JSUR Journal

Introduction

Living kidney donation is the best approach to increase the number of kidney transplants, reduce waiting times, and increase the recipient’s life expectancy by reducing the retransplant rate [1]. To increase living kidney donation and to decrease post-operative pain and morbidity that is associated with open donor nephrectomy, minimally invasive surgery was introduced into the field of living kidney donation. First, Laparoscopic Donor Nephrectomy (LDN) [2] and more recently, robotic-assisted laparoscopic donor nephrectomy (RALDN) [3], both provide a less invasive surgical approach as compared with open donor nephrectomy. RALDN is gaining popularity in the field of living kidney donation [3] and is associated with smaller incisions, shorter hospital stays, and lower risk ratios for the development of surgical site infections and symptomatic lymphoceles [3-4]. We wanted to evaluate the feasibility, safety, and clinical outcomes in using RALDN at our transplant center, including short and longer-term outcomes of kidney transplants performed using our surgical modifications of the conventional kidney transplant technique [5-7]. Results among 112 RALDN transplant recipients performed at our center since 2021 are reported here.

Materials and Methods

Patient Selection and Study Design

Between August 26, 2021 and December 12, 2024, 14 pediatric and 98 adult recipients of a kidney-alone transplant were performed consecutively at our center, using living donor kidneys obtained via RALDN and transplanted using a modified kidney transplant surgical technique [5-7]. This study was approved by the University of Miami Institutional Review Board and adheres to the ethical principles of the Helsinki Declaration, as revised in 2013. Transplant surgeons, pediatric and adult transplant nephrologists, and a multidisciplinary kidney transplant team that included anesthesiologists, social workers, pharmacists, nutritionists, pretransplant donor and recipient coordinators, donor advocates and finance counselors assessed both donors and (pediatric and adult) recipients. Each set of patients (donor and recipient) underwent an extensive laboratory workup, including comprehensive metabolic panel, electrolytes, serology, and complete blood count. Chest X-ray, abdominal ultrasound echocardiogram, and electrocardiogram were also completed. The donor had computed tomography angiography with intravenous contrast to assess kidney anatomy, vascular and collection systems plus any other kidney pathology. Living donor candidates were above 18 years of age, and regarding the data acquired for living donors, we compiled donor age, sex, race/ethnicity, height, weight, Body Mass Index (BMI), blood work, urinalysis, donor kidney biopsy, donor kidney size and renal vessel length. If the utilized living donor kidney had anatomic variants, back table vascular reconstruction was performed. Recipient demographics included age, sex, race/ ethnicity, cause of end stage renal disease, and calculated Panel Reactive Antibody (cPRA). All urologic, vascular, and other surgical complications were recorded. Urologic complications included ureteral leak, ureteral stricture, Ureteropelvic Junction (UPJ) obstruction, Vesicoureteral Reflux (VUR), and urinoma. Vascular complications included renal artery thrombosis, renal vein thrombosis, and renal artery stenosis. Other surgical complications included lymphocele development, wound complication (infection, dehiscence, or seroma), and development of a peri-renal hematoma or peri-renal collection. Suspected urologic complications were evaluated with renal ultrasonography, mercaptoacetyltriglycine scan, and/or antegrade nephrostogram. Urologic complications were treated by either percutaneous radiological procedures, surgery, or a combination of both. Suspected ureteral stenosis/ stricture was evaluated along with serial monitoring for BK virus replication (in blood). Voiding cystourethrogram was not routinely performed, as routine evaluation for vesicoureteral reflux was not considered to be necessary in our transplant recipients; therefore, only symptomatic reflux was evaluated and considered as a urologic complication. Suspected vascular and/or other surgical complications were first evaluated by renal ultrasonography and, if necessary, by computerized tomography scan or magnetic resonance angiography. Surgical vs. conservative treatment was determined according to test results and complication severity.

Immunosuppression

All recipients received standard induction immunosuppression intraoperatively and during the first week post-transplant with Antithymocyte Globulin (rATG) (1 mg/kg IV for 3 doses in most cases) and methylprednisolone (500 mg IV daily for 3 doses), followed by a tapering regimen to a maintenance dose for prednisone of 5 mg PO daily, coinciding with the achievement of therapeutic tacrolimus levels (target trough: 6–8 ng/mL). Once therapeutic tacrolimus levels were achieved, the plan was to discontinue the use of daily low-dose corticosteroids (i.e., corticosteroid avoidance). Of note, some patients received dual induction therapy with rATG and basiliximab (an older protocol). In addition, patients considered to be highly sensitized (with high cPRA or preformed donor specific antibodies) also received one dose of rituximab as part of induction therapy. Maintenance immunosuppression consisted of a calcineurin inhibitor (tacrolimus) and an antiproliferative agent (mycophenolate acid). Oral tacrolimus was initiated on post-operative day 2 (in patients with immediate graft function), with dosing adjusted based on therapeutic drug monitoring and renal function. Mycophenolate acid (720 mg twice daily) was also introduced on post-operative day 2, with adjustments made according to white blood cell count and gastrointestinal tolerance [8].

The Surgical Procedure

Living donor allografts were obtained via a RALDN. In performing a left RALDN, the patient was positioned in a modified lateral decubitus position on the right side to optimize left renal exposure. Adequate padding was applied to protect pressure points and prevent development of pressure neuropathies, and the operating table was flexed at the kidney level. Sterility was maintained by preparing and draping the abdomen followed by a procedural timeout to confirm patient identity, procedural details, and ABO compatibility. Pneumoperitoneum was established using Palmer’s technique with a Veress needle in the left upper quadrant, while careful monitoring maintained optimal intra-abdominal pressure. Under direct vision, robotic ports were inserted: an 8mm left subcostal port utilizing OptiView technology for a 5mm laparoscopic camera, an 8mm left periumbilical port, a 12mm left paramedian port, an 8mm suprapubic paramedian port placed through a Pfannenstiel incision, and a 12mm assistant port in the midline (Figure 1A). The robotic arms were configured with fenestrated bipolar forceps through the subcostal port, a highdefinition camera through the periumbilical port, monopolar curved scissors through the paramedian port - later switched to a vessel sealer, and ProGrasp forceps through the suprapubic port. The procedure began with an abdominal inspection to assess for any pathology. The left colon was mobilized, and the splenorenal ligament was dissected to expose the kidney, with the renal vein, left gonadal vein, and adrenal gland identified, dissected, and ligated using clips. The ureter was dissected to the left common iliac artery, and the kidney was mobilized for better renal hilum access. The kidney was liberated, renal artery and vein isolated, and lumbar veins managed. The kidney was then prepared for extraction by clipping and cutting the ureter, followed by stapling of the renal artery and vein. The kidney was placed in a retrieval bag, extracted through the Pfannenstiel incision. The rectus muscle was sutured with continuous PDS, and fibrin glue was applied for hemostasis. The procedure was concluded with the robotic system undocking and closure of skin incisions.

Figure 1: A) Port placement for robotic-assisted left donor nephrectomy. B) Port placement for robotic-assisted right donor nephrectomy.

In performing a right RALDN, the patient was placed in a modified lateral decubitus position on the left side, and the operating table was adjusted at the level of the kidney to improve renal exposure, with special attention being given to padding to prevent development of pressure neuropathies. Aseptic technique was adhered to in preparing and draping the abdomen, followed by a surgical timeout to confirm patient identity, procedural specifics, and ABO compatibility. Pneumoperitoneum was established using Palmer’s technique, inserting a Veress needle into the right upper quadrant. Robotic ports were placed under direct vision along the midclavicular line. An 8mm right subcostal port was placed using OptiView technology, which initially housed a 5mm laparoscopic camera. Additionally, an 8mm right periumbilical port, a 12mm right paramedian port, an 8mm suprapubic paramedian port via a Pfannenstiel incision, a 12mm assistant port between the initial ports along the midline, and a 5mm port at the xiphisternum for liver retraction were positioned (Figure 1B). With the system docked, ProGrasp forceps were used through the suprapubic port for tissue manipulation. Fenestrated bipolar forceps were inserted through the right paramedian port for delicate tissue manipulation. A high-definition laparoscopic camera provided visual guidance through the right periumbilical port, and monopolar curved scissors, later exchanged for a vessel sealer, were used through the right subcostal port for cutting and dissection. A comprehensive intra-abdominal inspection ruled out any malignancies. The right colon was mobilized medially, and the hepato-renal ligament was divided to release the upper kidney pole. For liver retraction, a laparoscopic grasper was employed. The renal vein and right gonadal vein were carefully dissected, and the ureter was isolated to the level of the right common iliac artery. Using the fourth robotic arm for elevation, access to the renal hilum was gained. The gonadal vein and right adrenal gland were dissected from their respective structures.

The kidney was liberated after dissecting Gerota’s fascia posteriorly. The renal artery and vein were exposed and sometimes clamped with a metal Bulldog clamp. The ureter was distally clipped and cut proximally to the clip. While the kidney was elevated using arms 1 and 4, the SureForm 45 instrument stapler from arm 3 was employed to secure the artery and vein. For kidney retrieval, the organ was placed in a Laparoscopic Specimen Retrieval System bag, which was introduced and removed through the Pfannenstiel incision. The rectus muscle was sutured with a continuous PDS suture, and fibrin glue was applied for hemostasis. To complete the procedure, the robotic system was undocked and skin incisions closed. No surgical drainage system was used in any part of the donor surgery. For pediatric and adult recipient operations, to access the retroperitoneal space, a modified (pediatric) or regular (adult) Gibson incision was executed in the right lower quadrant. To expose the right iliac vessels, the peritoneum was moved medially, and blunt dissection was carried out posteriorly to the right renal fossa. Exposition was supported by a Bookwalter retractor. The robotic-assisted procured graft was arranged on the back-table. The perinephric fat was resected up to the lower pole. Renal artery(s) and renal vein(s) were visualized and dissected, and their lengths were measured. Location and minimal dissection of the ureter was accomplished. Any identified anatomic variants were reconstructed as described below. The allograft was subsequently approached to the surgical area. First, an anastomosis with running 6-0 polypropylene sutures was completed between the donor´s renal vein and the recipient´s Inferior Vena Cava (IVC) (pediatric recipients) (Figure 2) or external iliac vein (adult recipients). Then, 7-0 polypropylene sutures were utilized to anastomose the donor´s renal artery to the recipient´s right common iliac artery (pediatric recipients) or external iliac artery (adult recipients) [5-7]. The ureteroneocystostomy was performed following our extravesical ureteroneocystostomy surgical technique without ureteral stent placement [7]. Jackson-Pratt drains were also not used at the time of transplant [5-7].

Figure 2: Computed tomography scan imaging of a two-year old recipient with an adult kidney allograft removed robotically occupying about half of the abdominal cavity.

Donor Vascular Variations and Reconstruction

Among the 28 donor kidneys that required back-table reconstruction, 27 underwent vascular reconstruction (14 requiring conjoining of two renal arteries, 12 requiring deceased donor vascular graft extensions of renal arteries and/or renal veins, and 1 requiring both procedures), and 1 underwent urologic reconstruction (i.e., 2 ureters were anastomosed together). In addition, one donor kidney underwent a lower pole cyst removal.

Statistics

Frequency distributions were determined for baseline categorical variables as well as for clinical outcomes that were dichotomous in nature. Mean and Standard Error (SE) were calculated (along with median and range) for baseline continuous variables as well as for clinical outcomes that were represented as continuous variables. Of note, Estimated Glomerular Filtration Rate (eGFR) was calculated among children (<19 years of age at transplant) using the updated Schwartz formula; eGFR was calculated among adults using the conventional race-based CKD-EPI formula. In addition, the following clinical outcomes that occurred during the first 12 months post-transplant were determined: Delayed Graft Function (DGF), surgical complications (vascular, urologic, wound complication, lymphocele, peri-renal hematoma, and peri-renal collection), Biopsy-Proven Acute Rejection (BPAR), graft failure (return to permanent dialysis or retransplantation, whichever occurred first), Death with a Functioning Graft (DWFG), and eGFR at 1, 3, 6, and 12 months post-transplant. Other than performing t-tests of association for mean eGFR between children and adults, no other formal statistical tests were performed in this study, just descriptive statistics.

Results

Fourteen children and 98 adults received an open kidney transplant with a RALDN graft. Donor and recipient demographics are detailed in Table 1. Mean recipient age was 42.8 ± 1.8 years [median=41.9, range: 3.1-80.6 years]. Male recipients comprised 63.4% (71/112); 59.8% (67/112) were Hispanic, and 6.3% (7/112) were African-American. Mean recipient BMI was 25.2 ± 0.5 kg/ m² [median=25.1, range: 14.9-38.4 kg/m²]. Among the 98 adult recipients, mean recipient age and BMI were 47.2 ± 1.6 years [median=46.1, range: 21.3-80.6 years] and 26.0 ± 0.4 kg/m² [median=26.1, range: 17.1-38.4 kg/m²], respectively, with 60.2% (59/98) being male, 62.2% (61/98) being Hispanic, and 7.1% (7/98) being African-American. Among the 14 pediatric recipients, mean recipient age and BMI were 11.8 ± 1.4 years [median=12.4, range: 3.1-18.9 years] and 19.8 ± 1.2 kg/m² [median=18.3, range: 14.9-31.4 kg/m²], respectively, with 85.7% (12/14) being male, 42.9% (6/14) being Hispanic, and 0.0% (0/14) being AfricanAmerican. Mean donor age was 40.0 ± 1.1 years [median=39, range: 18-68 years], with 56.2% (63/112) of donors being female. Living related donors represented 58.9% (66/112); living unrelated donors represented 41.1% (46/112). Left donor kidneys were utilized in 88.4% (99/112) of cases; right donor kidneys were utilized in 11.6% (13/112) of cases. Reasons for using the right donor kidney included: having a smaller right donor kidney volume (N=11), having a functional UPJ obstruction of the right donor kidney (N=1), and having 2 simple cysts on the right donor kidney (N=1, with one measuring 1.5cm). The pre-implant biopsy showed a mean percentage of sclerotic glomeruli being 5.8 ± 0.8% [median=3.6, range: 0.0-59.5%]. Notably, no intraoperative complications of the living donor patients were recorded, and all RALDN surgical steps were successfully completed robotically.

 [jg1]Please omit the blank row here.  One row should be, “2 RAs Anastomosed Together, and 2 RVs Reconstructed with DD Veins” along with its corresponding percentage: “0.9% (1/112)”. 

¹Reasons for using the right donor kidney included: having a smaller right donor kidney volume (N=11), having a functional UPJ obstruction of the right donor kidney (N=1), and having 2 simple cysts on the right donor kidney (N=1, with one cyst measuring 1.5cm).

Table 1: Distributions of Selected Baseline Variables (N=112).

In addition, no surgical drainage nor stent placement was used in recipients at the time of transplant. Median primary renal artery length was 3.5cm [range: 1.0-5.5cm]; median primary renal vein length was 4.0cm [range: 1.0-6.5cm]. Anatomic kidney variants were encountered in 28 cases as described in detail in the Materials and Methods section. Of these cases, 15 grafts had multiple renal vessels. The external iliac vein and artery were utilized for end-to-side vascular anastomosis in adult recipients, whereas IVC and common iliac artery were used for end-to-side vascular anastomosis in pediatric recipients. There were 13 right donor kidneys procured robotically, and in 11 of these cases, the right kidney had a smaller volume compared with the left kidney (results not shown). One right donor kidney had 2 cysts, and the last presented with a functional UPJ obstruction. Characteristics of the robotically procured kidney allografts are also described in Table 1. Mean CIT was 74.2 ± 13.3 minutes [median=54.5, range: 30-1528 minutes], and mean WIT was 26.7 ± 0.4 minutes [median=26, range: 18-41 minutes]. Mean EBL was 49.6 ± 8.7 cc [median=20, range: 5-800 cc]. Clinical outcomes, including surgical complications and renal function, are described in Table 2. One patient (0.9%, 1/112) developed DGF. During the first 12 months posttransplant, the observed percentages of patients who developed a urologic complication, vascular complication, wound complication, symptomatic lymphocele, peri-renal hematoma, and peri-renal collection were 3.6% (4/112), 0.0% (0/112), 0.9% (1/112), 0.0% (0/112), 2.7% (3/112), and 25.0% (28/112), respectively. Among the 4 patients who developed a urologic complication, the following details were observed: i) one patient developed necrosis of the ureter (with a ureteral leak) at 0.6 months post-transplant, which was treated with debridement of necrotic tissue, ureteral reimplantation, and stent placement, ii) one patient developed a ureteral stricture at 2.3 months post-transplant, which was treated with nephroureteral catheter placement and balloon plasty, iii) one patient developed UPJ obstruction (and hydronephrosis) at 3.9 months post-transplant, which was treated with balloon plasty, double J stent placement, and finally by robotic pyeloureterostomy (of note, this patient had received the right donor kidney having a functional UPJ obstruction, as mentioned above), and iv) one patient developed a grade IV VUR (and hydronephrosis) at 5.1 months post-transplant, which was treated with Deflux injection into the ureter and ureteral stent placement.

¹Among the 4 patients who developed a urological complication during the first 12 months post-transplant, the following details were observed: i) one patient developed necrosis of the ureter (with a ureteral leak) at 0.6mo post-transplant, which was treated with debridement of necrotic tissue, ureteral reimplantation, and stent placement, ii) one patient developed a ureteral stricture at 2.3mo posttransplant, which was treated with nephroureteral catheter placement and balloon plasty, iii) one patient developed UPJ obstruction (and hydronephrosis) at 3.9mo post-transplant, which was first treated with balloon plasty and stent placement, followed by robotic pyeloureterostomy, and iv) one patient developed grade IV vesicoureteral reflux (and hydronephrosis) at 5.1mo post-transplant, which was treated with Deflux injection into the ureter and ureteral stent placement.

²This patient developed wound dehiscence at 1.2mo post-transplant.

³Three patients developed a hematoma at day 0 (the first day) post-transplant; an evacuation was performed in one case in which the hematoma was due to coagulopathy.

⁴The median time-to-development of a perirenal collection was day 2 (range: day 0-1.8mo) post-transplant.

⁵A total of 4 patients developed a 2^nd surgical complication during the first 12mo post-transplant: i) one patient developed a peri-renal collection at 0.39mo post-transplant subsequent to developing a hematoma at day 0 post-transplant, ii) one patient developed necrosis of the ureter (with a ureteral leak) at 0.62mo post-transplant following the development of a peri-renal collection at 0.56 post-transplant, iii) one patient developed a 2^nd peri-renal collection at 1.4mo post-transplant following a 1^st peri-renal collection that developed at 0.33mo post-transplant; and iv) one patient developed a ureteral stricture at 2.3mo post-transplant following the development of a peri-renal collection at day 0 post-transplant.

⁶Grades of first BPAR for these 7 episodes included: Borderline (N=4), IA (N=2), and IIA (N=1); 3/7 cases received antilymphocyte treatment for the rejection episode (Borderline with microvascular involvement in 1 case, IA in 1 case, and IIA in 1 case). Median timeto-first BPAR for these 7 cases was 5.8 (range: 1.8-11.9) months post-transplant.

⁷The 112 study participants were transplanted between 8/26/21 and 12/12/24; date of last follow-up for this study was April 1, 2025. As of the last follow-up date, one patient (1/112) has experienced graft loss during the first 12mo post-transplant (a death with a functioning graft due to sepsis at 1.0mo post-transplant). Median follow-up among the 111 patients who were alive with a functioning graft at either 12mo post-transplant or last follow-up, was 12mo post-transplant. Among these 111 patients, 76.6% (85/111) have been followed through 12mo post-transplant.

⁸Among the 14 children (<19 years of age at transplant), the updated Schwartz formula was used in calculating eGFR. Among the 98 adults, the conventional race-based CKD-EPI formula was used in calculating eGFR.

Table 2: Distributions of Selected Outcomes Variables (N=112).