Iatrogenic injury to the urinary tract can be caused by any surgeon operating in or around the pelvis and the retroperitoneal abdominal space, with a general incidence of 0.3–1.5%.1
Of the urinary tract, the ureter is the most vulnerable to injury as it can be encountered at any level in the retroperitoneum and upper pelvis. This along with the occasional unexpected congenital anomaly makes the ureter especially vulnerable to injury.
COURSE OF PELVIC URETER WITH OPERATIVE SIGNIFICANCE (FIG. 1)
The ureter is 25–30 cm long in adults and courses down the retroperitoneum in an S curve. It consists of the abdominal, the pelvic, and the intramural segment.
The ureter begins at the level of the renal artery and vein posterior to these structures. This ureteropelvic junction usually coincides with the second lumbar vertebra on the left, with the right being marginally lower.
The ureter then continues anteriorly on the psoas major muscle, crossing under the gonadal vein at the level of the inferior pole of the kidney. The ureters course medial to the sacroiliac joint and then curve laterally in the pelvis. The colon and its mesentery are associated anterior to the ureters. Specifically, the cecum, appendix, and ascending colon lie over the right ureter, and the descending and sigmoid colon lie over the left ureter.
The ureter enters the pelvis at the pelvic brim at the base of the infundibulopelvic ligament, crossing the external iliac vessels from lateral to medial. This is one of the most common areas of ureteric injury during oophorectomy which can be avoided by two simple surgical principles: stay as close to the ovary as possible and if no adhesions, always lift and ligate.
The ureter then traverses down the lateral pelvic wall anterior and medial to the internal iliac artery.
It then crosses under the uterine artery (water under the bridge) at 1–1.5 cm away from the vaginal fornices on its way to the bladder insertion (Fig. 2).3
This is another vulnerable area of injury when ligating the uterosacral pedicle and also when suturing the vault which can be avoided by staying as close as possible to the uterus.
An important anatomical fact to note is that the left ureter has a more close relation to the anterior wall of vagina than the right,4 which explains why it is the left ureter close to the ureterovesical junction, which gets most commonly injured during hysterectomies.
The ureter has three physiologic narrowings: (1) the ureteropelvic junction, (2) the crossing over the iliac vessels, and (3) the ureterovesical junction. This is crucial in the manifestations of calculus disease. These narrowings may result in ureteral stones becoming trapped and obstructing at these specific levels. These narrowings may also limit retrograde instrumentation performed for diagnostic or therapeutic purposes.
SURGICAL SIGNIFICANCE OF URETERIC BLOOD SUPPLY
The nutrient arteries generally approach the ureteric wall from one direction which needs to be kept in mind by the surgeon to avoid devascularizing the ureter.
Above the pelvic brim, the nutrient arteries approach from the medial side and below the pelvic brim from the lateral side of the ureter.2
The supplying arteries and veins run through a layer of loose connective tissue to the adventitial vascular plexus called the mesoureter. This means that even if an arterial inflow is ligated, there will not be necrosis of the ureter because of its rich collateral anastomoses within the adventitial vascular plexus. But, unnecessary and excessive mobilization can devascularize the ureter and increase the risk of postoperative ureteric stricture (Fig. 3).
SURGICAL SIGNIFICANCE OF URETERIC NERVE SUPPLY
The sympathetic nerves supplying the ureter originate from the aortic plexus and its continuation, the superior hypogastric plexus, the paired hypogastric nerve, and the subsequent inferior hypogastric (pelvic) plexus. The nerves accompany the nutrient branches of the neighboring arteries and form circumarterial plexuses or run free in the connective tissue.
The parasympathetic pelvic splanchnic nerves usually arising from the second, third, and fourth sacral root traverse the inferior hypogastric plexus before its partition in its specific plexuses for the pelvic viscera.
In female, the branches of the uterovaginal plexus are themselves positioned a little lower than the uterine artery and the ureter. The branches of the vesical plexus run inferior to the terminal ureter and extend to the trigone of the bladder.
Note: In an antireflux procedure there is a high risk of injury to the nervous structures if dissection is performed dorsally to the trigone and dorsocaudally to the vesicoureteric junction. Careful dissection close to the terminal ureter (within the layer of mesoureter) avoids intraoperative injury to the pelvic autonomic nerves.
Mucosal irritation and luminal distention stimulate nociceptors whose afferents travel with sympathetic nerves and confer the visceral-type referred pain that results in the manifestations of ureteral colic. Pain or hyperesthesia may be sensed from the region of the ipsilateral ribs down to the labia.
MALFORMATIONS OF THE URETER
The ureter can be duplicated completely or incompletely, unilaterally or bilaterally.
Duplications of the ureter are of practical importance; the incidence of a ureteric duplication is 1:100. “Ureter duplex” denotes complete duplication of the ureter on one or both sides. The ureter arising from the cranial part of the renal sinus usually opens into the bladder more caudally than normal, while the ureter arising from the lower part of the renal sinus enters the bladder higher than the dystopic ureter (Weigert-Meyer law). Duplex ureter is due to the presence of two ureteric buds on one or both sides during embryogenesis.
Note: In cases of duplicated ureter, there is a common vascular supply within the ureteric sheath, so that resection of one of the ureters can endanger the blood supply of the remaining ureter and may lead to its necrosis.
The other ureteric anomalies include ureterocele, ectopic ureteral orifice, megaureter, ureteral atresia, ureteral diverticula, or a retrocaval ureter.
- Rosemarie F. Surgical Anatomy of the Ureter. Surgery Illustrated; 2007. Available from https://bjui-journals.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1464-410X.2007.07207.x [Last accessed on April, 2021].
- Sankpal RS, Karoshi M, Keith LG (Eds). Textbook of Simplified Laparoscopic Hysterectomy: Practical, Safe and Economic Methodology. New Delhi: Jaypee Brothers Medical Publishers; 2018. Also available from glowm.com [Last accessed on April, 2021].
- American Association for the Surgery of Trauma. [online] Available from: http://www.aast.org/injury/t15-20.html#ureter [Last accessed on March, 2019].
- Bartsch G, Poisel S (Eds). Operative Zugangswege in der Urologie. Stuttgart New York Thieme; 1994.