C h a p t e r 2 7
Disorders of the Bladder and Lower Urinary Tract
665
the absence of urinary tract infection or other obvious
pathology.”
25
The symptoms of urge incontinence, which are
caused by involuntary bladder contractions dur-
ing filling, may occur alone or in any combination.
They constitute overactive bladder when they occur
in the absence of other pathologic processes.
8,19,26–28
Regardless of the primary cause of overactive bladder,
two types of mechanisms are thought to contribute to
its symptomatology: those involving CNS and neural
control of bladder sensation and emptying (neuro-
genic) and those involving the smooth muscle of the
bladder itself (myogenic).
8,26,27
The
neurogenic
theory for overactive bladder pro-
poses that the CNS functions as an on–off switch-
ing circuit for voluntary control of bladder function.
Neurogenic causes of overactive bladder include stroke,
Parkinson disease, and multiple sclerosis. Other neuro-
genic causes of overactive bladder include increased sen-
sitization of the afferent nerves that sense bladder filling
or increased excitability to efferent nerves that produce
bladder emptying.
The
myogenic
causes of overactive bladder are
thought to result from changes in the properties of
the smooth muscle of the bladder itself. Bladder outlet
obstruction can prompt such changes. It is hypothe-
sized that the sustained increase in intravesical pressure
that occurs with the outlet obstruction causes a partial
destruction of the nerve endings that control bladder
excitability.
7
This partial denervation produces hyper-
excitability of the detrusor muscle, causing urgency
and frequency of urination due to spontaneous bladder
contractions. Disorders of detrusor muscle structure
and excitability also can occur as the result of the aging
process or disease conditions such as diabetes melli-
tus. Incomplete bladder emptying, a common accom-
paniment of overactive bladder, often exacerbates
symptoms.
Overflow Incontinence.
Overflow incontinence is an
involuntary loss of urine that occurs when intravesical
pressure exceeds the maximal urethral pressure because
of bladder distention in the absence of detrusor activ-
ity.
8
It can occur with retention of urine owing to ner-
vous system lesions or obstruction of the bladder neck
or urethral stricture. Outflow obstruction may occur
secondary to cystocele, uterine prolapse, or previous
incontinence surgery in women. In men, one of the most
common causes of obstructive incontinence is enlarge-
ment of the prostate gland. Person with this type of
incontinence may experience dribbling, weak urinary
stream, hesitancy, frequency, and nocturia.
Other Causes of Incontinence.
Other causes of
incontinence include decreased bladder compliance or
distensibility. This abnormal bladder condition may
result from radiation therapy, radical pelvic surgery,
or interstitial cystitis. Many persons with this disor-
der have severe urgency related to bladder hypersen-
sitivity that results in loss of bladder elasticity, such
that any small increase in bladder volume or detrusor
function causes a sharp rise in bladder pressure and
severe urgency.
Incontinence may occur as a transient and correct-
able phenomenon, or it may not be totally correct-
able and may occur with various degrees of frequency.
Incontinence may also present as nocturnal enuresis with
involuntary loss of urine during sleep, as post-micturi-
tion dribble, or continuous urine leakage.
18
Among the
transient causes of urinary incontinence are recurrent
urinary tract infections; medications that alter bladder
function or perception of bladder filling and the need
to urinate; diuretics and conditions that increase blad-
der filling; restricted mobility; and a state of confusion.
Night sedation may cause someone to sleep through the
signal that normally would waken them so they could
get up and empty their bladder and avoid wetting the
bed. Incontinence also may be caused by factors outside
the lower urinary tract, such as the inability to locate,
reach, or receive assistance in reaching an appropriate
place to void.
Diagnosis andTreatment
Urinary incontinence is not a single disease but a symp-
tom with many possible causes. As a symptom, it requires
full investigation to establish its cause.
20–24,27
This usually
is accomplished through a careful history, physical exam-
ination, blood tests, and urinalysis. A voiding record (i.e.,
diary) may be used to determine the frequency, timing,
and amount of voiding, as well as other factors associated
with the incontinence. Because many drugs affect blad-
der function, a full drug history is essential. Estimation
of the PVR volume is recommended for all persons with
incontinence.
Treatment or management depends on the type of
incontinence, accompanying health problems, and the
person’s age. It includes behavioral methods; exercises
to strengthen the pelvic floor muscles; pharmacologic
measures; surgical interventions; and, when urine flow
cannot be controlled, noncatheter devices to obstruct
urine flow or collect urine as it is passed.
28,29
Indwelling
catheters, although a solution to the problem of urinary
incontinence, usually are considered only after all other
treatment methods have failed. In some types of incon-
tinence, such as that associated with spinal cord injury
or meningomyelocele, self-catheterization may provide
the best means for controlling urine elimination (see
Chapter 36).
Behavioral methods include fluid management,
timed/prompted voiding, bladder retraining, and toi-
leting assistance. Bladder retraining and biofeedback
techniques seek to reestablish cortical control over blad-
der function by having the person ignore urgency and
respond only to cortical signals during waking hours.
Exercises of the pelvic muscles or Kegel exercises involve
repetitive contraction and relaxation of the pelvic floor
muscles and are an essential component of patient-
dependent behavioral interventions.
19
Pharmacologic treatment is aimed at using drugs
to alter the physiologic mechanisms that contribute
to the neurogenic or myogenic causes of incontinence
