Kidney Transplantation

Definition

Kidney transplantation is a surgical procedure to remove a healthy, functioning kidney from a living or brain-dead donor and implant it into a patient with non-functioning kidneys.

Purpose

Kidney transplantation is performed on patients with chronic kidney failure, or end-stage renal disease (ESRD). ESRD occurs when a disease or disorder damages the kidneys so that they are no longer capable of adequately removing fluids and wastes from the body or of maintaining the proper level of certain kidney-regulated chemicals in the bloodstream. Without long-term dialysis or a kidney transplant, ESRD is fatal.

Precautions

Patients with a history of heart disease, lung disease, cancer, or hepatitis may not be suitable candidates for receiving a kidney transplant.

Description

Kidney transplantation involves surgically attaching a functioning kidney, or graft, from a brain-dead organ donor (a cadaver transplant) or from a living donor, to a patient with ESRD. Living donors may be related or unrelated to the patient, but a related donor has a better chance of having a kidney that is a stronger biological "match" for the patient.

The surgical procedure to remove a kidney from a living donor is called a nephrectomy. The kidney donor is administered general anesthesia and an incision is made on the side or front of the abdomen. The blood vessels connecting the kidney to the donor are cut and clamped, and the ureter is also cut between the bladder and kidney and clamped. The kidney and an attached section of ureter is removed from the donor. The vessels and ureter in the donor are then tied off and the incision is sutured together again. A similar procedure is used to harvest cadaver kidneys, although both kidneys are typically removed at once, and blood and cell samples for tissue typing are also taken.

Laparoscopic nephrectomy is a form of minimally-invasive surgery using instruments on long, narrow rods to view, cut, and remove the donor kidney. The surgeon views the kidney and surrounding tissue with a flexible videoscope. The videoscope and surgical instruments are maneuvered through four small incisions in the abdomen. Once the kidney is freed, it is secured in a bag and pulled through a fifth incision, approximately 3 in (7.6 cm) wide, in the front of the abdominal wall below the navel. Although this surgical technique takes slightly longer than a traditional nephrectomy, preliminary studies have shown that it promotes a faster recovery time, shorter hospital stays, and less post-operative pain for kidney donors.

Once removed, kidneys from live donors and cadavers are placed on ice and flushed with a cold preservative solution. The kidney can be preserved in this solution for 24-48 hours until the transplant takes place. The sooner the transplant takes place after harvesting the kidney, the better the chances are for proper functioning.

During the transplant operation, the kidney recipient patient is typically under general anesthesia and administered antibiotics to prevent possible infection. A catheter is placed in the bladder before surgery begins. An incision is made in the flank of the patient and the surgeon implants the kidney above the pelvic bone and below the existing, non-functioning kidney by suturing the kidney artery and vein to the patient's iliac artery and vein. The ureter of the new kidney is attached directly to the bladder of the kidney recipient. Once the new kidney is attached, the patient's existing, diseased kidneys may or may not be removed, depending on the circumstances surrounding the kidney failure.

Since 1973, Medicare has picked up 80% of ESRD treatment costs, including the costs of transplantation for both the kidney donor and recipient. Medicare also covers 80% of immunosuppressive medication costs for up to three years, although federal legislation was under consideration in early 1998 that may remove the time limit on these benefits. To qualify for Medicare ESRD benefits, a patient must be insured or eligible for benefits under Social Security, or be a spouse or child of an eligible American. Private insurance and state Medicaid programs often cover the remaining 20% of treatment costs.

Preparation

Patients with chronic renal disease who need a transplant and do not have a living donor register with United Network for Organ Sharing (UNOS) will be placed on a waiting list for a cadaver kidney transplant. UNOS is a non-profit organization that is under contract with the federal government to administer the Organ Procurement and Transplant Network (OPTN) and the national Scientific Registry of Transplant Recipients (SR). Kidney availability is based on the patient's health status. The most important factor is that the kidney be compatible to the patient's body. A human kidney has a set of six antigens, substances that stimulate the production of antibodies. (Antibodies then attach to cells they recognize as foreign and attack them.) Donors are tissue-matched for 0 to 6 of the antigens, and compatibility is determined by the number and strength of those matched pairs. Patients with a living donor who is a close relative have the best chance of a close match.

Potential kidney donors undergo a complete medical history and physical examination to evaluate their suitability for donation. Extensive blood tests are performed on both donor and recipient. The blood samples are used to tissue type for antigen matches, and confirm that blood types are compatible. A panel of reactive antibody (PRA) is performed by mixing white blood cells from the donor and serum from the recipient to ensure that the recipient antibodies will not have a negative reaction to the donor antigens. A urine test is performed on the donor to evaluate his kidney function. In some cases, a special dye that shows up on x rays is injected into an artery, and x rays are taken to show the blood supply of the donor kidney (a procedure called an arteriogram).

Once compatibility is confirmed and the physical preparations for kidney transplantation are complete, both donor and recipient may undergo a psychological or psychiatric evaluation to ensure that they are emotionally prepared for the transplant procedure and aftercare regimen.

Aftercare

Kidney donors and recipients will experience some discomfort in the area of the incision. Pain relievers are administered following the transplant operation. Patients may also experience numbness, caused by severed nerves, near or on the incision.

A regimen of immunosuppressive, or anti-rejection, medication is prescribed to prevent the body's immune system from rejecting the new kidney. Common immunosuppressants include cyclosporine, prednisone, and azathioprine. The kidney recipient will be required to take immunosuppressants for the life span of the new kidney. Intravenous antibodies may also be administered after transplant surgery. Daclizumab, a monoclonal antibody, is a promising new therapy that can be used in conjunction with standard immunosuppressive medications to reduce the incidence of organ rejection.

Transplant recipients may need to adjust their dietary habits. Certain immunosuppressive medications cause increased appetite or sodium and protein retention, and the patient may have to adjust his or her intake of calories, salt, and protein to compensate.

Risks

As with any surgical procedure, the kidney transplantation procedure carries some risk for both a living donor and a graft recipient. Possible complications include infection and bleeding (hemorrhage). The most common complication for kidney recipients is a urine leak. In approximately 5% of kidney transplants, the ureter suffers some damage, which results in the leak. This problem is usually correctable with follow-up surgery.

The biggest risk to the recovering transplant recipient is not from the operation or the kidney itself, but from the immunosuppressive medication he or she must take. Because these drugs suppress the immune system, the patient is susceptible to infections such as cytomegalovirus (CMV) and varicella (chickenpox ). The immunosuppressants can also cause a host of possible side effects, from high blood pressure to osteoporosis. Prescription and dosage adjustments can lessen side effects for some patients.

Normal results

The new kidney may start functioning immediately, or may take several weeks to begin producing urine. Living donor kidneys are more likely to begin functioning earlier than cadaver kidneys, which frequently suffer some reversible damage during the kidney transplant and storage procedure. Patients may have to undergo dialysis for several weeks while their new kidney establishes an acceptable level of functioning.

The success of a kidney transplant graft depends on the strength of the match between donor and recipient and the source of the kidney. Cadaver kidneys have a four-year survival rate of 66%, compared to an 80.9% survival rate for living donor kidneys. However, there have been cases of cadaver and living, related donor kidneys functioning well for over 25 years.

Studies have shown that after they recover from surgery, kidney donors typically have no long-term complications from the loss of one kidney, and their remaining kidney will increase its functioning to compensate for the loss of the other.

Abnormal results

A transplanted kidney may be rejected by the patient. Rejection occurs when the patient's immune system recognizes the new kidney as a foreign body and attacks the kidney. It may occur soon after transplantation, or several months or years after the procedure has taken place. Rejection episodes are not uncommon in the first weeks after transplantation surgery, and are treated with high-dose injections of immunosuppressant drugs. If a rejection episode cannot be reversed and kidney failure continues, the patient will typically go back on dialysis. Another transplant procedure can be attempted at a later date if another kidney becomes available.

Resources

ORGANIZATIONS

American Association of Kidney Patients. 100 S. Ashley Drive, #280, Tampa, FL 33602. (800) 749-2257. 〈http://www.aakp.org〉.

American Kidney Fund (AKF). Suite 1010, 6110 Executive Boulevard, Rockville, MD 20852. (800) 638-8299. 〈http://www.arbon.com/kidney〉.

National Kidney Foundation. 30 East 33rd St., New York, NY 10016. (800) 622-9010. 〈http://www.kidney.org〉.

United Network for Organ Sharing (UNOS). 1100 Boulders Parkway, Suite 500, P.O. Box 13770, Richmond, VA 23225-8770. (804) 330-8500. 〈http://www.unos.org〉.

United States Renal Data System (USRDS). The University of Michigan, 315 W. Huron, Suite 240, Ann Arbor, MI 48103. (734) 998-6611. 〈http://www.med.umich.edu/usrds〉.

OTHER

Transweb. 〈http://www.transweb.org〉.

KEY TERMS

Arteriogram— A diagnostic test that involves viewing the arteries and/or attached organs by injecting a contrast medium, or dye, into the artery and taking an x ray.

Dialysis— A blood filtration therapy that replaces the function of the kidneys, filtering fluids and waste products out of the bloodstream. There are two types of dialysis treatment—hemodialysis, which uses an artificial kidney, or dialyzer, as a blood filter; and peritoneal dialysis, which uses the patient's abdominal cavity (peritoneum) as a blood filter.

Iliac artery— Large blood vessel in the pelvis that leads into the leg.

Immunosuppressive medication— Drugs given to a transplant recipient to prevent his or her immune system from attacking the transplanted organ.

Rejection— The process in which the immune system attacks tissue it sees as foreign to the body.

Videoscope— A surgical camera.