EXPERIMENTAL AND CLINICAL TRANSPLANTATION

The increasing adoption of minimally invasive surgery has led to more kidney transplant patients undergoing laparoscopic procedure. However, these surgeries rely heavily on visual feedback due to the lack of tactile sensation, placing the transplanted ureter (located outside the peritoneum) at high risk of iatrogenic injury. The near-infrared ray catheter is a fluorescent ureteral catheter designed to emit light visible under near-infrared irradiation, offering a novel solution for enhancing ureteral visibility. Although its utility has been demonstrated in general abdominal and pelvic surgeries, its application in renal transplant cases remains underreported. In this study, we reviewed our experience with 4 cases of laparoscopic pelvic surgery in kidney transplant recipients: 1 case of lymphocele fenestration and 3 cases of bilateral salpingo-oophorectomy with or without total abdominal hysterectomy. These surgeries posed important challenges because of the anatomical complexity and proximity of the ureter to the surgical field. In each case, the transplanted ureter, barely visible under natural light, was clearly delineated under near-infrared illumination, enabling precise and safe dissection. This approach not only minimized the risk of ureteral injury but also reduced surgical stress and potentially enhanced patient outcomes. Our findings highlighted the substantial safety and efficiency benefits of near-infrared ray catheters in laparoscopic surgeries for kidney transplant patients. Further research with larger patient cohorts and varied surgical settings are essential to fully validate its clinical impact.

Key words : Fluorescent catheter, Kidney transplant, Laparoscopic surgery

Kidney transplant (KT) is widely recognized as the standard of care for end-stage renal disease and offers improved long-term outcomes for patients. Concurrently, minimally invasive techniques, such as laparoscopic and robot-assisted surgeries, have become widely adopted, enabling safer and less invasive management of post-KT complications. However, unlike open surgery, laparoscopic pro-cedures depend heavily on visual cues because tactile sensation is absent, increasing the risk of iatrogenic injury to the transplanted ureter. This risk is particularly pronounced because of the atypical positioning of the ureter in KT patients.

To mitigate the risk of iatrogenic injury, fluo-rescent ureteral catheters have been developed to enhance the intraoperative visualization of the transplanted ureter. Among these, the near-infrared ray catheter (NIRC fluorescent ureteral catheter; Nippon Covidien) is specifically designed to emit visible light under near-infrared irradiation and provides a reliable solution for identification of the ureter during surgery. The effectiveness of the NIRC has been demonstrated in general abdominal and pelvic laparoscopic procedures through a reduction in the incidence of ureteral injuries.^1,2 However, only a few case studies have described its application in KT patients.^3,4 Each of these previously published case studies focused on individual cases that highlighted the need for broader clinical evaluation to establish the utility of the NIRC in this specific population.

In this report, we described our experience with 4 laparoscopic surgeries performed on post-KT pati-ents that involved the NIRC. By addressing the challenges of visualization of the transplanted ureter, this study demonstrates the practical utility of the NIRC to minimize the risk of ureteral injury and improve surgical outcomes, including enhanced safety and reduced intraoperative complications.

We describe 1 case that involved laparoscopic fenestration of a posttransplant lymphocele and 3 cases that involved laparoscopic bilateral salpin-gooophorectomy with or without total abdominal hysterectomy for ovarian or uterine tumors (Table 1). In all 4 cases, the NIRC was inserted intraoperatively and removed immediately after surgery, because there was no evidence of ureteral damage. All transplanted kidneys were located in the right iliac fossa, a common site for renal transplants; this location presents unique challenges for surgical visualization because of the atypical positioning of the ureter.

A 6F single J catheter (length, 70 cm) was used in all cases. The catheter was inserted retrogradely through the bladder under direct visualization with a cystoscope and fluoroscopy to ensure accurate placement and avoid trauma to the ureter. The only complication was slight hematuria, which resolved spontaneously and had no effect on the renal function preoperatively or postoperatively.

The near-infrared light penetrated to a depth of approximately 1 cm, which allowed for clear visua-lization of the ureter. Under natural light, it was difficult to distinguish the ureter from the surrounding tissues; however, near-infrared illumination allowed precise recognition of its course (Figure 1). This enab-led determination of a safe and accurate dissection line, reduced stress on the surgeon, and contributed to improved surgical safety and efficiency.

This is the first case series reported from a single institution to demonstrate the usefulness of the NIRC in multiple laparoscopic surgeries after KT. In all 4 cases, the transplanted ureter, which is difficult to identify under natural light, became visible using the NIRC. The NIRC was especially effective in the fenestration of a posttransplant lymphocele due to the proximity of the transposed ureter and the incision line. The prevalence of allograft injury in laparoscopic fenestration of a posttransplant lymphocele is reported to be 7%,⁵ which is more than 4 times the rate in open surgery (1.6%). This suggests the difficulty of visualizing the transplanted ureter under laparoscopy and the high risk of allograft injury due to surgical manipulation in close proximity to the transplanted ureter. We strongly believe that the use of the NIRC reduces the risk of unexpected iatrogenic allograft injury, especially when surgical manipulation is planned in the vicinity of the transplanted ureter.

Apart from our report, there are 2 other reports of pelvic surgery using the NIRC after KT.^3,4 One report involved laparoscopic fenestration of a post-KT lymphocele.³ Sekito and colleagues3 reported that, in addition to the use of an NIRC, the percutaneous insertion of a soft ureteroscope into the lymphocele made it safer to determine the dissection line. We were able to approach the lymphocele only from the abdominal side and to safely incise the cyst wall without emission from the NIRC. We consider that the use of the NIRC may be sufficient to safely perform the surgery and potentially shorten the operation time. However, in some cases, the thickness of the peritoneum or intra-abdominal adhesions may make it difficult to adequately observe NIRC emis-sions. In such cases, a combined percutaneous endoscopic technique may be effective. In another report that involved open transplant uretero-ureterostomy for transplant ureteral stenosis,⁴ Takai and colleagues reported the efficacy of the NIRC for identification of the transplanted ureter, which was otherwise difficult to detect visually or physically because of severe adhesion. In addition, retrograde ureteral catheterization may not always be feasible, particularly in patients with significant ureteral stenosis or altered anatomy due to prior urinary tract reconstruction. In such instances, alternative techniques, including antegrade catheter placement via percutaneous nephrostomy, may be necessary to ensure adequate visualization of the transplanted ureter.

Despite these benefits, risks remain associated with ureteral catheterization. Wood and colleagues have reported that 7 of 92 patients undergoing laparoscopic hysterectomy with ureteral catheteri-zation to prevent iatrogenic ureteral injury had experienced catheter-related hematuria, oliguria, or anuria.⁶ The group thus concluded that preoperative ureteral catheterization should not be routinely performed. The indications for catheterization in each case should be based on evaluation of the size of the lesion on preoperative imaging and the position of the lesion in relation to the transplanted ureter, as well as the detailed history of the patient, to predict the presence of adhesions. It is also important to minimize the duration of catheter retention by immediate removal of the catheter after the surgery.

The NIRC may also be useful in post-KT patients who require surgical procedures involving the transplanted ureter, such as laparoscopic low anterior resection for rectal cancer or robot-assisted laparoscopic radical prostatectomy for prostate cancer. Larger prospective studies in various types of surgery and comparisons with a control group are needed to consider the optimal adaptation of the NIRC.

The use of the NIRC in post-KT laparoscopic surgery was extremely beneficial for identification of the location of the transplanted ureter, and this technique likely reduces the risk of intraoperative ureteral injury. We believe that this report provides further support for the effectiveness of the NIRC in post-KT laparoscopic surgeries. However, further studies are needed to assess the broader indications for the NIRC in larger cohorts.

Volume: 23 Issue: 7 July 2025

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