The bladder, an important organ in the urinary system, stores urine produced in the kidneys and then voids it from the body. The bladder accomplishes this through complex interactions between the bladder muscle, the sphincter muscle between the bladder and urethra and the nerves throughout the bladder wall. Interference with these interactions can lead to incontinence, the involuntary leakage of urine. Overflow incontinence describes a condition in which small amounts of urine leak from the bladder when the bladder overfills due to incomplete voiding.
Enlarged Prostate
The male prostate, a gland that aids in reproduction, sits at the base of the penis below the bladder and surrounds the urethra. The prostate produces fluids for semen and enhances sexual pleasure and arousal. As men age, the prostate enlarges, a condition known as benign prostate hyperplasia. The National Kidney and Urologic Diseases Information Clearinghouse reports that more than half of men in their 60s and at least 90 percent of men in their 70s and 80s suffer from benign prostate hyperplasia.
As the prostate enlarges, it presses against the urethra, restricting the flow of urine from the bladder. When the bladder cannot release urine, it stops contracting, which causes it to become overfilled. The pressure from the increased urine volume leads to overflow incontinence.
Constipation
Both men and women can suffer from overflow incontinence caused by constipation. Constipation, defined by the National Digestive Diseases Information Clearinghouse as the occurrence of a bowel movement less than three times a week, causes unusually hard, dry stools that become difficult to eliminate. As stool fills up the rectum area, it can press against the bladder and/or urethra. The pressure on the urethra or bladder opening can restrict the flow of urine and cause overflow incontinence.
Medications
When the bladder becomes full, nerves in the bladder wall send messages to the brain, which responds by telling the bladder muscle to contract and the sphincter muscle to relax in order to push the urine out. Certain prescription medications can affect the ability of the bladder to contract. Anticholinergic medications describe a group of drugs that inhibit the action of acetylcholine---a neurotransmitter that helps send signals between nerves and muscles.
When acetylcholine binds to receptors on muscle cells, it triggers the muscle to contract. Anticholinergic medications, which include drugs classified as antidepressants, antipsychotics and antihistamines, block acetylcholine from binding, therefore relaxing the muscle. When anticholinergic drugs act on the bladder muscle, the bladder fails to contract and fails to release the urine. As the bladder overfills, overflow incontinence can occur.
Nerve Damage
Damage to the nerves within the bladder wall can interfere with the signaling to and from the brain. When the bladder fails to receive the signals to release the urine, the bladder overfills. Nerve damage can occur due to trauma, injury to the spinal cord or diabetes---a disease caused by a chronic high level of glucose in the blood.
