Which of the following is the MOST appropriate initial treatment for acute rejection of a renal allograft?
Although there are over 10 definitions of DGF1.
Correct Answer: C
Acute rejection typically presents in the first 6 months after renal transplantation and is cell mediated. The incidence of acute rejection has declined with current practices in induction and maintenance of immunosuppression. There are two histological forms of acute rejection, Acute T cell–mediated rejection and acute antibody-mediated rejection. Risk factors include human leukocyte antigen (HLA) mismatches, blood group incompatibility, prolonged cold ischemia time, DGF, and patients with previous episodes of rejection. Most patients are asymptomatic; the first sign is usually a rise in serum creatinine. Worsening hypertension and proteinuria >1 g/d are other signs of acute rejection. Diagnosis is confirmed with allograft biopsy. Treatment is with pulse methylprednisolone in most centers, with the dose and duration of pulse therapy depending on the grade of rejection. Maintenance immunosuppression therapy may also be intensified (eg, aim for higher tacrolimus levels). Antithymocyte globulin is typically used as a secondline agent and is coadministered with glucocorticoid therapy in higher grade rejection or rejection refractory to glucocorticoid pulse therapy. The expected reversal rate for a first episode of acute rejection is 60% to 70% with this regimen. Plasmapharesis can be effective in antibody-mediated rejection, but it is not first-line therapy. Therapy success is indicated by increases in urine output and a decrease in serum creatinine within 5 days of initiating treatment.
References:
A 54-year-old man is 18 months post kidney transplant. He presents with headaches and oliguria. Serum creatinine is 2.5 mg/dL from a baseline of 1.32 post transplant. His blood pressure is 190/101 mm Hg. He has no focal neurological signs. On reviewing his operative note from the kidney transplant, you note that the renal allograft was deemed a “difficult procurement,” and his postoperative course was complicated by delayed graft function (DGF). Biopsy is not consistent with rejection.
Which of the following is the next best step in workup of this patient?
Correct Answer: D
Transplant renal artery stenosis (TRAS) usually occurs between 3 months and 2 years after renal transplantation, but it can present at any time. It is a potentially curable cause of posttransplant hypertension, allograft dysfunction, and graft loss. Renal artery stenosis usually occurs close to the allograft renal artery surgical anastomosis. Risk factors include difficulties in procurement and surgical technique, atherosclerotic disease, cytomegalovirus infection, and DGF. It presents in most cases as refractory hypertension and allograft dysfunction. Although noninvasive imaging modalities such as Doppler ultrasonography, spiral computed tomography, and magnetic resonance angiography are useful in screening for TRAS, arteriography is the definitive diagnostic and treatment modality when TRAS is suspected based on noninvasive tests or clinical presentation. Once identified by arteriography, the stenosis can be corrected directly with angioplasty and stenting. It is important to rule out rejection before arteriography to optimize chances of graft function recovery.
A 63-year-old woman is 5 hours post live donor renal transplant and is complaining of abdominal pain. The nurse looking after the patient notices that the urinary catheter has not drained any urine in the last 90 minutes despite 1:1 replacement of fluids (1 mL of crystalloid infusion for every 1 mL of urine output during the previous hour). Obstruction of the catheter is ruled out.
Which of the following is the most likely cause?
Renal artery thrombosis is a devastating posttransplant complication that usually results in graft loss. Fortunately, it is an uncommon complication occurring in less than 1% of patients. Early identification and intervention is most important. It usually presents with sudden cessation of urine output and a tender, swollen graft. Risk factors include hypotension, hypercoagulable state, and multiple renal arteries. Diagnosis is usually made with color flow Doppler studies. Once the diagnosis is made, urgent surgical exploration and thrombectomy is indicated. Outcomes are unfavorable as the transplanted kidney does not have collateral vessels, and its tolerance of warm ischemia is poor.
Delayed graft function (DGF) after renal transplant is most commonly defined as:
Correct Answer: A
Although there are over 10 definitions of DGF in the literature, it is most commonly defined as the need for dialysis within 7 days of transplantation (69% of studies reviewed between 1984 and 2007 use this criteria for their definition). This definition offers a standard by which centers can report outcomes and define a clinical entity that can be studied to help improve graft and patient survival. It occurs in 20% to 50% of patients receiving a first cadaveric graft. It is characterized by acute tubular necrosis following renal transplantation. DGF occurs more commonly among recipients of deceased donor transplants compared with live donor transplants. DGF has significant effects on graft and patient survival as it can be associated with both acute and chronic allograft nephropathy and increased risk of graft failure. Risk factors include deceased donor and prolonged allograft ischemia times. Studies are currently ongoing to look at pretransplant, intraoperative, and posttransplant interventions that may reduce the risk of DGF and subsequent graft failure. These treatments focus on immunosuppression, ischemic preconditioning, and vasodilatory agents.
Click to expand