What term describes a small blister or sac filled with a clear fluid?

The term that describes a small blister or sac filled with a clear fluid is "vesicle." Vesicles are typically small, fluid-filled lesions on the skin that can appear as a result of various conditions, such as allergic reactions, infections, or skin irritations. They are usually less than 1 centimeter in diameter and can be filled with serous fluid, which is a clear, yellowish liquid.

Understanding the characteristics of a vesicle is crucial for skin care professionals, as it helps in diagnosing skin conditions accurately and providing appropriate treatment. While other terms like bulla refer to larger blisters, wheal describes a raised, itchy area often seen in allergic reactions, and excoriation refers to a scratch or abrasion on the skin, the distinction between these terms is important in the context of skin lesions and their care.