## Body Surface Area Estimation in Burns **Key Point:** The Rule of Nines is the most commonly used rapid bedside method for estimating BSA involvement in adult burns. ### Rule of Nines — Adult Distribution | Body Region | Percentage of BSA | | --- | --- | | Head and neck | 9% | | Each upper limb (anterior) | 4.5% | | Each upper limb (posterior) | 4.5% | | Anterior trunk | 18% | | Posterior trunk | 18% | | Each lower limb (anterior) | 9% | | Each lower limb (posterior) | 9% | | Genitalia | 1% | | **Total** | **100%** | **High-Yield:** The Rule of Nines divides the body into sections of 9% or multiples thereof, making rapid mental calculation feasible in emergency settings. Each arm = 9%, each leg = 18%, anterior trunk = 18%, posterior trunk = 18%, head = 9%, perineum = 1%. **Clinical Pearl:** While the Rule of Nines is quick and useful for triage, the Lund and Browder Chart is more accurate for precise BSA calculation, especially in children and for detailed burn center referral decisions. However, the Rule of Nines remains the standard for initial field assessment and transport decisions. **Mnemonic:** **RULE OF NINES** — Head 9, Each Arm 9, Each Leg 18, Trunk 36 (anterior 18 + posterior 18), Perineum 1 = 100%. [cite:Parikh Textbook of Forensic Medicine Ch 18]
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