What are the characteristics of 3rd degree frostbite?

• A. Freezing of skin and subdermal plexus
• B. Hemorrhagic bullae
• C. Skin necrosis
• D. Numbness

Answer: (A)

The main idea here is the depth of tissue freezing. Third-degree frostbite involves freezing that reaches the skin and the subdermal microvasculature, meaning the damage extends beyond the surface into deeper layers supplied by the subdermal plexus. This deep involvement disrupts blood vessels and tissue viability, leading to a high risk of necrosis as the tissue responds to the severe cold.

Hemorrhagic bullae and skin necrosis can occur with severe frostbite, but they are consequences of deep injury rather than the defining feature. Numbness can occur with frostbite because nerves are damaged, but it isn’t specific to the deepest degree. So the best single descriptor for third-degree frostbite is freezing of skin and the subdermal plexus, which captures the extent of tissue involvement.