Urinary tract injury in gynecologic surgery: Epidemiology and prevention

INTRODUCTION — The reproductive and urinary tracts in females are closely related anatomically and embryologically. Knowledge of this anatomy is essential in the prevention of urinary tract injury during gynecologic surgery. The primary approach to prevention is careful surgical dissection and knowledge of the position of urinary tract structures within the surgical field.

The prevention of urinary tract injury in gynecologic surgery, primarily hysterectomy, will be reviewed here. The identification and management of urinary tract injury in gynecologic surgery and hysterectomy are discussed separately.

●(See "Urinary tract injury in gynecologic surgery: Identification and management".)

●(See "Hysterectomy: Abdominal (open) route", section on 'Avoiding ureteral injury'.)

In this topic, when discussing study results, we will use the terms "woman/en" or "patient(s)" as they are used in the studies presented. However, we encourage the reader to consider the specific counseling and treatment needs of transgender and gender-expansive individuals.

EPIDEMIOLOGY — Ureteric injuries (recognized and unrecognized) and bladder injuries at benign gynecologic surgery are significant causes of morbidity and mortality.

Incidence — The overall rate of urinary tract injury associated with pelvic surgery in women ranges from 0.3 to 4 percent [1-6]. In a study of a large health care database including over 223,000 patients between 2007 and 2011, 81 percent of whom underwent hysterectomy for benign indications, ureteral injury occurred in less than 1 percent of patients (0.78 percent) and was unrecognized in 62 percent of cases [2]. Bladder injury is approximately three times more common than ureteral injury [1,6,7]. Up to 2.4 percent of patients may require concomitant urologic intervention after hysterectomy-related injury to the urinary tract [8].

Recognized and unrecognized ureteric injuries at the time of benign hysterectomy are a significant cause of morbidity and mortality. The incidence is so low that a particular surgeon may experience no or only a few cases of urinary tract injury in their career. However, because of the morbidity, mortality, and costs, prevention of injury is ideal. If an injury occurs despite every effort to avoid one, intraoperative diagnosis and management, with additional clinician help as needed, is preferred to postoperative recognition for minimizing postoperative sequelae and optimizing patient outcomes. (See "Urinary tract injury in gynecologic surgery: Identification and management".)

Mechanisms of injury — There are many ways the lower urinary tract can be compromised during or after surgery.

●Impact of thermal injury – Thermal damage from electrosurgery or other energy sources, such as laser or harmonic scalpel, is becoming a more frequent cause of injury to the urinary tract [9,10]. The expected thermal spread from devices ranges from 2 to 22 mm. In a systematic review of 90 studies, electrosurgery was the most common cause of ureteral injury (33 percent), while lysis of adhesions was the most common cause of bladder injury (23 percent) [7]. There is no standard time course for presentation of thermal injuries. (See "Overview of electrosurgery", section on 'Thermal spread'.)

●Injury of ureter – Additional potential mechanisms of intraoperative ureteral injury include [6]:

•Crushed with a clamp

•Kinked or ligated with a suture or staple

•Lacerated or transected during sharp or blunt dissection or while using an energy source

•Devascularization or denervation

●Injury of bladder ladder – Other mechanisms of intraoperative bladder injury include:

•Cystotomy.

•Laceration of the bladder wall with or without or breaching the bladder lumen.

•Devascularization or denervation.

•Accidental placement of an intravesical suture or staple. An intravesical suture may be symptomatic or asymptomatic, depending upon the type and location of the suture/staple in the bladder and coincident infection and/or stone formation.

Postoperatively, physiologic and pathologic processes can cause or exacerbate an injury to the urinary tract. These include edema, inflammation, hematoma, infection, abscess formation, ischemia, or necrosis.

Outcomes and consequences of injuries — While both recognized and unrecognized ureteral injury increased the risk of serious postoperative complications, the effect appears to be more pronounced with unrecognized injury [2].

●Direct surgical outcomes – In a retrospective database study including over 233,000 patients undergoing hysterectomy, recognized and unrecognized injury increased the adjusted odds ratios of 90-day hospital readmission (1.5 and 24.2, respectively), sepsis (2.0 and 11.9, respectively), nephrostomy tube placement (66.0 and 1792, respectively), and urinary tract fistula (5.9 and 124, respectively) when compared with no documented injury. While there was no significantly increased risk of acute renal failure or death for recognized ureteral injuries compared with no injuries, unrecognized injury was associated with a nearly 24-fold increased risk of acute renal failure and 40 percent increased odds for death [2].

●Additional adverse outcomes – Multiple other large health care and National Surgical Quality Improvement Program (NSQIP) database studies confirm that complex urinary tract injuries after benign hysterectomy result in significantly longer hospital stays, renal insufficiency, renal failure, transfusions, wound complications, readmissions, repeat surgeries, and increased health care costs compared with patients without injuries [4,11,12].

●Increased risk of vaginal fistula – When bladder injuries present postoperatively, genitourinary fistulas appear to be the most common presentation (74 of 76 in one series) [13]. Fistulas are more often associated with minimally invasive hysterectomy [3,4].

•(See "Urogenital tract fistulas in females", section on 'Epidemiology and risk factors'.)

•(See "Hysterectomy: Laparoscopic", section on 'Complications'.)

UNDERSTANDING RISK FACTORS — Risk factors for urinary tract injury in pelvic surgery are based upon characteristics of the patient, procedure, and surgeon. Overall risk of urinary tract injury is likely a complex interaction among all of these. There risks need to be considered and assessed prior to surgery (and intraoperatively) to avoid and minimize injuries.

Patient

●Common risk factors – Patient risk factors that impact urinary tract complications are conditions that distort pelvic anatomy, obscure tissue planes, make visualization of urinary tract structures difficult, or make the urinary tract more vulnerable to injury [3-6,8,11,12,14,15].

Commonly identified risk factors include:

•Prior pelvic surgery (laparotomy and/or prior cesarean birth)

•Endometriosis

•Urinary tract abnormalities (eg, duplicated ureter, pelvic kidney)

•History of pelvic irradiation

•Obesity

•Large pelvic mass

•Fibroids, including in the cervix and broad ligament

•Large uterus (>250 g)

●Impact of prior cesarean birth – Individuals with prior cesarean birth have approximately double the increased risk of urinary tract injury at the time of gynecologic surgery compared with those without prior cesarean birth (odds ratios [OR] range from 1.86, 95% CI 1.4-2.47 to 2.90, 95% CI 1.7-5.0) [15-19].

The risk of cystotomy increases with increasing number of prior cesarean births. In a retrospective review of patients undergoing hysterectomy, those with two or more prior cesarean births had an eightfold increased risk of incidental cystotomy compared with those without prior cesarean birth (OR 8.55, 95% CI 3.98-18.36) [18]. In multivariate analysis, the risk was highest in patients with four prior cesarean deliveries.

Procedure and route — Urinary tract injury occurs almost exclusively in major gynecologic surgery that involves surgical dissection in proximity to the ureters or bladder. Minor procedures (eg, hysteroscopy) or tubal surgery are rarely associated with this type of complication. Procedure type and route of surgery (ie, vaginal, laparoscopic, robot-assisted, or abdominal) impacts risk of a urinary tract injury. These factors are in turn influenced by the surgical indication, underlying pathology, degree of anatomic distortion, and surgeon experience. Rates of urinary tract injury by route of hysterectomy are reviewed separately. (See "Hysterectomy (benign indications): Patient-important issues and surgical complications", section on 'Urinary tract injury'.)

●Oophorectomy or hysterectomy – Although there is limited ability to report injury rates for each step during oophorectomy or hysterectomy, the steps of the procedure in which the ureter is most likely to be injured are listed below [6,20,21].

•Ligation of the ovarian vessels

•Ligation of the uterine vessels

•Closure of the angles of the vagina cuff

●Ureterolysis – The highest risk of denervation and/or devascularization is during ureterolysis; therefore, removal of all tissue surrounding the ureter should be avoided during gynecologic surgery performed for benign indications.

●Additional factors – Factors that can increase surgical risk include [1,5,6,14,22-24]:

•Surgery for malignancy

•Advanced pelvic reconstructive surgery

•Laparoscopic or robot-assisted hysterectomy – Large database studies consistently report increased risk of complex lower urinary tract injury with abdominal, laparoscopic, and robot-assisted hysterectomy while vaginal hysterectomy is associated with lower risk of complex injuries [3,4,25,26]. Confounders such as size and location of fibroids, endometriosis, prior pelvic surgeries, and prior cesarean birth all likely influence the approach, and thus, risk of injury.

The frequency of injury and comparison of the surgical routes for hysterectomy are presented in related topics:

-(See "Hysterectomy (benign indications): Patient-important issues and surgical complications", section on 'Urinary tract injury'.)

-(See "Hysterectomy (benign indications): Selection of surgical route", section on 'Comparison of routes of hysterectomy'.)

Surgeon — Increasing experience of the surgeon has correlated with a decrease in the frequency of urinary tract injury [27-29]. Surgery at facilities with lower hysterectomy volumes are associated with increased likelihood of genitourinary injury [4]. Reports vary regarding whether participation by surgical trainees increases the risk of injury [30-32].

PREOPERATIVE PLANNING

Medical history, physical examination, and surgical consent — Preoperative evaluation and preparation are focused on preventing operative urinary tract injury. A more general discussion of preoperative assessment for gynecologic surgery is presented separately. (See "Overview of preoperative evaluation and preparation for gynecologic surgery".)

●Patient history – Important elements of the history are prior pelvic surgery, radiation, or infection and known or suspected endometriosis. Congenital anomalies of the urinary tract (eg, duplicated ureters, pelvic kidney) may be suspected if there is a personal or family history of congenital anomalies of the urinary tract or reproductive tract, since these abnormalities often coexist. (See "Overview of congenital anomalies of the kidney and urinary tract (CAKUT)".)

●Patient examination – Assessment of the accessibility, size, and mobility of the pelvic organs at abdominal and pelvic examination will assist the surgeon in deciding the safest approach (open, laparoscopic, or vaginal) to surgery.

●Informed consent – Counseling about surgical risk, including the risk of injury, is part of the informed consent process prior to pelvic surgery. This discussion should be documented in the medical record and an informed consent document should be signed. (See "Informed procedural consent".)

Imaging — Contrast studies of the ureters may be useful in patients with known or suspected urinary tract anomalies.

●Magnetic resonance imaging (MRI) – In our experience, MRI is the most helpful preoperative imaging for any patients with large fibroids and/or suspected cervical and/or broad ligament fibroid(s). It is also helpful for retroperitoneal cysts or masses that increase the risks of urinary tract injury.

●Computed tomography (CT) urogram – Preoperative imaging with CT urography can be helpful in demonstrating structural abnormalities in the urinary tract [33]. We use this modality if MRI is not readily available.

•(See "Renal ectopic and fusion anomalies".)

•(See "Overview of congenital anomalies of the kidney and urinary tract (CAKUT)".)

INTRAOPERATIVE PREPARATION

Patient positioning — Patient positioning in the dorsal lithotomy rather than supine position provides better access for evaluation of the urinary tract with cystoscopy or other methods that require access to the urethra. (See "Urogynecologic surgery: Perioperative care issues", section on 'Positioning'.)

Additional equipment that we find helpful includes:

●Stirrups – Adjustable boot stirrups (figure 1) adjust from a low to high position. These stirrups offer many advantages over candy cane stirrups.

●Self-retaining retractor – A self-retaining retractor that does not interfere with the thighs (eg, Bookwalter (figure 2)) enhances surgical visualization and allows a second surgical assistant to stand between the patient's legs, which improves their ability to assist. This setup also facilitates performing cystoscopy more easily, with better visualization of the entire bladder.

In our practice, we place all patients in boot type stirrups and use a Bookwalter retractor for all open cases. This keeps our entire team (surgeon, surgical assistants, scrub, and circulating nurses) familiar and efficient with the equipment set-up and optimal use to get the best exposure. We take care to not use deep retractors in thin patients (eg, pressure on psoas muscle and compression injury of femoral nerve below this). We also loosen and retighten the retractors about every one to two hours as an additional measure to try to prevent nerve injury. (See "Nerve injury associated with pelvic surgery", section on 'Femoral nerve'.)

Bladder catheter — Placement of an indwelling bladder (Foley) catheter may be helpful in procedures in which there is a potential for urinary tract injury. If there is an increased risk of injury, a triple lumen (three-way) catheter can be used, which will allow instillation of contrast material if bladder injury is suspected. Persistent blood-tinged urine in the catheter output should prompt evaluation for urinary tract injury. Air in the urine collection bag has been reported as a sign of bladder injury, although the author has not had this experience. (See "Urinary tract injury in gynecologic surgery: Identification and management", section on 'Procedure and findings'.)

Prophylactic ureteral catheters (stents) — While placement of ureteral catheters (ie, stents) does not prevent ureteral injury, use of catheters can improve anatomic identification and assist in detecting injury should one occur [34].

●Our approach – If we anticipate challenging surgery because of preoperative risk factors (ie, large fibroid uterus, adhesions, endometriosis), we place ureteral catheters in the operating room prior to the start of the gynecologic procedure (preferred) or during the procedure if difficulty is encountered in locating the ureter(s) and/or their course through the operative field. Ureteral catheters are placed using a 22-French, 30-degree cystoscope and bridge deflector. We also preferentially use 5-French flexi-tip ureteral catheters (as opposed to whistle-tip ureteral catheters) to facilitate guidewire insertion and postoperative indwelling stent if this is needed for postoperative care. (See "Placement and management of indwelling ureteral stents", section on 'Stent placement'.)

•Preoperative patient selection – Ureteral catheters are potentially helpful for selected patients with known or suspected periureteral fibrosis or scarring, such as those with severe endometriosis, large cervical fibroids, broad ligament fibroids, or prior pelvic irradiation.

•Intraoperative catheter insertion – If we encounter unanticipated challenges during a surgical case (eg, severe endometriosis), we perform cystoscopy, insert ureteral catheters to help delineate ureter anatomy, and thus minimize the risks of an injury. To facilitate unplanned ureteral catheter insertion, we perform all major gynecologic surgical procedures with the patient in dorsal lithotomy position with boot-type stirrups and, for laparotomy, use a Bookwalter retractor.

●Supporting data – A 2020 meta-analysis of five trials including 1290 patients undergoing laparoscopic gynecologic surgery reported lower ureteral injury rates for patients undergoing prophylactic ureteral catheterization compared with those who did not (1 versus 2.7 percent; relative risk 0.44, 95% CI 0.20-0.97) [35]. There were no reported major catheter-related complications. While there appears to be a benefit in terms of ureteral injury rates, the absolute risk reduction is small.

●Ureteral catheter manipulation during surgery

•Laparotomy – At open surgery, ureteral catheters allow the surgeon to easily palpate the ureters prior to applying clamps or ligating pedicles proximal to the ureters. This avoids the need for extensive ureterolysis in these cases where severe periureteral fibrosis will make ureterolysis more challenging and/or the surgeon does not have advanced skills in ureterolysis. Similar to other centers, we find placing ureteric catheters just prior to (or during) difficult surgery quicker and associated with less bleeding and risk of ureteral devascularization than performing extensive ureterolysis [36].

•Laparoscopy – For challenging laparoscopic surgery, having the second assistant standing between the legs, moving the catheters slightly forwards and backwards helps us delineate the course of the ureter prior to laparoscopic cauterization and cutting of pedicles.

●Ureteral catheter insertion – In our practice, trainees perform the ureteral catheterization under direct supervision of an attending gynecologist who has the appropriate skills. In a retrospective chart review of 337 patients in whom prophylactic preoperative ureteric catheters were placed by a gynecologic surgical consultant or subspecialty trainee, bilateral catheter insertions were successful in 93 percent of patients, quick to insert (5.4 and 8.4 minutes, respectively), and associated with no intraoperative ureteric complications [36]. Postoperative complication rates were low; urinary tract infection rate in this cohort was 1.5 percent.

For those who are not trained in ureteral catheter insertion, the need to schedule a urologist is a practical barrier to ureteral catheter insertion prior to gynecologic surgery [37].

SURGICAL TECHNIQUE — Primary prevention is optimal; techniques include intraoperative identification of the bladder and ureters and avoidance of injury through meticulous surgical technique.

Relevant anatomy — Avoiding urinary tract injury requires constant knowledge of anatomic location. Anatomic variation and pelvic pathology may obscure tissue planes, thereby increasing the risks of an injury [1]. (See "Surgical female urogenital anatomy", section on 'Ureters'.)

●Ureters – The pelvic ureters are retroperitoneal structures that run from the renal pelvis to the bladder and can be injured during pelvic surgery at any point along their distal course (figure 3). The pelvic course of the ureters and most common sites of injury from superior to inferior can be summarized as follows [33,38,39]:

•The ureters enter the pelvis at the pelvic brim where they cross from lateral to medial, and anterior to the bifurcation of the common iliac arteries (picture 1). At this point, the ureter runs just medial to the ovarian vessels (picture 2).

•The ureters then descend into the pelvis within a peritoneal sheath (ureteric fold) attached to the medial leaf of the uterine broad ligament and the lateral pelvic sidewall (figure 4 and figure 5).

•Just inferior to the internal cervical os, the ureter passes under the uterine arteries in the cardinal ligament through a tunnel of areolar tissue to the anterolateral surface of the cervix (figure 3 and figure 6).

•The ureters then pass close to the anterolateral fornix of the vagina and enter the posterior aspect of the bladder.

●Bladder – The bladder is positioned anterior to the vagina, cervix, and lower uterine segment. The vesicouterine fold, or pouch, is a reflection of the anterior peritoneum that lays between the dome of the bladder and the lower uterine segment. The base is opposed to the cervix and vagina with the vesicocervical and vesicovaginal fascia. (See "Surgical female urogenital anatomy", section on 'Bladder'.)

The bladder is divided into the dome superiorly and the base inferiorly [38,40]. The base contains the trigone, including the ureters, which enter posteriorly, and the urethra, which exits at the most inferior aspect of the bladder.

Identify ureters — To minimize the risk of accidental ureteral ligation or transection when operating on pelvic structures we identify the ureter at the beginning of the surgery and at each step of a surgical procedure. Steps to identify the ureter include opening the retroperitoneum to directly visualize the ureter, visualizing the ureter, and peristalsis, through the peritoneum, and palpating the ureter. There are no high-quality data comparing these approaches regarding ureteral injury risk.

●Open the retroperitoneum – Opening the retroperitoneum, dissecting surrounding tissue, and directly visualizing the ureter provides the most accurate assessment of its location and course. We take the following steps when opening the retroperitoneum from an intraabdominal route (figure 3):

•Ligate and divide the round ligament to create an opening in the broad ligament [39,41].

•Palpate the external iliac artery. Continue using blunt dissection to open the broad ligament lateral to the external iliac artery and lateral and parallel to the ovarian vessels (which are within the infundibulopelvic ligament). Limit use of energy sources in close proximity to the ureter. As noted above, the expected thermal spread from devices ranges from 2 to 22 mm. (See 'Mechanisms of injury' above.)

•Expose the external iliac artery and vein.

•Dissect out the ureter from the surrounding tissue as it crosses over the vessels and is adherent to the medial leaf of the broad ligament. Visualization of peristalsis confirms that the ureter has been identified. Take care to avoid disrupting the vascular supply of the ureter, which may result in ischemia and necrosis [22].

●Direct visualization of ureter with peristalsis – Direct or laparoscopic visualization of the ureter is reasonable when the peritoneum is translucent and the ureter can be clearly seen. Visualization of peristalsis confirms identification of the ureter. One limitation is that visualization does not prevent mistaking other anatomic structures for the ureter, particularly if peristalsis is not clearly seen.

●Palpation – When the ureter cannot be visualized (eg, bleeding in operative field), we use palpation to attempt to identify the ureter. The ureter has a "rubber band-like" consistency and should snap when pulled gently; the ureter does not pulsate when palpated. However, palpation of the ureter can be misleading since many structures can have the same consistency as the ureter.

Bladder dissection — Injury to the bladder may occur while dissecting the bladder away from the lower uterus, cervix, and upper vagina during hysterectomy. In the absence of prior surgery in this area, the tissue plane is often easy to find and dissect regardless of surgical approach (laparoscopy, laparotomy, or vaginal). However, one or more previous cesarean deliveries may cause fibrosis and scarring and impede dissection. (See 'Patient' above.)

•Sharp dissection of bladder flap – Regardless of scar tissue from one or more prior cesareans, we always use sharp dissection, with or without electrosurgery, rather than blunt dissection when developing this tissue plane. Blunt dissection may result in increased bleeding or tearing of the bladder. Bladder injury that occurs with sharp, rather than blunt, dissection can often be easier to repair.

By performing sharp dissection of this plane for every case, the surgeon maintains the skills and confidence that facilitate bladder dissection in cases where a patient has had multiple cesareans. For these more challenging cases, the surgeon is not struggling with both a difficult dissection and an unfamiliar surgical technique.

•Direct visualization of laparoscopic trocar insertion – Bladder injury can occur during laparoscopic trocar insertion. Injury risk is reduced by placing secondary trocars under direct visualization and by completely draining the bladder before trocar insertion. (See "Complications of laparoscopic surgery", section on 'Entry-related bladder injuries'.)

Techniques specific to other structures

●Ligation of the ovarian vessels – Ligation of the ovarian vessels is a high-risk time for potential ureteral injury.

•Laparoscopic and open abdominal surgery – We visualize the ureter and confirm peristalsis as it courses along the pelvic sidewall. The ureter may be directly visualized through the peritoneum or require opening the peritoneal surface. Once the location of the ureter is confirmed at laparoscopy, we tent the peritoneum up and make a small incision in the peritoneum superior to the ureter but inferior to the ovarian vessels, parallel to both of these structures. This peritoneal incision serves as a visual marker (the ureter is below it). We then tent the peritoneum and make a second incision more superiorly along the pelvic sidewall, above the ovarian vessels, and use these two peritoneal incisions to help isolate and ligate our ovarian vessels. Alternately, after visualizing the course of the ureter in the retroperitoneum, ensuring one stays close to the ovary and away from the course of the ureter while desiccating and transecting the ovarian blood supply will also help avoid injury.

-(See "Hysterectomy: Abdominal (open) route", section on 'Avoiding ureteral injury'.)

-(See "Hysterectomy: Laparoscopic", section on 'Identification of the ureter'.)

•Vaginal surgery – Of note, during a vaginal approach to oophorectomy, the ureter is more difficult to visualize and is protected by clamping the ovarian vessels as close as possible to the ovary. (See "Hysterectomy: Vaginal", section on 'Adnexal evaluation and surgery'.)

●Ligation of the uterine arteries – The uterine vessels are skeletonized before ligation to visualize the ureter, which passes below the uterine arteries (figure 4). If the vessels have been isolated, it is not required to completely dissect out the ureter.

•When placing a clamp prior to ligating the vessels, care must be taken that only the vessels are included in the clamp.

•Mobilizing the bladder from the anterior cervix and displacing it inferiorly also shifts the ureters inferior to the uterine arteries prior to clamping the uterine arteries

Once the uterine vessels are ligated, the ureter will pass just inferior and lateral to this pedicle. Thus, to protect the ureter during subsequent dissection of the cardinal ligament, the clamp is placed medial to the uterine artery pedicle (figure 5).

●Vaginal cuff closure – The ureters enter the bladder posteriorly, along its interface with the anterior vaginal wall (figure 5). Thus, care must be taken during closure of the vaginal cuff to avoid both the ureters and bladder. As the bladder is dissected off the surface of the vagina or cervix and displaced inferiorly, the ureters will descend with the bladder to a level safely below the superior aspect of the cuff.

●Surgical exposure at hysterectomy – Elevation of the uterus in an antero-cephalad direction facilitates descent of the bladder and ureters away from the operative structures and decreases the risk of injury.

•Laparotomy – When performing abdominal hysterectomy through an open incision (laparotomy), the first assistant gently pulls the uterus up while the surgeon mobilizes the bladder and ligates the uterine arteries and the cardinal/uterosacral ligaments.

•Laparoscopy – During laparoscopic or robot-assisted hysterectomy, the second assistant gently pushes the uterus up using the uterine manipulator to accomplish the same maneuver.

•Vaginal route – At vaginal hysterectomy, placing clamps and suturing pedicles as close as possible to the cervix and uterus decreases the risk of ureteric injury.

Identifying a pelvic kidney — A pelvic kidney, which occurs in from 1 in 500 to 1 in 3000 individuals, may be encountered during gynecologic surgery. They are usually unilateral, retroperitoneal, irregular in shape, and may occur anywhere below the pelvic brim. The blood supply is invariably anomalous, often with branches coming from the aorta, common, external or internal iliac vessels, and vessels may come from both sides of the pelvis [42]. However, with increased access to high-quality preoperative imaging, intraoperative discovery of a pelvic kidney should be a rare occurrence. (See "Renal ectopic and fusion anomalies".)

Identification of an unsuspected pelvic kidney reduces the risk of damage to the kidney or its blood supply. In general, biopsy is avoided if a mass is suspected to be a pelvic kidney as biopsy can lead to bleeding and organ injury.

●Intraoperative exploration – During surgery, the presence of a retroperitoneal mass or anomalous ureteral anatomy suggests the presence of a pelvic kidney. During laparotomy, identification of a pelvic kidney can be made by palpating the abdominal retroperitoneum to confirm that there is no abdominal kidney, and then by identifying the ureter which exits the pelvic kidney [43].

●Intraoperative consult and/or imaging – Intraoperative urology consult and/or sonography (if available) may facilitate identifying a pelvic kidney.

CYSTOSCOPY TO DETECT INJURY — Cystoscopy (full terminology cystourethroscopy) is associated with a higher detection rate of urinary tract injuries compared with visual inspection alone, particularly for ureteral injuries. Routine use of intraoperative cystoscopy at the time of gynecologic surgery is a point of debate. Clinical use of cystoscopy as a diagnostic test for operative urinary tract injury is discussed separately. (See "Diagnostic cystourethroscopy (cystoscopy) for gynecologic conditions", section on 'Procedure' and "Urinary tract injury in gynecologic surgery: Identification and management", section on 'Cystoscopy'.)

●Universal cystoscopy – Whether or not to perform universal intraoperative cystoscopy as a screening test for urinary tract injury after major gynecologic surgery is a point of debate. There are no studies estimating sensitivity, specificity, or positive and negative predictive value of universal screening cystoscopy. In practice, these values will vary depending on a particular surgeon's knowledge and skill at utilizing intraoperative cystoscopy. (See "Urinary tract injury in gynecologic surgery: Identification and management", section on 'Debate of universal versus selective cystoscopy'.)

●Cystoscopy at time of hysterectomy – Specific to hysterectomy, a retrospective cohort study that compared universal with selective cystoscopy at the time of hysterectomy reported significantly fewer delayed urologic complications in the universal cystoscopy patients (0.1 versus 0.7 percent) but the absolute rates were low in both groups [44]. The observed reduction in delayed complications likely resulted from a reduction in vesicovaginal fistula (seven cases preuniversal cystoscopy to zero cases postuniversal), presumably because of the significant increase in recognized bladder injuries in the postuniversal cystoscopy group (85 postuniversal screening versus 52 percent preuniversal). (See "Urinary tract injury in gynecologic surgery: Identification and management", section on 'Cystoscopy'.)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Gynecologic surgery".)

SUMMARY AND RECOMMENDATIONS

●Incidence and mechanisms of injury

•Urinary tract injury during female pelvic surgery occurs in approximately 0.3 to 1.8 percent and may be as high as 2.4 percent of procedures. (See 'Incidence' above.)

•Thermal damage has become the most common etiology of urinary tract injury. Additional mechanisms of injury include laceration or obstruction from a surgical instrument (suture, clamp, stapling device, or energy source) or result from devascularization or denervation associated with tissue resection. (See 'Mechanisms of injury' above.)

●Risk factors – Risk factors for urinary tract injury are related to patient characteristics, underlying pathology, procedure, and surgeon. Overall risk of injury is likely a complex interaction among these risk factor categories. Surgeons need to be aware of these risks when planning surgery to avoid intraoperative injury. (See 'Understanding risk factors' above.)

●Preoperative planning

•General – Preoperative planning to avoid urinary tract injury includes focusing on the patient's history and physical examination as well as discussing risk as part of documented informed consent. (See 'Medical history, physical examination, and surgical consent' above.)

•Preoperative imaging – For patients with known or suspected urinary tract anomalies, retroperitoneal cysts, and/or cervical/broad ligament fibroids, we perform preoperative imaging, preferably magnetic resonance imaging (MRI) or computed tomography (CT) scan with contrast to facilitate surgical planning to minimize injury risk. (See 'Imaging' above.)

●Intraoperative preparation

•Patient positioning and bladder catheter – In our practice, we place patients undergoing major gynecologic surgery in dorsal lithotomy position with mobile boot-type stirrups and insert an indwelling bladder catheter. We find this positioning provides better access for evaluation of the urinary tract for cystoscopy compared with supine positioning.

-(See 'Patient positioning' above.)

-(See 'Bladder catheter' above.)

•Prophylactic ureteral catheter insertion – For individuals undergoing major gynecologic surgery that is anticipated to be complicated because of preoperative patient and/or anticipated surgical factors (eg, adhesions), we suggest prophylactic bilateral ureteral catheter (ie, stent) placement rather than no placement (Grade 2C). We also insert ureteral catheters intraoperatively when we experience unanticipated challenges that obscure ureter anatomy and increase risks. (See 'Prophylactic ureteral catheters (stents)' above.)

●Surgical technique

•Identify anatomy – Avoiding urinary tract injury requires constant knowledge of anatomic location. Anatomic variation and pelvic pathology may obscure tissue planes, thereby increasing the risks of an injury. (See 'Relevant anatomy' above.)

•Avoiding injury – To minimize the risk of accidental ureteral ligation or transection when operating on pelvic structures we identify the ureter at the beginning of the surgery and at each step of a surgical procedure. Ureteral identification can be done by opening the retroperitoneum to directly see the ureter, visualizing the ureter with peristalsis through the peritoneum, palpating the ureter (with or without ureteric catheters), or a combination of these. Alternately, the ureter and its peristalsis can be visualized through the peritoneum in some patients. When bladder dissection is performed, we use sharp rather than blunt dissection to reduce the risk of injury and because bladder injuries resulting from sharp dissection are often be easier to repair.

-(See 'Identify ureters' above.)

-(See 'Bladder dissection' above.)

●Role of cystoscopy – Cystoscopy (full terminology cystourethroscopy) is associated with a higher detection rate of urinary tract injuries compared with visual inspection alone, particularly for ureteral injuries. Routine use of intraoperative cystoscopy at the time of gynecologic surgery is an active point of debate and reviewed in detail in related content.

•(See 'Cystoscopy to detect injury' above.)

•(See "Urinary tract injury in gynecologic surgery: Identification and management", section on 'Debate of universal versus selective cystoscopy'.)