Diatom Test for Drowning
Definition
Acid digestion of bone marrow (femur or sternum) followed by microscopic examination for diatoms. Diatoms in marrow indicate that water was aspirated and circulated while the heart was beating, supporting antemortem drowning.
- Sample sites
- Bone marrow, femur or sternum
- Preparation method
- Acid digestion
- Detection method
- Microscopic examination
- Positive result implies
- Water aspiration while the heart was still beating
Common questions
Why is bone marrow used instead of lung tissue for the diatom test?+
Diatoms found in the lungs alone could have entered passively after death, but reaching the closed marrow cavity of bones such as the femur or sternum requires that the heart was still pumping to carry water through the circulation, which is why marrow presence is taken as stronger evidence of antemortem drowning.
What are the main criticisms of the diatom test?+
Contamination from the surrounding environment, diatom presence in some non-drowning deaths, and the acid digestion procedure itself have all been raised as sources of error, along with the test's dependence on the diatom content of the specific water body, which is why many forensic pathologists treat it as supportive rather than conclusive evidence.
Related terms
- Acetolysis
- Erdtman's 1934 extraction method. The sample is treated with a 9:1 mixture of acetic anhydride and concentrated sulphuric acid, which dissolves cellulose...
- Aperture
- An opening in the pollen wall through which the pollen tube emerges. Classified by shape into pores (porate), furrows (colpate) and combined...
- Diatom
- A microscopic alga with a silica cell wall (frustule) bearing species-specific surface ornamentation. Diatoms are abundant in freshwater, marine, and brackish environments....
- Forensic Palynology
- The application of pollen and spore analysis to legal investigations. A forensic palynologist identifies the species composition of pollen assemblages from crime-scene...
- Frustule
- The silica cell wall of a diatom, composed of two overlapping valves (epitheca and hypotheca). Frustules are taxonomically distinctive, chemically resistant to...
- Pennate vs Centric
- The two morphological groups of diatoms. Pennate diatoms are elongate with bilateral symmetry (Naviculaceae, Pinnularia, Cymbella). Centric diatoms are circular with radial...
- Sexine and Nexine
- The two layers of the pollen exine (outer wall). Sexine is the sculptured outer layer (spines, ridges, reticulum), nexine is the smoother...