The job of the urinary system is to eliminate waste from the body. The normal urinary system consists of two kidneys, with a tube (ureter) connecting each kidney to the bladder and another tube (urethra) that drains urine from the bladder out of the body. A ureteral obstruction is a blockage that occurs anywhere in this system.
Certain conditions may make you more prone to a ureteral obstruction including conditions present from birth (congenital), a tendency to make kidney stones or recent cancer surgery.
Duplication of the ureter. This common congenital condition causes two ureters to form on the same kidney. The second ureter can be either completely or partially developed. If either of these ureters does not function properly, urine can back up into the kidney and cause damage.
Ureteropelvic junction. This abnormality is a blockage in the connection between the kidney and ureter that stops urine flow and causes the kidney to swell and eventually stop working. This abnormality can be congenital, can develop with normal childhood growth, can result from an injury or scarring, or in rare cases, can develop from a tumor. It is more common among boys. Symptoms of this abnormality can vary from mild to severe so frequent monitoring by your doctor is recommended.
Ureterovesical junction. In this condition, the blockage occurs between the ureter and the bladder, causing urine to back up into the kidneys.
Ureterocele. When the ureter is too narrow and does not allow urine to flow normally, a tiny hernia (ureterocele) will develop, usually in the section of the ureter closest to the bladder. This hernia blocks urine flow, causing urine to back up into the kidney, which can damage the kidney.
Retrocaval ureter. In this rare condition (also known as circumcaval ureter or postcaval ureter), the ureter twists abnormally and can block the urine flow from the kidney to the bladder.
Intrinsic or extrinsic ureteral obstruction. This condition refers to a blocked ureter by various causes including:
Retroperitoneal fibrosis. This rare disorder (also called Ormond disease, retroperitoneal fasciitis or chronic retroperitoneal fibroplasias) occurs when fibrous tissue grows in the area behind the abdomen. The fibers may grow due to cancers or may result from taking certain medicines used to treat migraines. The fibers encircle and block the ureters, causing urine to back up into the kidneys.