Hyperacute rejection occurs within:

Ref. Robbins Pathology. 9th edition. Page. 233   Hyperacute Rejection This form of rejection occurs within minutes or hours after transplantation. A hyperacutely rejecting kidney rapidly becomes cyanotic, mottled, and flaccid, and may excrete a mere few drops of bloody urine. Immunoglobulin and complement are deposited in the vessel wall, causing endothelial injury and fibrin-platelet thrombi Glomeruli undergo thrombotic occlusion of the capillaries, and fibrinoid necrosis occurs in arterial walls. The kidney cortex then under- goes outright necrosis (infarction), and such nonfunctioning kidneys have to be removed.