Bloodstain Pattern Analysis Terminology

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


Passive Drop
Bloodstain drop(s) created or formed by the force of gravity acting alone.
Bloodstain Example - Passive Drop
Bloodstain Example - Passive Drop


This pattern was generated by allowing blood to drip off the tip of a finger approximately 45 cm above the target. The finger was moved slightly between each drop.

When the blood drop (a sphere) strikes a flat target (a plane) the shape formed on the surface by the blood drop is an ellipse. In cases where the impact angle is 90° the ellipse has the same major and minor axes length which is a circle. Passive drops will vary in shape and size depending on the volume of blood and the surface texture, but will generally be circular.

Alternate Terminology

Bevel & GardnerSpatter Family - Non-linear - Drip
James, Kish & SuttonPassive - Contact/Transfer - Drop - Single
WonderSpatter Groups - Cast-offs - Drip (Passive)
SWGSTAINClosest to Drip Stain - A bloodstain resulting from a falling drop that formed due to gravity.