## Rule of Nines in Adults **Key Point:** The Rule of Nines is the most widely used method for rapid estimation of burn surface area in adults. It divides the body into segments, each representing 9% or multiples of 9% of total body surface area (TBSA). ### Adult Rule of Nines Distribution | Body Region | Percentage of TBSA | | --- | --- | | Head and neck | 9% | | Each upper limb (arm + forearm + hand) | 9% | | Anterior trunk | 18% | | Posterior trunk | 18% | | Each lower limb (thigh + leg + foot) | 18% | | Perineum/genitalia | 1% | | **Total** | **100%** | **High-Yield:** Each lower limb accounts for **18% TBSA** (9% anterior + 9% posterior aspect). This is a fundamental fact tested frequently in NEET PG and INI-CET. **Clinical Pearl:** The Rule of Nines is less accurate for small, localized burns (use the patient's palm = ~1% TBSA for these) and must be modified in children, where the head represents a larger proportion (18%) and each lower limb represents 13.5%. **Mnemonic:** **"9-18-18 Rule"** — Head 9%, each arm 9%, anterior trunk 18%, posterior trunk 18%, each leg 18%, perineum 1%. [cite:Parikh Forensic Medicine 3e Ch 8]
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