A complex array of serious medical complications can influence recovery of the allograft after liver transplantation. In the peri- and immediate postoperative periods, complications that affect the allograft commonly include primary nonfunction, preservation or ischaemia reperfusion injury, thrombotic (particularly arterial) and nonthrombotic infarction, biliary obstruction and sepsis. The risk of acute (cellular) rejection is greatest in the second postoperative week and can be clinically indistinguishable from other causes of graft dysfunction at this time. Furthermore, the especially high levels of immunosuppression required in the first postoperative month to control acute rejection later predispose the transplant recipient to widespread opportunistic infections. Other potentially serious complications of immunosuppression include renal dysfunction, hypertension, hyperglycaemia, hypercholesterolaemia, hyperuricaemia, central and peripheral neuropathies, osteoporosis and lymphoproliferative disease. Chronic ductopenic rejection can become manifest as early as the second postoperative month and is the greatest obstacle to morbidity-free, long-term survival.

The differential diagnosis of the complications that affect the function and/or histological integrity of the graft may be facilitated by their chronologically distinct pattern of clinical presentation, but other clinical and laboratory investigations are usually required to confirm a diagnosis. Laboratory tests form an essential component of the diagnostic tools available to the transplant surgeon and physician, and changes in such tests may serve to prompt biopsy or a modification of therapy.