Both bruises and blood clots stem from problems with blood vessels and both can cause skin discoloration. Bruises usually happen when a physical trauma causes blood to leak into surrounding tissues. A blood clot is a collection of blood within a vessel. A bruise is more likely to show visible signs than a blood clot.

In this article, we discuss the differences between bruises and blood clots, what they look like, and their causes and treatments.

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Visible bruises, or contusions, usually develop when tiny blood vessels called capillaries burst, causing blood to leak into the surrounding tissue. This blood leakage leads to a visible skin discoloration. A person’s muscles, bones, and organs can also bruise, although this may not produce visible symptoms.

Damage to blood vessels can cause large amounts of blood to leak into the surrounding tissue, forming so-called hematoma. This collection of blood can then become sticky and harden. A hematoma that has formed may cause what looks like a bulging area of the skin. Doctors may refer to this as a superficial hematoma.

Blood clots typically occur inside larger blood vessels, such as an artery or a vein. Doctors refer to a blood clot as a thrombus. Blood clots may not produce visible symptoms. However, symptoms of a blood clot may become visible or palpable, especially if the blood clots develop near the surface of the skin or if they disrupt blood flow deep in an extremity.

Blood clot appearance

Most blood clots do not cause visible symptoms. Some blood clots can even cause swelling without any visible blood pooling.

One example of this is deep vein thrombosis (DVT), which typically results in swelling and skin discoloration in the legs. This is a medical emergency requiring immediate attention.

However, bruises and superficial hematomas can also cause skin discoloration. As a result, people may confuse the symptoms of bruises with those of hematomas or certain types of blood clots.

Bruise appearance

Bruises may appear red at the point of trauma before turning blue, black, or purple. As bruises heal, they will typically progress to a yellow or green color before turning brown as they begin to fade.

Bruises may also appear and progress differently on different skin tones.

Learn about bruises on dark skin here.

By contrast, pooled blood from a superficial hematoma typically presents as a dark blue, purple, or black patch. A person may also experience swelling and other skin discoloration over a hematoma.

Below are examples of visible bruising, superficial hematomas, and swelling from DVT.

Blood will naturally clot at the site of the capillary damage causing a bruise. However, bruises themselves do not cause blood clots.

In the case of a large trauma, bruises, hematomas, and blood clots may form independently of each other.

Bruises and blood clots often stem from damage to blood vessels. However, their exact causes and symptoms can vary.

Causes of bruises

Bruises typically develop after an injury, such as hard contact with an object, falling, or breaking a bone. These types of injuries can cause capillaries in the skin to burst. Bruises can occur anywhere on the skin.

Causes of blood clots

Blood clots are part of the natural process of healing after an injury.

Damage to an area causes coagulants in the blood called platelets to collect and clump together near the injury, which helps stop the bleeding. Blood can also clot without any apparent cause.

Small clots that form may disappear on their own. However, some blood clots become larger than necessary or form in places where there is no injury.

Learn more about what causes blood clots here.

Many of the symptoms of bruises and blood clots can be quite similar, but certain types of clots can cause much more severe effects.

Symptoms of bruises

Most bruises tend to cause skin discoloration that changes over time.

Bruises may be sore or painful to the touch as they heal. As the marks of the bruise fade, the pain tends to lessen as well.

Symptoms of blood clots

Unlike most bruises, blood clots do not always follow an exact pattern as they heal and may cause different symptoms depending on where they are in the body and which tissues they affect.

Blood clots and hematomas can lead to the following symptoms:

  • skin discoloration
  • swelling
  • skin tenderness
  • localized pain

People experiencing large blood clots or hematomas within muscles or organs will often require medical treatment.

A blood clot within a vein, called a venous thrombus, can block the flow of blood to parts of the tissue. When a piece of a venous thrombus breaks off and travels in the vein away from the original clot site, health experts call this a venous thromboembolism.

A blood clot in an artery is an arterial thrombus. A piece of an arterial thrombus can also break off and travel in the artery away from the original clot site. Doctors refer to this as an arterial thromboembolism.

An arterial or venous thromboembolism can be life threatening, as it can cause severe damage or death to cells.

Some examples of severe conditions that a thrombus can cause include:

  • Stroke: This occurs when a blood clot in any of the arteries travels to the brain or develops within the brain itself.
  • Heart attack: This happens when a blood clot develops in an artery of the heart.
  • Pulmonary embolism: This condition results from a blood clot developing in an artery of the lung.
  • Mesenteric ischemia: This occurs when a blood clot develops in an artery to the intestines.
  • DVT: This condition results from a blood clot occurring in any deep vein, most commonly in the leg.

Symptoms of a thrombus vary according to the organ and tissue that it affects and can include:

Anyone who thinks that they are experiencing the symptoms of a thrombus should seek immediate medical care.

There are many risk factors for blood clots and bruises, some of which people can manage by making lifestyle changes.

Risk factors for bruises

Bruises are a relatively common occurrence. Bumping into a hard surface is usually enough to cause a bruise. It may not take a significant impact, so sometimes, an individual will not remember how they got the bruise.

Learn about seven possible causes of bruising here.

Although most people will get a bruise at some point, specific factors may increase this likelihood.

Some drugs, including blood thinners, may lead to increased bleeding from blood vessels after an injury and, therefore, more bruising. This can occur with prescription blood thinners, such as warfarin, and over-the-counter (OTC) drugs, such as aspirin and fish oil supplements.

Some vitamin deficiencies or bleeding disorders may also make a person more prone to bruising and bleeding, while aging tends to make the skin and blood vessels more fragile.

Certain medical conditions can lead to abnormally low platelets or low clotting factors, resulting in easy bruising or bleeding. Some of these conditions are:

Risk factors for blood clots

Normal wound healing can involve blood clot formation. However, there are a number of risk factors for blood clots forming within blood vessels.

Genetic predisposition is a risk factor for abnormal blood clotting. Individuals may be more likely to experience excessive blood clotting if they have a family history of dangerous blood clots or have previously had them themselves.

According to the American Heart Association (AHA), other factors that may increase the risk include:

  • smoking tobacco
  • being pregnant
  • being over the age of 60 years
  • having obesity
  • sitting or resting for extended periods
  • undergoing hormone therapy
  • having recently undergone surgery

Other conditions may also make blood clots more likely. Among others, these include:

Anyone with severe pain at the site of an injury should contact a doctor for a full diagnosis. Normal bruising is rarely a cause for concern, but any unexplained bruising requires guidance from a doctor.

Certain severe medical conditions can cause unexplained bruising, bleeding, and blood clots. These conditions require proper diagnosis and treatment.

Individuals should speak with a doctor about any lasting bruises or those that appear alongside other symptoms, such as pain or swelling.

Anyone who suspects that they are experiencing symptoms of a thrombus should seek immediate medical attention. It is also advisable for people who have a higher risk of developing a thrombus to seek guidance from a doctor as a precaution.

Anyone who experiences the following should also contact a doctor:

  • a deep bruise after an injury
  • a lump under the skin that is firm to the touch
  • deep aching after a significant injury, such as a bicycle or car accident, sports injury, or fall

Doctors can generally diagnose superficial bruises by sight, taking into account any skin discoloration, tissue swelling, and other injuries. This is also the case for small blood collections under the fingernails or toenails, known as subungual hematomas.

Many doctors will use imaging tests to help diagnose a thrombus or hematoma after carrying out a physical examination and reviewing a person’s medical history.

Imaging tests for blood clots may include an ultrasound, CT, or MRI scan. These tests can help doctors look for blood clots both in blood vessels and within tissues and organs.

Bruises do not usually require any treatment.

However, healthcare professionals may recommend using home remedies, such as applying ice packs to the bruise to lessen swelling and then using heat packs, to alleviate symptoms. If a bruise is particularly painful or extensive, doctors may recommend OTC pain relievers.

If a doctor suspects that an underlying condition is causing the bruising, they may order additional tests or recommend treatments for the condition.

Depending on its cause and the organs and tissues that it affects, a hematoma may or may not require treatment. Sometimes, these blood collections may need medical treatment or surgical procedures, particularly if they occur without an injury.

To treat a thrombus, such as DVT, doctors will use medications to stop ongoing clotting and prevent future blood clots. This treatment may require a hospital stay. Injectable blood-thinning drugs, such as heparin, can help prevent new clots from forming.

In cases of stroke, heart attack, or pulmonary embolism, a person may receive a clot-busting medication called a thrombolytic. Doctors may also recommend that an individual use one or more blood thinners going forward to prevent their blood from clotting unnecessarily in the future.

Bruises, hematomas, and blood clots often result from damage to blood vessels.

Bruises generally heal on their own, as the formation of small blood clots due to cuts or injury is a normal part of the body’s healing process.

However, blood clots or hematomas in deep tissues may require further evaluation and treatment, depending on their location.

According to health experts, blood clots within vital blood vessels are a medical emergency and can become life threatening due to their effects on blood and oxygen flow.

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