A body is found with foam in the mouth and nostrils, waterlogged lungs (each weighing >700 g), and emphysema aquosum. Microscopically, alveoli are overdistended with pale material and foreign particles. Which ADDITIONAL autopsy finding would BEST support freshwater rather than saltwater drowning?
- A Hemoconcentration and higher serum sodium on right heart compared to left
- B Hemodilution of left heart blood and lower serum sodium on left side compared to right ✓
- C Presence of bilateral petechial haemorrhages in conjunctiva
- D Haemorrhagic gastric mucosa due to acid aspiration
Correct answer: B. Hemodilution of left heart blood and lower serum sodium on left side compared to right
Explanation
In freshwater drowning, hypotonic aspirated water is rapidly absorbed across alveolar membranes into the pulmonary circulation, causing haemodilution of left heart blood; serum sodium and chloride are lower in the left ventricle than the right. In saltwater drowning, hypertonic seawater draws plasma fluid into alveoli, causing haemoconcentration—higher electrolytes in the right heart. Petechiae occur in both. Gettler's test classically measured this chloride gradient; now electrolyte comparison between left and right cardiac blood is used.
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.