Urinary tract obstruction

[Tracie Lynn]

Urinary tract obstruction is a blockage that inhibits the flow of urine through its normal path (the urinary tract), including the kidneys, ureters, bladder, and urethra.

Blockage can be complete or partial.
Blockage can lead to kidney damage, kidney stones, and infection.
Symptoms can include pain in the side, decreased or increased urine flow, and urinating at night.
Symptoms are more common if the blockage is sudden and complete.
Testing can include insertion of a urethral catheter, insertion of a viewing tube into the urethra, and imaging tests.
Treatment can include measures to open up a blocked path and to treat the cause of the blockage.

A blockage (obstruction) anywhere along the urinary tract—from the kidneys, where urine is produced, to the urethra, through which urine leaves the body—can increase pressure inside the urinary tract and slow the flow of urine. An obstruction may occur suddenly or develop slowly over days, weeks, or even months. An obstruction may completely or only partially block part of the urinary tract. Sometimes only one kidney is affected, but obstruction may affect both kidneys.
The prevalence of urinary tract obstruction ranges from five in 10,000 to five in 1,000 depending on the cause. In children, obstruction is due mainly to birth defects affecting the urinary tract. Men, particularly those older than 60, are also more likely to be affected because, as men age, the prostate gland tends to increase in size (a condition called benign prostatic hyperplasia) and block the flow of urine.
Normally, urine flows out of the kidneys at extremely low pressure. If the flow of urine is obstructed, urine backs up behind the point of blockage, eventually reaching the small tubes of the kidney and its collecting area (renal pelvis), swelling (distending) the kidney and increasing the pressure on its internal structures. Such kidney distention is called hydronephrosis. The elevated pressure due to the obstruction may ultimately damage the kidney and can result in loss of its function. When the flow of urine is obstructed, stones (calculi) are more likely to form. An infection may develop when the flow of urine is obstructed because bacteria that enter the urinary tract are not flushed out. If both kidneys are obstructed, kidney failure may result.
Long-standing distention of the renal pelvis and ureter can also inhibit the rhythmic muscular contractions that normally move urine down the ureter from the kidney to the bladder (peristalsis). Scar tissue may then replace the normal muscular tissue in the walls of the ureter, resulting in permanent damage.
Partial and complete obstruction tend to cause similar problems, but most problems, and particularly kidney damage, are more severe when obstruction is complete.