## Rule of Nines in Adult Burns **Key Point:** The Rule of Nines is the standard rapid assessment tool for estimating TBSA involvement in burn injuries, essential for fluid resuscitation planning and triage. ### Adult Distribution (Rule of Nines) | Body Region | 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 = **18%** TBSA (not 9%). This is a common exam trap — students often confuse it with the upper limb percentage. ### Clinical Pearl The Rule of Nines is less accurate in children (head is proportionally larger, lower limbs smaller). Use the **Lund and Browder chart** for pediatric burns for greater precision. ### Mnemonic **"9-18-18-1"** → Head 9%, each arm 9%, anterior trunk 18%, posterior trunk 18%, each leg 18%, perineum 1%. **Warning:** Do not use the Rule of Nines for burns <10% TBSA or for detailed surgical planning — use the Lund and Browder chart instead. 
Sign up free to access AI-powered MCQ practice with detailed explanations and adaptive learning.