What causes petechiae?

Petechiae are tiny, pinpoint-sized red or purple spots that appear on the skin and are caused by bleeding into the skin or beneath the mucous membrane. This phenomenon occurs due to the rupture of small capillaries, leading to localized bleeding. Various factors can contribute to this type of bleeding, including physical trauma, certain medical conditions, or blood disorders that affect platelet function and blood clotting.

The other options, while they may describe different medical conditions or causes of other symptoms, do not directly relate to the mechanism behind petechiae. For example, the accumulation of fluid in blisters refers to a different skin condition where fluid collects within the outer layer of skin, not bleeding. Increased intracranial pressure may lead to various neurological symptoms or changes in consciousness, but it does not directly cause petechiae. Ruptured blood vessels in the eye typically result in different types of eye-related symptoms, such as subconjunctival hemorrhage, but do not account for petechiae appearing on the skin. Thus, the option regarding bleeding into the skin or mucous membranes accurately identifies the root cause of petechiae.