Adult-sized Kidneys Research Articles

Successful living-donor kidney transplantation after vena cava flow obstruction in a small recipient

Transplantation of an adult-size kidney into a mismatched pediatric recipient reduces transplant waiting time but may lead to potential complications related to vascular anastomoses and graft hypoperfusion. Our aim is to share our experience in the management of an early graft thrombosis due to a complete venous flow obstruction after a living-donor kidney transplantation in a small pediatric recipient, and the long term outcome after the graft recovery. A three-year-old male with end stage renal disease due to posterior urethral valves received a living-donor kidney transplant from his mother in the right side. Surgery was uneventful, but 2 h post-transplant, oligoanuria, hyperkalaemia and metabolic acidosis appeared. Döppler ultrasound detected increasing arterial resistance with diastolic inversion, and no venous flow into the graft. Exploratory surgery confirmed venous flow obstruction in both the renal vein and cava, due to compression of the graft renal artery. The graft was washed out with cold preservation fluid and the renal artery reanastomosed more distally. After 5 days with acute tubular necrosis, renal function was slowly recovered, reaching Schwartz glomerular filtration rate (GFR) of 77ml/min/1.73 2 at the fourth month post-transplant. After 5 years, the graft is still functioning with a creatinine of 0.88mg/dl and Schwartz GFR of 52ml/min/1.73 2 . Adult-size kidney transplantation into small recipients requires tailoring of the vascular anastomoses to the anatomical situation. Early diagnosis and prompt surgical exploration and treatment of graft venous thrombosis may lead to graft recovery, with long term graft survival.

Comparison of live donor predonation and post-transplant kidney volumes and glomerular size in pediatric patients weighing less than 15 kg - a retrospective study.

Renal transplantation of adult-size kidneys presents a size mismatch in small children. This study presents a comparison of live donor predonation and recipient post-transplant kidney volumes (k-vol) and glomerular size at 1year after transplantation. We analyzed 47 pediatric renal transplant recipients weighing <15kg between 2009 and 2017. The k-vol before and 1year after transplantation and glomerular size at implant and 1year post-transplant were evaluated. We estimated the relationships between these changes and graft function, and the factors associated with k-vol. Pretransplant k-vol was 158.1±25.1ml, and the k-vol at 1year post-transplant was significantly reduced by -17.2% to 132.3±27.3ml (P<0.001). Implant glomerular size showed the diameter was 165.3±15.1µm and the area 20737.1±3230.6µm2 . One-year post-transplant, the glomerular diameter was 150.6±11.4µm and the area 17428.3±2577.9µm2 , significantly reduced compared with implantation values (both P<0.001). The change in k-vol was affected by pretransplant abdominal cavity (ml/200ml cavity volume, partial regression coefficient=0.029, SE=0.009, P=0.004) and recipient's weight gain (ml/5% of weight gain, partial regression coefficient=0.020, SE=0.006, P=0.002). In small pediatric transplants, an adult-size kidney is acceptable with reduction in k-vol. Moreover, the post-transplant k-vol might be regulated by pretransplant physique and post-transplant somatic growth.

Donor considerations in pediatric kidney transplantation.

This article reviews kidney transplant donor options for children with end-stage kidney disease (ESKD). Global access to kidney transplantation is variable. Well-established national policies, organizations for organ procurement and allocation, and donor management policies may account for higher deceased donor (DD transplants) in some countries. Living donor kidney transplantation (LD) predominates in countries where organ donation has limited national priority. In addition, social, cultural, religious and medical factors play a major role in both LD and DD kidney transplant donation. Most children with ESKD receive adult-sized kidneys. The transplanted kidney has a finite survival and the expectation is that children who require renal replacement therapy from early childhood will probably have 2 or 3 kidney transplants in their lifetime. LD transplant provides better long-term graft survival and is a better option for children. When a living related donor is incompatible with the intended recipient, paired kidney exchange with a compatible unrelated donor may be considered. When the choice is a DD kidney, the decision-making process in accepting a donor offer requires careful consideration of donor history, kidney donor profile index, HLA matching, cold ischemia time, and recipient's time on the waiting list. Accepting or declining a DD offer in a timely manner can be challenging when there are undesirable facts in the donor's history which need to be balanced against prolonging dialysis in a child. An ongoing global challenge is the significant gap between organ supply and demand, which has increased the need to improve organ preservation techniques and awareness for organ donation.

Is there a functional disadvantage to using the external iliac vessels for vascular anastomosis in children and adolescents undergoing renal transplantation?

RT remains the best available strategy for addressing stage 5 chronic kidney disease in children and adolescents. Technical aspects of the procedure can have a clear impact on complications and health of the allograft, including DGF. Immediate optimal perfusion is paramount, thus choosing a target vessel has to take into account the flow demands imposed by an adult-size kidney in a proportionally smaller recipient. Herein, we explore the hypothesis that vascular anastomosis location can impact DGF adjusting for patient age and body size. Retrospective review of a single institution referral center transplant database, including information on 156 patients. We collected data on patient characteristics (age, height, BSA, gender, preoperative need for dialysis), donor source (deceased vs living), WIT/CIT, hemodynamics during the procedure, use of inotropes or diuretics, and location of the arterial and venous anastomoses. The primary outcome, DGF, was assessed by measuring the ttNC (in days), adjusting for age and BSA. Location of the arterial anastomosis was clearly impacted by age and donor size (Figure 1A). On univariate analyses, longer ttNC was associated with deceased vs living donor (11.8±11.5 and 4.3±5.0; P<0.001), preoperative need for dialysis (9.7±11.0 and 6.5±6.0, P=0.02), location of arterial anastomosis (aorta [n=21] 4.9±6.1, common iliac [n=93] 7.1±7.3, external iliac 14.7±14.5; P<0.001, Figure 1B) and venous anastomosis (vena cava [n=21] 5.6±6.3, common iliac [n=89] 7.1±7.6, external iliac [n=44] 13.8±14); P<0.001). On multivariable analysis, this association remained statistically significant when adjusting for recipient age, height, BSA, donor source, change in blood pressure with unclamping, and use of inotropes and preoperative dialysis. The detrimental effect on ttNC was more salient when comparing external iliac vs common iliac and aorta or vena cava. Our data suggest that anastomosis to a smaller caliber target vessel (ie, external iliac) in comparison with the common iliac or aorta/vena cava may be a risk factor for delayed return of graft function, independent of recipient size and donor source. This finding merit further evaluation, as it may help with intraoperative decision making during pediatric and adolescent RT.

Classification of abdominal vascular anomalies and use of 3D printing to support complex renal transplantation in children

BackgroundTransplantation is the treatment of choice for paediatric renal recipients. However, there are increased challenges in small (<20 kg) children who have complex abnormalities of the abdominal vascular system (aorta and inferior vena cava [IVC]). In this context surgical feasibility and planning is informed by review of medical images. Conventional presentation on a computer screen demands expertise in image interpretation if the spatial associations of complex anatomy are to be fully appreciated. We assessed the feasibility and potential utility of 3D printed models of patient-specific anatomy, as a means to facilitate transplantation. MethodsWe describe our management in five paediatric renal recipients with vascular anomalies (median age 7 years [IQR 4·5–13·0], median weight 18 kg [IQR 14·5–29·0]). We assessed the utility of 3D printing as a planning tool in four children with complex abnormalities (one retrospective case, three prospective cases) for whom implantation was uncertain as judged by conventional imaging. Surgically relevant donor and recipient anatomy was segmented from MRI or CT data (Mimics Medical v18.0, Materialise, Leuven, Belgium). The segmentation geometry derived from the extracted anatomical data was then exported in STL file format and physically fabricated with multimaterial, polyjet 3D printing technology (Objet500 Connex1, Objet-Stratasys). We assessed the value of models using questionnaires and geometric validation studies. FindingsFour (80%) of five children survived after one death from sepsis (with a functioning graft). At the latest median follow-up of 19 months (IQR 10·5–83·0) renal allograft survival was 100% (death censored) with a median estimated glomerular filtration rate of 55 mL/min per 1·73 m2 (IQR 45–66). We have previously classified these vascular anomolies on the basis of aortic and IVC patency (I=aorta patent, II=infrarenal segment occluded, III=suprarenal segment occluded, IV=all aorta occluded) and similarly for IVC patency (A–D). By independent questionnaire, all prospective 3D printed models were considered useful for preoperative planning, and thereby facilitated transplantation. In our retrospective proof of concept, Bland–Altman analysis found that the mean difference in vascular diameter between the printed model and segmentation geometry was −0·1 mm (95% CI −0·7 to 0·5), which was insignificant when compared with the measurement uncertainty (±0·4 mm) and the limits of surgical precision. All models showed geometrical consistency with preprinting designs and intraoperative anatomical correlation within surgical acceptance for crucial decision making. InterpretationVascular anomalies do not necessarily preclude transplantation, and a classification system could guide management. Our feasibility study of patient-specific 3D printing suggests that cases classified as sufficiently complex can benefit from this technology. Patient-specific models provide the surgical team with the full, 3D, accessible, haptic, and spatial appreciation of anatomy that is crucial in surgical decision making and planning. This technology can inform the selection of suitable anastamosis sites in the presence of anomalies and the best surgical approach for implantation of an adult-sized kidney into a small child. FundingNone.

Successful Kidney Transplantation in Children With a Compromised Inferior Vena Cava.

BackgroundChildren with a compromised inferior vena cava (IVC) were previously considered unsuitable for kidney transplantation because of the technical difficulties and the increased risk of graft thrombosis secondary to inadequate renal venous outflow.MethodsWe conducted a retrospective study of 11 transplants in 9 patients with end-stage renal disease and thrombosed IVCs who received adult kidney allografts between 2000 and 2015. The mean age at transplantation was 7.5 ± 3.5 years. A pretransplant diagnosis of the IVC thrombosis was made in 7 patients by magnetic resonance imaging and computerized tomography, whereas there were 2 instances of intraoperative discovery of the IVC thrombosis.ResultsIn the early cases, a kidney was placed intraperitoneally at the right iliac fossa with a venous anastomosis to the patent segment of the suprarenal IVC. After 2008, however, 6 adult-sized kidneys were subsequently placed in the left orthotopic position. Venous drainage was attained to the infrahepatic IVC (n = 3), left native renal vein (n = 2), and ascending lumbar vein (n = 1). Moreover, a venous bypass was created between the graft and the splenic vein in 2 children who showed high return pressure after the vessel was declamped.The mean glomerular filtration rate of the functioning 8 grafts 1 year posttransplant was 73.4 ± 20.4 mL/min per 1.73 m2. Of note, 6 of the grafts have been functioning well, with a mean follow-up of 66 months. Both 1- and 5-year graft survival were 81.8%.ConclusionsTransplantation into the left orthotopic position and the revascularization methods are an effective set of surgical techniques that could potentially be adopted as safe and reliable transplant approaches in children with IVC thrombosis.

Adult-sized Renal Transplantation in Small Pediatric Recipients Achieves Long-term Outcomes Comparable to Size-matched Transplantation

Background: The use of adult-sized kidneys seems applicable to low-weight children where size-matched donors are scarce. The aim of this study is to assess the impact of donor-recipient size mismatch on long-term renal graft and patient survival in small recipients, in order to optimize graft allocation. Methods: Between 1999-2010, 46 renal transplants were performed in recipients glomerular filtration rate (GFR), proteinuria, rejection episodes, graft and patient survival were analyzed and compared between groups at the time of transplantation (T0), at one (T1), two (T2), five years (T5), and at the end of the study (TF). Results: The mean renal size (longitudinal length in cm) was significantly different at T0, T1 and T2 between both groups (pT0<0.01; pT1<0.01; pT2<0.01), showing a significant increase in group B during the follow up, being similar to group A at T5 and TF (pT5=0.16; pTF=0.92). The mean GFR (ml/min/1.73 m2) was significantly higher at T0 in group A, compared to B (GFRA=148 ± 47; GFRB=111 ± 33; pT0=0.01); at T1 it decreased in A and increased in B (GFRA=127 ± 38; GFRB=121 ± 31; pT1=0.66), with similar values in both groups at T2, T5 y TF (pT2=0.83; pT5=0.15; pTF=0.90). During follow-up (8.6 ± 4.1 yrs) 9 grafts were lost, 2 in A and 7 in B. Two patients died in group B. No significant differences were observed in graft and patient survival at 5 and 10 years (p=0.66; p=0.19) neither proteinuria nor rejection. Conclusion: Adult-sized grafts in small recipients showed a reduction of the function, but remained a stable size. These grafts can be safely transplanted with comparable outcomes to size-matched kidneys.

The role of transesophageal echocardiography in transplantation of an adult-sized kidney to a small child

Transplantation of adult-sized kidneys to pediatric patients weighing less than 10 kg is a challenge to both surgical and anesthetic management. For survival of the graft, a large-size kidney graft transferred to a pediatric patient needs extraphysiological cardiac output to compensate for adequate renal blood flow. We report here a boy weighing 8.4 kg who received transplantation of a kidney donated by his 56.4-kg mother. Since monitoring of the central venous pressure was not accurate enough and Swan–Ganz catheterization was not feasible in this patient for monitoring the fluid status and cardiac function, we used transesophageal echocardiography to guide intravascular volume expansion and to titrate inotropic support during the surgery. It was demonstrated to be a useful tool for optimization of renal perfusion in this scenario. The transplanted graft served its function well.

Stanniocalcin Supports the Functional Adaptation of Adult-Sized Kidneys Transplanted Into the Pediatric Recipients

The functional adaptation of adult-sized kidney (ASK) grafts to the recipient's size is not completely reversible and is associated with irreversible histologic damage in the smallest recipients. The aim of the study was to unveil the molecular mechanisms underlying the functional adaptation of ASK transplants to small pediatric recipients. Because physiologic and functional adaption of ASK in infants is seen maximally at 3 months after transplantation, we selected 21 pediatric recipients of an ASK with protocol biopsies at engraftment and 3 and 6 months, without delayed graft function or interval rejection, and we conducted whole-genome expression profiles of the renal allograft biopsies at 3 months and correlated results with subsequent absolute glomerular filtration rate (aGFR). Seven hundred twenty-four unique genes correlated significantly with aGFR (q value <5%). Canonical pathway analysis identified overrepresentation of relevant pathways involved in regulation of tubular salt reabsorption and enzymatic pathways for organ development and hypertrophy. The single gene that correlated best with aGFR was stanniocalcin 1 (STC1). STC1 expression also correlated with the recipient's size at the time of transplantation and the chronic allograft damage index at 6 months. Functional adaptation of adult-sized grafts to the pediatric recipient is associated with molecular adaptation for normal-volume homeostasis of the recipient. Our finding also suggests that stanniocalcin (STC1) plays an important role on functional adaption in pediatric kidney transplantation.

Re: Pediatric Kidney Recipients With Small Capacity, Defunctionalized Urinary Bladders Receiving Adult-Sized Kidney Without Prior Bladder Augmentation

No AccessJournal of UrologyPediatric Urology1 Mar 2012Re: Pediatric Kidney Recipients With Small Capacity, Defunctionalized Urinary Bladders Receiving Adult-Sized Kidney Without Prior Bladder Augmentation Alan J. WeinM.D., Ph.D. (hon.) Alan J. WeinAlan J. Wein More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2011.11.072AboutFull TextPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail "Re: Pediatric Kidney Recipients With Small Capacity, Defunctionalized Urinary Bladders Receiving Adult-Sized Kidney Without Prior Bladder Augmentation." The Journal of Urology, 187(3), p. 1056 © 2012 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 187Issue 3March 2012Page: 1056 Advertisement Copyright & Permissions© 2012 by American Urological Association Education and Research, Inc.MetricsAuthor Information Alan J. Wein More articles by this author Expand All Advertisement PDF DownloadLoading ...

Surveillance biopsies in children post-kidney transplant

Surveillance biopsies are increasingly used in the post-transplant monitoring of pediatric renal allograft recipients. The main justification for this procedure is to diagnose early and presumably modifiable acute and chronic renal allograft injury. Pediatric recipients are theoretically at increased risk for subclinical renal allograft injury due to their relatively large adult-sized kidneys and their higher degree of immunological responsiveness. The safety profile of this procedure has been well investigated. Patient morbidity is low, with macroscopic hematuria being the most common adverse event. No patient deaths have been attributed to this procedure. Longitudinal surveillance biopsy studies have revealed a substantial burden of subclinical immunological and non-immunological injury, including acute cellular rejection, interstitial fibrosis and tubular atrophy, microvascular lesions and transplant glomerulopathy. The main impediment to the implementation of surveillance biopsies as the standard of care is the lack of demonstrable benefit of early histological detection on long-term outcome. The considerable debate surrounding this issue highlights the need for multicenter, prospective, and randomized studies.

Pediatric Kidney Recipients With Small Capacity, Defunctionalized Urinary Bladders Receiving Adult-Sized Kidney Without Prior Bladder Augmentation

Children with small capacity, defunctionalized urinary bladders present unique operative challenges. Thus, traditional practice has included pretransplant bladder augmentation, but this has several adverse consequences. A single-institutional, retrospective review from January 1, 2004 to December 31, 2008 was conducted. Twelve pediatric patients, whom had not undergone pretransplant bladder augmentation, did not have neurogenic bladders or require preoperative catheterization, and a small capacity defunctionalized bladders were included. All were managed by the same surgeon with a previously described ureteral implantation, and a 7F ureteral stent attached to a large diameter suprapubic catheter was removed in a joint manner without cystoscopy at 2 weeks. Data were collected on patient and graft survival, rejection episodes, urinary tract infection (UTI) requiring antibiotics, grade of vesicoureteral reflux, and posttransplant bladder capacity. One-year patient and graft survival rates were 100%. One patient experienced a clinical rejection episode, which was successfully treated. Five patients (41.7%) had a UTI requiring abx treatment within the first postoperative year, but at 1 year, all patients had sterile urinary tracts. After removal of suprapubic catheters and ureteral stents, all patients were able to void spontaneously. Seven patients had no posttransplant ureteral reflux, three had grade 1 reflux, and two had grade 3 reflux (both successfully treated). The average age estimated pretransplant bladder and 1 year posttransplant bladder capacity was 14.5% and 84% of expected, respectively. In pediatric end-stage renal disease patients with a small capacity defunctionalized bladder, it is reasonable to proceed with kidney transplantation without pretransplant bladder augmentation, thus avoiding an unnecessary surgery.

Standardizing resistive indices in healthy pediatric transplant recipients of adult-sized kidneys

Small pediatric recipients of an adult-sized kidney have insufficient renal blood flow early after transplantation, with secondary chronic hypoperfusion and irreversible histological damage of the tubulo-interstitial compartment. It is unknown whether this is reflected by renal resistive indices. We measured renal graft resistive indices and volumes of 47 healthy pediatric kidney transplant recipients of an adult-sized kidney in a prospective study for six months post-transplant. A total of 205 measurements were performed. The smallest recipients (BSA <or=0.75 m(2)) had higher resistive indices compared to recipients with a BSA between 0.75 and 1.5 m(2) (p < 0.0001) and to recipients with a BSA >or= 1.5 m(2) (p < 0.0001). Resistive indices increased during the first six months in the smallest recipients (p = 0.02), but not in the two larger recipient groups (BSA 0.75-1.5 m(2) and >or=1.5 m(2)). All three BSA groups showed a reduction in renal volume after transplantation, with the greatest reduction occurring in the smallest recipients. In conclusion, renal transplant resistive indices reflect pediatric recipient BSA dependency. The higher resistance to intra-renal vascular flow and significant decrease in renal volume in the smallest group likely reflect accommodation of the size discrepant transplanted adult-sized kidney to the smaller pediatric recipient vasculature with associated lower renal artery flow.

Renal transplantation in children with thrombosis of the inferior vena cava requires careful assessment and planning

Children with end-stage renal disease and inferior vena cava (IVC) thrombosis are rare, and their condition is complex and high risk for renal transplantation. Detailed imaging studies of the recipient's abdominal vasculature should be carried out prior to transplantation, followed by careful pre-operative joint planning by the pediatric transplant surgeon and nephrologist. Critical decisions need to be made as to whether a deceased child's kidney or an adult-sized kidney is to be used, and if the latter, whether it should be from a deceased or living donor. In addition, the contemplated site of the donor's renal vein anastomosis needs to be determined with a consideration of the possible consequences of the various choices. Sixteen cases of renal transplantation in children with pre-existing IVC thrombosis are reviewed, including the three reported by Shenoy et al. in this journal. With a full understanding of the difficulties noted, renal transplantation in a small child with IVC thrombosis can be successful. However, it requires thorough recipient assessment, coupled with a careful and thoughtful examination of options, to determine the best possible approach to the transplantation.

Successful renal transplantation in children in the presence of thrombosis of the inferior vena cava

Thrombosis of the inferior vena cava (IVC) has previously been considered to be a contraindication to renal transplantation in children because of the technical difficulties associated with surgery and the increased risk of graft thrombosis. We report three children with previous IVC thrombosis who underwent renal transplantation at our institution over the last 5 years. The pretransplant imaging of these patients included direct venography or magnetic resonance venography to evaluate venous outflow. Two children (19 kg and 36 kg) received deceased donor renal allografts with no surgical complications or delayed graft function. At the latest follow-up 3.0 and 4.6 years posttransplantation, respectively, they were well, with estimated glomerular filtration rates of 52 and 64 ml/min per 1.73 m(2), respectively. The third child underwent a live-related-donor renal transplant at the age of 4.9 years (weight 13.5 kg). There was primary graft nonfunction. Renal vein thrombosis was noted on postoperative day 12, with subsequent graft loss. Children with previous IVC thrombosis can be successfully transplanted with adult-sized kidneys provided detailed evaluation of the venous drainage has been performed. There is substantial risk of graft thrombosis, and detailed counselling regarding the specific risks of the procedure is essential.

The Evolution of Nonimmune Histological Injury and Its Clinical Relevance in Adult-Sized Kidney Grafts in Pediatric Recipients

To describe the evolution, risk factors and impact of nonimmune histological injury after pediatric kidney transplantation, we analyzed 245 renal allograft protocol biopsies taken regularly from the time of transplantation to 2 years thereafter in 81 consecutive rejection-free pediatric recipients of an adult-sized kidney. Isometric tubular vacuolization was present early after transplantation was not progressive, and was associated with higher tacrolimus pre-dose trough levels. Chronic tubulo-interstitial damage and tubular microcalcifications were already noted at 3 months, were progressive and had a greater association with small recipient size, male donor gender, higher donor age and female recipient gender, but not with tacrolimus exposure. Renal function assessment showed that older recipients had a significant increase in absolute glomerular filtration rate with time after transplantation, which differed from small recipients who showed no increase. It is concluded that progressive, functionally relevant, nonimmune injury is detected early after adult-sized kidney transplantation in pediatric recipients. Renal graft ischemia associated with the donor-recipient size discrepancy appears to be a greater risk factor for this chronic histological injury, suggesting that the exploration of additional therapeutic approaches to increase allograft perfusion could further extend the graft survival benefit of adult-sized kidneys transplanted into small children.

Renal Transplantation in Children 15 Kg or Less: The British Columbia Children’s Hospital Experience

Small infants are the most challenging group of patients to undergo renal transplantation. We reviewed the transplantation experience at our institution with children less than 15 kg at transplantation. We retrospectively reviewed the records of 24 recipients in a 20-year period. Technical and allograft outcomes were compared to those in the North American Pediatric Renal Transplant Cooperative Study database. Since the inception of our program 24 recipients weighing 15 kg or less who were 6 years or younger have undergone transplantation. Seven grafts (29%) were from living donors. At transplantation mean age was 3.1 years (range 1.8 to 5.7) and mean weight was 13.4 kg (range 9.0 to 15.7). Average cold and warm ischemic times were 14.1 hours (range 3.4 to 37.2) and 23.1 minutes (range 21 to 41), respectively. Early complications were ureteral stricture requiring pyeloureterostomy in 1 case, reversible acute tubular necrosis in 2 and early arterial thrombosis salvaged by immediate thrombectomy in 1. Delayed complications were arterial stenosis requiring angioplasty in 2 cases, and 3 delayed deaths related to malignant hypertension in 2 and sepsis in 1. No grafts were lost due to thrombosis. Mean serum creatinine at years 1 to 3 and 5 were 48.5, 67.5, 79.1 and 84.4 mumol/l, respectively. Graft survival was 92% (22 patients after censoring 1 who died with a functioning graft) at 2 and 5 years. Overall results compare favorably to those in the North American Pediatric Renal Transplant Cooperative Study. With a multidisciplinary team effort successful results can be achieved in this challenging group of patients.

Pediatric renal transplantation with considerations for successful outcomes

Renal transplantation in the pediatric population, although conceptually similar to that in adults, differs in many aspects. This review will focus on the issues unique to the pediatric recipient. In particular, we will focus on the incidence and etiology of end stage renal disease in children, and the results as measured by patient and graft survival. Pretransplant surgical considerations of timing of the transplant, management of congenital urologic abnormalities and the abnormal bladder will be addressed. Etiologies of renal failure unique to the pediatric population will be discussed, including autosomal recessive polycystic kidney disease, congenital nephrotic syndrome, inferior vena cava thrombosis, and primary hyperoxaluria Type 1. Lastly, special transplant surgical considerations including transplantation of an adult-size kidney (ASK) into an infant or small child and ureteral implantation, management of the urinary bladder, and fluid management in infants and small children will be discussed.

Safety and risk stratification of percutaneous biopsies of adult-sized renal allografts in infant and older pediatric recipients.

Allograft biopsies are the gold standard for evaluating renal graft dysfunction. Adult-sized kidney (ASK) allografts are placed extraperitoneally in older children and adults and transperitoneally in infant recipients. Transperitoneal graft biopsies may be accompanied by a greater risk of bleeding and bowel injury, although no standardized pediatric study of procedure risk relating to transplant placement exists. A retrospective single-center study of 328 consecutive ASK biopsies (277 extraperitoneal and 51 transperitoneal) performed since 1995 was conducted to stringently categorize all identified biopsy procedure complications (bleeding, transfusion requirement, bowel perforation, surgical intervention, and graft loss) relating to allograft placement, surveillance versus protocol biopsies, recipient age, and biopsy needle use, with risk stratification and recommendations for improving procedure safety. Two distinct methods of real-time ultrasound guidance were used. The overall incidence of all adverse effects was 16.1%, with perinephric hematomas accounting for 13.4% and gross hematuria accounting for 2.7%. Hematomas less than 1 cm accounted for 81.4% of all hematomas. Complications of transperitoneal biopsies (using a modified patient placement approach) paralleled those seen in extraperitoneally placed allografts (15.7% vs. 15.5%, P=0.976). Hematomas occurred more frequently (17.8% vs. 8.3%, P=0.010) in clinically indicated versus surveillance biopsies and with 16- versus 18-gauge biopsy needle use (43% vs. 13.3%, P=0.19). Pediatric allograft ASK biopsies can be performed with minimal adverse outcomes. Transperitoneal ASK placement is not a contraindication for percutaneous biopsy. Strategies to improve biopsy safety include recommendations for patient positioning for transperitoneal ASKs, improved techniques for real-time ultrasound guidance, and use of finer gauge needles.

A 100% 2-year graft survival can be attained in high-risk 15-kg or smaller infant recipients of kidney allografts.

Infants make up the most high-risk, difficult to care for subgroup undergoing kidney transplantation, with the lowest 1- and 2-year graft survival rates of any other age group. The principal causes of graft loss have been graft thrombosis, primary nonfunction, technical error, and irreversible acute rejection. Infants undergoing kidney transplantation can achieve near 100% graft survival at 2 years following surgery, despite their very high-risk status. Analysis of 45 consecutive kidney transplants performed in patients weighing less than or equal to 15 kg during an 8-year period beginning August 1991. Patients included complex referrals from throughout the United States and all received transplants and were cared for by the same pediatric kidney transplantation team. Mean weight at transplantation was 11. 2 kg. Renal failure was due to congenital or urologic causes in the majority (53%) of cases. Size-discrepant adult-sized kidney grafts were transplanted in 80% of patients; 64% received live-donor grafts; 78% were receiving dialysis prior to transplantation; and 27% had extremely small bladders (<20 cm(3)) requiring modification of the ureteral implantation. Excluding 1 transplant-unrelated death, graft and patient survival at 2 years was 100%. Eight-year patient and graft survival rates (for our combined live and cadaver donor series) were 89.6% and 84.6%, respectively. This compares favorably with much lower graft survival in low-risk adult recipients. Delayed graft function occurred in only 1 patient (2%). Rate of incidence of rejection was 9.3% within 2 years of transplantation and the overall rejection rate was 15.5%. No graft was lost to vascular thrombosis, primary nonfunction, technical error, or acute rejection. The mean creatinine level was 53.04 micromol/L (0.6 mg/dL) and 61.9 micromol/L (0.7 mg/dL) at 1 and 2 years, respectively, and 88.4 micromol/L (1.0 mg/dL) at 3, 4, and 5 years after transplantation. One hundred percent 2-year and excellent 8-year graft survival rates can be achieved in what has historically been the highest-risk and most difficult to care for patient subgroup undergoing kidney transplantation.