Potential of neonatal organ donation and outcome after transplantation

Organ transplantation is limited by access to suitable organs. Infant recipient waitlist mortality is increased due to the scarcity of size-matched organs. Neonatal organ donors have been proposed as an underutilized source of donor organs. However, the literature on the actual prevalence and outcome of neonatal organ donation and transplantation is fragmented and not well analyzed. This literature review aims to summarize the available literature on the potential of neonatal organ donation and to analyze published cases of neonatal organ transplantation. A systematic search of the Medline and Cochrane databases yielded 2964 articles, which were screened for eligibility. In total, 86 articles were considered eligible, of which 34 were included in the literature review: 8 articles describing the potential of neonatal organ donation programs, and 26 articles describing clinical transplantation. Current evidence suggests there is a large pool of potential neonatal organ donors. In contrast, the literature on neonatal organ donor utilization is sparse. However, case series of successful kidney, heart, liver, hepatocyte, and multivisceral transplantation using organs from neonatal donors are summarized. Although good posttransplant organ function was achieved, the use of neonatal organs is associated with increased risk of thrombosis in both kidney and liver transplantation. Neonatal organ donation is a promising alternative for expanding the current donor pool. Experience is limited, but reported patient and graft survival are acceptable and more research on the subject is warranted.

Complex Vascular Reconstruction of an En Bloc Pediatric Kidney Damaged during Organ Procurement

En bloc pediatric kidney (EBPK) allografts are a potential solution to expand the organ donor pool; however, EBPK transplantation has been traditionally considered suboptimal due to concerns of perioperative vascular and urologic complications. Accidental organ or vasculature injury during harvest is not uncommon; however, this does not necessarily mean that the organ should be discarded. Careful vascular reconstruction can be performed using donor vascular grafts, salvaging the organ without stenosis or thrombosis of the vessels. We report an extensive vascular reconstruction of the right renal artery, aorta, and inferior vena cava of a damaged EBPK allograft using a donor pediatric aorta vascular patch with the goal of avoiding postoperative vascular complications.

Comparison of Outcomes of Kidney Transplantation From Extremely Low Body Weight ≤5kg Versus Larger Body Weight Pediatric Donors

Background

Kidney transplantation from donors who weigh ≤5 kg is performed at only a few transplant centers owing to the high complication and low graft survival rates associated with this approach.

Methods

We retrospectively compared the results of kidney transplantation at our center between January 2015 and December 2019 based on the following pediatric donor criteria: donor body weight ≤5 kg (n=32), 5 kg< donor weight ≤20 kg (n=143), and donor weight >20 kg (n=110). We also perform subgroup analysis of kidney transplantation outcomes from ≤5 kg donors, using conventional (dual separate and classic en-bloc KTx)/novel (en-bloc KTx with outflow tract) surgical methods and allocating to adult/pediatric recipients.

Results

The death-censored graft survival rates from extremely low body weight ≤5kg at 1 month, and 1, 3, and 5 years were 90.6%, 80.9%, 77.5%, and 73.9%, respectively, which were significantly lower than that from larger body weight pediatric donors. However, the 3-, and 5-year post-transplantation eGFRs were not significantly different between the pediatric and adult recipient group. The thrombosis (18.8%) and urinary leakage (18.8%) rates were significantly higher in the donor weight ≤5 kg group. Compared with 5 kg< donor weight ≤20 kg group, donor weight ≤5kg group was at elevated risk of graft loss due to thrombosis (OR: 13.4) and acute rejection (OR: 6.7). No significant difference on the outcomes of extremely low body weight donor kidney transplantation was observed between adults and pediatric recipients. Urinary leakage rate is significantly lower in the novel operation (8.7%) than in the conventional operation group (44.4%).

Conclusions

Although the outcomes of donor body weight ≤5kg kidney transplantation is inferior to that from donors with large body weight, it can be improved through technical improvement. Donors with body weight ≤5 kg can be considered as an useful source to expand the donor pool.

Transplantation of En Bloc Pediatric Kidneys With a Bladder Segment Patch After a Complex Vascular Reconstruction: A Case Report

BACKGROUND

En bloc pediatric kidney (EBPK) allografts represent one potential solution to increase the number of organs available in the donor pool, thus facilitating transplantation of kidneys from young donors into adult recipients. However, EBPK transplantation has been traditionally considered suboptimal because of concerns for perioperative complications.

METHODS

An extensive reconstruction and successful transplantation of an EBPK allograft using same pediatric donor vascular grafts and a bladder patch aiming to avoid postoperative complications is presented in this report.

RESULTS

The warm ischemia time was 25 minutes. No surgical drainage or ureteral stent were used. Postoperative Doppler ultrasound showed laminar blood flow and normal parameters in both the external iliac and graft arteries, no collections, and no signs of obstructive uropathy. The patient had an uneventful recovery showing a creatinine level of 0.86 mg/dL and 0.85 mg/dL at 1 month and 3 months, respectively.

CONCLUSIONS

A refined back-table reconstruction of these allografts is crucial to avoid mishaps in the postoperative period.

Urologic complications after transplantation of 225 en bloc kidneys from small pediatric donors ≤20 kg: Incidence, management, and impact on graft survival

Pediatric en bloc kidney transplants (EBKs) from small deceased pediatric donors are associated with increased early graft loss and morbidity. Yet, urologic complications post-EBK and their potential impact on graft survival have not been systematically studied. We retrospectively studied urological complications requiring intervention for 225 EBKs performed at our center January 2005 to September 2017 from donors ≤20 kg into recipients ≥18 years. Overall ureteral complication incidence after EBK was 9.8% (n = 22) (12% vs 2% for EBK donors < 10 vs ≥ 10 kg, respectively [P = .031]). The most common post-EBK urologic complication was a stricture (55%), followed by urine leak (41%). In all, 95% of all urologic complications occurred early within 5 months posttransplant (median, 138 days). Urologic complications could be successfully managed nonoperatively in 50% of all cases and had no impact on graft or patient survival. In summary, urologic complications after EBK were common, associated with lower donor weights, occurred early posttransplant, and were often amenable to nonoperative treatment, without adversely affecting survival. We conclude that the higher urologic complication rate after EBK (1) should not prevent increased utilization of small pediatric donor en bloc kidneys for properly selected recipients, and (2) warrants specific discussion with EBK recipients during the preoperative consent process.

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.

Pediatric en bloc kidney transplantation from very small (≤10 kg) donation after circulatory death (versus brain death) donors: Single-center matched-pair analysis of 130 transplants

En bloc kidney transplants (EBK) from very small pediatric donation after circulatory death (DCD) donors are infrequent because of the perception that DCD adversely impacts outcomes. We retrospectively studied 130 EBKs from donors ≤10 kg (65 consecutive DCD vs 65 donation after brain death [DBD] transplants; pair-matched for donor weight and terminal creatinine, and for preservation time). For DCD vs DBD, median donor weight was 5.0 vs 5.0 kg; median recipient age was 57 vs 48 years (P = .006). Graft losses from thrombosis (DCD, 5%; DBD, 7%) or primary nonfunction (DCD, 3%; DBD, 0%) were similar in both groups (P = .7). Delayed graft function rate was higher for DCD (25%) vs DBD (14%) (P = .2). Graft survival (death-censored) for DCD vs DBD at 5 years was 87% vs 91% (P = .3). Median estimated GFR (mL/min per 1.73 m² ) was significantly lower for DCD recipients at 1 and 3 months; at 6 years it remained stable at 100 (DCD) and 99 (DBD). DCD impacted early posttransplant graft function, but did not appear to impart added risk for graft loss and long-term function. Very small (≤10 kg) DCD EBK donors should be considered as an option to augment the deceased kidney donor pool; larger studies with longer follow-up must confirm these findings.

Renal transplant from infant and neonatal donors is a feasible option for the treatment of end-stage renal disease but is associated with increased early graft loss

Kidney transplants from young pediatric donors are uncommonly performed in the UK. Published literature of kidney transplant from donors weighing less than 5 kg is sparse. We present our initial experience of en bloc kidney transplantation (EKT) from donors weighing less than 20 kg, including neonatal donors. All recipients undergoing EKT from donors under 20 kg at our center from January 2005 to October 2016 were included. Donor and recipient details were recorded from a prospective database. Electronic patient records were examined for follow-up data. Of 30 EKTs included, 15 were from ≤5 kg donors and 15 from >5 kg donors (median weight 3.4 and 12.7 kg, respectively). One-year graft survival for ≤5 kg and >5 kg donors for EKT was 86.7% and 93.3% (P = 0.85), respectively. Progressive improvement in estimated GFR (eGFR) was noted in both donor categories through first-year posttransplant but in the ≤5 kg donor category significant improvement was seen at 12 months compared to 3 months after transplantation (median eGFR 37.3 vs 70.0 mL/min/1.73 m² , P = 0.03). Two early graft losses were attributable to early vascular complications and one graft loss due to primary nonfunction. Our data show that kidney transplantation from such donors is a feasible option at centers with experience of EKT, albeit with increased risk of early graft loss.

Vascular complications in kidney transplant recipients

Vascular complications are a significant source of morbidity and mortality among renal transplant recipients. Imaging using ultrasound, CT, and MRI plays a key role in diagnosing such complications. This review focuses on the major vascular complications of renal grafts, which include transplant renal arterial and venous stenoses, arterial and venous thromboses, arteriovenous fistulas, and pseudoaneurysms. Etiology, diagnostic modalities useful for diagnosis, and imaging appearance will be presented.

Successful Repair of Bilateral Ureteral Stricture 3 Years after En Bloc Kidney Transplant: A Case Report

En bloc kidney transplants of small pediatric kidneys into adult recipients have been shown to have outcomes similar to transplants from standard adult deceased donors. Here, we report a 27-year-old male patient with successful repair of bilateral ureteral stricture 3 years after en bloc kidney transplant at the Shahid Modarres Hospital (Tehran, Iran). The patient received an en bloc deceased kidney donation from a 9-month-old infant. An end-to-end anastomosis of the aorta to the internal iliac artery and an end-to-side external iliac vein anastomosis to vena cava were performed. At an outpatient visit about 2.5 years later, the patient showed increasing levels of creatinine from 1.1 to 1.8 mg/dL compared with measurements at his 2-month visit. A computed tomography scan performed without any contrast agent at that time confirmed the existence of hydronephrosis in both the medial and lateral kidneys. A nephrostography showed a ureteral stricture. Because endoscopic surgery for ureteral dilatation was not successful, the decision was made to perform ureteral repair by the open surgical technique. The short length of the ureters resulted in the lateral renal pelvis being anastomosed to the bladder by flap (Boari flap). The ureter of the patient's native kidney was transected in the middle portion, and the distal ureter was anastomosed to the medial renal pelvis using the end-to-end method. Here, we showed that, despite limited experiences with pediatric donors, en bloc kidney transplant can be performed under the guidance of experienced surgical techniques and precise postoperative follow-up.