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Deactivating an overactive bladder

Overactive bladder (OAB) syndrome is defined as urgency, usually with increased frequency and nocturia, which may occur with or without urgency incontinence. OAB symptoms are common, affect both men and women and increase with age. Between 10 and 20 per cent of people suffer from it at some stage in their lives. The severity of symptoms vary widely, from a minor inconvenience to a significant social and isolating problem preventing a person from leaving home. Initial assessment of patients attending with symptoms of OAB syndrome should include a full subjective history, urinalysis and frequency volume chart (Figure 1, page 32). 

History

The history will ask about the patient’s subjective assessment and severity of symptoms. The duration of symptoms is important, as are symptoms such as enuresis in childhood and throughout life may indicate primary detrusor overactivity.  An assessment of the quality of voiding is important, for example, do they report incomplete emptying, hesitancy or straining? Aggravating factors such as cold weather and door-latch urgency add to the picture. The impact on quality of life is also extremely important. 

Assessment of bladder irritants such as caffeine intake in the form of tea or coffee is useful. Alcohol intake, especially beer, as it entails large volumes of fluids, is also important. 

Previous medical history is essential. Type 2 diabetes, cardiovascular disease, cerebrovascular disease, prior neurological history and any spinal or pelvic surgery may all impact on bladder function. A gynaecological and obstetric history is also helpful in women. Many medications may also impact on both the lower and upper urinary tract and aggravate urinary symptoms. These medications include diuretics, calcium channel antagonists, analgesics, especially opioids, and antidepressants and antipsychotics, all of which can alter urinary symptoms. 

Examination

Abdominal assessment of the bladder can occasionally reveal a palpable bladder suggestive of chronic retention. Prostate evaluation is essential in men. In women, vulvovaginal examination allows assessment of oestrogen status, pelvic organ prolapse, the quality of pelvic floor contraction, and may reveal stress leakage on coughing.

Initial urinalysis should be performed and an MSU sought if there is any abnormality. If not done recently, bloods should be sent to exclude diabetes (for example, fasting glucose or a HbA1c) and a PSA in men. A baseline renal function may also be helpful.

Diagnoses

OAB is a symptom cluster that encompasses nocturia, frequency, urgency and urge incontinence.  However, while OAB might indicate detrusor overactivity, there are many causes for the symptom cluster of OAB and not all will have detrusor overactivity. Many patients will have normal detrusor function on urodynamics, thus we need to consider other causes of symptoms before deciding on treatment for OAB.

Urinary incontinence, particularly in the elderly, can be caused or worsened by underlying diseases, especially conditions that cause polyuria, nocturia, increased abdominal pressure or central nervous system (CNS) disturbances. These conditions include:

Cardiac failure.

Chronic renal failure.

Diabetes.

Chronic obstructive pulmonary disease.

Neurological disease, including stroke and multiple sclerosis.

General cognitive impairment.

Sleep disturbances, eg, sleep apnoea.

Depression.

Metabolic syndrome.

Chronic constipation.

Carcinoma in situ of the bladder.

Painful bladder syndrome.

Pelvic pain syndromes.

Thus, a large differential must be considered before commencing treatment. Treatment of OAB symptoms will not result in a ‘cure’ unless the underlying condition is also addressed.

Presentations requiring onward referral for specialist management include recurrent urinary tract infection; haematuria; suspicion of prostate cancer (men); prolapse beyond the introitus (women); pain associated with the micturition cycle; and more rare problems such as a fistula or suspicion of a neurological condition (Figure 2, page 32).

Chart

The simplest tool available to objectively assess OAB is the frequency volume chart. Patients are asked to record the number of voids, the time of voiding and the quantity voided over three to seven days. Ideally, these should be typical working days and not all weekends. Charts that record actual output volumes are preferred rather than asking the patient to estimate as small, moderate or large volume. The European Association of Urology website has a downloadable bladder diary available for medical professionals.

A frequency volume chart will demonstrate the patient’s fluid intake and bladder habit and allows comparison to the normative values. In addition to assisting in diagnosis, it is often used to guide bladder training and behaviour modification for the individual patient.

A normal bladder has capacity of 300-to-600ml, voids  four-to-seven times per day (based on 1.5L fluid intake) with nocturia of 0-to-1, which commonly increases to two with increasing age.

Instructions are important. Ask the patient to drink and empty their bladder as they normally would. Occasionally, patients will modify their fluid intake, which results in an inaccurate representation of their bladder habit. The first piece of information to be extracted from the chart is the total daily volume of urine. Patients often underestimate their intake, and outputs of greater than three litres per day are not infrequent in patients complaining of OAB symptoms. 

Capacity

This is the largest single void throughout the FVC period and represents the maximum ‘holding’ capacity of the bladder. This is usually seen after rising at night or in the early morning. Very often, patients get up at night and void small quantities, well below their functional capacity. This might indicate poor sleep hygiene or obstructive sleep apnoea syndrome. You will not be wakened from sleep by your bladder unless you approach your functional capacity.

For example, if you wake three times at night and void an average of 150mls each time, and your functional capacity is 550mls, then it is highly unlikely your nocturia is caused by your bladder. Alternatively, if you are getting up each night and voiding 500mls each time, then it is likely your bladder is waking you and you have an excessive fluid intake (especially later in the evening) or you have nocturnal polyuria, whereby you make >33 per cent of your urinary output between 12 and 8am. 

Knowing the maximal functional capacity allows us to explain the rationale behind bladder retraining and improves motivation. For example, if a frequency volume chart demonstrates a number of voids of 250ml and then on other occasions hourly daytime voids of 50mls, we can explain to the patient that their bladder has proven that it has capacity to hold 250ml, but they are getting an urge and emptying at 50ml, even though it is not full. The idea that the bladder needs to stretch regularly to maintain its capacity is often something patients are not aware of, so this can help to explain that concept to them and they can learn to suppress these urges.

Treatment

Prior to drug therapy, patients should be offered conservative strategies, including lifestyle advice and behavioural modification, bladder retraining and pelvic floor exercises (Figure 3, page 32).

Identify and address factors such as fluid intake and bladder irritants (including caffeine, alcohol, spicy food, tomatoes and citrus fruits), weight loss and smoking. Patients may think that replacing tea with green tea will reduce bladder symptoms, however green tea is caffeinated and hence is still a bladder irritant. It is also known that constipation can contribute to urinary symptoms, so this should also be dealt with accordingly.

The bladder is an organ of ‘habit’. If patients have developed a habitual voiding pattern, the bladder will routinely contract when it is less than full. Bladder retraining is a method of enabling patients to defer the urge, thus increasing their bladder capacity, which over time results in longer times between voids and reduction in urgency.

Retraining starts by examining the frequency volume chart and using it to determine reasonable goals for individual patients. For example, it might be reasonable to suggest hourly voids, which are timed and regular by day. If the patient experiences urge, they should be advised to use simple motor tasks to occupy the S2 nerve root that supplies the bladder and the pelvic floor, calves and toes. As a result of this shared pathway, detrusor activity can be reduced by standing on toes or flexing the toes if sitting, stretching the calves, or putting pressure on the perineum, by sitting on the edge of a hard chair.

At the same time, they should try to distract the mind by focusing on work or household task until the urge subsides. 

Teaching patients simple relaxation and breathing techniques is a useful method of taking the mind off their urgency and reducing anxiety and muscle tension, which may be contributing to their symptoms. They can practise these techniques as part of a daily programme and then utilise them when they experience urgency.

Physiotherapy

In many patients with OAB, the pelvic floor muscles do not function optimally. Pelvic floor weakness is more common in women and is addressed by focused pelvic floor exercises. These are particularly useful for patients who present with mixed urinary incontinence (that is, a combination of stress and urge incontinence). Individual assessment and instruction by a specialist physiotherapist is highly recommended, as one-in-three will perform these exercises incorrectly with verbal cueing alone.

In other patients who present with urinary urgency, the pelvic floor muscles can be overactive and tight. The more they worry about urgency, the more they try to squeeze and tighten the pelvic floor muscles. Other symptoms which may present in patients with tight ‘non-relaxing’ pelvic floor muscles include pain in the pelvic region, dyspareunia (painful sexual intercourse) and difficult bowel evacuation. Physiotherapy focused on releasing these muscles and restoring normal function is extremely effective for many patients.

Pharmacotherapy

Pharmacological intervention for OAB is indicated when lifestyle changes and conservative management have failed and the patient continues to have bothersome symptoms. The choice lies between a conventional antimuscarinic or a Beta3 agonist. Side-effects of medical management are well documented for the antimuscarinics and include the classic dry mouth, which often leads to discontinuation of treatment, constipation, blurred vision and fatigue. There is limited evidence that one antimuscarinic is superior to an alternate for the cure or improvement of urgency or urge incontinence. Higher doses are more effective but result in more side-effects.

Single daily dosing leads to fewer side-effects. A transdermal oxybutynin patch has fewer side-effects such as dry mouth, but may lead to cessation of therapy due to skin reactions. As there is no consistent evidence to support the superiority of drug therapy over conservative management, drug therapy should only be employed after failure of conservative management using an extended-release formulation and escalating the dose as required. An early review to consider efficacy and side-effects is recommended. 

In elderly patients, it is essential to try conservative management initially and long-term therapy with antimuscarinic drugs should be used with caution, especially in those patients at risk of or suffering from dementia. Many other drugs also have antimuscarinic properties so it is important not to significantly increase the antimuscarinic load. 

Currently, there is a single Beta3 agonist available for the management of urinary incontinence.  It is equivalent to antimuscarinic therapy in patients with urge incontinence and may work in some patients who are refractory to antimuscarinic therapy. Adverse events are similar to placebo but the drug should be avoided in patients with uncontrolled or labile hypertension. As Beta3 agonists do not cross the blood-brain barrier, they should be considered in the elderly to avoid an additional antimuscarinic load. A recent trial has suggested that patients who respond inadequately to solifenacin 5mg may benefit more from the addition of mirabegron, rather than dose escalation of the solifenacin.

Desmopressin is a synthetic analogue of ADH (antidiuretic hormone) and is used primarily in the treatment of nocturnal enuresis in children. It is also effective, however, in the management of nocturnal polyuria but it is not licensed in the over-65s because of risk of hyponatraemia. A new formulation of desmopressin is being evaluated and it is likely to be licensed in the near future for this population. It may prove to be a useful adjunct in those patients who have significant nocturia due to nocturnal polyuria. 

Urology

When conservative strategies and pharmacotherapy have failed for OAB, referral to urology is recommended, where investigations such as urodynamics and flexible cystoscopy may add further diagnostic information and indicate further potential therapeutic interventions. Although urodynamics can be variable and hard to reproduce accurately, the presence of detrusor overactivity is often seen clearly. Bladder outlet obstruction and detrusor failure are also frequently identified, sometimes unexpectedly so. It is important to confirm that the findings on the urodynamic trace correlate with the patient’s symptoms. Thus, urodynamics may open new paths for treatment, such as clean self-intermittent catheterisation for detrusor failure. 

Neuromodulation

Currently, there are two types of neuromodulation recommended for patients with refractory OAB. Percutaneous sacral nerve stimulation involves implantation of a permanent electrode in the sacral foramen, while peripheral tibial nerve stimulation (PTNS) is delivered using a small needle electrode into the lower leg and a surface electrode on the dorsal aspect of the foot. A 12-week programme of PTNS has been proven to improve urinary (and faecal) urgency in many patients. Specialist physiotherapists in some centres are trained in this technique.

Botox

For patients with refractory OAB and documented detrusor overactivity, the injection of Botox into the bladder may result in significant improvement in urgency incontinence. Usually about 100iu of intravesical injections of onabotulinum toxin A (Botox) have been used to treat OAB symptoms for about 15 years now. Botox is injected in the supratrigonal portion of the bladder in about 20 0.5ml injections. While Botox may be effective for many patients, it effects will wear off with a median duration of response of about six months, after which the procedure may need to be repeated.  There are some drawbacks to treatment. Post-void residuals may increase significantly and therefore patients should be capable of performing self-intermittent catheterisation before undergoing the procedure. There is also an increased risk of bacteriuria and infection after Botox.

Extreme

In extreme and rare cases with severe incontinence and huge impairment of quality of life, augmentation cystoplasty or urinary diversion can be considered as a last resort after careful counselling and a multidisciplinary approach.

Resources

http://patients.uroweb.org/i-am-a-urology-patient/. The EAU website for patients has patient information leaflets for download on symptoms and management of OAB.

http://patients.uroweb.org/i-am-a-medical-practitioner/. The EAU website for medical practitioners contains free downloadable resources, including waiting-room posters and information, bladder diaries and pelvic floor handouts.

Further reading

EAU 2015 European Guidelines on Urinary Incontinence.

NICE 2013 National Institute for Clinical Excellence: Urinary Incontinence in Women.

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