Kidney Transplantation Exam Questions and Answers Fully Solved

Kidney Transplantation Exam Questions and Answers Fully Solved What subset of patients (status and GFR) are potentially acceptable candidates for transplantation? - Answers Patients with CKD and a GFR less than or equal to 20 mL/min What are five absolute contraindications to kidney transplantation? - Answers 1. active malignancy (except skin cancer) 2. acute infection (e.g. osteomyelitis, HIV w/measurable viral load, active HBV/HCV, etc) 3. chronically active systemic diseases (e.g. SLE, vasculitis, cirrhosis) 4. active substance abuse 5. immunological problems (i.e. donor/recipient mismatch) What are some relative contraindications to kidney transplantation? - Answers Advanced cardiopulmonary disease, extensive PVD, severe chronic liver disease, morbid obesity, uncontrolled psychiatric disorder, HIV w/unmeasurable viral load, any chronic illness with a life expectancy of less than 5 years What are three major preoperative immunological considerations? - Answers 1. ABO compatibility 2. HLA compatibility 3. Sensitization to HLA antigens What is likely to happen if an ABO incompatible donor kidney is transplanted? - Answers Hyperacute rejection due to preformed antibodies What are the three major HLA antigens measured in transplantation and which is the most important to match? - Answers A, B, and DR. DR seems to be the most important. (Note: each individual has two alleles of each of these, so there are a total of *six* antigens to match) What are panel reactive antibodies (PRA)? - Answers This is a lab test done with patient serum in which it is screened against a panel of known HLA-typed cells to measure reaction. A highly negative PRA indicates that a patient is less likely to have a reaction to a donor kidney, while a high PRA is predictive of a less favorable outcome. What is a donor-specific antibody? - Answers During PRA screening, it is possible to identify specific anti-HLA antibodies in the recipient's serum and to avoid these antibodies in choosing potential donors. What final crossmatch techniques are used prior to transplantation? - Answers Cytotoxicity assay: recipient serum is mixed with donor cells (e.g. peripheral blood lymphocytes, lymph node cells, etc), complement is added, and cells are observed for death after incubation. Flow cytometry can also be used to get a more accurate measure of reactivity. What are some preoperative measures used to prevent certain types of rejection? - Answers Plasmapheresis, IV immunoglobulin How does sensitization to HLA antigens occur? - Answers Previous exposure to foreign HLA antigens. Most commonly, this occurs in pregnancy and previous transplantation, but it could also occur in patients who have received blood transfusions. What is the difference between warm ischemia time and cold ischemia time? - Answers Warm ischemia time is the amount of time that the organ is disconnected from a blood supply and still at body temperature. Cold ischemia time is the amount of time that the organ is disconnected from a blood supply and kept at a low temperature in a bathing solution. How is a recipient chosen for deceased donor transplants? - Answers A computer-generated list is compiled immediately after HLA typing. The top patient is called, and if there are complications or the patient cannot be located, the next patient is contacted. Occasionally (e.g. with hyperkalemia), pre-operative dialysis is necessary to make the surgery safer. Where is the new kidney placed, and what is done with the recipients other kidney(s)? - Answers The donor kidney is placed extraperitoneally in the iliac fossa via a hockey stick incision. The native kidneys are not removed. What is the most difficult aspect of the transplantation surgery? - Answers Insertion of the fragment of the donor kidney's ureter into the recipient bladder. This requires the creation of a valve in the bladder wall to prevent vesicouretal reflux. How is the initial success of the transplant judged? - Answers Visually. Once the blood supply is connected, a successful transplant kidney will distend to nearly double its former volume and become red with oxygenated blood. If hyperacutely rejected, it will turn brown and appear necrotic (or perhaps white due to rapid clotting). What are some considerations for a differential of low urine output in a transplant patient? - Answers -Acute/chronic issues with the donor (anything that could cause AKI/CKD in a donor would fit here) -Cold/warm ischemia times