Surgical Advances in Laparoscopic Donor Nephrectomy

Since it was first described in the 1990s, conventional laparoscopic donor nephrectomy has been the standard of care at most major transplant centers. Clayman et al. described the first successful conventional laparoscopic nephrectomy in 1991 for intrinsic renal disease [1]. Several years later, a conventional laparoscopic donor nephrectomy procedure was successfully performed in a large animal model [2], while Ratner and colleagues described the first successful conventional laparoscopic live donor nephrectomy one year later [3]. Donor were discharged home within two days and most returned to work within two weeks postoperatively. Moreover, recipient outcomes were significantly better than deceased donor allografts.


Historical overview
Since it was first described in the 1990s, conventional laparoscopic donor nephrectomy has been the standard of care at most major transplant centers. Clayman et al. described the first successful conventional laparoscopic nephrectomy in 1991 for intrinsic renal disease [1]. Several years later, a conventional laparoscopic donor nephrectomy procedure was successfully performed in a large animal model [2], while Ratner and colleagues described the first successful conventional laparoscopic live donor nephrectomy one year later [3]. Donor were discharged home within two days and most returned to work within two weeks postoperatively. Moreover, recipient outcomes were significantly better than deceased donor allografts.
Over the next decade following the advent of conventional laparoscopic donor nephrectomy, the number of kidney transplants performed in the United States nearly doubled. The ability to perform the procedure using the conventional laparoscopic approach certainly influenced the willingness of donors to donate [4]. Moreover, the ease of donation has lead to more unexpected results, including altruistic donors, innovative protocols for ABO incompatibility and positive crossmatches, as well as kidney paired donation [5][6][7].
Laparoendoscopic single site surgery represents the next step in the evolution of conventional laparoscopic surgery. It is performed through a single small skin incision, often partially concealed at the umbilicus. Recently, several institutions, including our own, have reported on this technique for live donor nephrectomy [8][9][10]. Cosmesis, as well as possibly decreased postoperative pain and port-site related complications, are among the possible benefits compared to the conventional laparoscopic approach. Recipients have experienced similar postoperative results as those receiving allografts using the conventional laparoscopic procurement technique [11,12].

Initial evaluation
All potential donors undergo a complete surgical, medical, and psychological evaluation in accordance with the clinical practice guidelines established by the American Society for Transplantation and the Consensus Statement on the Live Organ Donor [13,14]. A discussion of the medical work-up is discussed elsewhere in this textbook. After a thorough medical and psychological evaluation, the patient is referred to the surgeon for preoperative consideration of anatomy and functional status of the donor kidneys.

Anatomy and functionality
The use of preoperative imaging is a vital component of proper surgical planning. This allows determination of potential donor kidney size, function, and anatomy. This allows for determination of the safest and most feasible surgical approach. Potential donors typically undergo spiral computed tomography (CT) scans with intravenous contrast administration with vascular reconstructions to properly assess the renal hilum prior to surgery [15]. Magnetic resonance angiography is an alternative to spiral CT for evaluation of potential kidneys. Renal scintigraphy usually obtained when there is a >1 cm size discrepancy between kidneys.

Laterality
Choosing the side of the nephrectomy should be given careful considering. The right kidney presents a technical challenge. Procurement of the right kidney using the endoscopic GIA stapling device to divide the anatomically shorter right renal vein results in losing anywhere from 1 cm to 1.5 cm from the total length [16]. This leads to a relatively short renal vein that complicates the recipient procedure and has been associated with acute renal vein thrombosis and early graft loss [17]. Short renal vasculature is no longer avoidable given surgical innovations. Left kidneys are preferentially chosen if the renal vasculature and function are comparable. Multiple left renal arteries or anomalous left renal veins are not absolute contraindications to procuring the left kidney [17]. The feasibility of procuring the right kidney has been clearly described from hand-assisted laparoscopy to the conventional laparoscopic approach to even using the laparoendoscopic single site approach [11,18,19].

Contraindications
The contraindications to laparoendoscopic single site surgery are the same as those for any laparoscopic abdominal procedure. Certainly, previous abdominal surgery further complicates any laparoscopic procedure; it does not confer an absolute contraindication. In fact, the rate of conversion of laparoendoscopic single site surgery remains relatively low (<5%) as has been our experience [12].

Positioning
Patients are placed in a modified flank position, and a 5 centimeter vertical periumbilical incision is made with the abdominal skin on stretch. After creation of a vertical midline anterior rectus fasciotomy, the abdomen is entered. The Gel Point device (Applied Medical, Rancho Santa Margarita, CA) as seen in figure 1 with three trocars already in place is inserted into the abdomen and pneumoperitoneum is established. Two 5-mm trocars and one 15-mm trocar are used. A bariatric 10-mm rigid laparoscope is used through the 15mm port with a right angle attachment for the light cord to maximize space for triangulation. Standard, non articulating laparoscopic instruments are used in the majority of the procedure. For right sided kidneys, a fourth trocar is placed through the Gelpoint device and a Diamond-Flex retractor (Genzyme Surgical Products, Tucker, GA) is used for exposure after mobilization of the right lobe of the liver by division of the triangular and coronary ligaments.

Left kidney
When procuring the left kidney using the laparoendoscopic single site procurement technique, the descending colon, pancreas and spleen are mobilized generously en bloc without the need for continuous retraction. The ureter and gonadal vein are identified and lifted off of the psoas muscle together, maintaining periureteral attachments and dissected towards the hilum. The lumbar vein, if present, is divided between titanium clips. The renal vein is skeletonized and the adrenal vein is divided between titanium clips, and the adrenal gland is released from the upper pole. The renal artery is dissected down to its aortic origin, and the interaortocaval region is skeletonized. Lastly, the posterior attachments were dissected free from the kidney. A 12-mm trocar replaces one of the 5-mm trocars in anticipation of using the EndoGIA vascular stapling device (United States Surgical, Norwalk CT).
Once the recipient team is ready, the ureter and gonadal vein are divided together at the pelvic brim. The renal artery and then vein are divided using the vascular stapling device. An Endocatch bag is introduced, and the allograft is gently entrapped and extracted by removing the Gel cap. If necessary, the fascial incision is extended 1-2 cm to facilitate removal of the graft, taking care to leave the overlying skin intact without further extension of the incision. Fascia and skin are closed in the standard fashion after ensuring adequate hemostasis. No articulating or specialized laparoscopic instruments are needed and no extraumbilical incisions need to be made. The incision is well-concealed in the umbilicus using this technique ( Figure 2).

Right kidney
The initial three trocars are placed as described above for left kidneys; however, the right kidney procurement technique requires a fourth trocar for retraction of the liver. Using mostly one handed dissection, the duodenum is kocherized bluntly to expose the inferior vena cava (IVC). The hepatic flexure is gently lifted and the plane between Gerota's fascia and the mesocolon is identified. The colon is bluntly dissected and mobilized in a medial and caudal direction, down to the iliac vasculature. The ureter and gonadal vein are identified and lifted off of the psoas muscle together, maintaining periureteral attachments and dissected towards the hilum. At this point, a fourth trocar (5mm) is placed through the Gelport TM device for retraction of the right lobe of the liver (Figure 3). The renal vein is skeletonized down to the level of the IVC. The renal artery is dissected medial to the lateral edge of the IVC to maximize length, and the interaortocaval region is skeletonized. The adrenal gland is dissected free from the medial upper pole of the kidney using a harmonic scalpel. Lastly, the posterior and lateral attachments are divided. A 12-mm trocar replaces one of the 5-mm trocars in anticipation of using the EndoGIA vascular stapler (United States Surgical, Norwalk CT).
Once the recipient team is ready, the ureter is divided at the pelvic brim. The kidney is then retracted laterally. Using an EndoGIA vascular stapler, the renal artery is divided first, followed by the vein, with the vein being divided flush with the IVC to maximize length. An Endocatch bag is introduced, and the allograft is gently entrapped and extracted.

Obese donors
Obese donors represent a technically more challenging population. The technique mirrors that of the normal BMI donors; however there are several important technical aspects to consider [20]. First, mobilization of adjacent organs may be more difficult. Given the amount of intra-abdominal fat, visualization may be more difficult. As a result, there may be increased difficulty in identifying key landmarks. Male donors have additional visceral adipose tissue which may make it more difficult to retract [21]. The amount of perirenal fat must be taken into consideration when planning safe extraction of the allograft from an obese patient to avoid a renal laceration [20]. The incision remains well-concealed, even this population ( Figure 4A&B).

Morbidity
The donor nephrectomy is a unique procedure, as it entails operating on a healthy individual, as opposed to surgery for specific disease processes. To justify the procedure, the potential complications must be minimized as donor safety should be the priority.
Initial studies evaluating donor safety compared the open to the conventional laparoscopic approach. Various studies and reviews have demonstrated a complication rate ranging from 0% to 38% using the open procurement approach and 0% to 30% with the conventional laparoscopic approach [22,23]. More recent studies have reported complications of less than 10% in conventional laparoscopic donor nephrectomy [24,25]. In a single surgeon series of 750 laparoscopic donor nephrectomies, Harper et al. used the modified Clavien-Dindo system and reported an overall complication rate of 5.5% [24]. The majority of complications were classified as minor, with most (66%) being grade 1. Moreover, there were only four cases converted to an open procedure (0.4%). These values are similar to our experience as our complication rate for conventional laparoscopic donor nephrectomy was approximately 7%. Moreover, only one patient in that cohort required conversion to an open procedure (0.15%) [25].
Given the relatively novel nature of the laparoendoscopic single site procurement technique, donor morbidity must remain minimal. We reported a similar complication rate (approximately 7%) large series of laparoendoscopic single site donor nephrectomies, comparable to our conventional laparoscopic procurement technique [12,25]. Other smaller, single center series have demonstrated similar outcomes comparing laparoendoscopic single site donor nephrectomies to conventional laparoscopic donor nephrectomies [26,27]. Kurien and colleagues reported the first randomized controlled trial of 50 patients comparing conventional laparoscopic donor nephrectomies versus laparoendoscopic single-site donor nephrectomies [28]. They reported an intraoperative and postoperative complication rate of 16% in the laparoendoscopic single-site donor group, which was similar to the conventional laparoscopic donor nephrectomy group.
Certain complications are more specific to the laterality of the donor kidney. For example, in right sided donors, liver lacerations and injuries to the retro-aortic renal arteries are more common. On the other hand, intraoperative complications related to splenic lacerations during mobilization of the splenic flexure of the colon or injuries to the supra-adrenal branches of the left renal vein are more common in left sided donors [29].

Technical considerations
The use of laparoendoscopic single site surgery in living donor kidney procurement offers a new set of challenges to the laparoscopic surgeon. Technical limitations including a reduced working space and lack of instrument triangulation make it a technically challenging procedure. These limitations are more pronounced in the obese patient, where difficulties in exposure and visualization already exist, including additional visceral adipose tissue that is more difficult to retract. Overweight male donors were even found to have higher rates of conversion to open procedures compared to overweight female donors, possibly related to the visceral fat distribution [21].
Procuring the right kidney poses additional threats as previous studies have demonstrated an increased risk of renal vein thrombosis [17,18]. Our initial experience with hand-assisted laparoscopy saw a renal vein thrombosis rate of less than 3% [30]. In fact, we had not had any cases of renal vein thrombosis with the conventional laparoscopic procurement technique, or even more recently, with the laparoendoscopic single site donor nephrectomy technique [19,30]. An important technical consideration is firing the stapling device flush against the IVC, while laterally retracting the kidney to maximize renal vein length to avoid this complication.
Various studies have compared outcomes of transplantation of kidneys with a single artery versus those with multiple arteries ( Figure 5). Most of these studies have demonstrated similar survival and graft function between the two groups [31][32][33]. However, other studies have shown that kidneys harvested with multiple arteries are technically difficult leading to increased complications, such as vascular thrombosis, increased bleeding during nephrectomy, and increased operating times [34]. Our experience using the laparoendoscopic single site donor nephrectomy technique to procure kidneys with multiple vessels has been similar to those with single renal arteries and veins (approximate complication rate of 6%).

Donor satisfaction
The true benefits of laparoendoscopic single site donor nephrectomy remain to be seen. Canes et al. compared 17 laparoendoscopic single site donor nephrectomies to a matched pair of 17 conventional laparoscopic donor nephrectomies and found no difference in standard perioperative parameters [27]. They did however identify superior patient scar satisfaction, decreased oral analgesic use, and improved convalescence in the laparoendoscopic single site cohort. Kurien and colleagues demonstrated no difference in convalescence parameters in their randomized controlled trial comparing 25 laparoendoscopic single site donor nephrectomies to 25 conventional laparoscopic donor nephrectomies [28]. The laparoendoscopic cohort did have less pain requirements and a one-half day improvement in hospital stay; however, the warm ischemia time was slightly increased in that cohort. In an analysis of our series of our first 100 laparoendoscopic single site donor nephrectomies, the laparoendoscopic group had a slight, but significant improvement in convalescence compared to a group of 100 matched conventional laparoscopic donor nephrectomies [12]. However, the laparoendoscopic group had significantly longer operative times by almost 30 minutes on average.

Allograft function
The benefit of live donor nephrectomy, compared to receiving an allograft from a deceased donor, is the prompt functionality of the allograft with more durable function. Comparisons of early and late allograft function in the recipient of open versus conventional laparoscopic donor nephrectomy have already been shown in several studies, including two randomized controlled trials [35,36]. Similarly, all recent studies comparing allografts procured with the laparoendoscopic single site technique have shown similar early allograft function compared to allografts via conventional laparoscopic approaches [10][11][12]28]. Moreover, these results have also been seen with right sided allografts, despite the shorter vasculature when compared to either right or left allografts [19,30]. In addition, allografts from obese donors have seen similar early allograft function as allografts from non-obese donor irrespective of procurement technique [20]. In all of these studies, the incidence of delayed graft function remained low (<5%).

Survival
Graft survival following conventional laparoscopic donor nephrectomy has been excellent. Given the infancy of the laparoendoscopic single site procurement technique, long-term or even intermediate-term follow-up remains limited. However, short-term follow-up suggests patient survival remains excellent at 1 year (100%) as well as overall graft survival at 1 year (98%) [11]. Kurien et al. demonstrated similar 1 year outcomes, including both patient and graft survival of 100% [28]. At the present, short-term outcomes appear similar to conventional laparoscopic procurement techniques.

Conclusion
The single incision approach represents a technological advancement in renal allograft organ recovery. Perhaps with time, this could represent a paradigm shift that will require evolution of instrumentation, technique, and training models, just as conventional laparoscopic donor nephrectomies did over a decade and a half ago. At this time, the benefits of single incision technique appears limited to superior cosmesis and a small improvement in convalescence. With time, however, the laparoendoscopic single site donor nephrectomy technique may further decrease the barriers to live organ donation and transplantation.