Urinary incontinence (enuresis) is the term for any involuntary leakage of urine as the person is unable to prevent the flow of urine out of the bladder. It is often referred to simply as poor bladder control but urinary incontinence often involves other structures of the genitourinary system as well.
Incontinence in Children and Elderly
Incontinence in infants and toddlers as well as the elderly are a fairly common phenomenon.
Primary enuresis is the type of incontinence where a child has not as yet developed bladder control. Diurnal enuresis (daytime incontinence) should not be present in a child over the age of 5 years since most children develop bladder control (continence) when awake by this age. However, nighttime continence takes longer to develop. In a child younger than 6 years, nocturnal enuresis may not be considered as a problem unless it has suddenly started up in a child who has previously had good bladder control (secondary enuresis).
In the elderly, age related changes in the urinary system can hamper bladder control and wetting may occur when sleeping or while awake without the person realizing that they have soiled themselves. Incontinence in the elderly (secondary enuresis) is more common in women and may be related to pelvic floor weakness caused by childbirth (postpartum) . Incontinence in elderly men is often related to benign prostatic hyperplasia (enlarged prostate). Age related incontinence is not the norm and if it develops later in life, the cause should be investigated and appropriate treatment instituted. Incontinence in the elderly may be acute and transient and could pass with time and treatment.
Incontinence in preteens, teens and adults should always be investigated as it may be a sign of some underlying pathology. An overactive bladder (weak bladder) may lead to enuresis on some occasions in these age groups. Medication like diuretics that increase urination may aggravate a case of incontinence but are usually not the cause of poor bladder control.
Bladder Control for Passing Urine
Urine is stored in the bladder, a hollow muscular organ that receives urine from the kidneys via two ureters (one on either side). The muscles of the bladder wall are relaxed to allow urine to collect within it and the internal and external sphincter muscles ensure that urine from the bladder does not empty into the ureter. These sphincter muscles remain contracted. When a person wants to voluntarily pass out urine (voiding), nerve signals cause the bladder muscles to contract thereby increasing the pressure and expelling the urine from the bladder. The sphincter muscles also relax to allow the urine to flow out into the ureter where it is then expelled into the environment.
There are two stages in the micturition cycle :
- Storage where the bladder fills with urine. The detrusor muscle (bladder wall muscle) is relaxed during this stage and the sphincters remain contracted to prevent the passing of urine.
- Voiding where urine is voluntarily passed out of the bladder, through the urethra and into the environment. During this stage the detrusor muscle contracts and increased pressure within the bladder while the sphincter muscles relax and allow urine to flow out.
Nerve supply to the bladder is as follows :
- Sympathetic stimulation (T10 to T12) causes relaxation of the detrusor muscle and contraction of the sphincter (closing).
- Parasympathetic stimulation (S2 to S4) causes contraction of the detrusor muscle and relaxation of the sphincter (opening).