Wound, Ostomy and Continence Nurses Society (WOCN) Practice Exam

What characterizes a blister?

1. Generalized redness

2. Serous fluid trapped under skin greater than 0.5cm in diameter

3. Scab of dried exudate of body fluid, blood, or pus

4. Serous fluid trapped under skin less than 0.5cm in diameter

The correct answer is: Serous fluid trapped under skin less than 0.5cm in diameter

A blister is characterized by serous fluid trapped beneath the skin, typically at least 0.5cm in diameter. This definition distinguishes blisters from other types of skin lesions and conditions. A blister forms as a protective response to factors such as friction, burns, or other types of injury, resulting in the accumulation of clear, usually sterile fluid in a raised area of the skin. In contrast, the description provided in the incorrect option indicates a blister smaller than 0.5cm, which more accurately describes a vesicle—a similar but distinct lesion type. Generalized redness and scabs of dried exudate do not fit the definition of a blister, as they represent different pathological processes and presentations within dermatological findings. Understanding the specific criteria for blisters versus other formations is essential for accurate diagnosis and treatment in skin care practice.