Living donor transplant: Right vs left kidney

Abstract

Khan et al’ single-centre, retrospective study on the use of right or left kidneys in living-donor renal transplantation, offers the opportunity to further discuss a complex and debated topic in clinical transplantation. In brief, the authors confirm that, despite the historical preference for left kidneys, attributed to their anatomical advantages during donor nephrectomy and recipient transplantation, right kidneys can provide excellent outcomes when donors and recipients are carefully selected, and a meticulous surgical technique is applied in every step of the process. Usefully, the article includes some practical tips to help less experienced surgeons address the technical challenges of right kidney transplantation, such as extended renal vein dissection or full mobilization of the iliac vein of the recipient to minimize tension during anastomosis. Although limited by the selective use of minimally invasive (MI) nephrectomy for left kidneys, this work underscores the importance of expanding the living-donor pool, challenging the traditional taboos, and facilitating access to transplantation for a wider population of patients around the globe. Properly designed studies with larger sample size, comparable MI surgical techniques, prospective data collection, and long-term donor and recipient outcomes are warranted.

Key Words: Kidney transplantation; Living donation; Organ procurement; Surgical technique; Surgical complications; Outcomes

Core Tip: As shown by Khan et al in their recent work, there is mounting evidence that living-donor transplants performed using right kidneys can provide recipient- and graft-related outcomes as good as the ones obtained transplanting left kidneys. Importantly, in high-volume centres with experienced surgeons, right-sided living-donor nephrectomies are not associated with increased surgical complications compared to left-sided procedures. As traditional open surgery is being replaced by minimally invasive techniques, future research should aim to conclusively validate the safety and efficacy of laparoscopic or robot-assisted donor nephrectomy also in challenging clinical scenarios, such as right or multiple-vessel kidneys.

TO THE EDITOR

We read with interest the article by Khan et al[1] comparing the outcomes of living-donor transplants performed using right or left kidneys, recently published in the World Journal of Transplantation. Although flawed by several methodological issues (i.e., small sample size, retrospective data collection, selective use of laparoscopy, and short follow-up), this study opens the door to further discussions on a complex and debated topic in solid organ transplantation (SOT). There has been a longstanding concern surrounding the use of right kidneys from living donors[2]. This bias has been further exacerbated by the increasing adoption of minimally invasive (MI) techniques for donor nephrectomy[3], as highlighted in recent meta-analyses[4,5].

The authors show that, despite the well-recognized anatomical disadvantages (observed in both donor and recipient surgery)[6], right kidneys can provide excellent results when careful risk minimization strategies and a meticulous surgical technique are applied in every single step of the process. Indeed, there is now evidence that living-donor transplants performed using right or left kidneys have comparable recipient and graft-related outcomes[7]. Furthermore, there are several studies demonstrating that right-sided living-donor nephrectomies are not associated with higher surgical complication rates compared to left-sided procedures[8,9]. Accordingly, we believe that, in current clinical practice, a living donor should not be discarded based on renal anatomy. Also, right or multiple-vessel kidneys should not be considered as a contraindication to MI donor nephrectomy[10,11].

STATUS QUO

Historically, there has been a preferential use of left kidneys for living-donor renal transplantation[12]. This preference is largely due to the longer renal vein in left kidneys, which facilitates vascular anastomosis and reduces the risk of renal vein thrombosis[13]. However, according to two recent meta-analyses comparing living-donor transplants performed using left or right kidneys[4,5], the differences in delayed graft function and technical graft loss rates observed in some studies, almost disappear when the centre effect is taken into account or, as suggested by Dobrijevic et al[2], the surgeons involved in the procedure have concluded their learning curve, managing to address the complexities of right kidneys with consolidated strategies.

The intrinsic anatomical challenges of right kidney transplantation can be further exacerbated by the specific technical constraints posed by MI approaches for living-donor nephrectomy[14,15]. In the setting of fully laparoscopic, hand-assisted laparoscopic, or robot-assisted nephrectomy, removing a patch from the inferior vena cava[16] or applying titanium clips and Hem-o-lok[17] rather than using a vascular stapler[18,19] for renal vein closure (to maximize the length of the vessels), would substantially (and perhaps unacceptably) increase the risk of bleeding for the donor[20]. Therefore, transplant surgeons dealing with organs procured with these techniques should be able to transplant kidneys with very short vessels, often requiring complex vascular reconstructions, modified implantation techniques, or extended mobilization of the iliac axis[21]. In our experience, the selective use of trans-peritoneal or retro-peritoneal hand-assisted laparoscopic nephrectomy (HALN), depending on the specific anatomical characteristics of the donor, proved particularly effective in reducing side selection bias and improving recipient outcomes, without additional risks for the donor[22]. Undoubtedly, in living-donor surgery, HALN provides several advantages compared to other MI techniques because it combines the benefits of reduced invasiveness with laparoscopic visualization while maintaining tactile feedback for anatomical dissection and immediate vascular control in case of severe bleeding[23]. As pointed out by Buell et al[24] back in 2002, the shorter learning curve required by naïve surgeons and the perceived safety of the procedure have favoured the widespread application of HALN, also in difficult surgical scenarios.

In the last decade, robot-assisted surgery (RAS) has emerged as a potential game-changer in many surgical specialties, including SOT[15]. The enhanced dexterity, precision, and three-dimensional visualization offered by robotic platforms could, at least in theory, address most of the technical issues commonly associated with right-sided living-donor nephrectomy and living-donor right kidney transplantation. Although the use of RAS in kidney transplant setting remains the prerogative of very few highly specialized centres, available studies show that, compared to fully laparoscopic or hand-assisted laparoscopic techniques, robot-assisted living-donor nephrectomy provides longer renal vessels, with shorter warm ischemia and extraction times[25-27]. Donor-related safety data (namely, peri-operative blood loss, surgical complications, and hospital stay) are also reassuring as much as the results concerning the duration of the learning curve[15]. Current experience with robot-assisted kidney transplantation is extremely scarce. Preliminary results suggest that robot-assistance might favour the application of MI techniques in the recipient, particularly in case of patients with complex vascular anatomy or obesity, but the logistical issues and the increased costs associated with pre-operative set up, extended operation time, and disposable devices required by robotic platforms may represent difficult challenges, particularly in the urgent setting of deceased-donor transplantation.

FUTURE DIRECTIONS

The methodological limitations of the study by Khan et al[1] undoubtedly reduce the generalizability of their findings as well as the strength of their conclusions. Nevertheless, these same limitations suggest how future research projects should be designed, aiming to capture the variability in donors' and recipients’ (demographic, clinical, and anatomical) characteristics[28-30], surgical techniques or operators' expertise, and local healthcare resources that may ultimately influence the outcomes of the entire organ donation and transplantation process. Remarkably, next studies are also expected to analyse both donor and recipient outcomes, considering that the risks and benefits associated with a specific MI donor nephrectomy technique must be weighed against the risk of premature transplant failure or impaired allograft function in the recipient. For this purpose, the length of follow-up, generally interrupted within a few months of transplant, should be extended[31]. Having access to long-term recipient data could help assess the effects of differences in donor-related warm ischemia and kidney extraction times on allograft function.

CONCLUSION

For many years, there has been a preferential use of left kidneys for living-donor kidney transplantation. However, current literature shows that living-donor transplants performed using right kidneys can provide recipient- and graft-related outcomes comparable to those obtained transplanting left kidneys. Importantly, there is now evidence that MI techniques can safely and effectively replace traditional open surgery for living-donor nephrectomy. Future research should aim to conclusively demonstrate the superiority of fully laparoscopic, hand-assisted laparoscopic, or robot-assisted donor nephrectomy also in difficult surgical scenarios such as right or multiple-vessel kidneys. Comprehensive long-term follow-up data for both donors and recipients are essential to accurately assess the cost-effectiveness of the proposed procedures, aiming to improve the entire clinical decision-making process. Emerging technologies, including augmented reality and artificial intelligence, may further enhance the outcomes of high-risk kidney transplants.

ACKNOWLEDGEMENTS

We thank Cesina Tamburri and Marta Ripamonti for their support.