A 32-year-old male farmer is brought to the emergency department with severe burns sustained while working near a sugarcane crushing unit. On examination, he has burns involving both anterior surfaces of the lower limbs, the entire anterior trunk, and the anterior surface of the right upper limb. Using the Rule of Nines, what is the approximate percentage of body surface area (BSA) affected?

Explanation

## Body Surface Area Estimation Using Rule of Nines **Key Point:** The Rule of Nines is the most widely used and rapid method for estimating BSA involvement in burns in adult patients during initial assessment and triage. ### Anatomical Distribution (Rule of Nines) | Body Region | Percentage of BSA | |---|---| | Head and neck | 9% | | Each upper limb (anterior + posterior) | 9% | | Each lower limb (anterior + posterior) | 18% | | Anterior trunk | 18% | | Posterior trunk | 18% | | Perineum/genitalia | 1% | | **Total** | **100%** | ### Calculation for This Case The patient has burns in: 1. **Both anterior lower limbs:** Each lower limb = 18% total (anterior + posterior). Anterior surface only = 9% per limb → **9% × 2 = 18%** 2. **Entire anterior trunk:** **18%** 3. **Anterior surface of right upper limb:** Each upper limb = 9% total. Anterior surface only = **4.5%** **Total BSA = 18% + 18% + 4.5% = 40.5% ≈ 45%** The closest answer among the options is **45% (Option A)**. The original explanation incorrectly rounded 40.5% down to 36% — there is no mathematical or clinical justification for that rounding. 40.5% is unambiguously closest to 45%. **High-Yield:** When only anterior or posterior surfaces are burned, divide the regional percentage by 2. The Rule of Nines assumes bilateral symmetry. (Reference: Parikh's Textbook of Medical Jurisprudence, Forensic Medicine and Toxicology; also consistent with standard surgical texts such as Bailey & Love.) ### Clinical Significance **Clinical Pearl:** Burns exceeding 15% BSA in adults (10% in children and elderly) require IV fluid resuscitation using the Parkland formula: 4 mL × BSA (%) × body weight (kg) of Ringer's lactate over 24 hours, with half given in the first 8 hours. **Warning:** The Rule of Nines is less accurate in children <10 years old (head represents 18%, each lower limb 13.5%) and in the elderly. For small, irregular burns, the **Lund and Browder chart** or **palm method** (patient's palm ≈ 1% BSA) is more accurate. **Mnemonic: "Rule of Nines"** - **9**: Head and neck, each arm - **18**: Each leg, anterior trunk, posterior trunk - **1**: Perineum