The ureters are two thick tubes which act to transport urine from the kidney to the bladder. They are roughly 25cm long and are situated bilaterally, with each ureter draining one kidney. In this article, we shall look at the anatomy of the ureters – their anatomical course, neurovascular supply, and clinical correlations.
The ureters arise in the abdomen as a continuation of the renal pelvis, and terminate in the pelvic cavity – where they empty into the bladder. The anatomical course of the ureters can therefore be divided into abdominal and pelvic components.
The ureters arise from the renal pelvis – a funnel like structure located within the hilum of the kidney. The renal pelvis receives urine from the major calyces. The point at which the renal pelvis narrows to form the ureter is known as the ureteropelvic junction. After arising from the ureteropelvic junction, the ureters descend through the abdomen, along the anterior surface of the psoas major muscle. Here, the ureters are a retroperitoneal structure (located behind the peritoneum) which travels underneath the abdominal wall. As it passes, it moves superiorly and laterally, supplying several branches to the anterior abdominal wall and greater omentum. Eventually, at the area of the sacroiliac joints, the ureters cross the pelvic brim, thus entering the pelvic cavity. At this point, they also cross the bifurcation of the common iliac arteries.
Once within the pelvic cavity, the ureters travel down the lateral pelvic walls. At the level of the ischial spines, they turn anteromedially, moving in a transverse plane towards the bladder. Upon reaching the bladder wall, the ureters pierce its lateral aspect in an oblique manner. This creates a one way valve, where high intramural pressure collapses the ureters – preventing the back-flow of urine.
The ureters are a structure that has developed via the ureteric bud from the mesonephric duct, and then followed the kidney during its ascend to the final lumbar position in the retroperitoneum. This long, ascending course has enabled the ureter to acquire vessels (arteries, veins, and lymph vessels) of different origin during its route. The arterial supply to the ureters can be divided into abdominal and pelvic supply - abdominal, which includes vessels from the renal artery, testicular/ovarian artery, and ureteral branches directly from the abdominal aorta, and pelvic, which includes vessels from the superior and inferior vesical arteries. Venous drainage is carried out by vessels that correspond to the aforementioned arteries. Nervous supply to the ureters is delivered via the renal, testicular/ovarian, and hypogastric plexuses. Sensory fibres from the ureters enter the spinal cord at T11-L2, with ureteric pain referred to those dermatomal areas.
The anatomical course of the ureters is of surgical importance, as they travel close to other structures in the pelvis. They must be identified during pelvic surgery to ensure that they are not accidentally damaged. In females, as they cross the pelvic brim, the ureters are in close proximity to the ovaries. Care must be taken not the damage the ureters during an oophorectomy, especially during the ligation of the ovarian arteries. Approximately 2cm superior to the ischial spine, the ureters run underneath the uterine artery. During a hysterectomy, where the uterus and uterine artery are removed, the ureter is in danger of being accidentally damaged. - a phrase that can be remembered using the phrase ‘water under the bridge’. In men, instead of the uterine arteries, the vas deferens cross the ureters anteriorly.
A ureteric calculus (or kidney stone) is the presence of a solid stone in the urinary tract, formed from minerals within the urine. A ureteric calculus is much more likely to form when the ureters have difficulty emptying the renal pelvis due to blockage or narrowing. This blockage can occur either within the ureters or the bladder, preventing urine from passing through and causing it to back up into the renal pelvis. This can increase the concentration of minerals within the urine, causing them to crystalize and form a calculus.
The presence of a ureteric calculus can cause painful sensations as it is passed through the ureters and bladder. It can also lead to obstruction of the urinary tract, causing infection or hydronephrosis, and subsequently, kidney failure. The treatment of a ureteric calculus is simply to pass it out through the flow of urine, or to surgically remove it. This can involve the use of lithotripsy, a procedure using shock waves to break up the stones, or the use of a ureteroscope, to directly locate the calculus and remove it.
In conclusion, the ureters have a complex anatomy, closely related to several other structures in the abdomen and pelvis. It is important to recognize these anatomical relationships, as the ureters must be identified during certain surgical procedures to ensure they are not accidentally damaged. Additionally, the ureters can suffer from pathological conditions, such as the formation of a ureteric calculus, which should be treated appropriately.
The point at which the renal pelvis narrows to form the ureter is known as the ureteropelvic junction. After arising from the ureteropelvic junction, the ureters descend through the abdomen, along the anterior surface of the psoas major, and are located as a retroperitoneal structure behind the peritoneum. At the area of the sacroiliac joints, the ureters cross the pelvic brim, thus entering the pelvic cavity, and also passing the bifurcation of the common iliac arteries.
Once within the pelvic cavity, the ureters travel down the lateral pelvic walls. At the level of the ischial spines, they turn anteromedially in a transverse plane towards the bladder, eventually piercing its lateral aspect in an oblique manner. This creates a one way valve, where high intramural pressure collapses the ureters, thus preventing the back-flow of urine.
The anatomical course of the ureters is of great importance in surgery, as they travel closely to other structures in the pelvis and must be identified to ensure that they are not accidentally damaged. In the female, as they cross the pelvic brim, the ureters are in close proximity to the ovaries and must be taken into account during an oophorectomy, particularly for the ligation of the ovarian arteries. Approximately 2cm superior to the ischial spine, the ureters run underneath the uterine artery, and during a hysterectomy, where the uterus and the uterine artery are removed, the ureters are in danger of being accidentally damaged. The relationship between the two can be remembered using the phrase 'water under the bridge'. In men, instead of the uterine arteries, the vas deferens cross the ureters anteriorly.
Ureters are hollow tubes, which are around 20-25cms in length, running from the kidneys to the bladder. They are divided into two distinct parts; an abdominal part and a pelvic part, which is wider and more dilated. The diameter of the ureter is between 0.5-1cm on its abdominal part, narrowing to around 0.2-0.25cm on the pelvic part.
The ureters are supplied by two sets of vessels; one is the vascular set, which is supplied by renal and gonadal arteries, and the other is the neural set, which supplies the ureters with both sympathetic and parasympathetic nerves.
Ureteric calculi, also known as kidney stones, are solid stones which form in the urinary tract from minerals found in the urine. These can obstruct urinary flow, causing renal colic (an acute and severe loin pain) and haematuria (blood in the urine). Ureteric calculi typically become stuck in three locations- the uretopelvic junction, the pelvic brim, and where the ureter enters the bladder. The gold standard investigation for suspected ureteric calculi is a CT scan of the kidneys, ureters, and bladder (CT-KUB).
In the female, the relationship between the ureter and the uterine artery can be variable, but usually occurs on the left side of the uterus. In the male, the vas deferens is related to the upper part of the ureter.
The ureter is a structure that has developed via the ureteric bud from the mesonephric duct, before following the kidney during its ascend to the final lumbar position in the retroperitoneum. This long, ascending course has enabled the ureter to acquire vessels (arteries, veins, and lymph vessels) of different origin during its route. The arterial supply to the ureters can be divided into abdominal and pelvic supply-
Venous drainage is carried out by vessels which correspond to the aforementioned arteries. Nervous supply to the ureters is delivered via the renal, testicular/ovarian and hypogastric plexuses. Sensory fibres from the ureters enter the spinal cord at T11-L2, with ureteric pain referred to those dermatomal areas.
