Certain patients are at increased risk of ureteral injury during endoscopic hysterectomy due to differences in anatomy. The right tools and techniques will protect them from injury and complications.
Dr. Magrina is the Barbara Woodward Lipps Professor of Obstetrics and Gynecology, Department of Gynecologic Surgery, Mayo Clinic Arizona.
He has no conflicts of interest to report with respect to the content of this article.
Ureteral injury can occur during many gynecologic operations, and particularly hysterectomy, regardless of the surgical approach. The pelvic ureter is the segment most commonly injured during gynecologic operations (91%), compared with 2% and 7% incidence of injuries to the upper and middle ureteral thirds, respectively.1
In most patients, the pelvic ureter can be easily identified in the upper pelvis at the level of the pelvic brim and also along the lateral pelvic peritoneum. The segment that is difficult to identify is the portion of the ureter between the intersection with the uterine artery and the bladder.
This article reviews how I identify and manage the course of the parametrial (paracervical) segment of the pelvic ureter in order to prevent injury to it during endoscopic, laparoscopic, or robotic hysterectomy.
Grasper is shown clipping the uterine artery as it crosses over the left ureter. This allows for moving the ureter out of harm's way while working in the area around the cervical neck. The ghosted instruments show subsequent steps in ligation: blunt dissection and gentle manipulation of the ovary with consequent drop of the ureter.
Incidence of injury
Before addressing the incidence of ureteral injuries, it is important to understand that unless otherwise indicated, reports of these complications reflect postoperative detection. That incidence is always lower than for injuries detected intraoperatively as reviewed below. The rates of ureteral injury discussed in this article are postoperative, unless otherwise noted.
The risk of ureteral injury at vaginal hysterectomy is higher (0.6%) than with an open abdominal approach (0.07%), and almost all such injuries occur when the surgery is done for prolapse.2 The main reason is the inability to see and sometimes palpate the ureter during vaginal surgery as compared to an open procedure. The introduction of laparoscopy and later robotics resulted in an increased number of urinary injuries of any type, including ureteral injuries. In time, the risk of ureteral injury with laparoscopy and robotics decreased surgeons’ awareness of the problem grew, instrumentation improved, and experience with endoscopic procedures increased.
A collective review of 236,392 patients who underwent gynecologic operations between 1994 and 2000 reported a risk of laparoscopic injury ranging from 0.02% to 1.7%, depending on the complexity of the operation.3 The risk of ureteral injury ranged from <1% to 2% in 2491 patients who underwent laparoscopic gynecologic surgery, based on data collected from several reports.4 In some reports, the most common injuries were due to electrocoagulation; laparoscopic-assisted vaginal hysterectomy (LAVH) was the procedure with the highest rate of ureteral injury.4
However, other reports have indicated that ureteral pelvic injuries can occur with the use of any mechanical or electrocoagulation devices, laser beams, loop suturing, trocars, or staple devices.5
The increased risk of ureteral injuries initially associated with laparoscopic procedures extended to other surgical specialties. An increased rate was noted when comparing ureteral injuries associated with all surgical specialties from 1986–1992 to 1993–1999 and 2000–2006, resulting in a 7-fold increase.6
The introduction of robotic technology had a similar impact. One study documented a 2.4% rate of ureteral injury during pelvic surgeries performed before robotics, compared with 11.4% after the implementation of the technology (P = 0.05).7
A 0.3% incidence of postoperatively detected ureteral injuries was reported in one series of 1300 LAVH and a 0.1% incidence was reported in another series of 7725 LAVH.8,9 A 0.7% incidence of ureteral injury was reported in association with robotic hysterectomy performed for complex pathology.10
The rate of ureteral injury is higher with intraoperative versus postoperative detection. The rate of intraoperative detection was 0.6% with use of cystoscopy in 3235 patients and 6 times lower (0.1%) for postoperative detection in 107,068.11 In 2 other studies, 89% and 93.7% of ureteral injuries, respectively, were not detected intraoperatively.11,12 Intraoperative cystoscopy identified about 90% of unrecognized ureteral injuries, 69% of which were easily managed, most by simply removing a suture.11
One reason for the lower rate of detection of postoperative ureteral entrapment is the lack of symptomatology following ureteral ligation. About half of intentional ureteral ligations did not result in renal symptomatology in a series of 26 inoperable patients with malignant ureteral fistulas undergoing intentional unilateral ureteral ligation.13
Intraoperative cystoscopy is useful to detect ureteral injuries such as entrapment and transection and facilitates immediate correction and avoidance of subsequent operations and/or permanent sequelae to the patient, and possible litigation to the surgeon. However, it is not useful for detection of ureteral injuries such as thermal damage or ischemia, which may result in subsequent ureteral sloughing.
Actually, there are no methods other than ureteral dissection and identification to prevent any type of ureteral injury.
The time to postoperative diagnosis of ureteral injury is variable and dependent upon the type and severity of the injury. That explains why in some series, a diagnosis was reported in an average of 6 days, whereas in others, it took 29 days.4,14 Patients with ureteral transections will present with urinoma in the immediate days after surgery.
Ureteral entrapment may be asymptomatic or patients may present within 1 week with flank pain or fever due to pyelonephritis.13 Thermal injuries may be diagnosed as long as 2 to 3 weeks after surgery.
There are several types of ureteral injuries and the most common consist of entrapment, transection, or thermal damage. Entrapment results in increased renal pelvis pressure within 4 hours, distal tubular atrophy in 1 week, proximal tubular atrophy in 2 weeks, and progressive glomerulosclerosis over 4 weeks, and permanent damage unless corrected within this period of time.13 Transection and thermal damage result in urine extravasation (urinoma) and chemical peritonitis.
Prior to endoscopic surgery, thermal ureteral injuries were almost non-existent and they became quite common with introduction of electrical instrumentation, whether monopolar or bipolar. In the latter case, it is not the electrical current but the steam generated from the application of the electrical current, with secondary boiling of the intracellular and extracellular fluids, that results in thermal injury.
In 12% of patients, the ureters are within 5 mm from the lateral cervical wall, unilaterally or bilaterally (Figure 1).15 We address these ureters as “cervical ureters” because they appear to be part of the cervix instead of the cardinal ligament. Laparoscopic and robotic instruments are usually 5 and 8 mm in diameter, respectively, indicating that 1 of 8 patients is at risk of ureteral injury during endoscopic hysterectomy even when a proper technique is used. The risk would appear to be greater with the use of a 10-mm vessel sealing device.
The use of a uterine manipulator or similar device in the vagina with cephalad displacement of the cervix will increase the distance between the ureter and the uterine artery and increase the safety of cardinal ligament coagulation and division. However, cephalad displacement does not guarantee prevention of ureteral injury because it may not achieve sufficient displacement if the ureter is adjacent to the lateral cervical wall.
Ureteral injury at endoscopic hysterectomy can occur at many points during hysterectomy, but this discussion will be limited to potential injuries during cardinal ligament division and vaginal cuff closure.
The ureter during cardinal ligament division.
Assessing the parametrial ureter’s proximity to the cervix requires visualizing the intersection of the ureter and the uterine artery (Figure 1), starting with identification of the ureter upstream, cephalad to the intersection and then along the lateral pelvic peritoneum.
As a rule, ureters coursing high in the lateral pelvic wall, at a distance from the uterosacral ligament, are usually lateral to the cervix, whereas those located near the uterosacral ligament usually course close to the cervix. However, the ureters can be found at any level on the lateral pelvic wall and can be at any distance from the cervix.
The ureter noted in Figure 1 appeared safe for cardinal ligament division because it was identified lateral to the cervix proximal to the crossing with the uterine artery (Figure 2). However, once followed to the uterine artery intersection, the ureter was noted to be adjacent to the cervix and at risk of injury (Figure 1). Whenever there is any suspicion of proximity, ureteral dissection to the crossing with the uterine artery is mandatory to prevent injury.
How to find the intersection of the ureter with the uterine artery.
The 2 surgical approaches to identifying the intersection of the ureter with the uterine artery are following the pelvic ureter or following the uterine artery.
1. Following the ureter. The level of the pelvic brim is the area in which it is easiest to identify the pelvic ureter. In that location, the ureter is superficial. Make a peritoneal incision lateral and parallel to the infundibulopelvic ligament below and above the pelvic brim to allow easy visualization of the ureter as it crosses over the common iliac artery (Figure 3).
Once identified, follow it along the lateral pelvic peritoneum until it intersects with the uterine artery.
2. Following the uterine artery. Make a peritoneal incision lateral and parallel to the infundibulopelvic ligament as indicated for the ureteral approach. Identify the external iliac artery and follow it cephalad to the common iliac artery bifurcation. Expose the internal iliac artery by simply displacing or dividing the loose areolar retroperitoneal connective tissue immediately ventral to the artery at the 12 o’clock position.
The superior vesical artery will become apparent as part of the anterior division of the internal iliac, and the uterine artery will be immediately medial to the takeoff of the superior vesical artery (Figure 4). Follow the uterine artery until it intersects with the ureter. Sometimes it may be difficult to identify the internal iliac or superior vesical arteries. In that case, place the lateral umbilical ligament under tension lateral to the bladder and follow it in retrograde fashion toward the origin of the superior vesical artery from the internal iliac artery. The uterine artery will be immediately medial to the origin of the superior vesical artery. Follow it as described for the uterine artery approach.
Lateral displacement of the ureter at risk.
Once the intersection of the ureter and uterine artery are identified (Figure 1) and in the presence of the so-called cervical ureter, there is no need to completely dissect the parametrial portion of the ureter, known as “unroofing of the ureter,” to prevent ureteral injury. The simple division of the uterine artery at its intersection with the ureter is adequate to visualize the direction of the parametrial ureter and also to laterally displace it, whenever necessary.
Elevate the uterine artery from the ureter and pass an instrument between the artery and the ureter (Figure 5). A vessel sealing device can then be safely applied to transect the uterine artery (Figure 6). Lateral displacement of the ureter (Figure 7), known as “rolling” the ureter, allows for a safe division of the cardinal ligament (Figure 8).
The cardinal ligament can now be safely divided with an electrocoagulation device (Figure 9). Use a blunt instrument to gently displace the ureter. Electrocoagulation is unnecessary unless the entire parametrial ureter needs to be dissected, which is almost never the case in a simple hysterectomy.
A variation of this approach consists of transection of the uterine artery at the level of the internal cervical os followed by lateral displacement of this pedicle. In a series of more than 1000 laparoscopic hysterectomies, no ureteral injuries were observed, according to J. Einarsson, MD (written communication, September 2014).
The ureter at vaginal cuff closure.
After the uterus is removed, the relative safety that the uterine manipulator affords in cephalad displacement of the cervix and vaginal fornices no longer exists. Some ureters may then be close to the vaginal fornix and at risk of entrapment. They may be found lateral to the cervix and appear safe from injury, but then may take a sharp medial course toward the vaginal fornix, and be included during closure of the vaginal cuff angles (Figure 10).
The ureter in Figure 10 was lateral to the cervix and safe for cardinal ligament division. However, it was noted to have a sharp turn toward the vaginal fornix in spite of cephalad displacement of the cervix by the vaginal cup. In that situation, when the displacement is removed, the ureter may be at risk of entrapment during vaginal cuff closure. In another patient (Figure 11), the right ureter was suspected to be close to the vaginal fornix and it was dissected. It was then noted coursing within 5 mm of the vaginal cuff and could have been easily incorporated during cuff closure.
In 12% of patients, the ureters are within 5 mm from the lateral cervical wall. This means that 1 out of 8 patients is at risk of ureteral injury during endoscopic hysterectomy. Cephalad displacement of the uterus with a uterine manipulator is helpful to reduce, but not to eliminate, the risk of injury. Identification of the intersection of the ureter with the uterine artery is necessary to determine the course of the ureter at risk.
Division of the uterine artery at its intersection with the ureter and lateral displacement of the ureter are necessary to prevent parametrial ureteral injury when the organ is suspected to be coursing adjacent to the cervix. The parametrial ureter is also at risk during closure of the vaginal cuff.
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