Postmortem lividity (livor mortis) that does NOT blanch on firm finger pressure after 8–12 hours indicates which postmortem change has occurred?

• A Autolysis of red blood cells within vessels
• B Intravascular thrombosis sealing capillaries
• C Skin develops subcutaneous emphysema from bacterial gas production
• D Haemoglobin diffuses out of vessels into perivascular tissues — postmortem haemolysis and imbibition ✓

Explanation

In the first 6–8 hours, livor mortis is blanchable because blood remains fluid and intravascular — pressure empties the congested capillaries. Beyond 8–12 hours, postmortem haemolysis releases free haemoglobin which diffuses into the perivascular tissues (haemolytic imbibition). Once haemoglobin is extravascular, pressure cannot move it, making lividity fixed and non-blanchable. This fixation time is a key TSD marker and is important for detecting body relocation (secondary livor in a position inconsistent with the fixed livor pattern).

Reference: The Essentials of Forensic Medicine and Toxicology (Narayan Reddy), 34th ed.

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Written and medically reviewed by the StethoPrep medical team.