Imaging of en bloc renal transplants: normal and abnormal postoperative findings

Cadaveric kidneys from donors less than 5 years old, previously considered inferior graft material, are now being successfully transplanted en bloc into children and adults. On the basis of our experience with 132 patients, we describe the general principles of the procedure and review the spectrum of normal and abnormal imaging findings in patients who have undergone this promising transplantation procedure.

Paired cadaveric kidneys obtained from donors less than 5 years old (mean age, 24 months) were transplanted en bloc to 132 patients (mean age, 37 years) at our institution between 1981 and 1991. All available medical, surgical, pathologic, and imaging records were retrospectively reviewed to define the surgical technique, 1-year survival rate of the graft, appearance of the transplant on postoperative imaging studies, and the prevalence of and imaging findings caused by vascular, urinary, infectious, and neoplastic complications after transplantation. Complications were confirmed by a definitive imaging study, surgical exploration, or study of a pathologic specimen.

Paired donor kidneys were transplanted en bloc extraperitoneally into the recipient's right or left iliac fossa, with intact portions of the donor aorta and inferior vena cava anastomosed to the recipient's external iliac artery and vein. One-year graft survival was 70% during the first 8 years of the study and 78% during the last 2 years. Postoperative imaging, particularly sonography and scintigraphy, clearly depicted the normal individual kidneys, urinary collecting systems, and en bloc vasculature. Postoperative complications were vascular (arterial stenoses and thromboses, venous thromboses, and pseudoaneurysms) in 18%, urinary (obstruction and anastomotic leak) in 11%, infectious (caliceal fungal balls) in 1%, and neoplastic (posttransplant lymphoma) in 1%. The complications involved one kidney in 60% of the patients and both kidneys in 40%. The imaging findings caused by these complications were similar to those caused by complications occurring after transplantation of single cadaveric kidneys; however, their detection was more difficult because of the complexity of the en bloc graft.

Because of the shortage of available donor organs, en bloc renal transplantation will most likely become increasingly popular. Familiarity with the imaging appearance of the normal transplant and of posttransplantation complications will allow radiologists to perform effective postoperative imaging evaluations.