Final answer:
To calculate a pressure ulcer's surface area, the nurse requires the ulcer's length and width measurements.
Step-by-step explanation:
To calculate the surface area of a patient's pressure ulcer, a nurse would need to use the measurements of length and width. Once these measurements are taken, they can be multiplied together to find the area. It is important to measure accurately since treatment and monitoring progress depend on these measurements. The depth of the ulcer is also clinically significant but is not used to calculate the surface area; rather, it helps categorize the severity of the ulcer.