彩色多普勒超声诊断早期移植肾急性排斥

目的探讨彩色多普勒超声图像数据分析在诊断早期移植肾急性排斥中的作用及临床价值.方法总结203例肾移植术后6～30d内行彩色多普勒超声检查,结合临床症状、生化检查并参照病理诊断,对二维灰阶图像、彩色血流图、血流频谱及阻力指数(RI)、搏动指数(PI)、收缩期与舒张期血流速度比(S/D)等参数进行回顾性分析.结果以彩色多普勒RI>0.78、PI>1.82、S/D>4.1为标准,结合彩色血流图及血流频谱形态,早期移植肾急性排斥正确诊断率可达85.7%.结论应用彩色多普勒超声诊断移植肾早期急性排斥并监测其功能恢复,具有快速、准确、无创等优点,可提早发现病情变化并指导治疗,提高移植肾存活率.     

应用彩色超声波监测移植肾血流变化的临床价值

通过对５１８例肾移植患者连续７６１次彩色超声波结果进行了回顾性分析，从６项超声指标中，比较了功能正常的移植肾与排斥，急性肾小管坏死，肾积水和环孢素肾毒性血液动力学变化。并提出了肾移植排斥时除阻力指数升高与舒张末期最小速度／血管内径，血流收缩期最大速度比值下降外，移植肾血流速度减慢，血流量减低。     

彩色多普勒血流显像及多普勒能量图在移植肾排斥反应中的应用

目的探讨彩色多普勒血流显像及多普勒能量图在检测移植肾排斥反应中的应用价值。方法对46例肾移植受者术后进行了彩色多普勒血流显像及多普勒能量图检查。根据检测结果将46例肾移植术后受者分为3组,移植肾正常组(30例)、急性排斥组(9例)和慢性排斥组(7例),并与超声引导下肾组织穿刺的病理检查结果进行比较。结果16例急、慢性排斥反应的患者移植肾动脉搏动指数及阻力指数均高于移植肾正常组;急性排斥组肾脏长径及肾皮质厚度明显大于移植肾正常组;慢性排斥反应时肾皮质厚度、肾脏长径、宽径均小于移植肾正常组。结论彩色多普勒血流显像及多普勒能量图对移植肾血流灌注及排斥反应判断有独特的优点,搏动指数、阻力指数以及肾皮质厚度可作为有无移植肾排斥的指标之一。     

彩色多普勒超声在肾移植后排斥反应诊断中的应用

目的 探讨彩色多普勒超声在移植肾排斥反应监测中的应用价值。方法 对68例肾移植患者采用彩色多普勒超声进行监测，观察移植肾的结构及体积、肾皮质厚度、肾动脉内径、血流灌注情况、血流动力学参数。结果术后随访最长者达4年，45例移植肾功能正常，未发生排斥反应者，其移植肾在彩色多普勒超声下表现为边界清晰，肾内结构清楚，皮、髓质界限分明，血流丰富。13例发生急性排斥反应者，彩色多普勒超声下可见移植肾明显肿大，肾实质血流信号稀少，叶间动脉呈断续闪烁状，弓形动脉几乎无血流信号。10例发生慢性排斥反应者，彩色多普勒超声下可见移植肾体积缩小，皮质变薄，肾皮质与肾髓质界限不清，肾内血管分枝稀疏，血管树不连续，弓形动脉及小叶间动脉往往不显示，为低速高阻血流。血流动力学参数显示，发生急性排斥反应者的肾动脉阻力指数及搏动指数明显增高，舒张期峰值流速减低；发生慢性排斥反应者的肾动脉内径明显缩小，收缩期峰值流速及舒张期峰值流速明显减低，血流灌注量明显减少，阻力指数及搏动指数明显升高，与肾功能正常者比较，差异均有统计学意义。结论对于肾移植患者的术后监测，彩色多普勒超声具有独特的优点，无创、便捷，其所测得的移植肾形态学数据和血流动力学参数对排斥反应的判断具有重要参考价值，可作为肾移植术后的常规峪测手段。     

Resistance Index Measured by Doppler Ultrasound as a Predictor of Graft Function After Kidney Transplantation

IntroductionDoppler ultrasound (US) has become the primary imaging technique for the evaluation of renal transplants. It provides information about the intrarenal resistance index (RI). A high RI is seen in every form of graft dysfunction. In this article, we review the utility of sonography, particularly the intrarenal RI measured early after renal transplant, as a predictor of acute and chronic clinical outcome in patients.ResultsRI is a valuable marker to determine graft function and related vascular complications. It reveals a strong correlation with serum creatinine levels measured days after transplant. Its elevation is typical for acute tubular necrosis and can be used to predict its duration. An RI >1 (absent end-diastolic flow) seen in the first weeks after transplant is associated with impaired renal graft recovery. In addition, it is an early predictor of chronic allograft nephropathy (even correlated with biopsy results), which will allow a change in therapy.ConclusionsRI measured serially in the early period after kidney transplantation is a valuable marker for determining renal graft function. It is also useful for demonstrating various types of graft dysfunction; however, it cannot differentiate between them. In recent studies, extrarenal factors in kidney transplantation (eg, recipient's age) may significantly influence RI in the recipient, demonstrating that RI depends on the vascular characteristics of the recipient and not on the graft itself.     

Clinical factors associated with graft fibrosis in kidney-transplant recipients on steroid-avoidance immunosuppression

Abstract: Background: Recent studies have documented good patient and graft outcomes and a low risk of acute rejection with steroid‐avoidance immunosuppression in kidney‐transplant recipients, but the risk of progressive graft fibrosis is not well studied. Methods: All adult primary kidney transplant or combined kidney and pancreas transplant recipients on steroid avoidance immunosuppression were eligible for study. All recipients received induction with antithymocyte globulin or basiliximab. Corticosteroids were stopped after day 4 post‐transplantation. Patients were maintained with tacrolimus and mycophenolate mofetil. Protocol biopsies were done at reperfusion and at one, four, and 12 months after transplantation. Results: Eighty one‐yr protocol biopsies with adequate specimens were obtained from 132 kidney or kidney–pancreas transplant recipients. Fifteen (19%) of the biopsies showed moderate to severe graft interstitial fibrosis (GIF) (Banff ci score ≥2). Recipients with GIF were older, had lower body mass index, greater human lymphocyte antigen (HLA) mismatch, older donors, serum creatinine ≥1.6 mg/dL at one month, a Banff ci score >0 on one‐month biopsy, BK nephropathy, and interstitial cellular infiltrates on the one‐yr biopsy. In the unadjusted logistic regression analysis, BK nephropathy, serum creatinine ≥1.6 mg/dL at one month, recipient age, Banff ci score >0 on one‐month biopsy, and donor age were the only variables associated with a higher risk of GIF on the one‐year biopsy. In the multivariate logistic regression model adjusted for these variables, BK nephropathy, serum creatinine ≥1.6 mg/dL at one month after transplantation, and recipient age were independently associated with the risk of GIF on the one‐year biopsy. Conclusion: In this small study of primary kidney or combined kidney–pancreas transplant recipients on steroid‐avoidance immunosuppression, we found that 19% had GIF on a one‐year protocol biopsy. BK nephropathy, serum creatinine ≥1.6 mg/dL one month after transplantation, and recipient age correlated with an increased risk for GIF on the one‐yr biopsy.     

High Mean Fluorescence Intensity Donor‐Specific Anti‐HLA Antibodies Associated With Chronic Rejection Postliver Transplant

In contrast to kidney transplantation where donor‐specific anti‐HLA antibodies (DSA) negatively impact graft survival, correlation of DSA with clinical outcomes in patients after orthotopic liver transplantation (OLT) has not been clearly established. We hypothesized that DSA are present in patients who develop chronic rejection after OLT. Prospectively collected serial serum samples on 39 primary OLT patients with biopsy‐proven chronic rejection and 39 comparator patients were blinded and analyzed for DSA using LABScreen^® single antigen beads test, where a 1000 mean fluorescence value was considered positive. In study patients, the median graft survival was 15 months, 74% received ≥ one retransplant, 20% remain alive and 87% had ≥ one episode of acute rejection. This is in contrast to comparator patients where 69% remain alive, and no patient needed retransplant or experienced rejection. Thirty‐six chronic rejection patients (92%) and 24 (61%) comparator patients had DSA (p = 0.003). Chronic rejection versus comparator patients had higher mean fluorescence intensity (MFI) DSA. Although a further study with larger numbers of patients is needed to identify clinically significant thresholds, there is an association of high‐MFI DSA with chronic rejection after OLT.     

Delayed presentation of arteriovenous fistula and pseudoaneurysms in a renal transplant patient 10 years after percutaneous allograft biopsy

A 51-year-old man was admitted with microscopic hematuria at 10 years after living donor renal transplantation. In order to distinguish between acute tubular necrosis and acute rejection, a graft biopsy was performed under ultrasound guidance at 1 month posttransplantation. Doppler sonography revealed 3 pulsatile cystic masses and an arteriovenous fistula (AVF) in the lower kidney pole. Selective transplant renal angiography revealed 3 pseudoaneurysms with an AVF supplied by a lobular artery in the lower pole. The diagnosis was AVF with pseudoaneurysm, which developed secondary to percutaneous renal allograft biopsy. Interventional treatment was performed because of the high risk for pseudoaneurysm rupture. The AVF and pseudoaneurysms were treated successfully by percutaneous transluminal embolization; renal function remained stable after embolization.     

Evaluation of renal transplant dysfunction by duplex Doppler sonography: a prospective study and review of the literature

A disconcertingly wide variation exists in the literature as to the accuracy of duplex Doppler sonography in the detection of acute renal transplant rejection. Sensitivities range from 9% to 76%. In an attempt to explain the disparity of results, we undertook a double-blind prospective study of the accuracy of duplex Doppler ultrasound in the detection of acute rejection in renal transplants. We scanned 49 consecutive patients with a total of 65 biopsies; 46 biopsies in 33 consecutive patients were included in our study. In our population, the prevalence of acute rejection was 61% (28/46). Using a resistive index (RI) cutoff of greater than 0.90 based on the main renal artery flow pattern, the sensitivity of our test was 43%, with a 67% specificity. The positive predictive value was 67%. Our results are contrasted and compared with the published data from other groups in a critical survey of the literature. We conclude that duplex Doppler sonography alone is inadequate to evaluate acute rejection in renal transplants.     

Predictive value of Doppler ultrasonography in renal transplantation

During a 17-month period, 268 Doppler sonography studies were performed on 46 consecutive renal transplant patients. There were 35 episodes of acute rejection in 10 patients, 8 episodes of delayed function and 47 episodes of high cyclosporine levels (greater than 800 ng/dl by TDX method) in 21 patients. Defining an abnormal resistive index (RI) as greater than 0.8 or a 20% increase above baseline, the test has a specificity of 99% and a sensitivity of 94% in the 1st month post-transplant and had an overall predictive value of 99%. Episodes of high cyclosporine levels ranging from 800 to 1650 ng/dl did not correlate with a high RI except in one circumstance with concurrent acute rejection. Within the 1st month post-transplant, only 1 false-negative study occurred. An additional 8 false-negative studies occurred beyond 1 month post-transplant. Patients with delayed function are separated into three groups based on the Doppler ultrasounds: Group I, patients with an accelerated acute rejection with high RI (N = 2); Group II, patients with true ischemic acute tubular necrosis with normal RI (N = 2); and Group III, patients with possible immunologically-mediated delayed function with intermediate RI between 0.6 and 0.8 (N = 4). Doppler ultrasound is a useful ancillary test to confirm the clinical suspicion of acute rejection. Since high cyclosporine levels do not cause an increase in RI, Doppler ultrasound may help to avoid confusion between acute rejection and cyclosporine toxicity. Additionally, this test may offer insight into the cause of early post-transplant renal dysfunction.     

Role of duplex Doppler sonography in diagnosis of acute allograft dysfunction—time to stop measuring the resistive index?

Measurement of vascular resistive index (RI) by duplex Doppler sonography (DDS) has been proposed as a non-invasive technique to detect the presence of acute rejection in renal allograft recipients. Our aim was to evaluate the clinical utility of this technique. From 107 patients we reviewed 159 biopsies that were performed from 1993 to 2001 for the investigation of acute allograft dysfunction. Histological findings were correlated with RI measurements by contemporaneously performed DDS. The majority of biopsies were carried out within the first 3 months post-transplantation (111/159). Sixty-eight biopsies showed acute rejection, 91 biopsies had findings other than rejection (acute tubular necrosis, CyA toxicity, recurrent GN). Using a threshold mean RI value of 0.9, the test had a specificity for acute rejection of 89%, but a sensitivity of just 6%. If the threshold was lowered the sensitivity rose, but specificity declined sharply. Average RI in the rejection group was not higher than in controls (0.73+/-0.11 vs 0.74+/-0.11, respectively). We conclude that measurement of RI by DDS does not contribute to the diagnosis of acute allograft dysfunction.     

The predictive value of arterial renal blood flow parameters in renal graft survival

BACKGROUND: Renal allograft survival depends on a number of factors, however, no reliable simple parameter has been shown to predict long-term outcome after transplantation. Ultrasound is recognized and relatively inexpensive, providing information about renal location, contour, and size. Doppler ultrasonography shows kidney morphology and hemodynamics. The aim of this study was the evaluation of whether Doppler ultrasound of renal arteries performed in the early stage after transplantation was a valuable predictor for long-term-outcomes. MATERIAL AND METHODS: The study included 17 female and 24 male patients, aged 17-69 years with stable graft function. The Doppler ultrasound of renal flow was done on the 1st and 3rd day after transplantaion, and estimated glomerular filtration rate (eGFR) on the 20th day. The measured indices were as follows: maximum blood flow velocity (V(max)), minimum blood flow velocity (V(min)), resistive index (RI), and pulsatile index (PI). The creatinine concentration was evaluated, and eGFR calculated. RESULTS: Mean renal and intrarenal artery RI increased to day 3 after transplantation, and then reduced. The mean renal and intrarenal V(max) at day 3 correlated positively with eGFR (r = 0.38; P = .015); (r = 0.45; P = .003, respectively). Mean renal and intrarenal V(min) correlated positively with eGFR (r = 0.50; P = .001; r = 0.41; P = .008, respectively). The mean renal and intrarenal V(max) and V(min) on day 1 did not correlate with eGFR. CONCLUSIONS: Early Doppler Ultrasonography of renal graft hemodynamics may be a valuable predictor of graft survival and long-term outcomes. Blood flow velocity within renal arteries seemed to be an important factor.     

Renal transplantation in sensitized recipients with positive luminex and negative CDC (complement‐dependent cytotoxicity) crossmatches

Recently, Luminex‐crossmatch (LumXm) was introduced. The aim of this study was to evaluate clinical outcomes in sensitized recipients with a positive Luminex‐crossmatch (LumXm (+)) and a negative complement‐dependent cytotoxicity crossmatch (CDCXm (?)) after renal transplantation. Fifty‐five renal transplant recipients with a CDCXm (?) and PRA class I or II ≥20% were enrolled in this study between February 2008 and December 2010 at Severance Hospital. Eighteen patients displayed LumXm (+) defined as LumXm positive class I or II and 37 patients displayed LumXm (?). Mean duration of follow‐up was 18.9 ± 8.3 months. During this period, no patient death or graft loss occurred. The incidence of biopsy‐proven or clinically presumed rejection was higher in the LumXm (+) group (n = 12, 66.7%) than in the LumXm (?) group (n = 6, 18.2%) (P = 0.001). All biopsy‐proven acute rejections (n = 12) were diagnosed as acute cellular rejection. No significant difference in mean serum creatinine level or eGFR was observed between the groups at 18 months post‐transplantation. The short‐term outcome of renal transplantation in sensitized patients with a LumXm (+) and a CDCXm (?) may be considered to be acceptable. However, patients with a LumXm (+) have a substantially higher immunological risk for the development of acute cellular rejection.     

Surgical transplant physical examination: correlation of renal resistance index and biopsy-proven chronic allograft nephropathy

BACKGROUND: Chronic allograft nephropathy (CAN) remains the leading cause of late renal allograft loss that is minimally responsive to therapy once graft dysfunction is clinically evident. A screening test capable of identifying individuals at high risk for CAN would be a valuable adjunct to patient care, but to be cost effective, should be administered during routine evaluations by transplantation clinicians. STUDY DESIGN: We have compared the resistive index (RI) as measured by Doppler ultrasonography with subsequent biopsy findings on 91 renal allograft recipients who had a subsequent protocol-directed biopsy at least 3 months after renal transplant. All ultrasonography was performed by the transplantation surgical staff without involving the radiology department or a separate appointment time. RESULTS: Twenty-one patients had RI >/= 80 (average 621 days posttransplantation). Among these individuals, the subsequent incidence of CAN was 38%. Length of time between initial assessment of increased RI and biopsy-proved CAN averaged 233 days. The remaining 70 patients with RI < 80 had an incidence of CAN of 11.4% (p = 0.018). There were minimal complications from these biopsies. Sensitivity and specificity of an elevated RI in predicting CAN were 50% and 83%, respectively. The negative predicted value of an elevated RI in determination of CAN was 89%. CONCLUSIONS: These results suggest that elevated RI is an early predictor of histologically relevant CAN, possibly a result of burgeoning vasculopathy. The technical expertise required to make this appraisal is well within the capabilities of transplantation surgeons and trainees. Early evidence of CAN may allow for a targeted change in therapy before clinically significant injury. Ultrasonography should become a routine part of a transplantation clinic evaluation.     

Cyclosporin A toxicity of the renal allograft--a late complication and potentially reversible

Cyclosporin A (CsA) has improved patient and organ graft survival, but the dichotomy of benefit and toxicity is still an issue. In a retrospective analysis of 392 renal transplant recipients we documented CsA nephrotoxicity (striped fibrosis, arteriolar wall hyalinosis) in 28 (7.1%) patients (23 male/5 female) in a follow-up of more than one year post transplantation. Median age at renal transplantation was 41 years (13-60) and the period between transplantation and graft biopsy was 42 months (12-122). Median CsA trough levels (ng/ml) at 12 months post transplantation, at time of graft biopsy and at last follow-up were: 114 (71-265), 130 (78-285), 66 (24-115). The following parameters were assessed at 12 months post transplantation, at time of biopsy and at last follow-up: s-creatinine (micromol/l), Doppler resistive index, systolic and diastolic blood pressure (mm Hg) and the number of antihypertensives. Median s-creatinine at 12 months post transplantation was 150.3 (94.6-247.5), at biopsy 225.4 (121.1-353.6) and at last follow-up 160.0 (106.1-247.5) (p < 0.001 for biopsy vs. last follow-up). Resistive index decreased from 0.70 (0.64-0.88) to 0.68 (0.51-0.84) (p < 0.005), systolic blood pressure from 137 (100-168) to 130 (105-144) (p < 0.05) and the number of patients with more than 4 antihypertensives from 10 to 6 between biopsy and last follow-up, with no acute rejection episodes after modification of immunosuppressive therapy (50% of previous CsA trough level and addition of azathioprine or mycophenolate mofetil). Conclusion: CsA nephrotoxicity occurs late after renal transplantation with increased systolic blood pressure and Doppler resistive index. Reduction of CsA improves renal function, reduces graft resistive index and systolic blood pressure.     

A Peripheral Blood Diagnostic Test for Acute Rejection in Renal Transplantation

Monitoring of renal graft status through peripheral blood (PB) rather than invasive biopsy is important as it will lessen the risk of infection and other stresses, while reducing the costs of rejection diagnosis. Blood gene biomarker panels were discovered by microarrays at a single center and subsequently validated and cross‐validated by QPCR in the NIH SNSO1 randomized study from 12 US pediatric transplant programs. A total of 367 unique human PB samples, each paired with a graft biopsy for centralized, blinded phenotype classification, were analyzed (115 acute rejection (AR), 180 stable and 72 other causes of graft injury). Of the differentially expressed genes by microarray, Q‐PCR analysis of a five gene‐set (DUSP1, PBEF1, PSEN1, MAPK9 and NKTR) classified AR with high accuracy. A logistic regression model was built on independent training‐set (n = 47) and validated on independent test‐set (n = 198)samples, discriminating AR from STA with 91% sensitivity and 94% specificity and AR from all other non‐AR phenotypes with 91% sensitivity and 90% specificity. The 5‐gene set can diagnose AR potentially avoiding the need for invasive renal biopsy. These data support the conduct of a prospective study to validate the clinical predictive utility of this diagnostic tool.     

Intraoperative resistance index measured with transsonic flowmeter on kidney graft artery can predict early and long-term graft function

Introduction

Resistive index (RI) measured by Doppler sonography in the early period after kidney transplantation is a well-known predictor of kidney transplant outcome. The purpose of this study was to analyze the impact of RI values calculated intraoperatively in renal allograft artery using transit time flowmetry (TTF) on both early and long-term kidney graft function.

Material and Methods

TTF was performed on 72 patients who received kidney grafts fed by a single artery. TTF was performed before wound closure. We excluded patients with an early acute rejection (n = 8), an early graft loss (n = 2), or primary graft nonfunction (n = 1). Recipients were divided into RI tertile groups. The initial kidney graft function was defined as immediate (IGF), slow or delayed. Kidney graft estimated glomerular filtration rate (eGFR) was analyzed upon long-term follow-up.

Results

Patients with a low RI (< 0.57) showed the highest incidence of immediate graft function (65% versus 5.3%), whereas the high RI group (> 0.70). Show the most frequent rate of delayed graft function (52.6% versus 15%). Recipients with low RI values displayed significantly better eGFR (by at least 12 mL/min/1.73 m²) than those with medium or high RI values at all analyzed times; subjects with medium or high RI showed similar eGFR at 48-months.

Conclusion

An high RI value measured intraoperatively was a valuable predictor of inferior early and long-term kidney graft function.     

Duplex sonographic measurements in allografted kidneys: a cross-sectional study

Objectives

The measurement of color Doppler sonography indices, such as resistive index (RI) and pulsatility index (PI), can help in the evaluation of an transplanted kidney. The aim of this study was to determine the correlation between Doppler sonography indices and demographic paraclinical findings in transplanted kidneys.

Methods

A cross-sectional study was performed on 47 (27 male and 20 female) unrelated living renal transplanted patients.

Results

The mean age, body mass index (BMI), time since transplantation, pulse pressure index (PPI), intrarenal RI and PI were 38 ± 13 years, 25 ± 4.5, 48 ± 31 months, 0.34 ± 0.06, 0.69 ± 0.06, and 1.3 ± 0.3, respectively. There were significant negative correlations between time since transplantation and intrarenal RI and PI (r = −.38, P < .01; r = −.4, P < .01, respectively). There was a significant correlation between patient age, creatinine clearance, and intrarenal RI (r = .30, P = .039; r = .3, P = .043, respectively). There were no significant correlations between intrarenal RI, PI, and BMI, cyclosporine trough level, PPI, recipient and donor sexes, and rejection episodes. Diabetic patients displayed higher RI (0.76 ± 0.02 vs 0.68 ± 0.06, P = .048) and patients with serum high-density lipoprotein (HDL) level < 40 mg/dL had higher PI than patients with HDL ≥ 40 mg/dL (1.6 ± 0.4 vs 1.2 ± 0.3, P = .006).

Conclusions

Intrarenal RIs did not decrease over a few years after transplantation. They can be a useful, feasible predictor of graft function. However, future multicenter trials should be performed to prove the predictive power of RI determination as a marker of renal function.     

Multimodal evaluation of renal perfusional changes due to extracorporeal shock wave lithotripsy

OBJECTIVES

To examine the effect of extracorporeal shock wave lithotripsy (ESWL) on renal perfusion before and after treatment, by assessing renal resistive index (RI) using colour Doppler ultrasonography (CDUS), magnetic resonance perfusion imaging (MRPI), radionuclide renography and big‐endothelin‐1 values (Big‐ET‐1).

PATIENTS AND METHODS

In 69 normotensive patients the RI was measured before, 1, 3, 6 and 24 h after ESWL using CDUS. The RI values, measured in interlobar/arcuate arteries, were correlated with the findings on MRPI, done before and within 24 h after ESWL. In addition, renal plasma flow (RPF, assessed on radionuclide renography) and Big‐ET‐1 levels (a potent vasoconstrictor peptide), served as a control for evaluating renal perfusion. The patients were stratified in three age groups, i.e. ≤39, 40–59 and ≥60 years, with 23 patients in each group.

RESULTS

The mean (sd ) RI increased significantly in the treated kidneys, from 0.64 (0.05) before to 0.72 (0.08) after ESWL (P = 0.001). Only in patients aged ≥60 years did the RI continue to increase over the 24 h. MRPI showed a decrease of renal blood flow (RBF) in all age groups, but most significantly in those aged ≥60 years. The radionuclide renography and big‐ET‐1 levels changed significantly only in the oldest group. The best correlation was between RI and RBF changes detected by MRPI.

CONCLUSIONS

ESWL obviously causes disturbances of renal perfusion, particularly in elderly patients (≥60 years). Measurement of RI with Doppler techniques might provide useful information for the clinical diagnosis of renal damage.     

Delayed graft function is not associated with an increased incidence of renal allograft rejection

Delayed graft function (DGF) is considered as a risk factor for renal allograft rejection, but this association might be confounded by diagnostic biases (e.g., higher biopsy frequency in patients with DGF, inclusion of clinically diagnosed rejection episodes, and limited details on the rejection phenotype). This retrospective study including 329 deceased donor transplantations aimed to clarify a causal relationship between DGF and rejection. DGF occurred in 93/329 recipients (28%), whereas immediate graft function (IGF) in 236/329 recipients (72%). The percentage of patients with ≥1 allograft biopsy within the first year post‐transplant was similar between the DGF and IGF group (96% vs. 94%; p = 0.60). The cumulative one‐yr incidence of biopsy‐proven clinical (35% vs. 34%; p = 0.62) and combined (sub)clinical rejection (58% vs. 60%; p = 0.79) was not different between the two groups. Furthermore, there were no differences regarding rejection phenotypes/severities and time frame of occurrence. By multivariable Cox regression analysis, donor‐specific HLA antibodies, younger recipient age, and immunosuppressive regimens were independent predictors for clinical rejection, while DGF was not. These results in an intermediate sized, but thoroughly investigated patient population challenge the concept that DGF is a risk factor for rejection and highlights the need for additional studies in this regard.