Petechiae and purpura: bleeding spots in the skin
Quick facts
- Petechia
- Pinpoint reddish or purplish spot, up to about 2 mm, that does not fade under pressure.
- Purpura
- Larger spot, between about 2 mm and 1 cm, which also does not fade under pressure.
- Cause
- Leakage of blood from the capillaries into the dermis.
- Simple test
- Press with a glass slide or a finger: if it does not blanch, it is bleeding, not vasodilation.
Petechiae and purpura are spots on the skin caused by blood that has escaped from the capillaries into the dermis. A petechia is pinpoint, up to about 2 mm. Purpura is larger, between about 2 mm and 1 cm. Both share one characteristic: they do not fade when the skin is pressed, which sets them apart from redness caused by dilated vessels.
How do you recognize and tell them apart?
| Finding | Size | Fades under pressure? | Note |
|---|---|---|---|
| Erythema | Variable | Yes | Vasodilation, inflammation |
| Petechia | Up to about 2 mm | No | Capillary bleeding |
| Purpura | About 2 mm to 1 cm | No | Slightly larger bleeding |
| Hematoma | Over 1 cm | No | Collection of blood, deeper |
The color changes over the days: from red to purple, then green and yellow, until it disappears. This cycle is the same as for a bruise and helps in guiding the patient.
Why does this come up in HOF practice?
In injectable procedures, small vessels can be injured and cause petechiae or ecchymosis at the site. They also appear in other situations that the professional needs to recognize.
- After puncture or suction: mechanical trauma can produce mild petechiae, which resolve on their own.
- Use of anticoagulants, antiplatelet drugs and supplements: they raise the chance of skin bleeding. Medication history is part of the medical history.
- Clotting or platelet disorders: spontaneous petechiae in several places can indicate a systemic disease. This is a case for referral.
- Differential with a vascular complication: a violaceous, painful spot with a reticulated (lace-like) pattern is not a petechia. It may indicate compromised circulation and must be treated as an emergency. See vascular occlusion and necrosis.
How do you guide the patient?
Most mild post-procedure petechiae and purpura are self-limiting and fade within days. The patient needs to know this beforehand, so as not to be alarmed. They also need a way to reach you in case something changes.
Also known as: hemorrhagic spots, petechiae, purpura.
Frequently asked questions
Is a petechia the same thing as a bruise?
No. A petechia is small and pinpoint. A bruise (hematoma) is a larger collection of blood under the skin that forms an extensive purple area. Both are blood leakage, at different scales.
When does a petechia need medical attention?
When it appears without trauma or a procedure, in large numbers, with fever, malaise or bleeding elsewhere. In those cases the assessment is medical, not aesthetic.