Ten years of experience with vascular complications in renal transplantation

Case report: Endovascular treatment of transplant renal artery stenosis in patient with normal color duplex ultrasound of the renal artery

Key Clinical Message

Proper diagnosis and treatment of vascular stenosis which is a possible complication of renal transplant is important in improving patients' quality of life and prognosis.

Abstract

One known consequence among recipients of renal transplants is graft renal artery stenosis. Early identification and therapy are crucial to avoid graft malfunction and the serious consequences that might arise due to elevated hypertension in several organs. We report a rare case of transplant renal artery stenosis in a mid-aged woman who presented with edema, hypertension, and increased creatinine 2 months after kidney transplant. The patient had normal renal arterial resistive index (RI) and perfusion index (PI), and there was only a modest decrease in perfusion on duplex ultrasound. Following the patient's renal stenting treatment, angiographic resolution was observed. After 14 days of regulated blood pressure following renal artery stenting, she was discharged from the hospital with her edema resolved. Considering complications in patients with clinical manifestations such as hypertension resistant to treatment and graft dysfunction, vascular stenosis is a notable issue to consider even in the context of normal renal arterial RI, PI, and duplex ultrasound. Proper diagnosis and treatment are of importance to improve patients' quality of life and prognosis.

A Rare Case of an Infectious Pseudoaneurysm due to Aspergillus flavus in the Setting of Renal Transplant

Renal transplant as a treatment option for end-stage renal disease (ESRD) is becoming increasingly prevalent. As with any other surgical intervention, complications may occur, including vascular ones. Pseudoaneurysms are particularly rare, with mycotic aneurysms reported in less than 1% of patients after renal transplant. Here, we present a case of an infected pseudoaneurysm involving the renal artery anastomosis, resulting in the explantation of the transplanted kidney. A 77-year-old man underwent deceased donor renal transplant for ESRD in the setting of diabetes and hypertension. He presented with acute kidney injury; a renal biopsy revealed mild active cellular rejection, treated with high-dose steroids. As renal function continued to deteriorate, a repeat renal biopsy was performed. During ultrasound-guided biopsy of the transplanted kidney, a possible aneurysm proximal to the anastomosis of the renal artery to the right external iliac artery was seen. A pelvic arteriogram showed a large 3 cm x 3.4 cm x 4 cm pseudoaneurysm arising directly off the right external iliac artery with the renal transplant artery filling from the distal side of this aneurysm. The patient was taken to the operation room for a re-exploration of his transplanted kidney and revision of the arterial anastomosis. Intraoperatively, necrotic tissue and purulence within the pseudo-aneurysm were noted with failure to salvage blood supply to the transplanted kidney; both the infected pseudo-aneurysm and renal transplant were resected. A portion of the aneurysm was sent to microbiology for culture; fungal cultures grew Aspergillus flavus. He was treated with isavuconazonium and improved clinically, though he subsequently expired following a sudden cardiac arrest. Given its rarity, most medical professionals will be unfamiliar with this unusual complication in renal transplant patients. Our case highlights the importance of pursuing imaging modalities to help identify vascular complications and discusses how to proceed after diagnosis is made. The importance of knowing this process is paramount in improving future patient outcomes.

Endovascular Management of Atherosclerotic Renal Artery Stenosis: Post-Cardiovascular Outcomes in Renal Atherosclerotic Lesions Era Winner or False Alarm?

Renal artery stenosis (RAS) is frequently associated with severe comorbidities such as reduced renal perfusion, hypertension, and end-stage renal failure. In approximately 90% of patients, renal artery atherosclerosis is the main cause for RAS, and it is associated with an increased risk for fatal and non-fatal cardiovascular and renal complications. Endovascular management of atherosclerotic RAS (ARAS) has been recently evaluated by several randomized controlled trials that failed to demonstrate benefit of stenting. Furthermore, the Cardiovascular Outcomes in Renal Atherosclerotic Lesions study did not demonstrate any benefit over the revascularization approach. In this review, we summarized the available data from retrospective, prospective and randomized trials on ARAS to provide clinicians with sufficient data in order to produce useful conclusions for everyday clinical practice.

Duplex Doppler sonography: is there clinical relevance to elevated renal vein velocity in kidney transplants?

PURPOSE

This study aims to determine a velocity threshold in the main renal vein (MRV) of renal transplants and evaluate the cause and clinical significance of elevated velocity.

METHODS

Maximum MRV velocity from 331 consecutive renal transplant Doppler ultrasounds in 170 patients was recorded. A priori, twice the median MRV velocity was selected as the threshold for elevation. Ultrasounds were divided into "early" and "late" periods based on time after transplantation. Charts were reviewed for outcomes associated with elevated MRV velocity. Endpoints included graft failure or death. Serum creatinine (Cr) levels among groups were compared, and temporal changes in MRV velocity were plotted.

RESULTS

A ≥70 cm/s was chosen as the threshold for elevated MRV velocity. Graft failure and complication/intervention rates were higher only in the "late" group with elevated MRV velocity. There was no association between elevated MRV velocity and death, no predilection for a particular biopsy result, and no difference in Cr levels among groups. The majority of elevated velocities occurred during the immediate postoperative period and resolved without intervention.

CONCLUSIONS

Elevated MRV velocity in the early postoperative period is a transient phenomenon not correlating with outcome or requiring intervention. In the late period, elevated MRV velocity is associated with entities including hydronephrosis, perinephric collections, and arteriovenous fistulae.

Ipsilateral leg swelling after renal transplantation as an alarming sign of Iliac vein stenosis

Iliac vein stenosis is a rare vascular complication of renal transplantation that may compromise allograft function if not recognized and corrected in a timely fashion. Because chronic venous stenosis may remain undiagnosed for several years, a high index of suspicion should be maintained until diagnosing this rare disease. A 56-year-old renal transplant recipient presented with unilateral leg swelling and renal dysfunction 16 years after transplantation. Computed tomography excluded deep vein thrombosis and revealed tight iliac vein stenosis on the side of the renal transplant. Following angiographic confirmation of the stenosis, endovascular treatment was successfully performed with a purposefully designed, self-expanding, venous stent. Ipsilateral leg swelling is an alarming sign for the diagnosis of iliac vein stenosis after renal transplantation. Percutaneous intervention with venous stent placement seems to be a safe and effective treatment of this rare condition.

Fax Extension of the Right Renal Vein With a Remodeled Receptor Saphenous Vein in a Living-Donor Kidney Transplant: A Case Report

The right kidney may be chosen for donor safety as the donor kidney in a living renal transplant. However, the short length of the right renal vein may increase technical difficulties and affect the implanted graft. We report a method that uses the remodeled receptor saphenous vein to reconstruct and extend the transplanted renal vein.

Ultrasonographic features of kidney transplants and their complications: an imaging review

Renal transplantation is the treatment of choice for managing patients with end-stage kidney disease. Being submitted to a very serious surgical procedure, renal transplant recipients can only benefit from follow-up imaging and monitoring strategies. Ultrasound is considered as the principal imaging test in the evaluation of renal transplants. It is an easily applied bedside examination that can detect possible complications and guide further imaging or intervention. In this imaging review, we present essential information regarding the sonographic features of healthy renal transplants, detailing the surgical technique and how it affects the sonoanatomy. We focus on various complications that occur following renal transplantation and their sonographic features by reviewing pertinent literature sources and our own extensive imaging archives.

Identification of risk factors for vascular thrombosis may reduce early renal graft loss: a review of recent literature

Renal graft survival has improved over the past years, mainly owing to better immunosuppression. Vascular thrombosis, though rare, therefore accounts for up to one third of early graft loss. We assess current literature on transplantation, identify thrombosis risk factors, and discuss means of avoiding thrombotic events and saving thrombosed grafts. The incidence of arterial thrombosis was reported to 0.2–7.5% and venous thrombosis 0.1–8.2%, with the highest incidence among children and infants, and the lowest in living donor reports. The most significant risk factors for developing thrombosis were donor-age below 6 or above 60 years, or recipient-age below 5-6 years, per- or postoperative hemodynamic instability, peritoneal dialysis, diabetic nephropathy, a history of thrombosis, deceased donor, or >24 hours cold ischemia. Multiple arteries were not a risk factor, and a right kidney graft was most often reported not to be. Given the thrombosed kidney graft is diagnosed in time, salvage is possible by urgent reoperation and thrombectomy. Despite meticulous attentions to reduce thrombotic risk factors, thrombosis cannot be entirely prevented and means to an early detection of this complication is desirable in order to save the kidneys through prompt reoperation. Microdialysis may be a new tool for this.

High venous pressure in the main renal vein causing development of peritransplant venous collaterals in renal transplant patients: a rare finding

We will show the sonographic appearance of peritransplant venous collaterals in renal transplants with renal venous hypertension. Three cases of renal transplants with pericapsular vessels were identified at our institution. Two cases were related to renal vein thrombosis. The third case had pericapsular vessels secondary to venous hypertension from arterialization of the transplant renal vein by a preexisting right thigh arteriovenous graft. The development of high venous pressures in renal transplants leading to the collaterals' venous drainage has been rarely described. This finding should be recognized as a rare complication of renal transplants but does not necessarily lead to transplant failure.

Close to transplant renal artery stenosis and percutaneous transluminal treatment

Purpose. To evaluate the efficacy of percutaneous transluminal angioplasty (PTA) in the management of arterial stenosis located close to the allograft anastomosis (close-TRAS). Materials and Methods. 31 patients with renal transplants were admitted to our institution because of persistent hypertension and impairment of transplant renal function and underwent angiography for vascular investigation. 27 were diagnosed suffering from transplant renal artery stenosis (TRAS), whereas 4 had severe iliac artery stenosis proximal to the transplant anastomosis (Prox-TRAS). 3 cases of TRAS coexisted with segmental renal arterial stenosis, whereas 3 other cases of TRAS were caused by kinking and focal stenosis in the middle of the transplanted renal artery. Results. Angioplasty and stenting were successfully applied to all patients with iliac artery stenosis as well as to those with TRAS and segmental artery stenosis. Two of three patients with kinking were well treated with angioplasty and stenting, whereas one treated only with angioplasty necessitated surgery. No major procedure-related complications appeared, and the result was decrease of the serum creatinine level and of the blood pressure. Conclusions. PTA is the appropriate initial treatment of TRAS and close-TRAS, with low morbidity and mortality rates, achieving improvement of graft function and amelioration of hypertension.

Parameters of Doppler ultrasound at five days posttransplantation as predictors of histology and renal function at one year

INTRODUCTION

In our center, a Doppler ultrasound (DU) is performed at 5 days after transplantation. The normal upper limit of flow velocity (FV) in the renal artery is 200-250 cm/s. The resistance index (RI) is considered elevated when >0.8. Elevation of the RI can be shown in all the forms of graft dysfunction.

OBJECTIVE

The objective of this study was to evaluate the capacity of the DU to predict the prognosis of graft function and histological damage at 1 year.

METHODS

We examined a retrospective cohort of patients undergoing renal transplantation between January 2004 and May 2007. The renal function was evaluated with serum creatinine measurements and glomerular filtration rate (GFR) estimates by the quadratic Modification of Diet in Renal Disease study equation. The biopsy specimen was evaluated according to the Banff 1997 classification.

RESULTS

The overall average age was 35 years, and 58% of the subjects were men. Eight cases (25.8%) showed abnormal DU. The Delta among those with normal DU was -0.94 versus 0.27 +/- 0.39 with abnormal DU (P < .005). There was no significance as far as the biopsy at 1 year.

CONCLUSIONS

Renal DU allows physicians to suspect complications at the first posttransplantation year. It shows a tendency to elevated blood pressure, as well as increased deterioration of renal function over the first year.

A phase III study of belatacept versus cyclosporine in kidney transplants from extended criteria donors (BENEFIT-EXT study)

Recipients of extended criteria donor (ECD) kidneys are at increased risk for graft dysfunction/loss, and may benefit from immunosuppression that avoids calcineurin inhibitor (CNI) nephrotoxicity. Belatacept, a selective costimulation blocker, may preserve renal function and improve long-term outcomes versus CNIs. BENEFIT-EXT (Belatacept Evaluation of Nephroprotection and Efficacy as First-line Immunosuppression Trial-EXTended criteria donors) is a 3-year, Phase III study that assessed a more (MI) or less intensive (LI) regimen of belatacept versus cyclosporine in adult ECD kidney transplant recipients. The co-primary endpoints at 12 months were composite patient/graft survival and a composite renal impairment endpoint. Patient/graft survival with belatacept was similar to cyclosporine (86% MI, 89% LI, 85% cyclosporine) at 12 months. Fewer belatacept patients reached the composite renal impairment endpoint versus cyclosporine (71% MI, 77% LI, 85% cyclosporine; p = 0.002 MI vs. cyclosporine; p = 0.06 LI vs. cyclosporine). The mean measured glomerular filtration rate was 4-7 mL/min higher on belatacept versus cyclosporine (p = 0.008 MI vs. cyclosporine; p = 0.1039 LI vs. cyclosporine), and the overall cardiovascular/metabolic profile was better on belatacept versus cyclosporine. The incidence of acute rejection was similar across groups (18% MI; 18% LI; 14% cyclosporine). Overall rates of infection and malignancy were similar between groups; however, more cases of posttransplant lymphoproliferative disorder (PTLD) occurred in the CNS on belatacept. ECD kidney transplant recipients treated with belatacept-based immunosuppression achieved similar patient/graft survival, better renal function, had an increased incidence of PTLD, and exhibited improvement in the cardiovascular/metabolic risk profile versus cyclosporine-treated patients.

An overview of renal transplantation: current practice and use of ultrasound

Imaging has played a major role in monitoring the well-being of the renal graft. Ultrasound, in particular, has been extremely helpful for the detection of postoperative complications related to the transplant kidney. From an imaging perspective, the complications of renal transplantation can be categorized into vascular complications, complications related to the collecting systems (urological complications), perinephric fluid collections, and parenchymal complications. Additionally, there are some complications that may occur, secondary to a transplant renal biopsy. To be able to correctly identify the complications associated with renal transplants, one should have a comprehensive understanding of various aspects of the transplant procedure and be familiar with the normal or expected findings after a transplant. This article provides an overview of renal transplantation and discusses the use of various imaging modalities in its evaluation. The various complications associated with renal transplant as well as renal biopsy are elaborated in this article with special emphasis on the use of ultrasound.

Risk factors for early renal graft thrombosis: a case-controlled study in grafts from the same donor

Renal graft thrombosis is an important cause of early graft loss. In a case-controlled analysis including only thrombosed kidneys and their counterparts from the same donors, we found that the right kidney as opposed to the left kidney was the only risk factor for early graft vascular thrombosis. No other recipient, donor, or perioperative factor was significantly associated with the complication. Our findings suggested that implantation of a right kidney might be followed by prophylactic anticoagulant or antiaggregant therapy.

Severe renal vein stenosis of a kidney transplant with beneficial clinical course after successful percutaneous stenting

A 51-year-old renal transplant recipient presented with marked renal function deterioration 13 months after renal transplantation. After exclusion of ureteral obstruction, transplant artery stenosis and acute rejection, the diagnosis of a severe renal vein stenosis was made by an MR scan. After angiographic confirmation of the stenosis, treatment was attempted with percutaneous stent angioplasty. The long-term clinical course was favorable, with marked improvement in renal function. Transplant renal vein stenosis is a rare, but potentially curable, cause of renal allograft functional deterioration.

May-Thurner syndrome in a pediatric renal transplant recipient--case report and literature review

Vascular complications post-renal transplantation are not very common and can be associated with increased risk of graft loss. We report an unusual case of a young, female teenager with asymmetrical leg swelling. After one month of transplantation, the patient developed a rise in serum creatinine with right leg swelling (ipsilateral to transplant) from compression of the iliac vein by a right renal transplant lymphocele, which resolved after lymphocele drainage. Subsequently, left leg swelling (contralateral to transplant) was noticed and the diagnosis of May-Thurner syndrome was made by MRV. The patient was successfully managed with oral Plavix, stockings and leg elevation. The allograft function remained stable at 18 months post-transplant.

A review of sonographic evaluation of renal transplant complications

In this article, we present an overview of renal transplantation with its complications and discuss the abilities and limitations of ultrasound in evaluating these complications. We included renal transplants performed at our institution between 1993 and 2006 and gathered data on more than 1,000 patients who developed graft dysfunction. We analyzed the ultrasound findings in different posttransplant complications and compared our findings with those in published literature. We present this review article that elaborates and categorizes various transplant complications from an ultrasound perspective. Based on imaging evaluation, the complications of renal transplantation can be divided into four major categories: peri-renal, renal parenchymal, renal collecting system, and renal vascular complications. Common complications included acute tubular necrosis, graft rejection, drug nephrotoxicity, hematoma, lymphocele, urinoma, hydronephrosis, and vascular complications. Ultrasound has a key role in identification and management of most of these complications. However, some parenchymal complications may only be diagnosed on renal biopsy. Ultrasound is a very powerful screening tool to assess renal transplant dysfunction and has a primary role in early diagnosis and management of structural and vascular complications, which may need surgical intervention to save the graft.

Complications of renal transplantation: ultrasonographic evaluation

OBJECTIVE

The purpose of this presentation is to show the ultrasonographic findings of complications of renal transplantation.

METHODS

We reviewed the ultrasonographic findings of complications of renal transplantation, including urologic complications, fluid collections, graft dysfunction, vascular complications, neoplasms, and recurrent native renal disease.

RESULTS

Specific ultrasonographic features of complications of renal transplantation have been illustrated.

CONCLUSIONS

Familiarity with the clinical setting and the appearance of potential renal transplant complications as depicted with the most commonly used modality, ultrasonography, will facilitate prompt, accurate diagnosis and treatment.

Donor risk factors for renal graft thrombosis

Graft thrombosis is one of the most devastating complications of transplantation. In obtaining consent prior to transplant, it is useful to share potential risk factors with the recipient. In order to do this, we explored the impact of different risk factors that could contribute to this complication. Using multivariate analysis we found that neither multiple vessels nor vascular injury had a bearing on the risk of graft thrombosis but atheroma did (P < .02).

Mycotic aneurysm of the renal transplant artery

A case of mycotic aneurysm secondary to septicemia is reported. A 59-year-old man with end-stage renal failure underwent renal transplantation from a living donor. On the fifteenth postoperative day, he was febrile and his arm around an entry wound of the drip infusion had infectious signs. Cultures of the blood and pus discharge grew Methicillin-resistant Staphylococcus aureus. Vancomycin was administered intravenously for 30 days. Then the existence of a mycotic aneurysm on the transplant artery was not suspected by computed tomography. After his infectious signs disappeared, examinations revealed a pseudoaneurysm measuring 4 cm in diameter at the site of anastomosis between the renal transplant and external iliac arteries by computed tomography. He has been carefully followed up with a conservative management. This is the first case of a mycotic aneurysm treated conservatively and displaying an uneventful course without rupture.

Interventional therapy of vascular complications following renal transplantation

Renal transplantation is accepted as the preferred treatment for most cases of end-stage renal disease. Postoperative vascular complications include stenosis or thrombosis of the transplant renal artery or arteriovenous fistulas after biopsy. Impaired arterial perfusion of the transplant may be the leading cause for graft dysfunction or refractory hypertension. Therefore, non-invasive imaging modalities are required to detect and locate vascular complications with high accuracy. Doppler ultrasound is suited as a screening method for the detection of impaired graft perfusion. Magnetic resonance imaging (MRI) is used for an accurate diagnosis of vascular complications and to support decision for appropriate surgical or interventional treatment. Minimal invasive techniques like percutaneous transluminal angioplasty and stent placement have evolved as safe procedures with a high technical success rate reducing substantial morbidity. They can be considered as an alternative to surgical treatment of transplant renal artery stenosis (TRAS). Embolization of severe arteriovenous fistulas is the method of choice if the feeding artery can be occluded through a microcatheter. In selected cases, even catheter-guided fibrinolytic treatment of arterial thrombosis might be considered, if instantaneous surgery is considered a high-risk procedure. This article reviews the imaging features of common vascular complications after renal transplantation with focus on MRI. In addition, interventional radiological techniques are described for the treatment of TRAS, acute thrombotic occlusion, and arteriovenous fistulas.

Complications of renal transplantation

Continued improvements in graft survival have led to widespread acceptance of renal transplantation as the preferred treatment for the majority of patients with end-stage renal disease. The long-term care of these patients is often provided away from transplantation centers. This article presents both the clinical and imaging features of renal transplantation complications and their interventional management. Urologic and vascular complications may occur. Vascular complications include renal artery stenosis and renal artery and renal vein thrombosis. Ultrasound can accurately depict and characterize many of the potential complications of renal transplantation and increasingly magnetic resonance imaging also facilitates this role. In addition, interventional radiologic techniques allow nonsurgical treatment.

Right renal vein elongation with the inferior vena cava for cadaveric kidney transplants: an old neglected surgical approach

INTRODUCTION

Short right renal vein is a frequent and well-known technical inconvenience that is commonly observed during transplantation of the right kidney. We present our experience with the elongation of short cadaveric right renal veins using the contiguous vena cava during cadaveric renal transplants.

METHODS

We performed 34 kidney transplantations with a short right renal vein requiring elongation using the inferior vena cava, to make the venous anastomosis technically feasible. The elongated right renal vein was anastomosed end to side to the external iliac vein in 24 patients, to the common iliac vein in 8 patients and to the inferior vena cava in 2 patients. The right renal artery with an aortic patch was implanted end to side in 33 patients, and end to end without aortic patch to the internal iliac artery in one patient.

RESULTS

In all cases, the vascular anastomoses were easily performed in the recipient and no thrombosis was observed.

CONCLUSION

Elongation of a short right renal vein with the inferior vena cava is a feasible mean to overcome technical problems that may compromise the results of cadaveric renal transplantation.

Study of Surgical Complications Between Primary and Secondary Renal Transplants

INTRODUCTION

In a retrospective study we reviewed the surgical complications of primary and secondary renal transplants in 1108 consecutive renal transplants.

PATIENTS AND METHODS

Between 1992 and 2001, 1108 consecutive renal transplants were performed using living related and unrelated donors. Sixty-five second grafts (group 1) were performed in patients of mean age 34.5 (range 18 to 55) and 1043 primary renal transplants (group 2) in patients of mean age 38.2 (range 10 to 63). One case in group 1 and 94 cases in group 2 were diabetic patients. Factors analyzed were vascular, wound, ureteral, and lymphocele complications.

RESULTS

The follow-up period ranged from 10 to 120 months (average 27.3). The mean creatinine level in patients with active grafts was 1.45 mg/dL. The last creatinine levels in the two groups were not significantly different. The rates of surgical complications were 4.6% in group 1 and 3.8% in group 2, including vascular complications (one case in group 1 and 16 in group 2), wound problems (nobody in group 1 and seven cases in group 2), lymphocele (two cases in group 1 and eight cases in group 2), and ureteral complications (nobody in group 1 and nine cases in group 2). The incidence of complications between the two groups did not show a significant difference (P = .72).

CONCLUSION

With some changes in the standard operation, surgical complications in second renal transplants are not more frequent than among the primary transplants. Therefore, we strongly recommend a second renal transplant when the primary graft has failed.

Vascular and nonvascular complications of renal transplants: sonographic evaluation and correlation with other imaging modalities, surgery, and pathology

Cadaveric or living donor renal transplantation is commonly performed in individuals with end-stage renal disease. In recent years, gray-scale sonography, coupled with color Doppler sonography (CDUS), power Doppler sonography (PDUS), or spectral Doppler sonography, has become the primary imaging modality for these patients. Postoperative serial sonography is performed to detect complications and aid in posttransplant management. In addition, sonography is used to guide percutaneous aspiration of fluid or biopsy to diagnose rejection or renal and perirenal masses. In this article we discuss the spectrum of sonographic findings, both vascular and nonvascular, of renal transplant complications, including but not limited to renal arterial and venous stenosis and thrombosis, peritransplant collections (lymphoceles, hematomas, urinomas, and seromas), posttransplant lymphoproliferative disorder, and postbiopsy complications (hematomas, pseudoaneurysms, and arteriovenous fistulas). We correlate sonographic findings with those from other imaging modalities (such as angiography, CT, and MRI) and findings at surgery and pathology when possible.

Management of thrombophilia in renal transplant patients

Renal allograft recipients with thrombophilia (a hypercoagulable state) are at higher risk for early allograft loss. Following an episode of allograft renal vein thrombosis in a patient subsequently diagnosed with protein C deficiency, we adopted universal screening for hypercoagulable risk factors. Patients with a history of a thromboembolic event underwent laboratory screening for thrombophilia. Eight patients with a defined hypercoagulable disorder or a strong clinical history of thrombosis even in the absence of hematologic abnormalities were treated with anticoagulation following renal transplantation. We reviewed the outcomes of these eight patients and all renal transplant recipients at our center who developed thrombotic complications after renal transplantation. Since the introduction of universal screening for hypercoagulable risk factors, 235 consecutive transplants were performed without allograft thrombosis. Eight patients with evidence of thrombophilia, recognized before renal transplantation, received perioperative heparin and postoperative oral anticoagulation. Two of these eight patients developed perinephric hematomas requiring evacuation, blood transfusion, and temporary withholding of anticoagulation. Of interest, two of the remaining 227 patients, not identified with thrombophilia before surgery, developed thrombotic complications after renal transplantation. A hypercoagulable disorder was subsequently documented in each. Identifying patients with thrombophilia before transplantation and defining their management presents many challenges. The risk of allograft thrombosis must be weighed against the risk of perioperative bleeding and the need for long-term anticoagulation. Recommendations for managing thrombophilia in renal transplant recipients are suggested based on our experience and review of the literature.

Ultrasonography in renal transplantation

Sonography is a simple, inexpensive, and readily available imaging modality that has become an essential component of the management of renal transplantation. It is indicated in almost all patients with acute renal failure and also is useful in the evaluation of pain, infection, and hematuria and the performance of percutaneous biopsy. Although many aspects of sonography are similar in native and transplanted kidneys, there are important differences and problems unique to the renal allograft, which form the basis for this review. The anatomy of renal transplantation and changes that accompany parenchymal disorders are discussed, but particular attention focuses on problems related to the urinary tract, fluid collections, and vascular disorders. By becoming more familiar with transplant sonography, nephrologists will be better able to incorporate this indispensable tool into the care of their patients.

Acute thrombosis of renal transplant artery: graft salvage by means of intra-arterial fibrinolysis

BACKGROUND

Arterial thrombosis in a transplanted kidney is a serious complication that usually leads to graft loss. The purpose of our study was to evaluate intra-arterial fibrinolysis as a treatment of acute renal transplant artery thrombosis and to determine the maximum period of occlusion allowing a reasonable chance of graft salvage.

METHODS AND RESULTS

Four patients underwent intra-arterial fibrinolysis for acute transplant artery thrombosis. Transplantations had been performed 29 days to 10 years before the fibrinolysis. Fibrinolysis was carried out by using recombitant tissue plasminogen activator (n=1) or urokinase (n=3). In one patient, anuric for 13 hr at admittance, fibrinolysis could not revascularize the graft artery. In a second patient, anuric for 48 hr at admittance, fibrinolysis did revascularize the graft artery, but dialysis could not be discontinued. In the two remaining patients, anuric for 19 and 20 hr at admittance, the graft artery was successfully revascularized and dialysis could be discontinued 1 week later. One of these two patients returned to dialysis 71 months later because of chronic rejection. Thirty-four months after the acute episode, the remaining patient had a patent artery and did not require dialysis.

CONCLUSIONS

Fibrinolysis seems an efficient treatment that may save transplants after up to 24 hr of the arterial occlusion.

The use of expanded criteria cadaver and live donor kidneys for transplantation

The use of expanded criteria donors (non-traditional donors) can help lessen the current shortage of kidneys available for transplantation. The use of older donors has accounted for a large measure of the increase in the organ donation rate; however, the most significant factors found to impact on transplant success negatively traditionally have been shown to be extremes of donor age and last-hour urine output. Less significant variables affecting success rates are average systolic blood pressure, terminal serum creatinine, and days of hospitalization. With the appropriate selection of organs from expanded donors, acceptable outcomes can be obtained. When living donors are selected properly, kidneys with anatomic variants without pathologic significance can be used safely. Kidneys with a heightened potential for the development of progressive disease should not be transplanted. Efforts to decrease the cold ischemia time by increasing the use of kidneys from expanded criteria donors may improve the outcome of transplantation further. Advances in surgical techniques, preservation solutions, and methods for predicting eventual long-term renal function in kidneys from expanded donors will be critical in allowing precise selection criteria for kidneys for transplantation, resulting in the optimum use of a scarce and precious resource. Until options such as xenotransplantation become clinically feasible, the challenge will be to identify which donor organs previously considered suboptimal can be used safely to expand the organ donor pool.

[Iliac pseudoaneurysm in non-functioning renal graft 10 years after embolization]

The arterial pseudoaneurysms are an infrequent complication or renal transplantation. Depending on her localization, are divided in intra and extrarenal. The first are relacionated with the practice of percutaneous needly biopsy. The seconds are associated with defects of vascular anastomose or infection onsurgical area (with relative precocious presentation). Presentation of case of a iliac pseudoaneurysm in non-functional kidney allograft embolizated ten years before. This pathology, for this clinic gravity, requires urgent surgical treatment.

Renal transplant complications. Minimally invasive management

Advancements in endourology, laparoscopic urology, and interventional radiology continue to influence the contemporary management of renal transplant complications. The successful implementation of these minimally invasive therapies significantly relies on careful patient selection; not all renal transplantation complications are suitable or amenable for this form of management--true for transplant ureteral complications and less so for other potential complications. With such a strategy, renal transplant complications can be managed efficiently and effectively with these minimally invasive modalities to minimize further recipient morbidity while also minimizing potential risk to the recipient and for the renal allograft.

Complications of renal transplantation: evaluation with US and radionuclide imaging

Following renal transplantation, patients are often evaluated with ultrasonography (US) or radionuclide imaging to assess renal function and the presence of possible complications. Both modalities are inexpensive, noninvasive, and nonnephrotoxic. A basic understanding of the surgical techniques commonly used for renal transplantation is useful when imaging these patients in order to recognize complications and to direct further imaging or intervention. The most frequent complications of renal transplantation include perinephric fluid collections; decreased renal function; and abnormalities of the vasculature, collecting system, and renal parenchyma. Perinephric fluid collections are common following transplantation, and their clinical significance depends on the type, location, size, and growth of the fluid collection, features that are well-evaluated with US. Causes of diminished renal function include acute tubular necrosis, rejection, and toxicity from medications. Radionuclide imaging is the most useful modality for assessing renal function. Vascular complications of transplantation include occlusion or stenosis of the arterial or venous supply, arteriovenous fistulas, and pseudoaneurysms. Although the standard for evaluating these vascular complications is angiography, US is an excellent noninvasive method for screening. Other transplant complications such as abnormalities of the collecting system and renal parenchyma are well-evaluated with both radionuclide imaging and US.

Sonography: a useful tool to detect the mechanical causes of renal transplant dysfunction

PURPOSE

The purpose of this study was to evaluate the utility of sonography in distinguishing between mechanical and nonmechanical causes for renal transplant dysfunction.

METHODS

We reviewed all ultrasound examination reports (n = 286) for 63 consecutive patients who received 64 renal transplants. We assessed the sensitivity and specificity of different degrees of hydronephrosis (mild, moderate, or severe) in detecting urinary tract obstruction; different volumes of new or increasing peritransplant fluid in detecting urine leaks; different total volumes of peritransplant fluid in predicting significant compression of the transplant; and Doppler vascular criteria for predicting arterial and venous occlusion.

RESULTS

All mechanical complications were detected (100% sensitivity) with specificities of 91.9% for ureteral obstruction (criterion, moderate hydronephrosis), 83.4% for urine leaks (criterion, any new fluid or any increase), 91.4% for fluid collections that compressed the transplant (criterion, > 100 ml), and 100% for vascular occlusion (criteria, no flow for arterial occlusion; no venous flow and reversal of arterial flow during diastole for venous occlusion).

CONCLUSIONS

Sonography is very useful in distinguishing between mechanical and nonmechanical causes for renal transplant dysfunction. It has high sensitivity and acceptable specificity in this setting.

External iliac vein thrombosis after renal transplantation: treatment by thrombolysis and stent placement: a case report

We present a patient with iliac vein stenosis and thrombosis, which occurred 2 weeks after renal transplantation and were secondary to a perivascular hematic collection. The vein stenosis was identified by color Doppler ultrasonography and venography. Computed tomography demonstrated a perivascular collection. One week later, control venography identified iliac vein thrombosis. The patient underwent pharmacological thrombolysis with local infusion of urokinase for 4 hr, percutaneous transluminal angioplasty, and percutaneous installation of a metallic stent (Wallstent), with immediate favorable results. The patient remains in stable condition at 2 years after the procedure.

Risk factors for vascular thrombosis in pediatric renal transplantation: a special report of the North American Pediatric Renal Transplant Cooperative Study

Vascular thrombosis remains a major cause of graft failure, accounting for 12.2% of failed index transplants and 19.2% of repeat transplants. We conducted a special study to identify the risk factors for vascular thrombosis. A total of 4394 transplants (2060 living donor [LD] transplants and 2334 cadaver donor [CAD] source transplants) were evaluated. The respective vascular thrombosis rates for LD and CAD transplants were 38/2060 (1.8%) and 100/2334 (4.2%) (P<0.001). Univariate analysis showed that the rate of graft loss due to thrombosis was significantly higher in younger children (less than 2 years of age) as compared with older age groups (2-5 years, 6-12 years, and more than 12 years of age) (9.0% vs. 5.5%, 4.4%, and 3.5% for CAD transplant recipients and 3.5% vs. 3.4%, 0.7%, and 1.9% for LD graft recipients). Recipients of kidneys from cadaver donors less than 5 years of age had a significantly higher thrombosis rate (8.3%) than did recipients from older donor groups (5-10 years, 4.5%; greater than 10 years, 3.2%). Recipients of kidneys with cold ischemia time greater than 24 hr also had a higher thrombosis rate (5.6%), as compared with recipients of kidneys with a shorter cold ischemia time (3.2%). Recipients of antilymphocyte therapy on day 0 or day 1 were at dimished risk of graft loss due to thrombosis (2.2% vs. 4.1%, P=0.001). Comparable trends were seen for both LD and CAD organ recipients. LD organ recipients with a history of prior transplantation had a significantly higher rate of thrombosis as compared with those who received a primary transplant (4.6% vs. 1.6%, P=0.005). For both LD and CAD organ recipients, the occurrence of acute tubular necrosis was a significnat risk factor for the development of thrombosis. Regression analysis showed that for LD organ recipients, a history of prior transplantation increased the risk for thrombosis, whereas increasing recipient age had a linear decreasing risk effect. The use of antilymphocyte antibody or cyclosporine on day 0/1 decreased the risk for thrombosis. For CAD kidney recipients, organ cold ischemia time greater than 24 hr increased the risk for thrombosis. The use of antibody induction therapy, donors greater than 5 years of age, and increasing recipient age were factors that decreased the risk for thrombosis.

Delayed graft function in renal transplantation: etiology, management and long-term significance

PURPOSE

In cadaveric renal transplantation a period of delayed graft function postoperatively is not uncommon and often associated with a poor outcome. We reviewed the biology of reperfusion injury and delayed graft function in renal transplantation, as well as its prevention, management and long-term effects.

MATERIALS AND METHODS

The medical literature covering acute tubular necrosis, delayed graft function in renal transplantation and immunology of ischemia reperfusion injury was reviewed.

RESULTS

Delayed graft function is clearly associated with poor allograft survival, and is caused by an interaction of ischemic and immunological factors. Technical and pharmacological maneuvers can improve early function rates. The response to ischemic injury is complex, and may increase graft immunogenicity and promote the chronic proliferative changes seen in chronic allograft nephropathy.

CONCLUSIONS

Improvement in early renal function should be a primary goal in renal transplantation to enhance early and long-term results. Basic research into the injury response may yield insights into renal pathophysiology.

Donor-related secondary haemorrhage complicating renal transplantation

We report two cases of secondary haemorrhage in renal transplant recipients that would appear to relate to their common donor. Our experience confirms the inadequacy of arterial repair in this setting. One patient, a middle aged diabetic male, required excision of his external iliac artery, but recovered without reconstructive surgery. In the second case nephrectomy was performed on day 8 because of accelerated rejection. This was followed by recurrent sepsis due to E. coli, which was implicated in the previous case. Haemorrhage from the donor aortic wall patch occurred 3 weeks later. We now recommend that if secondary haemorrhage occurs, recipients of other organs from the donor should be carefully monitored for evidence of infection. If this is found and a similar organism cultured, consideration to transplant nephrectomy should be made with removal of all donor tissue to avoid the risk of subsequent secondary haemorrhage.