A 28-year-old woman is admitted to the burns unit following a cooking accident. She sustained burns to her entire right upper limb, the anterior surface of her right lower limb, and her entire anterior trunk including the anterior chest and abdomen. A colleague estimates her TBSA as 45%. What is the most likely error in this estimation?

Explanation

## Analyzing TBSA Estimation Errors ### Correct Calculation for This Patient **Key Point:** Precise anatomical localization is critical when applying the Rule of Nines. Counting partial limbs requires careful documentation of anterior vs. posterior surfaces. | Burned Area | TBSA | | --- | --- | | Right upper limb (entire) | 9% | | Right lower limb (anterior only) | 9% | | Anterior trunk | 18% | | **Correct Total** | **36%** | ### The Colleague's Error The colleague calculated **45%**, which is 9% higher than the correct 36%. **Mnemonic:** **TBSA Error Check** — Always verify: (1) Which surfaces? (2) Which limbs? (3) Anterior vs. posterior trunk? **High-Yield:** A common mistake is counting the **entire lower limb (18%)** instead of just the anterior surface (9%). This introduces exactly a 9% discrepancy. - **If entire right lower limb was counted:** 9% + 18% + 18% = 45% ✓ (matches the colleague's error) - **Correct (anterior only):** 9% + 9% + 18% = 36% ### Why This Matters Clinically **Clinical Pearl:** A 9% overestimation can lead to: - Excessive fluid resuscitation (Parkland formula: 4 mL × kg × %TBSA over 24 hours) - Unnecessary ICU admission - Fluid overload complications (pulmonary edema, compartment syndrome) - Increased morbidity and mortality ### Rule of Nines Precision **Warning:** When a limb is partially burned, document the exact surfaces: - Anterior surface of lower limb = 9% - Posterior surface of lower limb = 9% - Entire lower limb = 18% [cite:Park 26e Ch 10]