Extrinsic Obstruction of the Ureter

The ureter is a thick-walled tube that transfers urine from the kidney to the bladder. It is approximately 10 inches long, with the upper half located in the abdomen and the lower half in the pelvic region. But what happens when the ureter becomes blocked? The information below should help you recognize this problem before it causes serious damage.

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What is extrinsic obstruction of the ureter?

Extrinsic obstruction of the ureter is a condition caused by organs and diseases that press against the ureter and cause a blockage within the ureter. The resulting blockage affects the flow of urine out of the ureter and can eventually cause urine to build up, which can injure the kidney.

Causes of extrinsic ureteral obstruction vary. Some of the causes are: 

• vascular disease
• benign conditions of the female reproductive system, such as pregnancy, mass lesions of the uterus or ovary, Gartner's duct cyst, endometriosis, uterine prolapse and intraoperative ureteral injury.

• diseases of the gastrointestinal tract, such as granulomatous disorders (Crohn's disease of the bowel), inflammatory disease of the appendix, diverticulitis and pancreatic lesions 

• diseases of the retroperitoneum

Frequently, the process is slow and causes no symptoms. However, if the obstruction is acute it will usually be accompanied by severe pain. Other symptoms may include fever, nausea, vomiting, difficulty urinating and bloody or cloudy urine.

Extrinsic obstruction of the ureter is a common urologic problem for which the diagnosis may be difficult to establish. However, imaging studies are essential in establishing the diagnosis. Such studies include intravenous urography (IVP), ultrasonography, CT scans and MRIs. These studies will often define the presence and location of the obstruction and may be able to establish the cause of the blockage. Appropriate laboratory studies include urinalysis and serum studies to assess the degree of kidney function.

Treatment is often dependent on the nature of the obstruction. Initial efforts are to obtain drainage of the kidney(s) that is followed by more definitive approaches to resolve the underlying disorder. Drainage of the kidney can be accomplished by one of two ways: placement of a ureteral stent — a narrow, hollow plastic tube that runs between the kidney and bladder and holds the ureter open to allow drainage of urine — or by a procedure called a nephrostomy in which a catheter is placed, guided by X-ray imaging or ultrasound imaging, through the skin into the kidney to drain urine.

The outcome varies. Any kidney damage caused by the obstruction can be permanent. However, if the cause of the obstruction can be diagnosed and treated early, the damage may be temporary. If only one kidney is affected, the other kidney usually continues to function adequately and kidney failure does not occur.

Risks may include stones and tumors in the surrounding areas.

Reviewed May, 2004

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Glossary Terms

abdomen:
	Also referred to as the belly. It is the part of the body that contains all of the internal structures between the chest and the pelvis.
acute:
	Acute often means urgent. An acute disease happens suddenly. It lasts a short time. Acute is the opposite of chronic, or long lasting.
benign:
	Not malignant; not cancerous.
bladder:
	The bladder is a thick muscular balloon-shaped pouch in which urine is stored before being discharged through the urethra.
bowel:
	Another word for intestines or colon.
catheter:
	A thin tube that is inserted through the urethra into the bladder to allow urine to drain or for performance of a procedure or test, such as insertion of a substance during a bladder X-ray.
CT scan:
	Also known as computerized tomography, computerized axial tomography or CT scan. A diagnostic imaging procedure that uses a combination of X-rays and computer technology to produce cross-sectional images of the body. Shows detailed images of any part of the body, including bones, muscles, fat and organs. CT scans are more detailed than general X-rays.
cyst:
	An abnormal sac containing gas, fluid or a semisolid material. Cysts may form in kidneys or other parts of the body.
diverticulitis:
	Inflammation of the diverticula along the wall of the colon.
endometriosis:
	Cells that normally grow inside the uterus grow outside the uterus instead.
gastrointestinal:
	Also referred to as GI. The stomach and the intestines.
gastrointestinal tract:
	The gastrointestinal tract starts from the mouth and proceeds to the esophagus, stomach, duodenum, small intestine, large intestine, rectum and anus.
granuloma:
	A small mass of healing tissue caused by chronic infection.
granulomatous:
	Characterized by a small mass of healing tissue caused by chronic infection.
inflammatory:
	Characterized or caused by swelling, redness, heat and/or pain produced in an area of the body as a result of irritation, injury or infection.
intraoperative ureteral injury:
	Injury to the ureter occurring during surgery.
intravenous:
	Also referred to as IV. Existing or occurring inside a vein.
intravenous urography:
	Also referred to as IVP, intravenous pyelogram or excretory urogram. An X-ray of the urinary tract. A dye is injected to make urine visible on the X-ray and show any blockage in the urinary tract.
ions:
	Electrically charged atoms.
IV:
	Also referred to as intravenous. Existing or occurring inside a vein.
IVP:
	Also referred to as intravenous pyelogram, intravenous urography or excretory urogram. An X-ray of the urinary tract. A dye is injected to make urine visible on the X-ray and show any blockage in the urinary tract.
kidney:
	One of two bean-shaped organs that filter wastes from the blood and discharge these waste products in urine. The kidneys are located on either side at the level of the 12th ribs toward the back. The kidneys send urine to the bladder through tubes called ureters.
lesion:
	A zone of tissue with impaired function as a result of damage by disease or wounding. Examples are scars, abscesses, tumors and ulcers.
MRI:
	Also referred to a magnetic resonance imaging. A diagnostic procedure that uses a combination of large magnets, radiofrequencies and a computer to produce detailed images of organs and structures within the body.
nephrostomy:
	A surgical incision into a kidney.
ostomy:
	A surgical procedure such as a colostomy or ileostomy, in which an artificial opening for excreting waste matter is created.
pancreatic lesions:
	Tissue of the pancreas that has impaired function as a result of damage by disease or injury.
pelvic:
	Relating to, involving or located in or near the pelvis.
peritoneum:
	Strong, smooth, colorless membrane that lines the walls of the abdomen and covers numerous body organs including the bladder.
retroperitoneum:
	Behind abdominal lining.
serum:
	Clear, watery body fluid.
stent:
	With regard to treating ureteral stones, a tube inserted through the urethra and bladder and into the ureter. Stents are used to aid treatment in various ways, such as preventing stone fragments from blocking the flow of urine.
stone:
	Small hard mass of mineral material formed in an organ.
tumor:
	An abnormal mass of tissue or growth of cells.
ultrasonography:
	A test in which sound waves are bounced off body tissue, and the echos are converted into a picture, for the purpose of medical examination or diagnosis, that are viewed on a monitor.
ultrasound:
	Also referred to as a sonogram. A technique that bounces painless sound waves off organs to create an image of their structure to detect abnormalities.
ureter:
	One of two tubes that carry urine from the kidneys to the bladder.
ureteral:
	Pertaining to the ureter. Also referred to as ureteric.
urinalysis:
	A test of a urine sample that can reveal many problems of the urinary system and other body systems. The sample may be observed for physical characteristics, chemistry, the presence of drugs or germs or other signs of disease.
urine:
	Liquid waste product filtered from the blood by the kidneys, stored in the bladder and expelled from the body through the urethra by the act of urinating (voiding). About 96 percent of which is water and the rest waste products.
uterine prolapse:
	The uretrus has slipped (dropped) from its normal position and the cervix is closer to or may protrude outside the vagina.
uterus:
	A hallow, muscular organ in the pelvis cavity of females in which the embryo is nourished and develops before birth.
vas:
	Also referred to as vas deferens. The cordlike structure that carries sperm from the testicle to the urethra.
vascular:
	Having to do with blood vessels.

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