In this study, the application of polymer clip to ligates the ureteral stump in retroperitoneal LNU was investigated. After transurethral BCE, a dual-channel resectoscope was used, and a 5-mm clip applier was used to deliver polymer clip, which ligated the ureteral stump. Thus, transurethral ligation of the distal ureter using polymer clip is a simple procedure that ensures accurate closure.
The internationally recognized extent of resection for nephroureterectomy includes the full-length ureter and the kidney, as well as the ureter in the intramural segment of the bladder; however, there are no uniform guidelines for the resection of the lower ureter and intramural ureter. Furthermore, the current operation methods do not completely address the issue of ureteral orifice closure. This does not conform to the principle of “tumor-free” zone, wherein the complete BCE and control of tumor/urine spillage into the operative field are not ensured. Therefore, the rate of intravesical recurrence after nephroureterectomy for UTUC is high (3–5).
Currently, in LNU, a working channel is added in the lower abdomen after retroperitoneal laparoscopic nephrectomy. The lower section of the ureter, particularly the intramural ureter and peri-vesical space, is managed in the same position. Although this operation is performed under direct vision, difficulties such as operator discomfort and unsatisfactory surgical field of view remain (10–12).
Many surgeons prefer transurethral resection of the intramural ureter for various reasons. First, transurethral BCE is performed under cystoscopy. After the distal ureter is surgically freed, the entire bladder cuff is pulled out of the bladder. This method effectively prevents additional surgical incisions and reduces the duration of the operation compared with open resection (13). However, a disadvantage of this method is that the risk of tumor and urine spillage will be increased after the bladder cuff is pulled out, resulting in postoperative seeding of tumor cells and local recurrence (14). Guo et al. performed continuous wave laser for the distal ureter after BCE in an attempt to close the distal end, but the outcomes were difficult to quantify and unsatisfactory (15). Sotelo et al. punctured the suprapubic region and ligated the distal ureter, which not only caused additional injury but also did not meet the “tumor-free” principle (16).
The polymer clip is a commonly used and most reliable device for vascular control in laparoscopic procedures. Moreover, clamping the distal ureter after a transurethral BCE is undoubtedly the most effective method to avoid shedding of tumor cells. However, due to the limitations of the current transurethral surgical instruments, polymer clip cannot be used during transurethral surgery; therefore, closing the stump of distal ureter remains difficult. The S-scope used in this study has the unique and advantageous feature of a relatively wide working channel, through which 5-mm-diameter laparoscopic instruments such as ultrasonic scalpel and suction device, as well as 5-mm clip applier, can be passed, allowing the ureteral stump to be easily clamped.
We believe that the transurethral closure of the distal end of the ureter using polymer clip has several advantages. First, accurate closure of the distal end of the ureter is possible. The polymer clips are usually used to close renal arteries and veins; the pressure of arterial blood is much higher than that of urine in the ureter. Therefore, it is effective in closing the ureter and can completely avoid urine spillage into the bladder or surgical field. Second, the 5-mm clip applier used is simple; therefore, it can be completed by a single operator and involves a short learning curve. Third, in the process of tissue removal, polymer clip is tightly fixed and cannot detach. Fourth, when electrosurgical resection is performed for hemostasis of the bladder wall, polymer clip does not burn. Fifth, regardless of the operation, ligation of the distal ureter can prevent compression and pulling of the ureter, even in the lower ureter, thereby ensuring that tumor cells do not enter into the surgical field. Sixth, the polymer clip at the distal end of the ureter can be used as a landmark to verify whether the full-length ureter has been excised or if any stump has been missed. Lastly, the polymer clip is low in cost and represents a small economic burden to the patient.
In addition, the transurethral BCE of the ureteral orifice is convenient for observing residual cancer in the bladder. If remnant cancer lesions are noted, they can be removed concurrently. In addition, no episodes of intra-abdominal spillage of blood and urine occur and there is limited interference with the abdominal organs because both nephrectomy and lower ureterectomy are completed in the retroperitoneal space.
Our technique also includes a number of limitations. First, after the cuff around the ureteral orifice is removed, it must be replaced with a specialized instrument before the clip applier can be inserted to close the ureteral stump. Second, the lateral decubitus position must be changed during nephrectomy, which prolongs the duration of anesthesia. Given the complex nature of UTUC, we believe that cystoscopy in the lithotomy position is beneficial for determining remnant cancer lesions in the bladder. Third, since the bladder incision is not sutured after BCE, a bladder wall defect is created, which is difficult to suture with available techniques and equipment. Nonetheless, an indwelling urinary catheter can be used for 7-10 days to maintain the bladder empty until the defect closes naturally. Although the closure of these bladder defects has been reported (17), this procedure remains difficult. Lastly, the patients in this study lack long-term follow-up, warranting further observation and evaluation.
In summary, the cystoscopy surveillance, RNU with BCE, the polymer clip ligation, and retroperitoneal laparoscopic nephrectomy effectively reduces intravesical recurrence.