The Straight Dope

Go Back   Straight Dope Message Board > Main > General Questions

Thread Tools Display Modes
Old 05-18-2001, 07:51 AM
phreesh phreesh is offline
Join Date: Nov 2000
First off, is there a difference between these two things?

Secondly, the mechanism at work here, as I understand it, is that blodd vessels are injured and they break and let blood into the whatever is next to the blood vessel (lower levels of skin, I suppose). Thus, you see a bruise or bed sore.

I have several queries about what you see and how they are repaired.

Why are bruises of different colours? Some are yellowish and some are blue and some are downright black. Also, when they are repaired, where does the blood that was there go? Are there clot problems, or do microscopic amounts generally leave fairly slowly?

That's a lot of ground to cover. Please feel free to tackle them all at once or just one part or another.

Reply With Quote
Old 05-18-2001, 08:02 AM
11811 11811 is offline
Join Date: Nov 2000
I think bruises are the result of a sudden impact. Bruises disappear when the blood trapped beneath the skin is reabsorbed.

Bedsores, also called decubitus ulcers, are from prolonged pressure: from staying in the same position (like in a hospital bed) for long periods of time. The skin starts to break down in a bedsore. Sometimes bedsores go all the way to the bone. I think you have to catch a bedsore very early in its development to cure it.

This information subject to correction.
I hate the people who love me, and they hate me! - Bender, Futurama
Reply With Quote
Old 05-18-2001, 08:04 AM
plnnr plnnr is offline
Join Date: Feb 2000
I believe these are distinctly different things - bruises arise from broken blood vessels in the skin with subsequent bleeding into the tissues. Bed sores are usually found around points where the bed-ridden person's body has been in constant contact with the mattress (bony parts are susecptible, too, IIRC). The weight of the body compresses blood vessels, cuts off the blood supply to patches of skin (which then dies), a sore develops and the necrotic skin is a prime breeding site for additional bacteria. That's why bed-ridden patients are turned every so often - to keep from any one particular spot from being in contact with the bed linen and mattress.
Reply With Quote
Old 05-18-2001, 08:47 AM
shell shell is offline
Join Date: Sep 1999
Bruises and bedsores

From Mosby's Medical, Nursing, and Allied Health Dictionary....

"Bruise (aka contusion, ecchymosis); a bluish discoloration of an area of skin or mucous membrane caused by the extravasation of blood into the subcutaneous tissues as a result of trauma to the underlying blood vessels or fragility of the vessel walls."

In layman's terms it means that someone with a bruise has had blood vessels break, and blood has escaped into the surrounding tissue under the skin.

"Bedsore (aka pressure ulcer, decubitus ulcer, pressure necrotis, pressure sore), an inflammation, sore, or ulcer in the skin over a bony prominence. It results from ischemic hypoxia of the tissues caused by prolonged pressure on them. Pressure ulcers are most often seen in aged, debilitated, immobilized, or cachectic patients. The sores are graded by stages of severity.
Stage one: nonblanchable erythema of intact skin-the heralding lesion of skin ulceration.
Stage two: partial-thickness skin loss involving epidermis and/or dermis.
Stage three: full-thickness skin loss involving damage or necrosis of subcutaneous tissue that may extend down to, but not through, underlaying facia.
Stage four: full-thickness skin loss with extensive destruction, tissue nectosis, or damage to muscle, bone, or supporting structures."

With bedsores, not enough oxygenated blood is able to reach the affected, or sore area. This usually happens over bony areas of the body (the tailbone, for example) when the body has been in one position for too long. Catch it early enough (stage one, hopefully), and it's easily treated. By the time you hit stage three or four however, it becomes difficult to treat and there's a greater chance of infection. I'd post some bedsore links but would rather not inadvertantly interfere with anyone's digestive process.
Reply With Quote
Old 05-18-2001, 09:10 AM
AWB AWB is offline
Join Date: Jun 1999
Originally posted by phreesh
Why are bruises of different colours? Some are yellowish and some are blue and some are downright black. Also, when they are repaired, where does the blood that was there go? Are there clot problems, or do microscopic amounts generally leave fairly slowly?
Black and blue bruises are fairly new injuries. The darkness is usually just an indication of the depth of the injury.

Yellow/brown bruises are bruises on the mend. The blood in them is decomposing down to biliruben, that stuff that makes your feces brown.

You'll see some bruises that are multicolored. They're yellow/brown near the outer perimeter, as that's where the blood is thinnest and the decomposition is more apparent.

I think little if any of the blood in a bruise is recycled. Once it has left a vessel, it's generally gone for good. Pressure in the vessels would keep it from re-entering via the rupture that let it out in the first place. It's just easier for the body to break the blood down and slowly re-absorb its components.
Merry Christmas from Courtney, the cutest child in the world!
Reply With Quote


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Forum Jump

All times are GMT -5. The time now is 05:11 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2016, vBulletin Solutions, Inc.

Send questions for Cecil Adams to:

Send comments about this website to:

Terms of Use / Privacy Policy

Advertise on the Straight Dope!
(Your direct line to thousands of the smartest, hippest people on the planet, plus a few total dipsticks.)

Publishers - interested in subscribing to the Straight Dope?
Write to:

Copyright 2016 Sun-Times Media, LLC.