The most probable causes of graft dysfunction depend on the amount of time that has passed since the transplantation.

Immediate Postoperative Period. After a live donor transplant, the kidney begins functioning right away in roughly 95% of cases. After a deceased donor transplant, however, there may be some degree of DGF, which may last for days, weeks, or even months.

Hyperacute rejection occurs minutes to hours after transplantation, and it is often diagnosed in the operating room immediately after revascularization of the allograft. Such rejection reflects the presence of preformed antibodies that target antigens on the allograft, such as HLA class I proteins, HLA class II proteins, or ABO blood group antigens. A patient may become HLA-sensitized by previous blood transfusions, pregnancies, or prior transplants. No matter the cause, the presence of preformed antibodies leads to rapid immune complex formation, complement-mediated inflammation, and activation of the coagulation cascade with subsequent allograft thrombosis. The allograft is rapidly lost and must be removed. This complication is rarely seen in current transplantation due to preoperative crossmatch testing performed between the recipient serum and donor cells, as described previously.