Overactive bladder

OAB is a condition of frequent urging to urinate
If there is loss of bladder control then it is known as urge incontinence.
- More than 40% of people with overactive bladder have incontinence.
- Conversely, about 40% to 70% of urinary incontinence is due to overactive bladder.

Risk factors include obesity, caffeine, and constipation. Poorly controlled diabetes, poor functional mobility, and chronic pelvic pain may worsen the symptoms.

The amount of urine passed during each urination is relatively small.
Pain while urinating suggests that there is a problem other than overactive bladder.
Prevalence: 7–27% of men and 9–43% of women.

OAB is characterized by a group of four symptoms:

Urgency is the hallmark symptom of OAB. It is Sudden, compelling desire to pass urine that is difficult to ignore.
Urge incontinence is a form of urinary incontinence characterized by the involuntary loss of urine occurring for no apparent reason.
Like frequency, the person can track incontinence in a diary to assist with diagnosis and management of symptoms.
Some people with urge incontinence also have stress incontinence and this can complicate clinical studies.

Causation: Unknown.
It is often associated with Overactivity of the detrusor muscle
It is also possible that the increased contractile nature originates from within the urothelium and lamina propria, and abnormal contractions in this tissue could stimulate dysfunction in the detrusor or whole bladder.

Obviously storage phase of voiding is disturbed

During storage, bladder pressure stays low, because of the bladder's highly compliant nature.
The tension increases as bladder fills. Therefore, the pressure increase is slight until the organ is relatively full.
The bladder's smooth muscle has some inherent contractile activity; however, normally, stretch receptors in bladder wall initiate a reflex contraction that has a lower threshold than the inherent contractile response of the muscle.

Action potentials carried by sensory neurons from stretch receptors travel to the sacral segments of the spinal cord through the pelvic nerves. Since bladder wall stretch is low during the storage phase, these afferent neurons fire at low frequencies.
Low-frequency afferent signals cause relaxation of the bladder by inhibiting sacral parasympathetic preganglionic neurons and exciting lumbar sympathetic preganglionic neurons.
Conversely, afferent input causes contraction of the sphincter through excitation of Onuf's nucleus, and contraction of the bladder neck and urethra through excitation of the sympathetic preganglionic neurons.

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