A patient dies 72 hours after suspected arsenic poisoning. At autopsy the stomach contents have been sent for analysis. Mees' lines (transverse white bands on nails) are found. The BEST specimen for confirming arsenic poisoning in this delayed death scenario is:
- A Stomach contents only
- B Urine collected via catheter postmortem
- C Vitreous humour, which concentrates arsenic selectively
- D Scalp hair and nails, which archive arsenic exposure over weeks-to-months ✓
Explanation
Arsenic is deposited in keratin-rich tissues (hair and nails) within 2–4 weeks of ingestion and remains archived for months to years. Scalp hair grows approximately 1 cm/month, so segmental analysis of a 3 cm hair sample can reconstruct 3 months of arsenic exposure history. Mees' lines in nails appear 4–6 weeks after acute exposure and are a clinical indicator. Stomach contents yield arsenic only if ingestion was recent. Urine is the best specimen for acute arsenic exposure (within 1–4 days) but unreliable postmortem. Vitreous does not selectively concentrate arsenic.
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.