Regarding livor mortis, all of the following statements are correct EXCEPT:

Explanation

## Livor Mortis: Pathophysiology and Timeline **Key Point:** Livor mortis is a post-mortem hypostasis caused by gravitational settling of deoxygenated blood in dependent vessels after circulatory cessation. ### Appearance and Timeline | Feature | Details | |---------|----------| | **Color** | Purple-red due to deoxygenated hemoglobin (not oxygenated bright red) | | **Onset** | 30 minutes to 2 hours post-mortem | | **Distribution** | Appears in dependent (lowest) areas of the body, NOT fixed anatomical sites | | **Blanching** | Initially blanches with pressure (reversible); becomes fixed after 8–12 hours | | **Fixation mechanism** | Hemolysis of RBCs and staining of vessel walls and tissue | ### Why Each Statement Is Evaluated **Statement 1 (Correct):** Purple-red color is pathognomonic for deoxygenated hemoglobin; this is the defining feature of livor mortis. **Statement 2 (Correct):** The 30 min–2 hour timeline is the classic teaching point for livor mortis appearance. **Statement 3 (Correct):** Fixation occurs after 8–12 hours due to RBC hemolysis and tissue staining; this is why early livor can be blanched but late livor cannot. **Statement 4 (INCORRECT):** Livor mortis appears in **dependent areas** (lowest points due to gravity), not in fixed anatomical regions like the face and neck. Body position determines livor distribution: - Supine body → livor on back and buttocks - Prone body → livor on face, chest, anterior abdomen - Hanging → livor in legs and lower trunk **Clinical Pearl:** Absence of livor mortis in a dependent area or livor in a non-dependent area suggests the body was moved post-mortem — a crucial forensic finding. **High-Yield:** The distinction between **blanching livor** (early, reversible) and **fixed livor** (late, irreversible) is frequently tested; fixation timing (~8–12 hours) is a key landmark.