A body recovered from a pond is suspected to have drowned. Water samples from the drowning medium and from the closed organs (brain, bone marrow) are digested and examined microscopically. A positive diatom test supports antemortem drowning because:
- A Diatoms are produced endogenously by decomposition of lung tissue
- B Diatoms multiply rapidly inside the lungs after immersion
- C Diatoms present in water circulate to distant organs only when the heart is still beating ✓
- D Diatoms dissolve in water but persist in bone marrow after death
Correct answer: C. Diatoms present in water circulate to distant organs only when the heart is still beating
Explanation
Diatoms are siliceous unicellular algae present in water. If drowning occurred while alive, active circulation carries diatoms from the lungs into the systemic circulation, lodging them in closed organs such as the brain, kidneys and bone marrow. Finding matching diatoms in these organs supports antemortem drowning. The main criticism is passive contamination and postmortem penetration of diatoms into open organs, which is why closed organs and marrow are sampled, and species matching with the water source is required.
Reference: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy), 34th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.