According to “rule of nines”, burns involving perineum are:: (A) 1%, (B) 9%, (C) 18%, (D) 27%
Answer is A. Burn Size (% BSA)

Determination of burn size estimates the extent of injury.
Burn size is assessed by Wallace rule of nines (By Alfred Russel Wallace)

Wallace Rule of Nines:

In adults:

- Each upper extremity: 9%
- Head and neck: 9%
- Lower extremities: 18%
- Anterior and posterior aspects of the trunk: 18%
      - Perineum and genitalia: 1%

Children have a relatively larger proportion of body surface area in their head and neck, which is compensated by a relatively smaller surface area in the lower extremities.

 - In infants: Head and neck- 21%; Each leg-13%

Berkow formula is used to accurately determine burn size in children.
For estimating smaller burns: Area of open hand (including palm and extended fingers) of the patient is approximately 1% of TBSA.
This method is helpful in evaluating splash burns and burns of mixed distribution.