Laboratory monitoring of nonrenal allograft rejection.

A variety of methods have been proposed to monitor organ allograft rejection using blood, urine, or body fluids. None of these methods, however, have fulfilled the expectations. Biopsy histology has remained a gold standard in the evaluation of in situ events in the graft. Fine needle aspiration biopsy, although invasive, is less traumatic than needle or open biopsy, particularly during the immediate postoperative course when the frequency of acute cellular rejection is the highest. These histologic and cytologic methods should always be used in combination with other methods of clinical diagnostic tests, particularly infection diagnostics.