The rule of nines is used to estimate which aspect of a burn injury?

• A. Age of patient
• B. Burn depth
• C. Total body surface area burned
• D. Infection risk

Answer: (C)

Estimating how much of the body surface is burned is essential for guiding treatment and fluid needs. The rule of nines gives a quick, approximate measure of total body surface area burned by dividing the body into regions that are each about 9% (or multiples) of the total. For an adult, the head and neck account for 9%, each arm 9%, each leg 18%, the chest and back together 36% (split as 18% for the anterior trunk and 18% for the posterior trunk), and the perineum 1%. This TBSA burned figure is used to plan resuscitation and monitor severity, not to judge how deep the burn is, which requires wound assessment. It also doesn’t directly determine age or infection risk, though larger burns can influence those factors. So, the rule of nines is a quick method to estimate the total body surface area burned. In practice, more precise charts (like Lund and Browder) may be used for children, where body proportions differ.