Asst test is performed by your doctor in the clinic; patient’s venous blood was placed in sterile plastic tubes and allowed to clot at room temperature for 30 minutes. Then the serum was separated by centrifugation at 500 x g for 15 minutes and kept in aliquots for use in the ASST. Sample (50 µl) of autologous serum and 0.9% sterile saline (for negative control) were separately injected intradermally into the volar aspect of the patient’s forearm skin with 27G needle, leaving gaps of at least three centimetres. A skin prick test with histamine (10 µg/µl) was used as a positive control. Areas known to have been involved in spontaneous wheals in the last 24 hours were avoided. Skin prick tests with histamine were interpreted after 15 minutes. Wheals and flare responses were measured after 30 minutes. A positive ASST was defined as a serum-induced wheal which was both red and had a diameter of 1.5 mm or more than the saline-induced response at 30 minutes.