Petechia

A petechia, plural petechiae, is a small (1–2 mm) red or purple spot on the skin, caused by a minor bleed (from broken capillary blood vessels).

Petechia refers to one of the three descriptive types of bleeding into the skin differentiated by size, the other two being purpura and ecchymosis. Petechiae are by definition less than 3 mm.

The term is almost always used in the plural, since a single lesion is seldom noticed or significant.

Causes

The most common cause of petechiae is through physical trauma such as a hard bout of coughing, holding breath, vomiting or crying, which can result in facial petechiae, especially around the eyes. Petechiae in this instance are harmless and usually disappear within a few days. Petechiae may be a sign of thrombocytopenia (low platelet counts) when platelet function is inhibited (e.g., as a side effect of medications or during certain infections), or in clotting factor deficiencies. They may also occur when excessive pressure is applied to tissue (e.g., when a tourniquet is applied to an extremity or with excessive coughing or vomiting).