Analysis of Ureteral Injuries for Laparoscopic Rectal Cancer Surgery

Introduction

Ureteral injury is a common complication during the procedure of rectal surgery. Different incidences of ureteral injuries have been reported. For example, a study designed by Andersson and Bergdahl ¹ showed that rectal surgical procedures accounted for 0.7%–5.7% of ureteral injuries. Campos ² reported an incidence for ureteral injuries of 0.6% for colorectal surgery. Serious consequences including fever, infection, renal failure, and even death, will result from this complication if timely treatment cannot be performed. Until now, few studies focused on ureteral injuries for laparoscopic rectal cancer surgery have been reported.

From July 2007 to July 2013, patients with resectable rectal cancer received laparoscopic surgery in our hospital. Among these patients, 11 cases had the complication of ureteral injuries. Data of these patients were reviewed with the aim of evaluating the characteristics of ureteral injuries during the procedure of laparoscopic rectal surgery and analyzing the related reasons.

Subjects and Methods

Between July 2007 and July 2013, 1120 patients with rectal cancer underwent laparoscopic surgery in the Cancer Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, China. Of these patients, 11 cases had the complication of ureteral injuries during the operative procedure. Data of the 11 patients were collected and analyzed retrospectively. Preoperatively, definite diagnosis of rectal cancer was made by colonoscopy with biopsy for all patients. Physical examination, abdominal computed tomography scan, abdominal ultrasound, and barium enema were routinely implemented for preoperative evaluation.

Of the 1120 operations, 950 cases were completed by two senior surgeons, and 170 cases were completed by six junior surgeons. A surgeon who had completed more than 200 rectal operations was defined as a senior, whereas a surgeon who had completed fewer than 40 rectal operations was denoted as a junior.

Following the radical resection principle, the laparoscopic-assisted technique was performed. Using the medial-to-lateral dissection method, the mesocolon was opened with a ultrasonic knife along Toldt's line and was dissociated further along Toldt's space. The inferior mesenteric vessel was exposed and ligated by an endoscopic linear (straight) cutter (model YZB/USA 3859-2010; Ethicon Endo-surgery, LLC, Blue Ash, OH). Lymph nodes of the inferior mesenteric artery pedicle and the mesentery lymph nodes were removed. According to the total mesorectal excision principle, the lateral ligament of the rectum and sacrum anterior was separated. Transection of the rectum by a contour cutter (model YZB/USA 0572-2010; Ethicon Endo-surgery, LLC) through a small abdominal incision was done after the laparoscopic procedure. Then the specimen was removed, and the bowel stump was prepared for anastomosis. For abdominoperineal resection, all of the procedures, including ligation of the vessel, separation of the bowel, dissection of lymph nodes, and transection of the bowel, were completed under laparoscopy. The perineal operation was performed by another two surgeons.

All these 11 cases of ureteral injuries were detected and confirmed intraoperatively. The repair of ureteral injury, which was performed by the urologist, was started after the completion of the laparoscopic procedures, including separation of the bowel, dissection of lymph nodes, and transection of the bowel for abdominoperineal resection. For the conversion to an open procedure, all procedures for repair of ureteral injuries were performed through a larger incision, which was made in the lower abdomen, and all ureteral injuries were repaired by the end-to-end method. First, the injured ureter was separated exactly with a view to avoiding tensile force after anastosmosis. The next step was to trim off the ureteral stump, including removal of inactive stump. A double-J stent was placed through the stump of the ureter, and the ureteral stump was sewn up securely by biological absorbable surgical suture. An intraoperative abdominal X-ray was performed after the completion of ureteral anastomosis in order to confirm the correct position of both ends of the double-J stent. Patients were asked to proceed with bladder function training 2 weeks after the operation. All patients were followed up and examined by cystoscopy every 2 months after discharge from the hospital. The double-J stent was removed by cystoscopy 6 months after the operation.

Results

Of the 11 patients, 6 cases were in males, and 5 cases were in females. The mean body mass index was 26.6 kg/m², with 2 patients having a body mass index of >30 kg/m². Seniors accounted for 2 cases of ureteral injuries, and juniors accounted for 9 cases. The total incidence of ureteral injuries from laparoscopic rectal surgery was 0.98% in this study. The incidence of left ureteral injuries was 72.7% (8/11), which was higher than for the right side (3/11, 27.3%). Ureteral injuries occurred at the three following locations: (1) at the takeoff of the inferior mesenteric artery (5 cases), (2) the small pelvic inlet (4 cases), and (3) where the infundibulopelvic ligament crosses the pelvic brim (2 cases). Injuries of the pelvic ureter were most common. Laceration was the only type in this study. Five ureteral injuries resulted from cutting with the endoscopic linear (straight) cutter, and six injuries resulted from dissection with the ultrasonic knife.

There was no ureteral injury associated with port placement. The reasons for ureteral injuries in this study were as follows: the first reason was massive ligation or cutting off without recognizing an anatomical structure (5 cases), the second reason was unfamiliarity with the normal anatomical structure under laparoscopy and unskilled laparoscopic operation (3 cases), the third reason was an abnormal anatomical structure due to invasion of the tumor (2 cases), and the fourth reason was an unusual anatomical variation of the ureter (1 case) (Table 1). There was no case with ureterostoma and ureterostegnosis during the follow-up period.

Discussion

Ureteral injury is one of the major complications of rectal surgery. Based on the mechanism of injury, ureteral injuries can be classified as laceration, ligation, devascularization, and energy-related. ³ The laceration was the only type in our study. Different incidences of ureteral injuries have been reported.^4–8 Some studies showed that the incidence of ureteral injuries does not change obviously with the introduction and adoption of minimally invasive surgical techniques. ³ In contrast, a study designed by Palaniappa et al. ⁹ confirmed that a significant increase was found in the incidence of iatrogenic ureteral injuries with laparoscopy compared with open colectomies. The incidence of ureteral injuries in our study was 0.98%, which was similar to the results reported previously, and the left ureter was more likely to be damaged. The procedure of dissociation and ligation may lead to the increasing possibility of left ureteral injuries because the left ureter is near to the inferior mesenteric artery, which should be ligated for a rectal operation. We thought the anatomical characteristic was the main reason for the higher incidence of left ureteral injuries.

Separating the inferior mesenteric artery and dissociating colorectal mesenteries should be performed in Toldt's space, which exists between the colorectal mesenteries and anterior renal fascia and is the natural cover for defense of the left ureter. ¹⁰ The possibility of left ureteral injury may increase when Toldt's space is broke through. After the pelvis is entered, the ureter, which is down between the front wall of the rectum and the posterior wall of the urinary bladder, is near to the lateral rectal ligament, and the ureter can be damaged when the lateral rectal ligament is separated. In females, the ureter crosses dorsal to the ovary and underneath the broad ligament, within 2 cm of the uterine vessels, and this location is where a majority of injuries occur during surgery.

Various reasons account for ureteral injuries. Massive ligation or cutting off without recognizing the anatomical structure was the main reason in our study. The ureter is not easy to recognize under laparoscopy because of several factors. Obesity and serious abdominal cavity adhesions may be two common reasons. During the procedure of separating the inferior mesenteric artery, it is more difficult to distinguish the left ureter when bleeding occurs or Toldt's space is broke through. Forced separation or ligation may result in ureteral injuries. We thought patience and careful watchfulness were two key points for becoming an excellent laparoscopic surgeon and for reducing the operative complication rate. Massive ligation should be avoided. Unfamiliarity with the normal anatomical structure under laparoscopy is another common reason for ureteral injuries. Anatomy under laparoscopy has a lot of differences compared with what is observed under direct vision. Inexperienced surgeons have the possibility of mistaking the ureter for blood vessels or fascia sometimes. Inaccurate judgment may lead to injuries of the ureter by mistake. Normal anatomical structure may be changed because of invasion of the tumor. Meanwhile, an unusual anatomical variation of the ureter can be found for some patients. ¹¹ Distinguishing and protecting the ureter may be more difficult because of these changes. The incidence of ureteral injuries is associated with the experience of surgeons. Operations completed by inexperienced surgeons or surgeons who are in the period of the learning curve had a higher complication rate, which has been confirmed by several centers.^12–14

How to reduce the incidence of ureteral injuries during the procedure of laparoscopic rectal surgery may be an interesting topic. Here are some suggestions based on our results: prior to starting a laparoscopic rectal surgery, both ureters above the pelvic brim should be identified; the course of the distal ureter should be confirmed; appropriate tissue planes should be searched and protected when performing laparoscopic operation; extending the dissection too far laterally should be avoided; and it is crucial to convert the resection to an open procedure in a timely fashion.