A hematoma is a collection of blood outside of a blood vessel. It occurs because of an injury to a blood vessel, allowing blood to seep out into surrounding tissues where it does not belong. Hematomas can occur anywhere in the body and are commonly caused by an injury such as a fall, an accident, or trauma from a surgical procedure. The blood from a broken blood vessel seeps out through the damaged vascular wall and forms a pool of blood under the skin.
Small hematomas may resolve on their own, but larger ones often need medical treatment to prevent potential complications. An untreated hematoma risks infection, expansion in size putting pressure on surrounding tissues, and calcification. Knowing how a hematoma progresses if left alone can help underscore the importance of proper treatment.
What is a Hematoma?
A hematoma, sometimes called a blood tumor or simply a blood clot, refers to a damaged blood vessel that has allowed blood to leak into surrounding tissue. This pooled blood is initially soft and movable under the skin. It eventually hardens and calcifies if left alone.
Hematomas can occur on the surface of the skin or deeper in soft tissue. Some of the most common locations include:
- Under the fingernails after a smashed finger
- On the leg after a blunt force injury
- On the head after a traumatic brain injury
- In the muscle after an intramuscular injection
- On internal organs like the kidney, spleen, and liver after abdominal trauma
The severity depends on the amount of bleeding and location. Small bruises may not be significant, but a hematoma inside the cranium after a head injury can be deadly.
Stages of Hematoma Progression
A hematoma typically progresses through several stages if it is not drained or absorbed quickly. The stages include:
1. Swelling Phase
Immediately after the blood vessel injury occurs, blood leaks out through the damaged vascular wall and starts pooling underneath the skin. More blood continues seeping into the area, causing significant swelling.
The blood is still liquid, allowing it to spread through surrounding soft tissues. As it enlarges, it puts pressure on nerves and other structures. This is why a hematoma usually causes pain, numbness, tingling, or weakness in the affected region.
2. Coagulation Phase
After initial bleeding, the body begins sealing off the damaged vessel to stop further blood loss. Platelets and coagulation factors are activated to form a fibrin mesh securing the vascular breach. This stops additional bleeding from the original injury site.
However, the blood already disbursed under the skin remains. During the coagulation phase, the liquid blood transitions to a more gelatinous state and eventually hardens. The hematoma takes on a thick, jelly-like consistency.
3. Organization & Resolution Phase
During the organization stage, the hematoma starts resolving as the body removes the unwanted blood. Phagocytes enter the area to digest the blood cells and proteins. Blood vessel growth (angiogenesis) occurs to allow new capillaries to remove the hematoma.
During this time, the area may change colors as the blood breaks down. A bluish hue is common as hemoglobin releases. The area usually becomes warm and tender to the touch.
In a hematoma that is resolving well, the blood clot will slowly shrink in size over several days to weeks. However, any remnants left behind can calcify. This leads to the long-term complications discussed below.
Complications of an Untreated Hematoma
While a minor hematoma may resolve without issue, larger untreated clots can lead to complications including:
Infection
The pooled blood and damaged tissue provide an ideal environment for bacteria to grow. Signs of infection include worsening pain, swelling, redness, warmth, fever, and pus drainage. An infected hematoma needs immediate medical drainage and antibiotics.
| Symptoms | Treatment |
|---|---|
| Increasing pain, swelling, redness | Antibiotics, surgical drainage |
| Fever | Antibiotics |
| Pus drainage from wound | Antibiotics, drainage |
| Flu-like symptoms | Antibiotics |
Enlargement & Pressure Effects
As more blood spills into the hematoma, it expands in size and puts pressure on surrounding structures. This can compress nerves, blood vessels, organs, muscles, bones, and skin. Compression can lead to:
- Numbness, tingling, pain, or paralysis in limbs if nerves are impacted
- Compromised blood flow to extremities or organs if blood vessels are compressed
- Difficulty breathing from a hematoma pushing on the trachea or lungs
- Bowel or bladder dysfunction from pressure on these organs
- Bone erosion if the growing hematoma pushes on bones
- Skin and muscle damage if these tissues are squashed
Surgical drainage is often required to alleviate this pressure before permanent damage occurs. The longer the compression persists, the less chance full function will recover.
Calcification
Without the body’s ability to fully resorb the hematoma, calcium deposits begin collecting in the area. These calcifications cause the hematoma to permanently harden. The blood clot essentially turns into bone.
This bony hard mass can limit mobility and function, especially if over a joint. Calcifications can also destroy surrounding cartilage and bone.
Surgery to remove calcified hematomas is difficult and may only be partially successful. Preventing calcification is ideal, when possible, through early appropriate drainage.
Seek Prompt Medical Care for Severe Hematomas
Minor bruises and hematomas often heal without issue. However, if a hematoma is large, appears to be expanding, or is compressing critical structures, prompt medical evaluation is recommended.
Signs that a hematoma requires urgent care include:
- Rapid swelling and increasing size
- Extreme pain, numbness, or weakness
- Difficulty moving a joint or body part
- Skin discoloration, such as purplish or grey hue
- Coolness or loss of pulses to an extremity
- Shortness of breath or difficulty breathing
- Abdominal pain, nausea, or vomiting
- Altered mental status or confusion
- Fever, pus, or other signs of infection
Depending on the location and severity, the hematoma may be drained surgically or with a needle aspiration. Anti-inflammatory medication, pain management, and antibiotics are also used as needed. Supportive treatments help prevent complications until the injured body can fully absorb and resolve the unwanted blood mass.
With appropriate medical care, most hematomas resolve without permanent effects. However, an untreated hematoma can have devastating consequences over time through repeated bleeding episodes, enlargement, infection, and calcification. Prompt treatment provides the best chance for a quick and full recovery.
Conclusion
A hematoma occurs when a damaged blood vessel leaks blood into surrounding tissue. The blood initially pools as a liquid before coagulating and hardening. Over time, the body works to absorb and clear the unwanted blood. However, this process can lead to complications if the hematoma is large or expanding.
Potential problems include enlargement, infection, pressure on vital structures, and calcification. Small stable hematomas may heal spontaneously. However, larger or worsening ones require medical treatment to drain the blood and prevent permanent effects. Catching a problematic hematoma early is crucial to ensure the best outcome and prevent complications.