Successful eradication of renal allograft abscess by CT-guided percutaneous pigtail drainage: A case report

RATIONALE

Renal allograft abscess is an infrequent complication in kidney transplant recipients. The mainstay of treatment is adequate drainage and optimal antibiotic administration.

PATIENT CONCERNS

A 25-year-old female who presented with dysuria, frequency, chills, fever, and allograft pain was initially diagnosed with a urinary tract infection complicated by septic shock 15 months after kidney transplantation. Ultrasound depicted a hypoechoic mass and contrast-enhanced computed tomography (CT) revealed a lesion with no enhancement in the renal allograft. CT-guided percutaneous pigtail drainage placement was implemented.

DIAGNOSES

Blood-stained pus was aspirated from the lesion in the renal allograft. The aspirate culture revealed Escherichia coli and Proteus mirabilis with an antibiogram consistent to urine culture. The diagnosis of renal allograft abscess originated from urinary tract infection was confirmed.

INTERVENTIONS

The patient underwent CT-guided percutaneous pigtail drainage and conducted culture of the aspirate.

OUTCOMES

The patient's symptoms immediately abated after drainage and renal allograft function recovered normally. Ultrasound and CT showed total regression of the renal allograft abscess at the 1-month outpatient follow-up.

LESSONS

Heightened alertness should be attached to that severe urinary tract infections presenting with sepsis shock and antibiotic treatment non responders are likely to progress to renal allograft abscess in kidney transplant recipients. CT-guided percutaneous pigtail drainage was a safe and effective minimally invasive treatment.

Interventional Management of Vascular Complications after Renal Transplantation

BACKGROUND

 Kidney transplantations are increasing due to demographic changes and are the treatment of choice for end-stage renal disease. Non-vascular and vascular complications may occur in the early phase after transplantation and at later stages. Overall postoperative complications after renal transplantations occur in approximately 12 % to 25 % of renal transplant patients. In these cases, minimally invasive therapeutic interventions are essential to ensure long-term graft function. This review article focuses on the most critical vascular complications after renal transplantation and highlights current recommendations for interventional treatment.

METHOD

 A literature search was performed in PubMed using the search terms "kidney transplantation", "complications", and "interventional treatment". Furthermore, the 2022 annual report of the German Foundation for Organ Donation and the EAU guidelines for kidney transplantation (European Association of Urology) were considered.

RESULTS AND CONCLUSION

 Image-guided interventional techniques are favorable compared with surgical revision and should be used primarily for the treatment of vascular complications. The most common vascular complications after renal transplantation are arterial stenoses (3 %-12.5 %), followed by arterial and venous thromboses (0.1 %-8.2 %) and dissection (0.1 %). Less frequently, arteriovenous fistulas or pseudoaneurysms occur. In these cases, minimally invasive interventions show a low complication rate and good technical and clinical results. Diagnosis, treatment, and follow-up should be performed in an interdisciplinary approach at highly specialized centers to ensure the preservation of graft function. Surgical revision should be considered only after exhausting minimally invasive therapeutic strategies.

KEY POINTS

  · Vascular complications after renal transplantation occur in 3 % to 15 % of patients.. · Image-guided interventional procedures should be performed primarily to treat vascular complications of renal transplantation.. · Minimally invasive interventions have a low complication rate with good technical and clinical outcomes..

CITATION FORMAT

· Verloh N, Doppler M, Hagar MT et al. Interventional Management of Vascular Complications after Renal Transplantation. Fortschr Röntgenstr 2023; DOI: 10.1055/a-2007-9649.

Value and limitations of sonography in kidney transplant recipients with special attention to the resistive index - An update

Kidney transplantation has become the standard treatment for end-stage renal disease. Even though the success rates are high, early and late post-transplant complications remain a major clinical problem due to the risk of graft failure. Therefore, it is of highest interest to early diagnose post-transplant complications. Ultrasound with color coded Duplex analysis plays a crucial role in imaging mechanical and vascular complications. In this article, we give an update of the visualizable complications in kidney transplant recipients and discuss the value of resistive index (RI) measurement with its limitations in allograft rejection.

Wireless implantable optical probe for continuous monitoring of oxygen saturation in flaps and organ grafts

Continuous, real-time monitoring of perfusion after microsurgical free tissue transfer or solid organ allotransplantation procedures can facilitate early diagnosis of and intervention for anastomotic thrombosis. Current technologies including Doppler systems, cutaneous O2-sensing probes, and fluorine magnetic resonance imaging methods are limited by their intermittent measurements, requirements for skilled personnel, indirect interfaces, and/or their tethered connections. This paper reports a wireless, miniaturized, minimally invasive near-infrared spectroscopic system designed for uninterrupted monitoring of local-tissue oxygenation. A bioresorbable barbed structure anchors the probe stably at implantation sites for a time period matched to the clinical need, with the ability for facile removal afterward. The probe connects to a skin-interfaced electronic module for wireless access to essential physiological parameters, including local tissue oxygenation, pulse oxygenation, and heart rate. In vitro tests and in vivo studies in porcine flap and kidney models demonstrate the ability of the system to continuously measure oxygenation with high accuracy and sensitivity.

Successful endovascular management with a covered stent of an external iliac pseudoaneurysm following allograft nephrectomy using CO2 as contrast medium: a case report

Iodinated contrast agents for angiography in chronic kidney disease (CKD) patients could further deteriorate their renal function leading to adverse sequelae. The use of carbon dioxide (CO₂) is reported in the literature and has been safely used for a variety of angiographic procedures, particularly to guide aortic and renal interventions. We report the case of the successful endovascular treatment with a covered stent of a right external iliac artery pseudoaneurysm following graft nephrectomy in a CKD patient, using CO₂ as contrast medium.

Evaluation of Renal Allograft Vasculature Using Non-contrast 3D Inversion Recovery Balanced Steady-state Free Precession MRA and 2D Quiescent-interval Slice-selective MRA

BACKGROUND AND OBJECTIVES

Renal transplant patients often require periodic imaging to evaluate the transplant vessel anastomosis for potential vascular complications. The use of non-contrast enhanced magnetic resonance angiography (NCE-MRA) techniques is encouraged in these patients because they are at increased risk of nephrogenic systemic fibrosis (NSF) due to their renal insufficiency. This study aimed to evaluate the performance of two NCE-MRA techniques (three-dimensional [3D] balanced steady-state free precession [bSSFP] with inversion recovery and quiescent-interval slice-selective [QISS]) for the evaluation of renal allograft vasculature in patients with clinical suspicion, or Doppler ultrasound, or both of arterial anastomotic stenosis.

METHODS

A total of 43 patients were included in this retrospective study. Two radiologists independently scored the images from 3D bSSFP and QISS MRA sequences for image quality and confidence in anastomosis interpretation, and the degree of stenosis at the arterial anastomosis. Correlations with digital subtraction angiography (DSA) were carried out when available. In addition, inter-rater agreement was calculated.

RESULTS

In total, 43 patients underwent QISS and 3D bSSFP MRA. For QISS, all cases were adequate for evaluation. For 3D SSFP, 86% of cases were adequate for evaluation. There was a good-to-excellent inter-rater agreement for all scores and an excellent correlation between NCE-MRA and DSA results when available (12 patients).

CONCLUSIONS

QISS and 3D SSFP showed good inter-rater agreement for image quality and stenosis grade, with more cases being of adequate image quality that used QISS. Further study is required; however, NCE-MRA shows potential as a risk-free alternative to CTA and contrast-enhanced MRA (CE-MRA) for the evaluation of arterial anastomoses in renal transplant patients.

Endovascular Treatment of Transplant Renal Artery Stenosis: A Systematic Review and Meta-analysis

OBJECTIVE

Endovascular treatment through either percutaneous transluminal angioplasty (PTA) alone or stenting has been previously used as a treatment for transplant renal artery stenosis (TRAS). This review aimed to investigate the results of endovascular treatment for renal artery stenosis in transplanted kidneys as compared with the outcomes of interventions, medical management, and graft survival in non-TRAS patients.

METHODS

A systematic review of PubMed, Google Scholar, Cochrane, and Scopus was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines in which studies that reported outcomes of the treatment of TRAS via the endoluminal approach were identified, and their results were meta-analyzed.

RESULTS

Fifty-four studies with a total of 1522 patients were included. A significant reduction of serum creatinine level was found, favoring the stenting group, with a mean difference of 0.68 mg/dL (95% confidence interval (CI), 0.17-1.19; Z=2.60, p=0.0009). Comparison of pre- and post-intervention values of any intervention revealed a significant decrease in overall serum creatinine level (0.65 mg/dL; 95% CI, 0.40-0.90; Z=5.09, p=0.00001), overall blood pressure, with a mean difference of 11.12 mmHg (95% CI, 7.29-14.95; Z=5.59, p=0.00001), mean difference in the use of medications (0.77; 95% CI, 0.29-1.24; p=0.002), and peak systolic velocity (190.05; 95% CI, 128.41-251.69; p<0.00001). The comparison of serum creatinine level between endovascular interventions and best medical therapy favored endovascular intervention, with a mean difference of 0.23 mg/dL (95% CI, 0.14-0.32; Z=5.07, p<0.00001). Graft survival was similar between the treated patients and those without TRAS (hazard ratio, 0.98; 95% CI, 0.75-1.28; p=0.091). The overall pooled success rate was 89%, and the overall complication rate was 10.4%, with the most prevalent complication being arterial dissection.

CONCLUSION

The endovascular treatment of TRAS improves graft preservation and renal function and hemodynamic parameters. PTA + stenting appears to be a more effective option to PTA alone in the stabilization of renal function, with additional benefits from decreased restenosis rates. Further high-quality studies could expand on these findings.

Is Bigger Better? Living Donor Kidney Volume as Measured by the Donor CT Angiogram in Predicting Donor and Recipient eGFR after Living Donor Kidney Transplantation

BACKGROUND

The role of kidney volume measurement in predicting the donor and recipient kidney function is not clear.

METHODS

We measured kidney volume bilaterally in living kidney donors using CT angiography and assessed the association with the donor remaining kidney and recipient kidney (donated kidney) function at 1 year after kidney transplantation. Donor volume was categorized into tertiles based on lowest, middle, and highest volume.

RESULTS

There were 166 living donor and recipient pairs. The mean donor age was 44.8 years (SD ± 10.8), and donor mean BMI was 25.5 (SD ± 2.9). The recipients of living donor kidneys were 64% male and had a mean age of 43.5 years (SD ± 13.3). Six percent of patients experienced an episode of cellular rejection and were maintained on dialysis for a mean of 18 months (13-32) prior to transplant. Kidney volume was divided into tertiles based on lowest, middle, and highest volume. Kidney volume median (range) in tertiles 1, 2, and 3 was 124 (89-135 ml), 155 (136-164 ml), and 184 (165-240 ml) with donor eGFR ml/min (adjusted for body surface area expressed as ml/min/1.73 m2) at the time of donation in each tertile, 109 (93-129), 110 (92-132), and 101 ml/min (84-117). The median (IQR) eGFR in tertiles 1 to 3 in kidney recipients at 1 year after donation was 54 (44-67), 62 (50-75), and 63 ml/min (58-79), respectively. The median (IQR) eGFR in tertiles 1 to 3 in the remaining kidney of donors at 1 year after donation was 59 (53-66), 65 (57-72), and 65 ml/min (56-73), respectively.

CONCLUSION

Bigger kidney volume was associated with better eGFR at 1 year after transplant in the recipient and marginally in the donor remaining kidney.

Renal transplant evaluation: multimodality imaging of post-transplant complications

With advancements in surgical techniques and immuno-suppression, renal transplantation is established as the most effective treatment option in patients with end-stage renal disease. Early detection of renal allograft complications is important for long-term graft survival. Late clinical presentation often causes diagnostic delays till the time allograft failure is advanced and irreversible. Imaging plays a key role in routine surveillance and in management of acute or chronic transplant dysfunction. Multimodality imaging approach is important with ultrasound-Doppler as the first-line imaging study in immediate, early and late post-transplant periods. Additional imaging studies are often required depending on clinical settings and initial ultrasound. Renal functional MRI is a rapidly growing field that has huge potential for early diagnosis of transplant dysfunction. Multiparametric MRI may be integrated in clinical practice as a noninvasive and comprehensive "one-stop" modality for early diagnosis and longitudinal monitoring of renal allograft dysfunctions, which is essential for guiding appropriate interventions to delay or prevent irreversible renal damage. With rapidly increasing numbers of renal transplantation along with improved patient survival, it is necessary for radiologists in all practice settings to be familiar with the normal appearances and imaging spectrum of anatomical and functional complications in a transplant kidney. Radiologist"s role as an integral part of multidisciplinary transplantation team continues to grow with increasing numbers of successful renal transplantation programs across the globe.

Multimodality imaging of pancreas-kidney transplants

Simultaneous pancreas-kidney transplant remains a treatment option for patients with insulin-dependent diabetes mellitus type 1, aimed at restoring normoglycemia, alleviating insulin dependency, avoiding diabetic nephropathy, and thereby improving the quality of life. Imaging remains critical in the assessment of these transplant grafts. Ultrasound with Doppler remains the primary imaging modality for establishing baseline assessment of the graft as well as for evaluating vascular, parenchymal, and perigraft complications. Noncontrast MR imaging is preferred over non-contrast CT for evaluation of parenchymal or perigraft complications in patients with decreased renal function, although contrast-enhanced CT/MR imaging may be obtained following multidisciplinary consultation in cases with high clinical and laboratory suspicion for graft dysfunction. Catheter angiography is reserved primarily for therapeutic intervention in suspected or confirmed vascular complications. An understanding of the surgical techniques and imaging appearance of a normal graft is crucial to identify potential complications and direct timely management. This article provides an overview of surgical techniques, normal imaging appearance, as well as the spectrum of imaging findings and potential complications in pancreas-kidney transplants.

Imaging of Renal Transplant Complications throughout the Life of the Allograft: Comprehensive Multimodality Review

The kidney is the most commonly transplanted solid organ. Advances in surgical techniques, immunosuppression regimens, surveillance imaging, and histopathologic diagnosis of rejection have allowed prolonged graft survival times. However, the demand for kidneys continues to outgrow the available supply, and there are efforts to increase use of donor kidneys with moderate- or high-risk profiles. This highlights the importance of evaluating the renal transplant patient in the context of both donor and recipient risk factors. Radiologists play an integral role within the multidisciplinary team in care of the transplant patient at every stage of the transplant process. In the immediate postoperative period, duplex US is the modality of choice for evaluating the renal allograft. It is useful for establishing a baseline examination for comparison at future surveillance imaging. In the setting of allograft dysfunction, advanced imaging techniques including MRI or contrast-enhanced US may be useful for providing a more specific diagnosis and excluding nonrejection causes of renal dysfunction. When a pathologic diagnosis is deemed necessary to guide therapy, US-guided biopsy is a relatively low-risk, safe procedure. The range of complications of renal transplantation can be organized temporally in relation to the time since surgery and/or according to disease categories, including immunologic (rejection), surgical or iatrogenic, vascular, urinary, infectious, and neoplastic complications. The unique heterotopic location of the renal allograft in the iliac fossa predisposes it to a specific set of complications. As imaging features of infection or malignancy may be nonspecific, awareness of the patient's risk profile and time since transplantation can be used to assign the probability of a certain diagnosis and thus guide more specific diagnostic workup. It is critical to understand variations in vascular anatomy, surgical technique, and independent donor and recipient risk factors to make an accurate diagnosis and initiate appropriate treatment.^©RSNA, 2019.

Percutaneous application of fibrin sealant in surgically recalcitrant urinomas following oncocytoma resection

Surgical application of fibrin sealant is well established as a hemostatic agent. However, reports of its percutaneous application and its uses within the urinary tract are limited. Presented below are two patients with recalcitrant urinomas despite diversion therapy following partial nephrectomy for oncocytomas. Both patients were successfully treated with percutaneous application of fibrin sealant via a sheath at the time of percutaneous perinephric drain removal. Follow-up imaging demonstrated resolution of the urinomas with stabilization of creatinine. Percutaneous application of fibrin sealant may be considered as an alternative treatment for recalcitrant urinomas prior to surgical intervention, though more studies are required to confirm its effectiveness and safety.

Percutaneous transluminal angioplasty alone versus stent placement for the treatment of transplant renal artery stenosis

PURPOSE

The purposes of this retrospective study were to assess the efficacy of endovascular techniques for the treatment of transplant renal artery stenosis (TRAS) by analyzing technical and clinical success and to compare the results of percutaneous transluminal angioplasty (PTA) alone to those of stenting.

MATERIALS AND METHODS

A retrospective analysis was conducted on 31 patients who underwent endovascular treatment for TRAS between January 2012 and December 2017. There were 23 men and 8 women with a mean age of 60.5±14 (SD) years (range: 24-81 years). Ten patients (10/31; 32%; 8 men, 2 women; median age, 63 years) were treated with PTA alone and 21/31 (68%; 15 men, 6 women; median age, 65 years) with metallic stent placement. Several variables including serum creatinine level, glomerular filtration rate, arterial blood pressure value, antihypertensive medication obtained before and after treatment were compared. Technical success was assessed for each procedure. Clinical success was defined as a 15% drop in serum creatinine level, a decrease greater than 15% in mean blood pressure values or a decrease greater than 10% in mean blood pressure values with a reduction in the number of antihypertensive drugs needed for hypertension control.

RESULTS

Technical success was obtained in all patients [31/31; 100%; 95% confidence interval (CI): 89-100%] and clinical success in 27/31 patients (87%; 95%CI: 71-95%). Four patients (4/31; 13%; 95%CI: 5-29%) underwent repeat endovascular intervention. Mean serum creatinine level and mean arterial blood pressure values were significantly lower after treatment (177.4 and 93.8μmol/l, respectively) compared to before treatment (319.4 and 106.7μmol/l, respectively) in the stent group but not in the group treated with PTA alone (P=0.0012 and P=0.002, respectively).

CONCLUSION

The endovascular approach is safe and effective in the management of TRAS and stenting, depending on the morphology of the stenosis, should be the treatment of choice when possible.

Imaging-Related Risk Factors for Bleeding Complications of US-Guided Native Renal Biopsy: A Propensity Score Matching Analysis

PURPOSE

To evaluate imaging-related hemorrhagic risk factors for ultrasound (US)-guided native kidney biopsy.

MATERIALS AND METHODS

A retrospective review was conducted of adult patients who underwent US-guided native kidney biopsy at a single center between January 2006 and March 2016 and identified 37 of 551 patients (6.72%) with postbiopsy bleeding complications, including 11 major complications (2.00%; n = 11) and 26 minor complications (4.72%; n = 26). Ten patients with major complications and 20 with minor complications were matched with 20 control subjects each by propensity score matching based on age, needle size, number of cores, blood pressure, partial thromboplastin time, prothrombin time, platelet count, and estimated glomerular filtration rate.

RESULTS

Biopsy needle passing through the renal sinus was identified in the patients with major (6 of 10; 60%) and minor complications (8 of 20; 40.0%) but not in the control groups. For patients with major complications, the needle-sinus distance was significantly shorter (5.11 mm ± 7.32 vs 11.14 mm ± 3.54; P = .023) and the needle-capsule distance was significantly longer (17.52 mm ± 8.04 vs 9.28 mm ± 3.29; P = .0004) than in control subjects. The bimodal distribution of cortical tangential angles (< 30° or ≥ 60°) in minor complication cases (17 of 20; 85.0%) was significantly greater than in the control group (8 of 20; 40.0%; odds ratio = 8.50; P = .004).

CONCLUSIONS

This study identifies imaging risk factors in US-guided native kidney biopsy and recommends an algorithm to manage them, including appropriate needle path position between the renal capsule and sinus and proper needle cortical tangential angle.

Risk factors for transplant renal artery stenosis after live donor transplantation

Background

Renal transplant surgeons are making increasing use of live donor kidneys with multiple renal arteries. This study aimed to identify independent risk factors for the development of transplant renal artery stenosis (TRAS) in the modern era of complex arterial reconstruction for multiple vessels.

Methods

Multivariable logistic regression analysis with a stepwise variable deletion model was used to identify risk factors for the development of TRAS in a consecutive series of live donor kidney transplants.

Results

Of 506 kidney transplants, 19 (3·8 per cent) had evidence of significant TRAS on CT angiography. Functional TRAS, defined by improvement in BP control or renal function after correction of a stenosis by angioplasty, occurred in 13 of 506 patients (2·6 per cent). Independent risk factors for TRAS were: use of an explanted internal iliac artery graft from the recipient (odds ratio (OR) 4·95; P = 0·020) and total ischaemia time (OR 1·82; P = 0·010). TRAS was associated with a lower 5-year allograft survival rate (79 versus 88·7 per cent; P = 0·020) but only one graft loss was attributed directly to TRAS. The 5-year allograft survival rate after internal iliac artery grafting was 86 per cent.

Conclusion

Although use of an internal iliac artery graft is an independent risk factor for TRAS after live donor kidney transplantation, this technique is still a useful option for complex arterial reconstruction.

Imaging non-vascular complications of renal transplantation

In patients with end-stage renal disease, the treatment of choice for most patients is renal transplantation. Complications that occur after kidney transplant can be broadly divided into vascular and non-vascular categories. Non-vascular complications can further be divided into surgical and medical categories. When evaluating renal transplant imaging, it is helpful to consider the occurrence of complications in a timeline from time of surgery. Ultrasound is often the first modality used for evaluation of renal transplants particularly in the early postoperative period. Contrast-enhanced ultrasound can be a helpful adjunct in evaluating certain complications such as hematoma, rejection, and infection. Computed tomography (CT) is also helpful in accurately diagnosing complications. Surgical complications include perinephric fluid collections (hematoma, urinoma from urine leak, abscess, and lymphocele), urinary obstruction, and incisional fluid collections and hernias. One major category of medical complications that affect the renal parenchyma includes rejection (hyperacute, acute, and chronic), delayed graft function, acute tubular necrosis (ATN), and nephrotoxicity. Infection, renal calculi, and neoplasms such as post-transplant lymphoproliferative disease are medical complications that occur after renal transplantation. It is important for radiologists to be aware of the ultrasound and CT findings of the surgical and medical complications after renal transplant for prompt identification and treatment.

Standardized Duplex Ultrasound-Based Protocol for Early Diagnosis of Transplant Renal Artery Stenosis: Results of a Single-Institution Retrospective Cohort Study

Transplant renal artery stenosis (TRAS) is the most frequent vascular complication after kidney transplantation (KT) and has been associated with potentially reversible refractory hypertension, graft dysfunction, and reduced patient survival. The aim of the study is to describe the outcomes of a standardized Duplex Ultrasound- (DU-) based screening protocol for early diagnosis of TRAS and for selection of patients potentially requiring endovascular intervention. We retrospectively reviewed our prospectively collected database of KT from January 1998 to select patients diagnosed with TRAS. The follow-up protocol was based on a risk-adapted, dynamic subdivision of eligible KT patients in different risk categories (RC) with different protocol strategies (PS). Of 598 patients included in the study, 52 (9%) patients had hemodynamically significant TRAS and underwent percutaneous angioplasty (PTA) and stent placement. Technical and clinical success rates were 97% and 90%, respectively. 7 cases of restenosis were recorded at follow-up and treated with re-PTA plus stenting. Both DU imaging and clinical parameters improved after stent placement. Prospective high-quality studies are needed to test the efficacy and safety of our protocol in larger series. Accurate trial design and standardized reporting of patient outcomes will be key to address the current clinical needs.

Transplant renal artery stenosis caused by the stretch of an artey branch: a case report and literature review

Background

Renal transplant is the preferred treatment option for these patients with end-stage renal disease. Transplant renal artery stenosis (TRAS) is one of the most common and serious vascular complications after renal transplantation, and most of the TRAS occurred in the anastomosis. The complication must be diagnosed and treated timely, otherwise the function of transplanted kidney may be losed.

Case presentation

A 46-year-old male with end-stage renal disease of unknown cause received a cadaveric renal transplant one year ago. Although three antihypertensive medications were administrated, his blood pressure gradually increased to 190/120 mmHg 3 weeks posttransplantation. Also the level of creatinine increased to 194 μmol/L.Color Doppler ultrasonography indicated a decreased resistance index (RI) in intrarenal arteries and increased blood flow of the transplant renal artery, therefore, a vascular complication of TRAS was suspected. Arteriography was performed and demonstrated TRAS caused by stretch of an artery branch, and the TRAS occurred in the distal site of the anastomosis instead of the anastomosis. Percutaneous transluminal bare stent implantation treatment was successfully performed. Satisfactory clinical efficacy with improvement in transplant renal function and renovascular hypertension was achieved after the interventional treatment.

Conclusion

To our knowledge this is the first reported case of TRAS caused by stretch of an artery branch. When refractory hypertension and allograft dysfunction are presented posttransplantation, TRAS should be suspected. Color Doppler ultrasonography as a non-invasive examination may provide some valuable information, three-dimention CT can be useful for further diagnosis, but is seldom necessary. Arteriography provides the definitive diagnosis of TRAS. Percutaneous transluminal stent implantation treatment of TRAS has high success rate with minimal invasion and complications. When an artery branch situated on the stenosis, a bare stent rather than covered stent is the preferred choice.

Vascular Complications After Renal Transplant: A Single-Center Experience

OBJECTIVES

Despite surgical and medical advances, vascular complications are still among the major concerns after renal transplant, with a reported incidence of 3% to 15%. We evaluated the incidence and management of our transplant team 's vascular complications over 40 years.

MATERIALS AND METHODS

From November 1975 to the present, we have performed a total of 2594 renal transplant procedures. Of these, 1997 grafts (76%) were obtained from living donors, and 597 grafts (24%) were obtained from deceased donors. All renal transplant procedures, including those performed in pediatric patients, used the extraperitoneal approach to the contralateral iliac fossa. Revascularization was performed for all grafts. A single end-to-end internal iliac artery anastomosis was performed in 1082 patients (41.8%), an end-to-side external iliac artery anastomosis was performed in 1289 patients (49.7%), and an end-to-side common iliac artery anastomosis was performed in 66 patients (2.5%). In 157 procedures (6%), there were at least 2 renal arteries, and both internal iliac arteries or external iliac arteries were used for anastomosis.

RESULTS

We observed 57 vascular complications (2.1%) in 54 renal transplant procedures. The most frequent complication was renal artery stenosis (n = 17; 0.6%). There were 8 instances of renal artery thrombosis (0.4%), 7 of renal artery kinking (0.3%), 5 of renal vein thrombosis (0.2%), 9 of renal vein kinking (0.5%), 3 of external iliac artery dissection (0.01%), 5 renal vein lacerations (0.2%), and 3 renal artery lacerations (0.01%). We performed urgent surgery for 41 vascular complications; 38 were managed successfully. Percutaneous interventional techniques were used successfully for 18 vascular complications.

CONCLUSIONS

The vascular complication rate in our patients is lower than that reported in the literature. Surgical complications can be minimized with careful transplant technique and close follow-up, as early diagnosis is crucial to early management and successful treatment of complications.

Renal pseudoaneurysm formation post allograft biopsy: a case report

Renal pseudoaneurysm (PSA) is a rare complication post kidney transplant biopsy that accounts for less than 1% of allograft dysfunction. Imaging guidelines in the diagnosis of renal PSA have not yet been developed owing to the low occurrence and limited data availability. However, contrast-enhanced CT and magnetic resonance angiography (MRA) are the preferred modalities in detecting PSA owing to the high contrast and spatial resolution. However, magnetic resonance angiography is preferred since non-contrast imaging techniques can see blood flow patterns in renal PSA without the use of contrast media that may alter renal function. We present a rare complication in a 48-year-old male receiving a living related kidney transplant and found to have renal PSA post allograft biopsy. We review the clinical features, imaging and treatment outcome with the developed PSA in the transplanted kidney post allograft biopsy.

Surgical Complications Following Kidney Transplantations: A Single-Center Study in Hungary

Surgical complications (SCs) are still high potential causes of graft loss. The incidence has a huge amount of variations depending on many factors. Our aim was to study the postoperative technical complications following kidney transplantations (KTs) during a 5-year period between 2011 and 2015. In the observed time frame there were 47 SCs occurring in 32 (19.4%) patients of 165 KTs. Every complication was classified into 3 groups: vascular (11; 6.6%), urologic (16; 9.7%), and any others (20; 12.1%). The most common postoperative SCs in our center were hemorrhage (14; 8.5%), urinary leakage (12; 7.2%), and renal artery stenosis (6; 3.6%). Twenty-seven patients, 84% of those having had a SC, needed an intervention, mainly a surgical correction (28; 62%). Half of these interventions (21; 51%) were performed due to urologic reasons. As possible predicting factors, we studied the type of arterial and ureter anastomosis in relation to onset of vascular and urologic complications. There was no significant correlation. The same was true for any donor and/or recipient demographic parameters. However, the presence of SCs impaired both patient and graft survival. The cumulative 6-month, 1-, 3-, and 5-year patient survival rates were 97% versus 99%, 93% versus 99%, 84% versus 97%, and 84% versus 97% for patients with/without (w/wo) a SC, respectively (P = .028). The cumulative 6-month, 1-, 3-, and 5-year graft survival rates were 81% versus 96%, 77% versus 94%, 68% versus 86%, and 54% versus 86% for the same 2 groups, respectively (P = .003).

Acute thrombosis of a transplanted renal artery after gastric ulcer bleeding in a patient with a long-term well-functioning renal allograft: A case report and literature review

BACKGROUND

Acute thrombosis of a transplanted renal artery is a serious vascular complication following renal allograft transplantation, which usually occurs within the first month after transplantation and often results in graft loss. It rarely occurs beyond the first month, except in a rejected kidney or in a kidney with high-grade transplant renal artery stenosis.

RESULT

A 65-year-old male with a history of type 2 diabetes mellitus, hypertension, pulmonary tuberculosis, and end-stage renal disease was previously treated with hemodialysis (HD). He received a kidney transplant and had a well-functioning graft for 2 years. He presented to our emergency department with gastric ulcer bleeding and received treatment involving an endoscopic submucosal epinephrine injection, a proton pump inhibitor, and blood transfusions. Nine days later, he complained of sudden lower abdominal pain and had acute anuric kidney failure. Renal ultrasonography revealed an absence of blood flow to the allograft kidney. Renal artery angiogram demonstrated complete occlusion of the transplanted renal artery. After thrombectomy and percutaneous transluminal angioplasty (PTA) with stent placement, 60% stenosis of the proximal renal artery with distal perfusion was noted. However, his graft function did not improve, and he received HD again. Histopathology of the transplanted kidney revealed ischemic tubular nephropathy with focal infarction without rejection.

CONCLUSION

This is the first case of acute thrombosis of the transplanted renal artery following gastric ulcer bleeding in a patient with a long-term well-functioning graft kidney.

Influence of Various Living Donor Kidney Measurements in Relation to Recipient Body Measurements on Posttransplant Allograft Functional Outcomes

OBJECTIVES

Donor kidney measurements may affect outcomes of transplanted allografts. We tested allograft and recipient measurements on kidney allograft outcomes. In this study, we compared the effects of kidney allograft volumes, which were measured using computed tomographic angiography before transplant, and allograft weight, which was measured during surgery, in relation to the recipient's body weight and body mass index on kidney function at 6 and 12 months after transplant.

MATERIAL AND METHODS

We included 74 patients (40 female and 34 male patients, mean age of 50.42 ± 9.75 y) in this study.

RESULTS

Intraoperative allograft weight was 182.68 ± 40.33 g (range, 104-266 g). The allograft volume measured using computed tomographic angiography scanning was 123.34 ± 24.26 mL (range, 78-181 mL). The estimated glomerular filtration rates of the recipients at 6 and 12 months after transplant correlated negatively with age and recipient body mass index but correlated positively with allograft volume/recipient body weight, allograft volume/recipient body mass index, allograft weight, allograft weight/recipient body weight, and allograft weight/recipient body mass index values, as concluded by univariate analyses. From multivariate analyses, we found variables of interest presumed to significantly affect the 12-month estimated glomerular filtration rates, including recipient age, allograft volume/recipient body weight, allograft volume/recipient body mass index, allograft weight, allograft weight/recipient body weight, and allograft weight/recipient body mass index.

CONCLUSIONS

Transplanted allograft and recipient body values may be used as predictors of estimated glomerular filtration rates 6 and 12 months after transplant.

Interventional Management of Vascular Renal Transplant Complications

Renal transplantation is the therapy of choice in patients with end stage renal disease. Although transplant rejection remains the most common complication after renal transplantation, vascular anatomical complications occur in 1%-23% of renal transplant recipients. Interventional radiologists play an important role in the management of these complications. This review discusses the role of image-guided interventions within the context of multidisciplinary patient management. Particular emphasis is given to anatomical considerations unique to this patient population, techniques used for image-guided interventions, and outcomes of image-guided interventions.

Endovascular management of iatrogenic renal arterial lesions and clinical outcomes

PURPOSE

We aimed to evaluate iatrogenic renal arterial lesions, including pseudoaneurysm, arteriovenous fistula, and arteriocaliceal fistula, their management by endovascular embolization, and the clinical results.

METHODS

Fifty-five patients (forty males, fifteen females) with a median age of 40 years (range, 8-85 years), who underwent endovascular embolization of iatrogenic renal arterial lesions between March 2003 and December 2013 were included in this retrospective study. Types of iatrogenic lesions and details of embolization procedures were reported. Estimated glomerular filtration rate (eGFR), renal function tests, hemoglobin, and hematocrit levels before and after embolization were recorded and compared.

RESULTS

Median follow-up was 24 months. We identified 53 pseudoaneurysms, 30 arteriovenous fistulas, and 11 arteriocaliceal fistulas in 55 patients, after percutaneous nephrolithotomy (n=26), renal biopsy (n=21), nephrostomy (n=3), renal surgery (n=3), and extracorporeal shock wave lithotripsy (n=2). Median number of pseudoaneurysms was 1 (range, 1-4) with a median size of 7 mm (range, 1.5-35 mm). Fifty-one patients underwent coil embolization. Median number of coils was 5 (range, 2-21) and median renal parenchymal loss was 5% (range, 1%-50%). There were no significant differences between pre- and postoperative eGFR and serum parameters.

CONCLUSION

Iatrogenic renal arterial lesion can be a life threatening condition. Superselective coil embolization is a safe, minimally invasive treatment option with minimal renal parenchymal loss and without significant change in renal function.

Successful technical and clinical outcome using a second generation balloon expandable coronary stent for transplant renal artery stenosis: Our experience

Transplant renal artery stenosis (TRAS) is a vascular complication frequently seen because of increase in the number of renal transplantations. Early diagnosis and management is essential to optimize a proper graft function. Currently, the endovascular treatment of TRAS using angioplasty and/or stenting is considered the treatment of choice with the advantage that it does not preclude subsequent surgical correction. Treatment of TRAS with the use of stents, particularly in tortuous transplant renal anatomy presents a unique challenge to an interventional radiologist. In this study, we present three cases from our practice highlighting the use of a balloon-expandable Multi-Link RX Ultra coronary stent system (Abbott Laboratories, Abbott Park, Illinois, USA) for treating high grade focal stenosis along very tortuous renal arterial segments. Cobalt-Chromium alloy stent scaffold provides excellent radial force, whereas the flexible stent design conforms to the vessel course allowing for optimal stent alignment.

Minimally invasive salvage therapy for transplanted renal allografts

PURPOSE

To evaluate the effectiveness of interventional therapy for complications of transplanted renal allografts.

MATERIALS AND METHODS

Between January 2009 and March 2014, 14 patients underwent interventional therapy for complications of renal allografts. Complications included transplant renal artery stenosis (TRAS), TRAS combined with pseudoaneurysms, transplant renal venous kinking and ureteral obstruction (UO). Serum creatinine (S.Cr) levels were evaluated before and after procedure. The characteristics and procedure outcomes of these patients with vascular and nonvascular complications were also analyzed.

RESULTS

All primary procedures were successfully performed, which included percutaneous transluminal angioplasty (PTA) for TRAS (n = 4), stenting and coil embolization for TRAS combined with pseudoaneurysms (n = 1), stenting for renal vein kinking (n = 2), and percutaneous nephrostomy (PCN) for UO (n = 7) and secondary antegrade stent placement in six UO patients after 1 week of PCN. No major procedure related complications occurred. S.Cr level subsequently improved from 6.0 ± 3.6 to 2.6 ± 2.1 mg/dL (p < 0.001), as well as patients' clinical features within 1 week after procedure. In our study, the onset time of vascular complications was earlier (<6 months) than nonvascular complications with significant difference (p < 0.001). During follow-up, the patient with TRAS and pseudoaneurysms suffered acute rejection 1 month after treatment and received transplant renal artery embolization. One patient with TRAS showed restenosis 4 months after procedure, and was retreated successfully with stenting. Thirteen cases reserved their transplanted renal allografts.

CONCLUSION

Interventional therapy could be prior considered for transplanted renal allograft complications as its effectiveness and minimal invasiveness in saving the transplanted renal grafts.

Femoro-femoral Bypass for Graft Salvage in a Renal Transplant Patient With Aorto-iliac Occlusion: A Case Report

As vascular diseases are becoming more prevalent among renal transplant recipients, complications related to renal artery anastomosis are likely to occur more often. Here we report a renal transplant patient treated with femoro-femoral bypass who had renal allograft dysfunction due to aorto-iliac occlusive disease (AIOD) proximal to renal artery anastomosis. We performed living donor renal transplantation in the left iliac fossa of a 41-year-old male. At post-transplant 30 months, he was admitted with hypertension, increase in serum creatinine, and claudication of his left leg. Doppler ultrasonography showed poor flow characteristics of the renal allograft. Total occlusion of the left common iliac artery was diagnosed on angiography. Since endovascular approach was unsuccessful, we performed right-to-left femoro-femoral bypass to provide retrograde blood flow to the renal allograft. The patient was discharged at postoperative day 3 with decreased serum creatinine, normal blood pressure, no claudication, and normal flow characteristics in Doppler ultrasonography. AIOD should be suspected in renal transplant patients in case of hypertension, allograft dysfunction, and ipsilateral leg ischemia. Femoro-femoral bypass is a safe surgical procedure that may be performed in patients who cannot be treated using an endovascular approach.

Iatrogenic-related transplant injuries: the role of the interventional radiologist

As advances in surgical techniques and postoperative care continue to improve outcomes, the use of solid organ transplants as a treatment for end-stage organ disease is increasing. With the growing population of transplant patients, there is an increasing need for radiologic diagnosis and minimally invasive procedures for the management of posttransplant complications. Typical complications may be vascular or nonvascular. Vascular complications include arterial stenosis, graft thrombosis, and development of fistulae. Common nonvascular complications consist of leaks, abscess formation, and stricture development. The use of interventional radiology in the management of these problems has led to better graft survival and lower patient morbidity and mortality. An understanding of surgical techniques, postoperative anatomy, radiologic findings, and management options for complications is critical for proficient management of complex transplant cases. This article reviews these factors for kidney, liver, pancreas, islet cell, lung, and small bowel transplants.

Comparing the diagnostic accuracy of contrast-enhanced computed tomographic angiography and gadolinium-enhanced magnetic resonance angiography for the assessment of hemodynamically significant transplant renal artery stenosis

To compare diagnostic accuracy of contrast-enhanced computed tomographic angiography (CTA) and gadolinium-enhanced magnetic resonance angiography (MRA) for the assessment of hemodynamically significant transplant renal artery stenosis (TRAS). After institutional review board approval, records of 27 patients with TRAS confirmed on digital subtraction angiography (DSA) were retrospectively reviewed. A total of 13 patients had MRA and 14 had CTA before DSA. Two board-certified fellowship-trained radiologists, one each from interventional radiology and body imaging blindly reviewed the DSA and CTA or MRA data, respectively. Sensitivity (SN), specificity (SP), positive predictive value, and negative predictive value of MRA and CTA were estimated using 50% stenosis as the detection threshold for significant TRAS. These parameters were compared between modalities using the Fisher exact test. Bias between MRA or CTA imaging and DSA was tested using the Wilcoxon signed-rank test. Two patients were excluded from the MRA group owing to susceptibility artifacts obscuring the TRAS. The correlation between MRA and DSA measurements of stenosis was r = 0.57 (95% CI:-0.02, 0.87; P = 0.052) and between CTA and DSA measurements was r = 0.63 (95% CI: 0.14, 0.87; P = 0.015); the difference between the 2 techniques was not significant (P = 0.7). Both imaging modalities tended to underestimate the degree of stenosis when compared with DSA. MRA group (SN and SP: 56% and 100%, respectively) and CTA group (SN and SP: 81% and 67%, respectively). There were no significant differences in detection performance between modalities (P>0.3 for all measures). We did not find that either modality had any advantage over the other in terms of measuring or detecting significant stenosis. Accordingly, MRA may be preferred over CTA after positive color Doppler ultrasound screening when not contraindicated owing to lack of ionizing radiation or nephrotoxic iodinated contrast. However, susceptibility of artifacts owing to surgical clips at the anastomosis may limit diagnostic utility of MRA as found in 2 of 13 patients. Trend towards no significant difference between the CTA and enhanced MRA in the detection of hemodynamically significant TRAS.

Ultrasonographic evaluation of the renal transplant

Ultrasonography is an excellent tool for evaluation of the renal transplant in the immediate postoperative period and for long-term follow-up. In this article, normal imaging findings and complications of renal transplantations are described. Disease processes are divided into vascular, perinephric, urologic and collecting system, and parenchymal abnormalities. Attention is paid to the time of occurrence of each complication, classic imaging findings, and potential pitfalls.

Renal Transplant Complications: Diagnostic and Therapeutic Role of Radiology

Kidney was the first and is the most frequently transplanted organ. Despite improved surgical techniques and transplantation technology, complications do occur and, if left untreated, may lead to catastrophic consequences. Renal transplantation complications may be vascular (eg, renal artery and vein stenosis and thrombosis, arteriovenous fistula, and pseudoaneurysms); urologic (eg, urinary obstruction and leak, and peritransplantation fluid collections, including hematoma, seroma, lymphocele, and abscess formation); and nephrogenic, including acute tubular necrosis, graft rejection, chronic allograft nephropathy, and neoplasm. Early diagnosis and treatment of these complications are paramount to prevent graft failure and other significant morbidities to the patients. Radiology plays a pivotal role in the diagnosis and treatment of these complications, with minimally invasive percutaneous techniques. In this article, we reviewed renal transplantation anatomy, a wide range of complications that may occur after renal transplantation surgery, typical imaging appearances of the complications on varies imaging modalities, and percutaneous interventional techniques that are used in their treatment.

Outcomes of Percutaneous Management of Anastomotic Ureteral Strictures in Renal Transplantation: Chronic Nephroureteral Stent Placement with and without Balloon Dilatation

PURPOSE

This study was designed o evaluate outcomes of percutaneous management of anastomotic ureteral strictures in renal transplants using nephroureteral stents with or without balloon dilatation.

METHODS

A retrospective audit of 1,029 consecutive renal transplants was performed. Anastomotic ureteral strictures were divided into two groups: nephroureteral stent only (NUS) and NUS+PTA (nephroureteral stent plus percutaneous transluminal angioplasty), with each cohort subdivided into early versus late presentation (obstructive uropathy occurring <90 day or >90 days from transplant, respectively). Overall and 6-month technical success were defined as removal of NUS any time with <30 % residual stenosis (any time lapse less or more than 6 months) and at >6 months, respectively. Patency was evaluated from NUS removal to last follow-up for both groups and compared.

RESULTS

Sixty-seven transplant patients with 70 ureteric anastomotic strictures (6.8 %, n = 70/1,029) underwent 72 percutaneous treatments. 34 % were late (>90 days, n = 24/70), and 66 % were early (<90 days, n = 46/70). Overall technical success was 82 % (n = 59/72) and 6-month success was 58 % (n = 42/72). Major and minor complications were 2.8 % (n = 2/72), and 12.5 % (n = 9/72). NUS+PTA did not improve graft survival (p = 0.354) or patency (p = 0.9) compared with NUS alone. There was no difference in graft survival between treated and nontreated groups (p = 0.74).

CONCLUSIONS

There is no advantage to PTA in addition to placement of NUS, although PTA did not negatively impact graft survival or long-term patency and both interventions were safe and effective. Neither the late or early groups benefited from PTA in addition to NUS. Earlier obstructions showed greater improvement in serum creatinine than later obstructions.

Endovascular interventions for managing vascular complication of renal transplantation

Renal transplantation is a well-established treatment for patients with end-stage renal disease. Although the procedure is commonly undertaken with a high rate of initial technical success, a low but significant risk of vascular complications can develop and ultimately threaten the transplanted kidney. Complications include transplant renal artery stenosis, extraparenchymal and intraparenchymal pseudoaneurysm and arteriovenous fistula formation, and stenosis of native iliac arteries due to aortoiliac occlusive disease. Historically, open surgical correction of these complications has been associated with high morbidity and the risk of graft loss. Endovascular approaches are better tolerated by renal transplantation patients and are used increasingly for management of vascular complications associated with kidney transplantation. We review the contemporary diagnosis and treatment of these complications using endovascular techniques.

Correlation between CT-based measured renal volumes and nuclear-renography-based split renal function in living kidney donors. Clinical diagnostic utility and practice patterns

INTRODUCTION

Living donor evaluation involves imaging to determine the choice of kidney for nephrectomy. Our aim was to study the diagnostic accuracy and correlation between CT-based volume measurements and split renal function (SRF) as measured by nuclear renography in potential living donors and its impact on kidney selection decision.

METHODS

We analyzed 190 CT-based volume measurements in healthy donors, of which 65 donors had a radionuclide study performed to determine SRF.

RESULTS

There were no differences in demographics, anthropometric measurements, total volumes, eGFR, creatinine clearances between those who required a nuclear scan and those who did not. There was a significant correlation between CT-volume-measurement-based SRF and nuclear-scan-based SRF (Pearson coefficient r 0.59; p < 0.001). Furthermore, selective nuclear-based SRF allowed careful selection of donor nephrectomy, leaving the donor with the higher functioning kidney in most cases. There was also a significantly higher number of right-sided nephrectomies selected after nuclear-based SRF studies.

CONCLUSION

CT-based volume measurements in living donor imaging have sufficient correlation with nuclear-based SRF. Selective use of nuclear-scan-based SRF allows careful selection for donor nephrectomy.

Complications of transplantation. Part 1: renal transplants

Vascular complications after solid-organ transplantation are not uncommon and may lead to graft dysfunction and ultimately graft loss. A thorough understanding of the surgical anatomy, etiologies, and types of vascular complications, their presentation, and the options for management are important for managing these complex patients. This article reviews the basic surgical anatomy, vascular complications, and endovascular management options of vascular complications in patients with renal transplants.