Ecchymosis is the medical term for a large bruise. This discoloration occurs when blood vessels near the skin’s surface are damaged, causing red blood cells to leak into the surrounding subcutaneous tissue. The trapped blood pools under the skin, creating a visible flat patch that does not blanch, or turn white, when pressure is applied. While often the result of a minor injury, ecchymosis can sometimes signal an underlying health issue.
Defining Ecchymosis and Its Appearance
Ecchymosis is specifically defined by its size, presenting as a flat area of discoloration measuring more than one centimeter in diameter. This distinguishes it from smaller bleeding points, such as petechiae, which are pinpoint spots less than three millimeters, and purpura, which range between three millimeters and one centimeter. The lesion is always flat, differentiating it from a hematoma, which is a raised collection of clotted blood within the tissue.
The characteristic color changes of an ecchymosis follow a predictable healing cycle as the body works to reabsorb the pooled blood. Initially, the area appears reddish-purple due to the presence of oxygenated hemoglobin in the leaked red blood cells. Within a few days, the color progresses to a blue or black hue as the oxygen is metabolized and the hemoglobin begins to break down.
The subsequent transition to green and then yellow reflects the body’s process of breaking down hemoglobin. Macrophages convert the heme component of hemoglobin first into a green pigment called biliverdin. This biliverdin is then processed into bilirubin, which gives the lesion a distinct yellowish tint before the body fully clears the blood remnants. Finally, some iron is stored as a brownish compound called hemosiderin before the skin returns to its natural tone, a process that typically takes one to three weeks.
Common and Underlying Causes
The most frequent cause of ecchymosis is direct physical trauma, such as a fall, a bump against a hard object, or a sports injury, which ruptures small blood vessels without breaking the skin. Medical procedures, including injections, blood draws, and surgical incisions, also commonly result in localized ecchymosis due to deliberate or accidental vessel disruption. However, not all large bruises are the result of a remembered injury, and these can point toward systemic factors.
Certain medications can significantly increase the likelihood of developing ecchymosis, even from minor forces. Anticoagulants, often called blood thinners, and nonsteroidal anti-inflammatory drugs (NSAIDs) interfere with the blood’s normal clotting mechanism, leading to greater blood leakage when a vessel is damaged. Corticosteroids, whether taken orally or applied topically over a long period, can induce ecchymosis by weakening the structural support for the capillaries.
Age-related skin changes also contribute to easy bruising. As individuals age, the skin loses protective fat and collagen, and the blood vessel walls become more fragile. This lack of structural support makes the capillaries susceptible to rupture from even the slightest force. Underlying medical conditions can also impair the body’s ability to stop bleeding, such as liver disease, which reduces the production of necessary clotting factors. Furthermore, disorders affecting blood components, like thrombocytopenia (low platelet count) or certain blood cancers, prevent effective clot formation, resulting in spontaneous or easily provoked ecchymosis.
When to Seek Medical Attention
While most ecchymoses resolve on their own, certain characteristics warrant an evaluation by a healthcare provider. Any large bruise that appears without a clear cause or known injury should be investigated, especially if it occurs on the abdomen, back, or face. Ecchymosis that is massive or rapidly expanding in size may indicate significant internal bleeding and requires immediate medical attention.
If the discoloration does not fade or change color after two weeks, or if it recurs repeatedly in the exact same location, a doctor should be consulted. Warning signs that suggest a more serious underlying issue include ecchymosis accompanied by systemic symptoms or other signs of a bleeding problem. These symptoms include:
- A fever
- Unexplained weight loss
- Joint pain
- Frequent or hard-to-stop nosebleeds
- Gum bleeding
- Blood in the urine or stool