Ureteric injury during obstetric and gynaecological surgery – an update


Introduction

Iatrogenic ureteric injury is a known and dreaded complication of surgery by obstetricians and gynaecologists, and is associated with significant morbidity and implications for litigation. The anatomic proximity of the ureters to the genital tract places them at risk of injury during pelvic surgery, which could damage to renal function. This article highlights the incidence, aetiology and common types of ureteric injury, along with their prevention, diagnosis, management options and medico-legal implications.

 

Figure 1. Anatomical course of the pelvic ureter and common sites of ureteric injury.

 

Anatomical course of the pelvic ureter

Gynaecological operations that were traditionally done by open surgery are increasingly being done laparoscopically. Though visibility is improved, there is loss of depth perception of the operative field, and the inability to palpate various structures, like the ureter, may make accurate identification a little trickier. Therefore, it is imperative that surgeons have a thorough knowledge of pelvic anatomy to aid identification of the ureter at open and laparoscopic surgery. Each ureter is 25 – 30cm in length. The abdominal part lies anteriorly on the psoas muscle and at the level where the common iliac artery bifurcates into the internal and external iliac arteries, it crosses the internal iliac vessels to enter the pelvis. The ovarian vessels travel in the infundibulo-pelvic ligament of the ovary and cross the ureters anteriorly and laterally to the iliac vessels. The anteromedial surface of the ureter is covered by peritoneum, and it runs posterior to the ovary and then deep into the broad ligament and through the cardinal ligament. The uterine artery crosses the ureters anteriorly in the posterior uterine fold of peritoneum, like the ureters are “water under the uterine-artery bridge”. The distance between the ureter and the cervix is about 1.5cm. The ureter then courses out to the ischial spines and continues medially onto the anterior vaginal fornix. It then penetrates the base of the bladder just above the trigone (Figure 1). The blood supply to the upper third of the ureters comes from the renal and ovarian arteries, the middle third is supplied by the aortic branches and the common iliac arteries, and the lower third, by the uterine, vaginal, middle haemorrhoidal, vesical and hypogastric vessels.

 

Aetiology

Ureteric injuries can occur during “simple” routine pelvic surgeries, such as hysterectomies, and the risk increases in the presence of comorbidities. The most notable sites of ureteric injury are:

  1. At the pelvic brim as the infundibulo-pelvic ligament is being divided (in 30 percent of cases)
  2. The ovarian fossa during resection of ovaries or ovarian remnants (in 19 percent of cases)
  3. Lateral to the cervix during division of the uterine artery, the uterosacral ligament and the cardinal ligament (in 51 percent of cases)1

The left ureter is more commonly damaged in the pelvis than the right, because the position of the right ureter is almost always constant and crosses the external iliac artery, whereas the left lies closer to the midline and crosses the common iliac artery.

 

Incidence

The incident rate for ureteric injury has stayed at approximately one percent in obstetric and gynaecological surgery. Ureteric injury occurs in approximately 0.5–1.5 percent of traditional open gynaecological surgery, 0.09 percent at caesarean sections2 and in 1.1 percent of laparoscopic surgeries.3 In a study looking at the changing incidence and aetiology of ureteric complications, it was found that there was an increase in the number of hospital referrals for ureteric damage, from 13 to 41 per 10,000 admissions, as the proportion of laparoscopic surgeries increased, and this was found to be statistically significant.4   

Amongst the factors that increase the risk of ureteric injury are the presence of comorbidities like pelvic inflammatory disease, endometriosis, previous pelvic surgery, pelvic adhesions, neoplasms and congenital anomalies. Additionally, a distorted pelvic anatomy and cervical and broad ligament fibroids, may increase the chance of uretic damage, as well as a difficult or complex surgery, previous pelvic radiation and pelvic adhesions. Uterine, cervical and broad ligament masses, congenital anomalies of the ureter and haemorrhages are also contributing factors, as well as merely carelessness of the surgeon.

Most of these factors have the potential to alter the expected course of the ureter. In pregnancy, the ureters are dilated and exposure is difficult, which increases the risk of ureter damage during a caesarean section and subsequent hysterectomies. Ureteric injury is significantly higher where the risk is increased due to the aforementioned factors (2.7 percent), than when none of those factors are present (0.9 percent).5 Ureteric injuries at laparoscopic hysterectomies were found to be most common in local hospitals (2.6 percent), followed by central (1.1 percent) and university hospitals (0.9 percent).6

 

 

Types of ureteric injury

Ureteric injury may result from suture ligation, kinking by suture, crushing and loss of blood supply resulting in devascularisation of the ureter. Furthermore, damage could be caused by electrocautery, cryoablation, avulsion, or partial laceration or transection of the ureter. The grade of injury can be used to predict the complexity of repair, and outcomes regarding morbidity and mortality. The American Association for the Surgery of Trauma have classified ureteric injuries under a scale, which includes the grade, type, and description of injury:

  • Grade I – Hematoma; contusion or hematoma without devascularisation
  • Grade II – Laceration; less than 50 percent transection
  • Grade III – Laceration; 50 percent or greater transection
  • Grade IV – Laceration; complete transection with less than 2cm of devascularisation
  • Grade V – Laceration; avulsion with greater than 2cm of devascularisation 13

Some trauma centres have revised their grading to include all collecting systems, renal pelvis injuries and segmental arterial and/or venous injuries under Grade IV and limiting their grade V to main renal artery and/or vein injuries, including laceration, avulsion, and thrombosis.14

 

Diagnosis of ureteric injury

The time at which ureteric injury is diagnosed determines the outcome for the patient. Intraoperative diagnosis allows for early repair of the ureteric injury, which makes the repair easier compared to a delayed repair, and reduces morbidity. Undiagnosed ureteric injury is a cause of significant postoperative morbidity, as it can affect renal function in about 25 percent of cases. One reason for delayed diagnosis is the assumed clinical presentation of gross haematuria, which is an unreliable sign for the need for further investigation when ureteric damage is suspected, as gross haematuria is absent in about 30 percent of cases.15 Maintaining a high index of suspicion and checking for the integrity of the ureter in gynaecology and obstetric operations is vital. This diagnosis can be made intra-operatively and post-operatively by the clinical diagnosis of leakage of urine and contrast-imaging of the renal tract.

 

Intra-operative diagnosis

This type of diagnosis is made in only about 8.6 percent16 of cases, when urinary leakage and extravasation is observed, but this is not seen in approximately 30 percent of patients that have had major or vascular injuries.17 Visual inspection may reveal ureteric wall discoloration and contusion, but it should be noted that ureteric vermiculation (visible spontaneous peristalsis to propel the urine through its lumen) does not exclude the possibility ureteric injury. When inspection is inconclusive, intraoperative recognition may be facilitated by intravenous injection of indigo carmine, which may confirm patency of the ureter by ejaculation of dye through the ureteric orifices and could be visualised at intraoperative cystoscopy. Intraoperative cystoscopy with dye and cystoscopic ureteral catheterisation both allow for early recognition of obstructive ureteral injuries, and so should be considered in complex surgical operations in gynaecology. This may reduce the rate of late postoperative diagnosis.

 

Post-operative diagnosis

Diagnosis of ureteric injury is made post operatively in 70 percent of cases.16 Symptoms and signs of undiagnosed ureteric damage are nonspecific. They include abdominal pain, fever, flank pain, haematuria, and a small, weak urinary stream. Additionally, signs of shock, cellulitis, peritonitis and a prolonged ileus, are indicative of damage, as well as persistent drainage from the vaginal vault, ureterovaginal fistula or operative drain.
In cases of bilateral ureteral injury, anuria and uraemia are clinical signs. About five percent of patients remain asymptomatic and may present years later with a non-functional kidney and secondary hypertension. Radiological investigations used for the diagnosis of ureteric injury include intravenous urography (an x-ray taken after intravenous radiopaque dye), retrograde urography (an x-ray taken after a radiopaque dye is instilled directly into the end of the urethra) and delayed abdominal and pelvic spiral computerised tomography (CT) scan of the renal tract to visualise the entire course of the ureter and extravasation of radiological contrast material. These are the most sensitive investigations used to evaluate the integrity of the renal tract, with almost 100 percent sensitivity with delayed CT.

Other investigative methods include ultrasound scan for hydronephrosis, renal tract haematoma, urinoma and fluid collection, which are suggestive of ureteric injury. Early postoperative ureteral jet ultrasonography may enable early detection and determine the degree of ureteric obstruction, however until evidence supports its value, it should not be routinely offered.17 Serum leucocytosis and a raised C-Reactive Protein are indicative of sepsis, secondary to extravasation of urine, and a high level of serum creatinine and urea may highlight the effect on kidney function, especially following ureteric occlusion.

 

Preventive measures

Proper preoperative assessment of patients will identify patients at relatively high risk of ureteric injury. They may require investigations in order to identify any ureteric variations, for example; an ultrasound scan to identify pelvic masses and intravenous urography to identify hydronephrosis and anatomical variant of the urinary tract.

The most effective way of preventing ureteric injury is meticulous surgical technique and a thorough knowledge of pelvic anatomy and the course of the ureter and the common sites of ureteric injury are likely to occur in obstetric and gynaecological surgery. The surgeon should be ureter – conscious at all pelvic surgery and aim to have adequate exposure and direct visualisation of the ureter especially in the high risk complex cases.  Caution should be taken when using diathermy, ligating pedicles, blind clamping the blood vessels during haemorrhage, and operating along the course of the ureter. Early assistance from the urologist should be sought in high risk cases, at preoperative assessment, and at surgery to help identify the course of the ureter in complex cases as well as early intra-operative management of ureteric injury.

Intraoperative cystoscopy is also recommended to help prevent delayed diagnosis of ureteric injury if the rate of ureteric injury is thought to be high and there are concerns about the integrity of the ureters.8 Ureteric stenting allows for visual and manual identification of the course of the ureter during surgery, however stenting itself can be associated with the risk of ureteric damage. In a review of this practice, the incidence of ureteric injury in high risk patients who had prophylactic ureteric catheters was one percent and 2.7 percent in those without.5 Stenting is known to cause significantly more postoperative flank pain, bladder pain, urinary symptoms, overall pain and total narcotic use in patients than in those who do not undergo stenting.19 Its prophylactic use has been found to have no statistical significance and the need to insert a stent has to be individualised.

 

Management

The management of ureteric injury depends on the site, length and type of injury complicating a particular operation. The results of a repair are not necessarily related to the type of treatment used, and some studies have shown success rates of 87 percent, 88 percent and 90 percent for delayed open surgical, endoscopic urological and immediate intra-operative repair respectively.20

 

 

Stenting of the ureter usually lasts for about four to six weeks, and one of the commonest stents used is the double-J stents. Complications of ureteric stenting are urinary tract infection, migration and malpositioning, encrustation and stent fracture, erosion and fistula formation. The stent should be monitored while in place, removed or changed when indicated, and warning signs of complications should be promptly managed.

To fix a complete transection of the ureter, the reconstruction method of the upper third is uretero-ureterostomy, for the distal and middle third of the ureter, it is Boari flap, for reconstruction of the distal ureter, the method is psoas hitch, and ureteric implantation is used for injury to the extreme distal ureter. Other methods include Ileal ureter, appendix interposition, trans-ureteroureterostomy, ureterocalycostomy and renal autotransplantation. Percutaneous nephrostomy may preclude ureteric stent placement in the interim, if the diagnosis is delayed, if the patient is septic, or if there is a haematoma or abscess at the injury site. Bladder decompression using a trans-urethral Foley or suprapubic catheter is required to prevent leakage around the site of repair. The possible complications following the repair of ureteric injury are listed in Box 1.

 

 

 

Medico-legal implications

Early operative repair of ureteric injury achieves good results unless the injury is severe. Litigation is less likely if the diagnosis is prompt, repair is successful and the patient is treated with consideration. In a review of claims secondary to ureteric injury in obstetrics and gynaecology, most injuries were discovered post – operatively and failure to dissect the ureter despite indications for this procedure was the most common type of negligence.22 This emphasises the importance of adequate preoperative assessment, especially in high risk patients, and the early involvement of the urologist for his or her opinion and assistance at surgery. If a patient sustained a urinary tract injury from hysterectomy, there is a high relative risk of litigation with major disability, but a lower chance of this injury being permanent, which is usually more likely after an obstructed ureter compared with other types of urinary tract injuries.23

The surgeon is therefore obliged to inform the patient beforehand, of the possible risk of injury to the ureter and any implications. Consent, communication and meticulous documentation are essential, and help patients make informed choices on their surgical treatment. Written information for patients is also recommended.

 

Conclusion

Iatrogenic ureteric injury is a rare but serious complication of obstetric and gynaecology surgery. Morbidity and mortality from this complication can be prevented by adequate pre-operative assessment, good surgical technique, and visualisation of the ureter. Anticipation and high index of suspicion of ureteric injury, early urological referral, and appropriate investigation of suspected ureteric injury is also of high importance. The surgeon has the responsibility to ensure that patients are properly selected, and that pre-, intra- and post-operative events are meticulously documented.

 

References

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