(see Roth, Alvin E., Tayfun Sonmezand M.Utku Unver A Kidney Exchange Clearinghouse in New England American Economic Review, Papers and Proceedings, 95,2, May, 2005, 376-380.
As with many discussions of organ transplantation, discussions of efficiency are interspersed with discussions of ethics, and almost no good deed goes unquestioned (recall the story of the kidney doc who donated a kidney to a patient*). The current issue of Transplantation has a comment that takes issue with some of the prior discussion of ethics.
Compatible-Incompatible Live Donor Kidney Exchanges, by David Steinberg,Transplantation, 91(3):257-260, February 15, 2011.
Abstract: "The participation of an immunologically compatible donor-intended recipient pair in a kidney exchange that is unnecessary for them can significantly increase the number of kidneys available for transplantation. Despite their utilitarian value transplant ethicists have condemned this type of organ exchange as morally inappropriate. An opposing analysis concludes that these exchanges are examples of moral excellence that should be encouraged."
*Doctor's unique donation prompts ethical concerns: A Chicago-area nephrologist's gift of a kidney to her patient raises the question of whether doctors should be living organ donors.