What percentage of total body area corresponds to the groin and buttocks in the Rules of Nines?

• A. 9%
• B. 4.5%
• C. 1%
• D. 18%

Answer: (C)

The main idea is how the Rules of Nines assigns fixed percentages to body regions to quickly estimate burn surface area. The groin area (genitalia) is a single region that accounts for 1% of total body surface area. The buttocks aren’t assigned a separate 1% value; they’re part of the posterior trunk, which is 18% in total. So there isn’t a combined “groin plus buttocks” 1% figure to memorize. If a burn involves the groin, you use 1% for that region; if it involves the buttocks, that contribution falls under the posterior trunk’s 18%. Therefore, the best match among the options for the groin area itself is 1%.