Putrefaction produces a range of gases and chemicals. Which combination is SPECIFICALLY responsible for the greenish-black skin discolouration seen in putrefaction, beginning in the right iliac fossa?

• A Hydrogen sulphide reacting with haemoglobin to form sulphmethaemoglobin ✓
• B Carbon dioxide accumulation in the subcutaneous tissue
• C Methane production by Clostridium perfringens causing skin emphysema
• D Haemolysis releasing free haemoglobin that stains the dermis

Explanation

The characteristic greenish-black discolouration of putrefaction results from hydrogen sulphide (H₂S) produced by gut bacteria combining with haemoglobin to form sulphmethaemoglobin (green) and iron sulphide (black). The process starts in the right iliac fossa because the caecum harbours the largest bacterial population and lies closest to the anterior abdominal wall. Methane does contribute to skin emphysema (bloating/blistering) but not the colour. Free haemolysis causes postmortem lividities, not the greenish tint.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.