## Rule of Nines in Adults **Key Point:** The Rule of Nines is the most widely used method for rapid estimation of total body surface area (TBSA) affected by burns in adults. ### Distribution by Body Region | Body Region | Percentage of TBSA | | --- | --- | | Head and neck | 9% | | Each upper limb (arm + forearm + hand) | 9% | | Chest | 9% | | Abdomen | 9% | | Each lower limb (thigh + leg + foot) | 18% | | Genitalia and perineum | 1% | | **Total** | **100%** | **High-Yield:** Each upper limb accounts for **9% TBSA** — this is a frequently tested fact in burn management and forensic assessment of burn injuries. **Mnemonic:** **"9-18 Rule"** — 9% for head/neck and each arm; 18% for each leg; remainder distributed to trunk and perineum. ### Clinical Application **Clinical Pearl:** The Rule of Nines allows rapid triage and fluid resuscitation calculation (Parkland formula: 4 mL × kg body weight × %TBSA burned) in the acute burn setting. Accuracy is critical for determining hospital admission, transfer to burn centres, and prognostic assessment. **Warning:** The Rule of Nines is less accurate in children (head is proportionally larger: 18%) and in very obese patients. In such cases, the Lund and Browder chart provides more precision. [cite:Vij's Textbook of Forensic Medicine and Toxicology 6e Ch 16]
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