Bloodstain Pattern Analysis Terminology

Note: At the 2009 IABPA meeting in Portland, OR, USA, the IABPA membership voted to adopt the SWGSTAIN recommended terminology.


Expirated Blood
Blood that is blown out of the nose, mouth, or a wound as a result of air pressure and/or air flow which is the propelling force.
Bloodstain Example - Expirated Blood
Bloodstain Example - Expirated Blood


This example was generated by taking blood and mixing it with saliva in the mouth. The blood was then forced out by coughing. Any remaining blood was allowed to flow from the mouth and fall onto the target.

In the image there are several air bubbles, lighter coloured stains, and string-like stains that are not entirely linear. Note that when blood is mixed with saliva, it changes its physical characteristics.

Alternate Terminology

Bevel & GardnerSpatter - Non-linear - Impact - Expectorate
James, Kish & SuttonSpatter - Projection Mechanism - Expirated
WonderSpatter Groups - Impact - Respiratory (Expiration)
SWGSTAINExpiration Pattern - A bloodstain pattern resulting from blood forced by airflow out of the nose, mouth, or a wound.