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:
- At the pelvic brim as the infundibulo-pelvic ligament is being divided (in 30 percent of cases)
- The ovarian fossa during resection of ovaries or ovarian remnants (in 19 percent of cases)
- 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
