A 25 year old female patient has sustained burns to the back of the right arm, front of the entire left leg, and perineum. Using the Rule of Nine, calculate the total body surface area percentage that is burned?

Correct Answer: 22.5%

Correct Answer Explanation (A):

Using the Rule of Nines, the total body surface area burned is:

Back of one arm = 4.5%

Front of one leg = 9%

Perineum = 1%

Total = 14.5%

This method is critical for guiding initial fluid resuscitation and treatment planning. The Rule of Nines is an approximation for adults and is adjusted for children due to different body proportions.

Incorrect Answer Explanations:

22.5%

This total would be consistent with, for example, the entire right arm (9%) + entire left leg (18%), which equals 27% — but even that’s higher. Choosing 22.5% may result from mistakenly adding both the front and back of the left leg (9% + 9%) or assuming both sides of the right arm are burned. This option reflects overestimation.

28%

This figure does not correspond to any combination of the burned areas in the scenario. It likely results from double-counting regions or misapplying the Rule of Nines. It also ignores that only part of the arm and leg are affected.

36%

This is a significant overestimation. It would reflect burns to both arms and legs, which does not match the patient's described injuries. Learners choosing this might confuse front and back surfaces or misapply the 18% total leg rule.