The ureter is a muscular tube that acts as a conduit in the body’s waste disposal system. It is part of the larger urinary system, which functions to filter blood and remove liquid waste. The ureter transports urine from the kidney, where it is produced, down to the bladder, where it is stored before elimination.
The Ureter’s Structure and Role
The ureter is a slender tube, typically measuring between 10 to 12 inches (25 to 30 centimeters) in length in an adult. Its walls are composed of three distinct layers, including a middle layer of smooth muscle fibers. These muscular walls actively propel urine toward the bladder, rather than simply relying on gravity.
This urine movement is achieved through a process called peristalsis, which involves rhythmic, wave-like contractions of the smooth muscle. These contractions begin in the renal pelvis and push small, concentrated volumes of urine, or boluses, down the tube. This active transport mechanism ensures that urine flows in one direction, regardless of body position.
A specialized junction exists where the ureter connects to the bladder, known as the ureterovesical junction. Here, the ureter passes through the bladder wall at an oblique angle, creating a flap-like valve. This structural arrangement prevents the backflow of urine from the bladder back up toward the kidneys, guarding against urinary tract infections and potential kidney damage.
Common Issues Affecting the Ureter
The most frequent issue affecting the ureter is the passage of a kidney stone, a condition known as ureterolithiasis. These stones are hard deposits of minerals and salts that form in the kidney and then travel into the ureter, often getting stuck in the narrow passageway. When a stone attempts to pass, it triggers intense, wave-like pain, medically termed renal colic, as the ureter’s muscles spasm in an attempt to push the obstruction along.
The pain is typically described as severe and sharp, originating in the flank or back, just below the ribs. As the stone moves down the ureter toward the bladder, this pain often radiates downward to the lower abdomen and groin area. The obstruction caused by the stone can block urine flow, leading to a backup of fluid that causes the kidney to swell.
This blockage and the irritation to the ureteral lining commonly lead to other symptoms, including nausea, vomiting, and hematuria (the presence of blood in the urine). The pain often comes in waves, corresponding to the peristaltic contractions of the ureter trying to expel the stone. Once the stone nears the bladder, it may cause a frequent or urgent need to urinate, often accompanied by a burning sensation.
Other conditions can also compromise the ureter’s function, such as a ureteral stricture, which is an abnormal narrowing of the tube. Strictures are usually caused by internal scarring from previous kidney stone passage, surgical injury, or radiation therapy. This narrowing impedes urine flow, causing urine to back up and potentially leading to a dull ache in the flank and recurrent urinary tract infections.
How Doctors Investigate Ureter Health
Doctors rely on several techniques to visualize the ureter and diagnose issues like blockages or strictures. The computed tomography (CT) urogram is a specialized CT scan. This procedure involves injecting an iodine-based contrast material into a vein, which then travels through the kidneys and into the ureters.
The contrast material highlights the entire urinary tract, allowing doctors to see the size, shape, and structure of the ureters in detail. This imaging method is effective for identifying the precise location and size of kidney stones or any abnormal narrowing. Ultrasound is another common imaging technique, often used as a quick, non-radiation option to check for fluid backup, or hydronephrosis, which indicates an obstruction in the ureter.
For a closer look, a procedure called ureteroscopy may be performed. This involves inserting a thin, flexible instrument called a ureteroscope directly into the ureter through the bladder. This allows the physician to visually inspect the interior lining of the tube. The visualization aspect provides direct, detailed information about the cause of a blockage, such as a stone or scar tissue.