Quick Answer: What Is Bodily Fluid Detection Testing?
Bodily fluid detection testing identifies biological substances such as semen, saliva, blood, or urine on personal items. These tests detect specific biological markers that help laboratories determine whether a particular bodily fluid may be present on an item.
What Is Bodily Fluid Detection Testing?
Bodily fluid detection testing is used to determine whether biological fluids may be present on an item such as clothing, bedding, or other personal materials.
These tests are commonly used when investigating biological evidence associated with physical contact or intimate activity.
Laboratories analyze items for markers that indicate the possible presence of specific biological fluids.
Common fluids tested include:
Semen
Saliva
Blood
Urine
Identifying these substances can provide important information about how biological evidence may have been deposited on an item.
Types of Bodily Fluid Detection Tests
Different biological fluids contain unique proteins and chemical markers that laboratories can analyze.
Each fluid type requires specialized testing methods.
Semen Detection Testing
Semen detection testing identifies biological markers associated with seminal fluid.
The semen detection test offered by Validity Genetics is a confirmatory RSID semen detection test that identifies the human-specific protein semenogelin.
Because semenogelin is specific to seminal fluid, detecting this protein provides strong scientific confirmation that seminal fluid may be present on the tested item.
Learn more about semen detection testing here: How Semen Detection Test Work.
Saliva Detection Testing
Saliva detection tests analyze samples for biological markers associated with human saliva.
Saliva may sometimes be found on items such as:
Clothing
Skin-contact surfaces
Personal fabrics
Objects that have been bitten or licked
These tests look for biological substances commonly found in saliva that can help determine whether saliva may be present on the tested item.
Blood Detection Testing
Blood detection testing identifies markers associated with blood.
Blood may sometimes be present on:
Clothing
Fabrics
Bedding
Personal items
Laboratories analyze biological markers associated with blood to determine whether blood may be present on an item.
Urine Detection Testing
Urine detection testing analyzes samples for compounds associated with urine.
Urine may sometimes be detected on:
Clothing
Bedding
Personal fabrics
These tests analyze biological markers associated with urine to determine whether urine may be present on the tested material.
Presumptive vs Confirmatory Testing
Bodily fluid detection testing may involve two types of testing methods.
Presumptive Tests
Presumptive tests are screening tests that suggest the possible presence of a biological fluid.
These tests are often used as an initial step to identify areas of interest on an item.
Examples include:
Acid phosphatase screening tests
PSA screening tests
These tests may indicate that a fluid could be present, but they are not always specific to one biological substance.
Confirmatory Tests
Confirmatory tests are designed to identify biological markers that are specific to a particular fluid.
These tests provide stronger scientific evidence because they detect proteins or markers unique to the biological fluid being tested.
For example, RSID semen detection tests identify semenogelin, a protein specific to human seminal fluid.
Confirmatory testing provides greater confidence when determining whether a specific biological fluid is present.
Items Commonly Submitted for Bodily Fluid Testing
Many different types of personal items may contain biological evidence.
Common examples include:
Underwear
Bedsheets
Towels
Clothing
Blankets
Personal fabrics
These materials can retain biological substances depending on how they were used and stored.
Learn more about items that may be tested here: What Samples Can Be Used For DNA Testing.
How Bodily Fluid Detection Relates to DNA Testing
Bodily fluid detection testing may sometimes be performed alongside DNA testing.
If biological fluid is detected on an item, laboratories may attempt to extract DNA from the material present.
If sufficient DNA is recovered, a DNA profile may be generated and compared to reference samples.
Learn more about how DNA evidence is interpreted here: Using DNA To Prove Cheating.
How Long Biological Evidence May Remain
Biological fluids may remain detectable on fabrics depending on environmental conditions.
Factors that influence detectability include:
Washing
Fabric type
Time
Environmental exposure
Learn more about this topic here: How Long Does DNA Stay on Clothing?
Using Biological Evidence to Understand What Happened
Bodily fluid detection testing provides scientific tools for identifying biological substances on personal items. By detecting markers associated with semen, saliva, blood, or urine, laboratories can help determine whether biological fluids may be present on a tested item.
Understanding how these tests work helps individuals better interpret laboratory findings and determine whether additional DNA testing may be appropriate.
