Q:My brother is having a kidney transplant because he has polycystic kidneys. The new kidney will be added in a different spot. His kidneys are very enlarged but won't be removed from his body. Why not?

A:In most cases, even for patients with polycystic kidney disease (a genetic disorder that causes the formation and growth of cysts in the kidneys), surgeons don't remove the person's native kidneys during kidney transplantation. Instead, the surgeon usually places the new kidney in the lower abdomen. The blood vessels of the new kidney are attached to blood vessels in the lower part of the abdomen, just above the leg. The new ureter — the tube through which urine flows out of the kidney — is connected to the bladder.

In some cases, surgeons may have to remove the native kidneys. For patients with polycystic kidney disease, for example, this removal may be necessary because of pain or discomfort, recurrent infection, bleeding from or into the kidney cysts, or extremely large kidneys that prevent a kidney transplant. Evidently, your brother's kidneys, though enlarged, do not pose this problem.

Native kidneys can be removed before transplantation, but there are several reasons doctors don't like to do this. First, removing the kidneys is a major operation that can require six to eight weeks of recovery time. Second, if the person who needs a kidney transplant isn't already undergoing dialysis — an artificial way to remove waste and excess salt and fluid from the blood when your kidneys can't — removing the kidneys requires dialysis to begin immediately. Third, some people require blood transfusions during or after kidney removal. Those transfusions can result in the development of antibodies that can attack and destroy a new kidney. If those antibodies develop, they could prevent a successful transplant.

It is possible for native kidneys to be removed after kidney transplantation if they cause problems such as the ones listed above. This is often preferable to removing them before the transplant because people tend to recover more quickly if they have a functioning kidney. Also, the risk of developing antibodies following blood transfusion is not as great after transplantation because the immunosuppressive drugs given to prevent rejection of the new kidney also fight the creation of antibodies.

If the kidneys must be removed after transplant, the procedure usually involves laparoscopic surgery. The surgeon inserts a tiny camera through a small incision, which allows the surgeon to see the kidney in detail. The surgeon then inserts surgical instruments through two or three additional small incisions and removes the kidneys. Laparoscopic surgery is less invasive than traditional open surgery, typically resulting in less pain after surgery, faster recovery time and less scarring.

Patrick Dean, M.D., transplantation surgery,

Mayo Clinic, Rochester, Minn.

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Medical Edge is an educational resource and doesn't replace regular medical care. E-mail a question to medical edge@mayo.edu or write to Medical Edge from Mayo Clinic, c/o TMS, 2225 Kenmore Ave., Suite 114, Buffalo, NY 14207. For more information, go online to www.mayoclinic.org.

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