Bitter-Almond Odour
Definition
The characteristic smell of hydrogen cyanide, detectable at autopsy in approximately 40% of people (a genetically determined anosmia to HCN). Present in the stomach, lungs, and blood in cyanide-poisoning deaths.
- Associated with
- Hydrogen cyanide poisoning
- Detectable by
- Roughly 40% of examiners (genetic anosmia in the rest)
- Found in
- Stomach, lungs, blood at autopsy
- Field
- Forensic toxicology, chemical asphyxia
Common questions
Why can't an autopsy rely on the absence of bitter-almond odour to rule out cyanide?+
A genetically determined inability to smell hydrogen cyanide affects a substantial minority of people, so a pathologist without that specific anosmia gene may simply be unable to detect the odour even when cyanide is present, making laboratory confirmation necessary regardless of what is or is not smelled.
Where should an examiner check for the bitter-almond odour during autopsy?+
It is most reliably noted on opening the stomach, given that oral ingestion is the common route, though it can also be present in the lungs and blood, so multiple body compartments are checked during the examination.
Related terms
- Carboxyhaemoglobin (COHb)
- The compound formed when carbon monoxide binds to haemoglobin at the oxygen-binding site, with an affinity 200-250 times greater than oxygen. Produces...
- Cherry-Red Livor Mortis
- Bright pink-red post-mortem lividity produced by the spectral absorption shift of carboxyhaemoglobin; also seen in cyanide poisoning and hypothermia. Distinguished from natural...
- Co-Oximetry
- Spectrophotometric analysis of blood that simultaneously quantifies oxyhaemoglobin, deoxyhaemoglobin, carboxyhaemoglobin, methaemoglobin, sulphhaemoglobin, and total haemoglobin by their distinct absorption wavelengths. The primary...
- Cytochrome C Oxidase (Complex IV)
- The terminal electron acceptor in the mitochondrial respiratory chain, inhibited by both cyanide and hydrogen sulphide. Inhibition prevents oxidative phosphorylation and ATP...
- GC-FID
- Gas chromatography with flame ionisation detection. The standard analytical method for quantifying cyanide and methanol in blood and tissue specimens. Provides both...
- Knockdown Pattern (H2S)
- The scene distribution of multiple H2S victims clustered at the entrance or access point of a confined space, as first responders and...
- Sulphhaemoglobin (SHb)
- A modified haemoglobin species in which one or more pyrrole rings is sulphonated by reaction with hydrogen sulphide. Produces green-brown blood and...