Today, I’m writing about a clinical observation that I’ve not seen documented in the doctor books. Maybe it has and I’ve missed it. You be the judge.

I call this particular observation the “greasy blood” sign. You have probably seen it before in your practice as a trauma professional. It is present when you see blood (usually venous) coming from an extremity puncture wound or laceration. What makes it unique is the presence of what looks like drops of oil floating on the surface of the blood.

Here are some learning points about this “greasy blood” sign:

• What you are actually seeing is fat from bone marrow issuing from an underlying fracture
• It is most commonly seen in blunt trauma with an open fracture
• It generally comes from femur or tib/fib fractures, although I’ve seen it a few times from upper extremity fractures
• If it is associated with a penetrating injury, it is always a gunshot and typically the underlying fracture is very comminuted

Have you seen this sign in your practice? If so, tweet or comment and share any nuances you’ve experienced.