sinus thrombosis is a rare type of stroke caused by a clot in the brain’s venous sinuses. Symptoms can include headaches, vision problems, weakness on one side of the body, and seizures.

Jugular vein thrombosis

Jugular vein thrombosis can happen due to infection or other causes. It may lead to serious complications but can be hard to diagnose because symptoms can vary.

Cavernous sinus thrombosis

Main article: Cavernous sinus thrombosis

Cavernous sinus thrombosis is a specialized type of brain vein clot that can spread from infections on the face. It can cause symptoms like double vision and spread of infection to other parts of the brain.

Causes

Thrombosis happens when a blood clot forms inside a blood vessel, stopping blood from flowing properly. Some people have a higher chance of getting this because of things like inflammation.

There's something called Virchow's triad that talks about three main things that can lead to thrombosis: changes in blood flow, problems with the blood vessel walls, and the blood being more likely to clot. Some risk factors make it more likely for clots to form in veins, while others make it more likely in arteries. Even newborn babies can sometimes get these clots.

Mechanism

Main article: Virchow's triad

Thrombosis happens when a blood clot forms inside a blood vessel, blocking blood flow. The main reasons for this are listed in Virchow's triad: certain body conditions that make clotting easier, injury to the blood vessel lining, and changes in blood flow. As people get older, their risk for thrombosis can increase because of things like smoking, diet, lack of exercise, and other health problems.

When the lining of a blood vessel gets damaged—for example, from injury, surgery, or infection—it can expose parts of the vessel that normally aren't in contact with blood. This can trigger the body to form clots. Changes in blood flow, like when blood slows down or pools, can also increase the chance of clots forming. This can happen after long periods of sitting, such as during a long airplane flight, or in conditions like heart problems. Certain diseases, like cancer, can also raise the risk of blood clots.

Prevention

After surgery, doctors often give a medicine called heparin to help prevent blood clots, but they must be careful because it can increase the risk of bleeding. Blood clots can cause serious problems or even death, especially for people in hospitals. Because of this, doctors work hard to stop clots from forming.

For patients having surgery, special stockings and other methods are used to keep blood flowing. In serious cases, doctors may recommend certain medicines or place a filter to protect the blood flow. These steps help keep people safe during their hospital stays.

Treatment

The way to treat thrombosis depends on where it is in the body, how it affects the person, and the chance of problems from treatment.

Anticoagulation

The main article is: Anticoagulant

Medicines like Warfarin and vitamin K antagonists can be taken by mouth to help stop blood clots from forming. In some cases, a medicine called heparin may be given by injection for better results. However, these medicines can sometimes cause bleeding, so doctors watch the blood closely. Some people can safely manage their treatment at home, but this is more common in some places than others. Other medicines like direct thrombin inhibitors and direct Xa inhibitors are also used now instead of Warfarin.

Thrombolysis

Thrombolysis uses special medicines to break down blood clots. This can be risky because it may also cause bleeding, so it is usually only used in serious cases like severe stroke or a big blockage in the lungs.

Surgery

If a blood clot in an artery causes serious problems in a limb, surgery might be needed.

Endovascular treatment

In some cases, doctors can remove the clot using special tools through a tube.

Antiplatelet agents

For blood clots in arteries, medicines like aspirin can help stop more clots from forming.

Targeting ischemia/reperfusion injury

The main article is: Reperfusion injury

When blood flow returns to an area that didn’t have blood for a while, it can sometimes harm the tissues. This happens in certain heart conditions and can be a big reason why people still have serious health problems even after treatment. Doctors are studying ways to protect the tissues during these treatments to help improve outcomes.

Neonatal thrombosis

For babies who develop blood clots, treatments can include watching closely, using special ointments, medicines, or surgery. However, there isn’t strong evidence to show which treatments work best for babies, and more research is needed.