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26318 Silica Clotting Time (SCT)

Silica Clotting Time (SCT)
Test Code: SCT
Synonyms/Keywords

​PTT-LA, Lupus Anticoagulant PTT

Test Components

​SCT ratio

Specimen Requirements
Fasting RequiredSpecimen TypePreferred Container/TubeAcceptable Container/TubeSpecimen VolumeSpecimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
​No​*Platelet Poor Citrated Plasma​Citrated Blue Top Tube (BTT)​0.75 mL​0.75 mL​0.5 mL
Collection Processing Instructions

​One 0.75 mL citrated Blue Top Tube (BTT) plasma aliquot.

If more than one coagulation test is ordered, a separate aliquot is needed for each test

-Collect in Citrated Blue Top Tube (BTT)

-Citrate anticoagulant must be adjusted for HCT >55%

-Tube must be at least 90% full

-Invert completely 3-4 times (without shaking) to mix

*See Instructions for:  Preparation of Platelet Poor Plasma

Specimen Stability Information
Specimen TypeTemperatureTime
​Plasma ​ ​​Room Temp​4 hours
​Refrigerated​4 hours
​Frozen (-70)​6 months
Rejection Criteria

Clotted or Hemolyzed sample

Contamination with IV or Hickman Line fluids

Specimens that thaw during storage or transport

Performing Laboratory Information
Performing LocationDay(s) Test PerformedAnalytical Time

Methodology/Instrumentation

​Marshfield​Monday, Wednesday, Friday​Less than 2 hours​ACL TOP 550
Test Information

​To increase the sensitivity and specificity of the laboratory diagnosis of lupus anticoagulants (LA) both the DRVVT and the SCT should be ordered.  These two tests have been combined as a Lupus Anticoagulant Panel (LAPAN) test order.

Lupus anticoagulant testing (DRVVT and SCT) should not be performed on patients receiving rivaroxaban, apixaban, dabigatran, or warfarin.  For patients on these medications, one may consider anticardiolipin antibody and/or anti-beta-2 glycoprotein 1 antibody testing.

See Lab Clinical Practice Guidlines for more information 

Reference Range Information

SCT ratio:  <=1.16 Negative for LA

SCT ratio:  >1.6 Positive for LA

Outreach CPTs
CPTModifier
(if needed)
QuantityDescriptionComments
​85732​Optical Clot Detection
Synonyms/Keywords

​PTT-LA, Lupus Anticoagulant PTT

Test Components

​SCT ratio

Ordering Applications
Ordering ApplicationDescription
​COM​Silica Clotting Time
Portal​​​Silica Clotting Time
​Cerner​​Silica Clotting Time
If the ordering application you are looking for is not listed, contact your local laboratory for assistance.
Specimen Requirements
Fasting RequiredSpecimen TypePreferred Container/TubeAcceptable Container/TubeSpecimen VolumeSpecimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
​No​*Platelet Poor Citrated Plasma​Citrated Blue Top Tube (BTT)​0.75 mL​0.75 mL​0.5 mL
Collection Processing

​One 0.75 mL citrated Blue Top Tube (BTT) plasma aliquot.

If more than one coagulation test is ordered, a separate aliquot is needed for each test

-Collect in Citrated Blue Top Tube (BTT)

-Citrate anticoagulant must be adjusted for HCT >55%

-Tube must be at least 90% full

-Invert completely 3-4 times (without shaking) to mix

*See Instructions for:  Preparation of Platelet Poor Plasma

Specimen Stability Information
Specimen TypeTemperatureTime
​Plasma ​ ​​Room Temp​4 hours
​Refrigerated​4 hours
​Frozen (-70)​6 months
Rejection Criteria

Clotted or Hemolyzed sample

Contamination with IV or Hickman Line fluids

Specimens that thaw during storage or transport

Test Components

​SCT ratio

Reference Range Information

SCT ratio:  <=1.16 Negative for LA

SCT ratio:  >1.6 Positive for LA

For more information visit:
Performing Laboratory Information
Performing LocationDay(s) Test PerformedAnalytical Time

Methodology/Instrumentation

​Marshfield​Monday, Wednesday, Friday​Less than 2 hours​ACL TOP 550
For billing questions, see Contacts
Outreach CPTs
CPTModifier
(if needed)
QuantityDescriptionComments
​85732​Optical Clot Detection
For most current information refer to the Marshfield Laboratory online reference manual.