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Urinary incontinence is broadly defined as "involuntary passage of urine which causes a social or hygiene problem", [1].


Whatever the type and cause of incontinence, it is a distressing and embarrasing condition, which many patients find difficult to initiate a consultation about. Patients may be isolated socially by their embarrasment and worry over leaving the house so you can make a big positive change in their lives with very small interventions, [2].


Often, multiple types of incontinence may be affecting the patient (see Fig 1 below), so it is important to discover which is causing the greatest reduction in the quality of life, especially as some treatments will make one type of incontinence better and the other worse.


The four key types of incontinence (functional, stress, urge and overflow) are discussed below. Nocturnal enuresis (nightime bedwetting in children) would also come under this heading but it is really a paediatric condition and beyond the scope of this article, [1]...


Fig 1. The overlapping pattern of incontinence

The overlapping pattern of incontinence





Incontinence is common in the elderly and increases with age, (Fig 2). Prevelence in institutionalised adults is as high as 50%, [2]. However, it is estimated that less than half of adults with moderate-severe incontinence have ever mentioned it to a medical practitioner!



Fig 2. Incidence of incontinence by age (adapted from [2])

Incidence of incontinence by age



* Risk Factors *

Organic Disease [2,3]

  • Impaired mobility form other medical issues
  • Obesity
  • UTIs
  • Prostatic enlargement (carcinoma, BPH)
  • Renal stones
  • Stricture
  • Chronic cough
  • Continual straining to empty bowels
  • Neurological disease or organic brain damage (stroke)
  • Pelvic tumours
  • Stool impaction


Iatrogenic [3,4]

  • Diuretics
  • Muscle Relaxants
  • Sedatives
  • Prostate surgery
  • Hysterectomy
  • Forceps delivery of child


Patient Factors [5]

  • Alcohol
  • Caffeine
  • Citric Acid
  • Smoking


* Risk Factors *

General [2]

  • Increasing age
  • Institutionalisation (up to 50% of residents)


Female Specific [2,3]

  • Female gender - the biggest risk factor for incontinence
  • Pregnancy
  • Vaginal Delivery
  • Menopause - reduced oestrogen allows thinning of tissues
  • Hysterectomy







    Male Specific [6]

    • Prostate procedures of any type
    • Benign Prostatic Hyperplasia (BPH)
    • Prostatitis
    • Prostate Carcinoma



      Normal Micturition


      Bladder Filling Phase [7]

      Sympathetic tone (eminating from L2) dominates, tightening the smooth muscle of the Internal Urethral Sphincter (IUS) and the detrusor muscle relaxes, allowing the bladder volume to increase.


            Voiding Phase [7]


            1. Proprioceptors (stretch receptors) in the detrusor are stimulated. These:
            2. Stimulate parasympathetic motor neurones, which in turn stimulate detrusor (bladder wall) muscle contraction via reflex arc through S2-S3 up to the brain stem (1. on Fig. 3). They also:
            3. Inhibit somatic motor neurones (contained in the pudendal nerve from S2-S3) to the skeletal muscle of the external urethral sphincter (EUS), allowing external sphincter opening.
            4. Brain cortex can override the reflex by inhibiting the parasympathetic fibres to the bladder and reinforcing the somatic input to the EUS until the individual is ready to void, at which point the PNS inhibition and somatic reinforment are removed, allowing the PNs to instigate detrusor contraction with no resistance to the flow from the EUS.


            If any of these is overcome, insufficient, or hyper-sensitive, then incontinence may well develop.


            It can be useful to know the levels of spinal cord innervation as loss of just parasympathetic and pudendal-innervated function but preservation of sympathetic function could help to identify the level of the causative lesion.


            Fig 3. Urinary bladder innervation

            Urinary bladder innervation




            Functional Incontinence


            The simplest to understand, but often most difficult to treat because:


            • Patients are unable to physically get to a toilet before voiding due to disability or reduced mobility;
            • Commonly occurs after stroke, trauma, or with dementia;
            • Unfamiliar surroundings are also a common cause... [1,2]





            Stress Incontinence


            Increased intra-abdominal pressure causes leakage past an incompetent external urethral sphincter (Fig. 4), [1]. This is:


            • The most common form of incontinence overall.
            • Commonly occurs when coughing, laughing or sneezing, sometimes while running, jumping or lifting heavy objects.
            • Very rarely occurs at night, [2].




            Sphincter incompetence in men usually occurs from sphincter damage following prostate surgery, such as a TURP. Men often experience this transiently for 6-12 months after prostate surgery, though this often spontaneously resolves as long as denervation has not occured, [2,6].


            In women, it is often caused by weakness in the pelvic floor muscles or a tear in the pubocervical fascia, which allows the proximal urethra and bladder neck to herniate into the vagina and reduces the resistance against increased abdominal pressure that can be generated, [2,3].


            Fig 4. Stress incontinence mechanism (adapted from [1,2,7])

            Stress incontinence mechanism




            Urge Incontience


            This is characterised by reduced bladder capacity due to excessive and inappropriate detrusor contraction. It is:


            • The most common type of incontinence in hospital.
            • Common in the elderly.
            • A common cause of nocturnal incontinence.


            Patient typically has 'urgency': the sudden urgent need to pass urine, followed shortly after by uncontrollable urination before they can reach the toilet.


            Causes are thought to include decresed cortical inhibition of detrusor contraction and detrusor insability due to bladder irritation. In half of all patients, instability is associated with poor detrusor function resulting in very freqent incomplete voiding, [5]. Further details [Patient UK].




            Overflow Incontinence


            In the case of overflow incontinence, partial obstruction of the urethra or the bladder neck causes urinary retention until the increased pressure in the bladder overcomes the resistance and some urine leaks (left-hand illustration in Fig. 5), [1,2]. This is:


            • Common in men with prostatic obstruction (eg BPH) or after spinal cord injury, [1].
            • Common in women with cystocoeles or following surgery in the area, [3].


            Longstanding outlet obstruction or detrusor insufficiency causes a hypotonic, flaccid and distended bladder. Such outflow obstruction necessitates constant overstretching of the detrusor, causing it to eventually become unable to generate sufficient pressure to overcome the obstruction and fully empty the bladder (detrusor hypotonia or insufficiency is often a consequence of lower motor neurone damage, such as in diabetic neuropathy or sacral spinal cord injury), [2,7].


            Urine thus slowly collects in the bladder as it is produced by the renal system, much like water collecting behind a dam in a river. Once the pressure is sufficient for it to overcome the blockage in the outlet, micturation occurs - this is like water flowing over the top of a dam once it is full (right-hand image in Fig, 5). This results in lots of very small, sometimes uncontrollable voidings as it only takes a small increase in pressure to tip the balance - voluntarily this can be provided by the patient contracting their detrusor muscle in an already over-filled bladder, but it can also occur when the bladder has filled to a sufficient level from the slow renal production of urine, or in combination with features of stress incontinence, [1,2,4,7].


            Untreated, this can eventualy go on to cause the patient to be admitted with urinary retention or ureteric reflux - potentially resulting in hydronephrosis, [4]. Further details [Patient UK].


            Fig 5. Overflow incontinence (adapted from [2,4,7])

            Overflow incontinence






            Incontinence necessitates an extensive work-up to determine its underlying cause and chose the most appropriate treatment. The investigations commonly employed can be divided into:


            Non-Invasive [2,8]

            • Frequency/Volume Chart
            • Clean-catch mid-stream urine sample:


            * Dip-stick test for leucocytes, protein and nitrates (checking for a urinary tract infection) and blood, glucose and protein for renal damage.

            * If urine dip is positive then the sample may be sent to the lab to try and culture an infecting bacteria and check its sensitivity to antibiotics.

            * If indicated, light microscopy can be performed to look for specific structures in the urine such as casts (suggestive of glomerulonephritis), or for particular micro-organisms. Further details [Patient UK].


            Physical examination [2,3,6]

              • Check for central issues like neurological disorders or dementia
              • Check for a local cause;


                * Digital Rectal Examination in men for Prostatic enlargement (eg Benign Prostatic Hypertrophy - BPH or prostatic carcinoma).

                * Check for gynacological cause in women.


                Blood Sampling [2]

                • Standard infective marker screen; c-reactive protein (CRP) and erythrocyte sedimentation rate (ESR)
                • PSA if male with suspected prostate issue
                • Renal function if renal failure also suspected;


                  * Urea - ureamia (high blood urine level) indicates possible renal impairment (or just dehydration).

                  * Creatinine, which is excreted by muscle as creatinine phosphatase and freely filtered by the glomerulus without tubular reabsorption; thus used to estimate the rate of filtration of blood by the glomerulus (called eGFR) to detect the presence of renal failure.

                  * Electrolytes; sodium, potassium, chloride and bicarbonate.


                    Imaging [2]

                    • Ultrasound - stone, faecal impaction, retention
                    • MRI for neurological cause;


                    Urodynamics (summary - full description immediately below), [2,9]

                    • Flow Rate of micturation
                    • Post-void residual volume
                    • Cystometry
                    • Electromyography (EMG);





                    Urodynamics covers a wide range of investigations for lower urinary tract symptoms (LUTS), all of which can be combined into the numbered procedure below for a full urodynamics work-up.


                    • Often used in women to differentiate between stress and urge incontinenece, or decide which is the dominant problem in mixed incontinence.
                    • Particularly important if surgery is a possible option and allow a definitive diagnosis.
                    • Even experienced urologists use Urodynamics testing to demonstrate detrusor instability.
                    • Generally, if they are experiencing nocturnal incontinence, it is more likely to be detrusor instability.



                    Individual Urodynamics investigations [9]


                    • Flow rate - patient voids into a container which measures the rate and approximate volume of fluid flow and produces a graph of this over time. Often accompanied by monitoring of abdominal pressure via a rectal sensor and cystic pressure via a thin catheter (called pressure uroflowmetry) to pin down the precise cause of voiding difficulty.


                    • Post-void Residual Volume - patient is asked to fully void themselves, then a catheter is inserted (or a bladder scanner used for an estimate) to measure the volume of fluid remaining.


                    • Cystometry, Cystometrogram (CMG) & Leak Point Pressure - a catheter in the bladder allows warm saline to be pumped in, and the pressure measured. A further sensor in the vagina or anus allows monitoring of the intra-abdominal pressure. As the bladder is filled, the patient performs activities that are likely to provoke incontinence, such as standing, lifting, laughing and coughing. These actions are noted on the pressure graph by the operator. The abdominal/vaginal sensor allows the subtraction of the influence of abdominal pressure changes (eg from breathing or coughing) from the bladder response to these changes. Measurement of the pressure in the bladder at which the patient feels it is full, and the presence of involuntary detrusor muscle contractions can be observed - allowing bladder hyper-responsiveness to be identified. Any leaking of urine is recorded and can be quantified on the cystic pressure graph as a reduction in pressure, allowing a urine leak point pressure to be determined. See Fig 6 below for an example cystometry set-up.


                    • Pressure flow studies conducted at the end of cystometry can point to outflow obstruction such as prostatic enlargement, or women with a prolapsed bladder.


                    • Electromyography (EMG) - some catheter probes allow the electrical activity in the sphincters and the detrusor to be measured if nerve or muscle damage is suspected. Stick-on pads similar to ECG tabs can be placed near the sphincter instead.



                    Full Urodynamics work-up [9]


                    Preparation - patients need to come to the test with a full bladder


                    1. They will need to urinate into a Uroflowmetre to graph the rate at which urine exits and look for any voluntary voiding abnormalitites.
                    2. Two very fine catheters are inserted up the patient's urethra - one to fill the bladder with warm saline, the other to measure the pressure within.
                    3. Another pressure sensor will usually be inserted into the rectum to measure the abdominal pressure.
                    4. The patient's bladder will be slowly filled with warm saline, with the filling being stopped at various points to encourage the patient to cough, laugh, jump about, lift objects or anything else that normally provokes their incontinence.
                    5. Sometimes the patient will void involuntarily at some point and this will conclude the study, normally they will be asked to void into the Uroflowmetre again with the catherters still inserted.
                    6. Any comments about fullness or the desire to urinate are tagged on the study trace at the time they occur, allowing associations to be drawn between say the patient coughing, and a change in abdominal pressure.


                    Sometimes the study may be performed with x-ray observations and contrast used instead of saline (called fluoroscopy), allowing images of the urinary tract during micturation to be aquired. Further Details: [Patient UK][UK Urodynamics page] - latter is quite detailed so read Patient UK first.


                    Fig 6. Cystometry procedure (image - taken from [10])

                    Cystometry procedure





                    Management of Urge Incontinence


                    Conservative [5]


                    • Reduce Caffeine intake
                    • Increase water intake as this dilutes the irritating substances, but this is to be spread as lots of small amounts over the day to avoid rapidly stretching the detrusor muscle. Reduced intake in the evenings to avoid nocturnal incontinence. If already drinking large quantities, try reducing intake to see if bladder distention causes contractions.
                    • Advise Weight loss if BMI is over 30.
                    • Bladder Training to try not go to the toilet except fixed times during the day (say on arrival at work, then not again until lunchtime for instance). Pelvic Floor Exercises will help the patient to enforce their minds control over their bladder - over time the bladder should stop contracting randomly. Should be tried for at least six weeks as the first line treatment.


                    Medical [5]


                    Antimuscarinics and Anticholinergics:


                    • Oxybutynin - blocks parasympathetic transmission, preventing overactivity of the bladder, often used in conjunction with bladder training.
                    • Propiverine is an effective anticholinergic - useful for overactive bladders but only if there is no evidence of urinary incontinence.
                    • Intravaginal oestrogens may benefit postmenopausal women with vaginal atrophy.
                    • Antispasmodics are available.
                    • Trycyclic antidepressants help.


                    Surgical [5]


                    • Sacral Neuromodulation - electrical stimulation of the nerves to supress overactivity of the detrusor muscle.
                    • Bladder Augmentation (Augmentation Cystoplasty) to increase the bladder's capacity by combining tissue from the intestine into the bladder wall. Carries a small risk of malignancy.
                    • Botulinium A Injections into the bladder wall cause it to increase in volume.
                    • Formation of a Neobladder, generally from a section of ileum or large bowel (gastric and colonic tissue is also used) is another alternative but is generally offered if other options have been declined. There are issues surrounding the complete removal of peristalsis, continued mucous secretion and the far higher electrolyte losses from bowel tissues as opposed to the original bladder wall.


                    Further Details [Patient UK]



                      Management of Stress Incontinence


                      Conservative [2,3,11]


                      • Pelvic Floor Exercises to strengthen the pelvic floor; takes a long time (often >3months) and commitment, but can be very successful when taught well by a good nurse specialist. Both males and females benefit from this.
                      • Vaginal Cones.
                      • Biofeedback.
                      • Electrical Stimulation.


                      Medical [2]


                      • Duloxetine (SNRI) - works like an SSRI but also blocks re-uptake of Noradrenaline. This is second line in those who do not want or are unsuitable for surgery.


                      Surgical [2,3,11]


                      • Intramural Bulking Injection - Collagen or silicone injection into urethral wall just distal to the bladder neck. Not as successful as sling procedures and as the initial success fades away over time, often neccesitating repeat injections.
                      • Colposuspension ♀ where the bladder and uterus are released from the weakened pelvic floor, brought back to their normal positions and the weakened floor and adjoining ligaments stitched to strengthen them. Risk of post-operative obstruction - up to 20%.
                      • Sling Procedure - Trans Obturator (TOT), Suburethral (SUT)♂ and Tension free Vaginal (TVT)♀ Tapes can be inserted to support a prolapsed urethra and return the EUS to full function. The tapes are either the patients own muscle grafts or teflon or gortex synthetic fibres. Risk of post-operative obstruction - up to 20%.
                      • Aritificial Sphincter Insertion - can have serious side effects though - often only considered if previous surgery has failed.




                        Management of Overflow and Functional Incontinence


                        Conservative [2]


                        • Regular, timed trips to the toilet can help.
                        • Continence pads can be offered to assist with those times when they don't quite make it. These are now heavily rationed on the NHS and may soon not be available. There are also issues with dignity and self esteem, especially relating to odour control.


                          Interventional [2,3,4,6]


                          • Treat the underlying cause - for overflow this is usually bladder outlet obstruction - ♂ Treat prostatic hypertrophy, whether BPH or prostatic carcinoma. Functional incontinence may be improved by helping the patient mobilise more easily whether this is simply placing rails throughout their residence right the way through to a full hip replacement.
                          • Intermittant self-catheterisation may be the best solution, especially if the obstruction is not resectable.
                          • Long-term catherisation - Some patients may be better suited or require a suprapubic or indwelling urethral catheter, especially if there are other issues such as cognitive impairment or a reduced ability to mobilise where pressure sores make continence a particularly important issue.




                            Red Flags


                              • Incontinence with saddle anaesthesia and leg weakness = possible cuada equina lesion, a neruological emergency, [12].
                              • Continuous Incontinence = significant pathology such as a fistula, chronic outflow obstruction or neurological problem, [2].



                                Wave Goodbye to Incontinence!




                                Further Reading

                                Urinary Incontinence:

                                Lower Urinary Tract Symptoms in Women

                                Lower Urinary Tract Symptoms in Men

                                Chronic Urinary Retention

                                Detrusor Instability and Irritable Bladder

                                Urodynamic Studies

                                Bladder control

                                Genitourinary Prolapse

                                Cauda Equina Syndrome



                                1. Kumar P. Clark M. Clinical Medicine 7th Edition, Elsevier, 2009
                                2. Patient UK. Urinary Incontinence (last accessed 24/02/2012)
                                3. Patient UK. Lower Urinary Tract Symptoms in Women (last accessed 24/02/2012)
                                4. Patient UK. Chronic Urinary Retention (last accessed 24/02/2012)
                                5. Patient UK Detrusor Instability and Irritable Bladder (last accessed 24/02/2012)
                                6. Patient UK. Lower Urinary Tract Symptoms in Men (last accessed 24/02/2012)
                                7. Guyton A. Hall J. Textbook of Medical Physiology 11th Edition, Elsevier, 2006
                                8. Patient UK Urinalysis (last accessed 24/02/2012)
                                9. Patient UK. Urodynamic Studies (last accessed 24/02/2012)
                                10. Test Database. Bladder control (last accessed 24/02/2012)
                                11. Patient UK. Genitourinary Prolapse  (last accessed 24/02/2012)
                                12. Patient UK. Cauda Equina Syndrome (last accessed 24/02/2012)

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