According to the 'Rule of Nines' for rapid estimation of total body surface area (TBSA) affected by burns in adults, what percentage of TBSA does each arm represent?

Explanation

## Rule of Nines for Adult TBSA Estimation **Key Point:** The Rule of Nines is a rapid field assessment tool that divides the adult body into segments, each representing 9% or multiples of 9% of total body surface area. ### Adult Rule of Nines Distribution | Body Region | TBSA % | |---|---| | Head and neck | 9% | | Each arm (upper limb) | 9% | | Chest | 9% | | Abdomen | 9% | | Each leg (lower limb) | 18% | | Anterior trunk | 18% | | Posterior trunk | 18% | | Perineum/genitalia | 1% | | **Total** | **100%** | **Mnemonic:** **9-18-1 Rule** - **9%:** Head + each arm + chest + abdomen (4 regions × 9%) - **18%:** Each leg + anterior trunk + posterior trunk (3 regions × 18%) - **1%:** Perineum **High-Yield:** Each arm = 9% (front + back combined). This is frequently tested in NEET PG because students confuse it with the 4.5% figure (which applies only to the anterior or posterior surface of one arm, not the entire arm). **Clinical Pearl:** The Rule of Nines is used for rapid triage and fluid resuscitation calculation (Parkland formula: 4 mL × %TBSA × body weight in kg over 24 hours). Accuracy is critical for burn management decisions in the first hours post-injury.