The diatom test (Incinerator-acid digestion test) in suspected drowning cases is considered positive for antemortem drowning when diatoms are found in which organ?

• A Lung tissue only, since lungs are in direct contact with water
• B Bone marrow of the sternum or femur, indicating haematogenous dissemination ✓
• C Liver and spleen only, since they filter circulating diatoms
• D Brain tissue, since diatoms cross the blood-brain barrier in drowning

Explanation

The diatom test for drowning is most forensically significant when diatoms are found in the bone marrow (particularly of the femur or sternum) rather than just the lungs. Diatoms in the lungs alone can result from postmortem flooding of the airways; however, diatoms reaching the systemic circulation require the heart to be pumping (i.e., the victim was alive and aspirating water). Circulating diatoms are then filtered and deposited in bone marrow, kidneys, liver, and brain — their presence in bone marrow specifically confirms antemortem water aspiration and is considered the most reliable positive diatom test finding.

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.