Hess test is done to assess -

Hess capillary resistance test or tourniquet test is done by tying sphygmomanometer cuff to the upper arm and raising it in between diastolic and systolic pressure for 5 minutes. Presence of more than 20 petechiae over the cubital fossa is considered a positive test. The test is positive in increased capillary fragility as well as in thrombocytopenia.