by Rob Lamberts, M.D.
What are Bruises?
A reader named Emily recently asked me the following:
“Dr. Rob, can you tell me about bruises? What should I do when I get one? And why do they itch? I’ve always wondered about that.”
The medical term for a bruise is hematoma. Bruises happen when part of the body encounters blunt trauma. You can find good examples of blunt trauma every week on the popular TV show America’s Funniest Videos. On the show, people receive blunt trauma in amazing ways and usually in very unfortunate places. Doctors call blunt trauma to the human body a contusion. AFV is accurate, though, as scientists estimate that 25% of all contusions happen when people stand too close to a piñata.
What Causes Bruises?
So what happens after the cameras stop rolling? The blunt trauma to the unfortunate body causes small blood vessels under the skin to break, letting the blood seep into the surrounding tissue.
Before moving on, I need to mention that that bruises don’t just happen to the skin. You can bruise a bone, your liver, or your brain. The mechanism is the same, blunt trauma leading to blood seeping into the tissue of one of these organs, but it can obviously be more serious. It also has a better chance of winning the $10,000 prize.
So what happens after the blood seeps into the soft tissue? The red blood cells break and spill their insides out into the surrounding tissue. The most significant substance from inside the red blood cells is called hemoglobin. Hemoglobin is the protein that makes blood red. In the bloodstream, it binds to oxygen and carries it from the lungs to the parts of your body that need it. Hemoglobin that is bound to oxygen is bright red, and turns darker and bluish in color when it loses the oxygen. That is why the veins under your skin are blue -- they are the thinner-walled blood vessels that take the blood back to the lungs after the oxygen is taken off.
Why Do Bruises Hurt?
When the red blood cells break open, they release substances that signal the body to bring in the white blood cells. The white blood cells are the paramedics of the body, but instead of using teeny little stretchers, they actually eat the hemoglobin and other things let out by the broken red blood cells. Any paramedics listening to this podcast shouldn’t get any ideas from this. The white blood cells then release more substances that cause the swelling and redness known as inflammation.
Inflammation is what makes the bruise hurt so dang much. The redness and swelling are from the increased blood flow that occur to speed the healing. The pain serves to remind the injured person to steer clear of situations that could cause additional trauma.
Why Do Bruises Turn Colors?
You may have noticed that bruises go through a series of colors before they go away. Maybe you haven’t noticed this, but you have to trust me on this one. If you still don’t believe me, find the nearest piñata, blindfold a kid, and stand real close. You’ll soon have a hematoma of your very own, and you’ll see I speak the truth.
The colors of a bruise appear courtesy of proteins being broken down inside the white blood cells.
The colors of a bruise appear courtesy of proteins being broken down inside the white blood cells. The first color is purple, which is caused by the hemoglobin being broken down and losing its oxygen. That happens immediately after the injury and persists until all of the hemoglobin is broken down. The purple part of a bruise is called ecchymosis.
Let me pause now to take a moment and personally thank whoever made up the word ecchymosis. It is definitely on my top-ten of medical words, and is very handy at parties when you want to impress people.
Not that I would do that.
The first breakdown product of hemoglobin is called biliverdin, which appears within a few days of the contusion. Please don’t confuse biliverdin with Billy Virdon, who was manager of the Pittsburgh Pirates in the 70’s. To my knowledge, Billy Virdon never seeped into soft tissue only to be eaten by white blood cells. Let’s hope not. Biliverdin is green, a color that can sometimes be seen in bruises.
The green biliverdin is then converted to a yellow molecule called bilirubin. That process takes anywhere between a few days and several weeks, depending on the size of the bruise. Once bilirubin is made, it dissolves in the blood stream and is carried off to the liver and kidneys for final processing and excretion. (Is this when the bruise becomes finally healed?)
Some may recognize bilirubin as the substance that causes many babies to turn yellow not long after they are born. That is called jaundice, and happens to babies when their bodies break down special red blood cells they need before they are born. There are other causes of jaundice, but I’ll leave that for another article.
Why Do Bruises Itch?
Which brings me to the question that has kept Emily up at night for all these years: why do bruises sometimes itch? While I couldn’t find a definitive reference on this, I have a pretty good guess. One website I found suggested that histamine (one of the substances released to cause inflammation) is the culprit, but that happens early in the process -- not the time when most of the itching occurs.
I think the itch is caused by bilirubin. It is well known that elevated bilirubin levels can make a person’s skin itch (although it’s not clear why it does). It seems reasonable to conclude that the bilirubin produced by a maturing bruise is the source of the itch. That’s my best guess. If anyone can find a more definitive explanation, please send it my way.
Quick and Dirty Tips For Bruises
Now that you know about what causes bruises, here are my quick and dirty tips on how to deal with bruises.
Tip #1 - Stay away from piñatas
This is self-explanatory.
Tip #2 - Don’t worry about small bruises
Bruises are just part of the body’s process of fixing itself when things get messed up. They shouldn’t be thought of as something bad, but rather just a part of healing. Putting ice on a bruise and taking anti-inflammatory medications (like ibuprofen) can make the pain less, but isn’t necessary unless the bruise is large.
Tip #3 - Consult your doctor for large bruises
Large bruises generally come from bad injuries. Bad injuries don’t always look bad from the outside, hiding the presence of serious problems injuries. Large bruises can also cause a person to become mildly jaundiced and even cause fever. Your doctor can make sure you don’t have internal damage and can help you minimize your pain.
Tip #4 - Seek attention for bruises in certain places
Be careful with bruises on your neck. Neck bruises can compress your windpipe -- even if they don’t look serious from the outside -- and make it difficult to breathe.
Bruises on the nose and ears cause other problems. These structures are comprised of cartilage, which can be damaged significantly in the presence of a bruise. This can result in significant deformity of the nose and ears – something that could threaten your modeling career.
But a hematoma on the head, or a goose egg, is actually not as bad as it looks. These bumps can appear suddenly and can look impressive, but they really aren’t usually that serious. Bruises on the skull have no way to go but out, and so pop out quickly. The presence of a goose egg by itself is not a reason to go to the doctor. Instead look for changes in mental status or loss of consciousness, which could indicate bleeding into the brain.
Tip #5 - Seek medical attention for bruises that occur without injury or multiple unexplained bruises.
Bruises on your back and bruises that appear without cause can be a sign of a serious problem. Treatment with aspirin or other blood thinners can make people more prone to bruises, but so can diseases that compromise the blood’s ability to clot. If you are worried about bruises like this, go to your doctor to make sure it is nothing serious. It is far better to overreact than to stay at home with a serious problem.
Tip #6 - If you get it on film, you could get it in cash
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That’s it for bruises. I hope I didn’t bruise anyone’s ego in the process, and I hope I answered all of Emily’s questions. If you have questions you want answered, send them to email@example.com.
Catch you next time! Stay healthy!