Underactive Bladder Syndrome (UAB) describes symptoms of difficulty with bladder emptying, such as hesitancy to start the stream, a poor or intermittent stream, or sensations of incomplete bladder emptying. The physical finding of detrusor pressurization of insufficient strength or duration to ensure timely and efficient bladder emptying is properly termed "detrusor underactivity" (DU) (Abrams et al., 2002). Historically, UAB and DU (as well as others such as 'bladder underactivity') have been often used interchangeably (Rigby D, 2005), leading to both terminologic and pathophysiologic confusion.

Patients with UAB have a diminished sense of bladder filling and consequently are often found to have DU as an underlying finding, however bladder outlet obstruction and less frequently volume hypersensitivity ("OAB") can be associated with UAB symptoms (Chapple et al., 2015).

Overactive bladder is characterized by a group of four symptoms: urgency, urinary frequency, nocturia, and urge incontinence. Urge incontinence is not present in the "dry" classification.

Urgency is considered the hallmark symptom of OAB, but there are no clear criteria for what constitutes urgency and studies often use other criteria. Urgency is currently defined by the International Continence Society (ICS), as of 2002, as "Sudden, compelling desire to pass urine that is difficult to defer." The previous definition was "Strong desire to void accompanied by fear of leakage or pain." The definition does not address the immediacy of the urge to void and has been criticized as subjective.

Urinary frequency is considered abnormal if the person urinates more than eight times in a day. This frequency is usually monitored by having the patient keep a voiding diary where they record urination episodes. The number of episodes varies depending on sleep, fluid intake, medications, and up to seven is considered normal if consistent with the other factors.

Nocturia is a symptom where the person complains of interrupted sleep because of an urge to void and, like the urinary frequency component, is affected by similar lifestyle and medical factors. Individual waking events are not considered abnormal, one study in Finland established two or more voids per night as affecting quality of life.

Urge incontinence is a form of urinary incontinence characterized by the involuntary loss of urine occurring for no apparent reason while feeling urinary urgency as discussed above. Like frequency, the person can track incontinence in a diary to assist with diagnosis and management of symptoms. Urge incontinence can also be measured with pad tests, and these are often used for research purposes. Some people with urge incontinence also have stress incontinence and this can complicate clinical studies.

It is important that the clinician and the patient both reach a consensus on the term, 'urgency.' Some common phrases used to describe OAB include, 'When I've got to go, I've got to go,' or 'When I have to go, I have to rush, because I think I will wet myself.' Hence the term, 'fear of leakage,' is an important concept to patients.

There is no standardized evaluation of the symptoms of UAB, in part due to the historic terminologic confusion. A thorough history aimed at detecting underlying disease or prior pelvic surgeries is certainly necessary. As a perception of volume mishandling, a voiding diary (to assess voided volumes and frequency of voiding) and a post-void residual volume would be valuable information. Uninstrumented uroflow, neurologic and pelvic examination may contribute valuable information. Imaging looking for abnormal bladder morphology or vesicoureteral reflux/hydronephrosis may be helpful. If low-pressure urine storage can be assured, and the urinary reservoir is known to be limited to the bladder, the general value of urodynamic study in UAB is unclear. In specific situations, invasive urodynamics may be helpful to distinguish bladder outlet obstruction from DU, although this distinction can be difficult.

Overactive bladder (OAB) is a condition where there is a frequent feeling of needing to urinate to a degree that it negatively affects a person's life. The frequent need to urinate may occur during the day, at night, or both. If there is loss of bladder control then it is known as urge incontinence. More than 40% of people with overactive bladder have incontinence. About 40% to 70% of urinary incontinence is due to overactive bladder, It is not life-threatening. Most people with the condition have problems for years.

The cause of overactive bladder is unknown. Risk factors include obesity, caffeine, and constipation. Poorly controlled diabetes, poor functional mobility, and chronic pelvic pain may worsen the symptoms. People often have the symptoms for a long time before seeking treatment and the condition is sometimes identified by caregivers. Diagnosis is based on a person's signs and symptoms and requires other problems such as urinary tract infections or neurological conditions to be excluded. The amount of urine passed during each urination is relatively small. Pain while urinating suggests that there is a problem other than overactive bladder.

Specific treatment is not always required. If treatment is desired pelvic floor exercises, bladder training, and other behavioral methods are initially recommended. Weight loss in those who are overweight, decreasing caffeine consumption, and drinking moderate fluids, can also have benefits. Medications, typically of the anti-muscarinic type, are only recommended if other measures are not effective. They are no more effective than behavioral methods; however, they are associated with side effects, particularly in older people. Some non-invasive electrical stimulation methods appear effective while they are in use. Injections of botulinum toxin into the bladder is another option. Urinary catheters or surgery are generally not recommended. A diary to track problems can help determine whether treatments are working.

Overactive bladder is estimated to occur in 7-27% of men and 9-43% of women. It becomes more common with age. Some studies suggest that the condition is more common in women, especially when associated with loss of bladder control. Economic costs of overactive bladder were estimated in the United States at 12.6 billion USD and 4.2 billion Euro in 2000.

The pathophysiology of the condition results from neuronal plasticity associated with bladder afferents and motor neurons innervating the external urethral sphincter. People with this condition generally experience daytime and night time wetting, urinary retention, and often have a history of urinary tract and bladder infections. Constipation and encopresis are often associated with this condition.

Overflow incontinence is a form of urinary incontinence, characterized by the involuntary release of urine from an overfull urinary bladder, often in the absence of any urge to urinate. This condition occurs in people who have a blockage of the bladder outlet (benign prostatic hyperplasia, prostate cancer, or narrowing of the urethra), or when the muscle that expels urine from the bladder is too weak to empty the bladder normally. Overflow incontinence may also be a side effect of certain medications.

Overflow incontinence occurs when the patient's bladder is always full so that it frequently leaks urine. Weak bladder muscles, resulting in incomplete emptying of the bladder, or a blocked urethra can cause this type of incontinence. Autonomic neuropathy from diabetes or other diseases (e.g. Multiple sclerosis) can decrease neural signals from the bladder (allowing for overfilling) and may also decrease the expulsion of urine by the detrusor muscle (allowing for urinary retention). Additionally, tumors and kidney stones can block the urethra. Spinal cord injuries or nervous system disorders are additional causes of overflow incontinence. In men, benign prostatic hyperplasia (BPH) may also restrict the flow of urine. Overflow incontinence is rare in women, although sometimes it is caused by fibroid or ovarian tumors. Also overflow incontinence can be from increased outlet resistance from advanced vaginal prolapse causing a "kink" in the urethra or after an anti-incontinence procedure which has overcorrected the problem. Early symptoms include a hesitant or slow stream of urine during voluntary urination. Anticholinergic medications may worsen overflow incontinence. NSAIDs medications may worsen overflow incontinence.

Most children with vesicoureteral reflux are asymptomatic. Vesicoureteral reflux may be diagnosed as a result of further evaluation of dilation of the kidney or ureters draining urine from the kidney while in utero as well as when a sibling has VUR (though routine testing in either circumstance is controversial). Reflux also increases risk of acute bladder and kidney infections, so testing for reflux may be performed after a child has one or more infections.

In infants, the signs and symptoms of a urinary tract infection may include only fever and lethargy, with poor appetite and sometimes foul-smelling urine, while older children typically present with discomfort or pain with urination and frequent urination.

Neurogenic bladder dysfunction, sometimes simply referred to as neurogenic bladder, is a of the urinary bladder due to disease of the central nervous system or peripheral nerves involved in the control of micturition (urination). Neurogenic bladder usually causes difficulty or full inability to pass urine without use of a catheter or other method.

Vesicoureteral reflux (VUR), also known as vesicoureteric reflux, is a condition in which urine flows retrograde, or backward, from the bladder into the ureters/kidneys. Urine normally travels in one direction (forward, or anterograde) from the kidneys to the bladder via the ureters, with a 1-way valve at the vesicoureteral (ureteral-bladder) junction preventing backflow. The valve is formed by oblique tunneling of the distal ureter through the wall of the bladder, creating a short length of ureter (1–2 cm) that can be compressed as the bladder fills. Reflux occurs if the ureter enters the bladder without sufficient tunneling, i.e., too "end-on".

It is the loss of small amounts of urine associated with coughing, laughing, sneezing, exercising or other movements that increase intra-abdominal pressure and thus increase pressure on the bladder. The urethra is supported by fascia of the pelvic floor. If this support is insufficient, the urethra can move downward at times of increased abdominal pressure, allowing urine to pass.

Most lab results such as urine analysis, cystometry and postvoid residual volume are normal.

Some sources distinguish between urethral hypermobility and intrinsic sphincter deficiency. The latter is more rare, and requires different surgical approaches.

Urinary tract obstruction is a urologic disease consisting of a decrease in the free passage of urine through one or both ureters and/or the urethra. It is a cause of urinary retention.

Bladder sphincter dyssynergia (also known as detrusor sphincter dysynergia (DSD) (the ICS standard terminology agreed 1998) and neurogenic detrusor overactivity (NDO)) is a consequence of a neurological pathology such as spinal injury or multiple sclerosis. which disrupts central nervous system regulation of the micturition (urination) reflex resulting in dyscoordination of the detrusor muscles of the bladder and the male or female external urethral sphincter muscles. In normal lower urinary tract function, these two separate muscle structures act in synergistic coordination. But in this neurogenic disorder, the urethral sphincter muscle, instead of relaxing completely during voiding, dyssynergically contracts causing the flow to be interrupted and the bladder pressure to rise.

Causes of urinary tract obstruction include:

- Bladder stone and renal stone

- Benign prostatic hyperplasia

- Obstruction as a congenital disorder.

Urinary incontinence (UI), also known as involuntary urination, is any leakage of urine. It is a common and distressing problem, which may have a large impact on quality of life. It is twice as common in women as in men. Pelvic surgery, pregnancy, childbirth, and menopause are major risk factors. It has been identified as an important issue in geriatric health care. Urinary incontinence is often a result of an underlying medical condition but is under-reported to medical practitioners. Enuresis is often used to refer to urinary incontinence primarily in children, such as nocturnal enuresis (bed wetting).

There are four main types of incontinence:

- Urge incontinence due to an overactive bladder

- Stress incontinence due to poor closure of the bladder

- Overflow incontinence due to either poor bladder contraction or blockage of the urethra

- Functional incontinence due to medications or health problems making it difficult to reach the bathroom

Treatments include surgery, pelvic floor muscle training, bladder training, and electrical stimulation. The benefit of medications is small and long term safety is unclear.

Any condition that impairs bladder and bladder outlet afferent and efferent signaling can cause neurogenic bladder.

It is often associated with spinal cord diseases (such as syringomyelia/hydromyelia), injuries (like herniated disks), and neural tube defects including spina bifida.

It may also be caused by brain tumors and other diseases of the brain, pregnancy and by peripheral nerve diseases such as: Diabetes, Alcoholism (and Vitamin B12 deficiency).

It is a common complication of major surgery in the pelvis, such as for removal of sacrococcygeal teratoma and other tumors.

Stress incontinence, also known as stress urinary incontinence (SUI) or effort incontinence is a form of urinary incontinence. It is due to insufficient strength of the closure of the bladder.

Bladder rupture (rupture of bladder, ) may occur if the bladder is overfilled and not emptied. This can occur in the case of binge drinkers who have consumed large quantities of fluids, but are not conscious of the need to urinate due to stupor. This condition is very rare in women, but does occur. Signs and symptoms include localized pain and uraemia (poisoning due to reabsorbed waste).

The most common symptoms of IC/BPS are suprapubic pain, urinary frequency, painful sexual intercourse, and waking up from sleep to urinate.

In general, symptoms may include painful urination described as a burning sensation in the urethra during urination, pelvic pain that is worsened with the consumption of certain foods or drinks, urinary urgency, and pressure in the bladder or pelvis. Other frequently described symptoms are urinary hesitancy (needing to wait for the urinary stream to begin, often caused by pelvic floor dysfunction and tension), and discomfort and difficulty driving, working, exercising, or traveling. Pelvic pain experienced by those with IC typically worsens with filling of the urinary bladder and may improve with urination.

During cystoscopy, 5–10% of people with IC are found to have Hunner's ulcers. A person with IC may have discomfort only in the urethra, while another might struggle with pain in the entire pelvis. Interstitial cystitis symptoms usually fall into one of two patterns: significant suprapubic pain with little frequency or a lesser amount of suprapubic pain but with increased urinary frequency.

A prostatic stent is a stent used to keep open the male urethra and allow the passing of urine in cases of prostatic obstruction and lower urinary tract symptoms (LUTS). Prostatic obstruction is a common condition with a variety of causes. Benign prostatic hyperplasia (BPH) is the most common cause, but obstruction may also occur acutely after treatment for BPH such as transurethral needle ablation of the prostate (TUNA), transurethral resection of the prostate (TURP), transurethral microwave thermotherapy (TUMT), prostate cancer or after radiation therapy.

The symptoms of a cystocele may include:

- a vaginal bulge

- the feeling that something is falling out of the vagina

- the sensation of pelvic heaviness or fullness

- difficulty starting a urine stream

- a feeling of incomplete urination

- frequent or urgent urination

- fecal incontinence

- frequent urinary tract infections

A bladder that has dropped from its normal position and into the vagina can cause some forms of incontinence and incomplete emptying of the bladder.

Urinary bladder disease includes urinary bladder inflammation such as cystitis, bladder rupture and bladder obstruction (tamponade).

The signs and symptoms of hydronephrosis depend upon whether the obstruction is acute or chronic, partial or complete, unilateral or bilateral. Hydronephrosis that occurs acutely with sudden onset (as caused by a kidney stone) can cause intense pain in the flank area (between the hips and ribs). Historically, this type of pain has been described as "Dietl's crisis". Conversely, hydronephrosis that develops gradually will generally cause either attacks of a dull discomfort or no pain. Nausea and vomiting may also occur. An obstruction that occurs at the urethra or bladder outlet can cause pain and pressure resulting from distension of the bladder. Blocking the flow of urine will commonly result in urinary tract infections which can lead to the development of additional stones, fever, and blood or pus in the urine. If complete obstruction occurs, kidney failure may follow.

Blood tests may show impaired kidney function (elevated urea or creatinine) or electrolyte imbalances such as hyponatremia or hyperchloremic metabolic acidosis. Urinalysis may indicate an elevated pH due to the secondary destruction of nephrons within the affected kidney. Physical examination may detect a palpable abdominal or flank mass caused by the enlarged kidney.

The most common types of urinary incontinence in women are stress urinary incontinence and urge urinary incontinence. Women with both problems have mixed urinary incontinence. After menopause, estrogen production decreases and in some women urethral tissue will demonstrate atrophy with the tissue of the urethra becoming weaker and thinner. Stress urinary incontinence is caused by loss of support of the urethra which is usually a consequence of damage to pelvic support structures as a result of childbirth. It is characterized by leaking of small amounts of urine with activities which increase abdominal pressure such as coughing, sneezing and lifting. Additionally, frequent exercise in high-impact activities can cause athletic incontinence to develop. Urge urinary incontinence is caused by uninhibited contractions of the detrusor muscle . It is characterized by leaking of large amounts of urine in association with insufficient warning to get to the bathroom in time.

- Polyuria (excessive urine production) of which, in turn, the most frequent causes are: uncontrolled diabetes mellitus, primary polydipsia (excessive fluid drinking), central diabetes insipidus and nephrogenic diabetes insipidus. Polyuria generally causes urinary urgency and frequency, but doesn't necessarily lead to incontinence.

- Enlarged prostate is the most common cause of incontinence in men after the age of 40; sometimes prostate cancer may also be associated with urinary incontinence. Moreover, drugs or radiation used to treat prostate cancer can also cause incontinence.

- Disorders like multiple sclerosis, spina bifida, Parkinson's disease, strokes and spinal cord injury can all interfere with nerve function of the bladder.

- Urinary incontinence is a likely outcome following a radical prostatectomy procedure.

- About 33% of all women experience UI after giving birth; women who deliver vaginally are about twice as likely to have urinary incontinence as women who give birth via a Caesarean section.

A cystocele, also known as a prolapsed bladder, is a medical condition in which a woman's bladder bulges into her vagina. Some may have no symptoms. Other may have trouble starting urination, urinary incontinence, or frequent urination. Complications may include recurrent urinary tract infections and urinary retention. Cystocele and a prolapsed urethra often occur together and is called a cystourethrocele. Cycstocele can negatively affect quality of life.

Causes include childbirth, constipation, chronic cough, heavy lifting, hysterectomy, genetics, and being overweight. The underlying mechanism involves weakening of muscles and connective tissue between the bladder and vagina. Diagnosis is often based on symptoms and examination.

If the cystocele causes few symptoms, avoiding heavy lifting or straining may be all that is recommended. In those with more significant symptoms a vaginal pessary, pelvic muscle exercises, or surgery may be recommended. The type of surgery typically done is known as a colporrhaphy. The condition becomes more common with age. About a third of women over the age of 50 are affected to some degree.