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capillary fragility test; tourniquet test
Indications:
- assessment of platelet-vessel wall interactions
Epidemiology:
- rarely performed
Principle:
- increasing the intravascular pressure by inflation of a blood pressure cuff results in gaps between capillary endothelial cells
- extravasation of erythrovytes does not normally occur due to occlusion by platelets
- petechiae form if platelets are decreased or dysfunctional
Procedure:
- with the patient supine, a blood pressure cuff (on upper arm) is inflated to the midpoint between the systolic blood pressure & diastolic blood pressure (< 100 mm Hg) with the pressure maintained for 5 minutes
- the cuff is removed & the arm raised into the air for 1-2 minutes
- petechiae on the arm is a positive test
Related
capillary fragility
General
clinical procedure
References
- Vanderbelt University: Capillary Fragility test
http://www.pathology.vcu.edu/education/PathLab/pages/hemostasis/cotests/capillaryfragility.html