There is wide variation in the reported prevalence of UI worldwide. It affects about 3.5 million people in the UK. The prevalence is approximately twice as common in females compared to males and increases with age (Table 5.1).2 International studies show a gradual increase in the prevalence of female UI during adulthood to 30%, stabilizing between the ages of 50 and 70y old, before rising again.3 Approximately 50% of women suffer stress UI, 11% urgency UI, and 36% mixed UI.3

Stress urinary incontinence (SUI): involuntary urinary leakage on effort, exertion, sneezing, or coughing.1 It is due to hypermobility of the bladder base, pelvic floor and/or intrinsic urethral sphincter deficiency. When confirmed on urodynamic testing, it is termed urodynamic stress incontinence. It was further categorized by Blaivas4 (using videourodynamics) into:

Urgency urinary incontinence (UUI): involuntary urine leakage accompanied by or immediately preceded by urgency (a sudden, strong desire to void).1 Previously called ‘urge’ urinary incontinence, it is due to an overactive detrusor muscle. The urodynamic diagnosis is termed ‘detrusor overactivity incontinence’. It is a component of the overactive bladder syndrome (see OAB p. 148).

Mixed urinary incontinence (MUI): involuntary leakage associated with urgency and also with exertion, effort, sneezing, or coughing.1 It contains symptoms of both SUI and UUI.

Overflow incontinence: is leakage of urine when the bladder is abnormally distended with large residual volumes. Typically, men present with chronic urinary retention (with a degree of detrusor failure) and dribbling incontinence. This can lead to back pressure on the kidneys and renal failure in 30% of patients. BOO must be corrected; detrusor failure can be managed with clean intermittent self-catheterization (CISC) or indwelling catheter.

Nocturnal enuresis: the complaint of loss of urine occurring during sleep.1 The prevalence in adults is about 0.5%5 and 7-10% in children aged 7y old.6 Nocturnal enuresis can be further classified into primary types (never been dry for longer than a 6-month period) or secondary (the re-emergence of bedwetting after a period of being dry for at least 6-12 months; see p. 694). In an adult male, nocturnal incontinence may be an indicator of high-pressure chronic retention (see p. 120).

Post-micturition dribble: involuntary loss of urine immediately after the individual has finished passing urine, usually after leaving the toilet in men or after rising from the toilet in women.1 In men, it is due to pooling of urine in the bulbous urethra after voiding.

A recent standardization report by the International Urogynaecology Association and the International Continence Society on female pelvic floor dysfunction7 recommend new definitions, including:

Bladder diaries: record fluid intake, the frequency and volume of urine voided, incontinent episodes, pad usage, and degree of urgency over a 3-day period.

Urinalysis ± culture: treat any infection and reassess symptoms.

Flow rate and post-void residual (PVR) volume: patients need to void 150mL of urine for an accurate result. A reduced flow rate suggests BOO or reduced bladder contractility. The volume of urine remaining in the bladder after voiding (PVR) is also informative (<50mL is normal; ” class=LK href=”javascript:void(0)” target=right xpath=”/CT{06b9ee1beed594192fe83c602fef4af9a59e63f847d6df62927a64e26327cf0ce6725aa5d6838b26ae7cb4b2d41b2bfd}/ID(AB2-M1)”>> 200mL is abnormal; 50-200mL requires clinical correlation). PVR is measured with transabdominal USS.

Pad testing: weighing of perineal pads to estimate urine loss after a specific time or provocation test. It is performed with a full bladder. A pad weight gain >1g is positive for a 1h test and a pad weight gain >4g is positive for a 24h test. This is not standardized and not always reliable.

Blood tests, imaging (USS) and cystoscopy: indicated for complicated cases with persistent or severe symptoms, haematuria, bladder pain, voiding difficulties, recurrent UTI, abnormal neurology, previous pelvic surgery or radiation therapy, or suspected extraurethral incontinence.

Urodynamics (see p. 68)

Sphincter electromyography (EMG): measures electrical activity from striated muscles of the urethra or perineal floor and provides information on synchronization between the bladder muscle (detrusor) and external urethral sphincter.

This accounts for up to 50% of reported UI in women and causes the symptoms of involuntary urinary leakage on effort (e.g. lifting), exertion (e.g. running), sneezing, and coughing. It is associated with an intrinsic loss of urethral strength and/or urethral hypermobility.

External urethral sphincter damage (from pelvic fracture, prostatectomy, pelvic surgery, or radiotherapy).

Neurological disorders causing sphincter weakness (SCI, multiple sclerosis, spina bifida).

Approximately 30% of women will report symptoms of MUI, with involuntary urinary leakage associated with urgency and also with exertion, effort, sneezing, or coughing. The underlying aetiologies and evaluation remain the same as for SUI and UUI, but also consider further investigation to rule out pathologies such as bladder cancer, stones, and interstitial cystitis. The aim of management is to treat the predominant symptoms first.

The aim is to achieve urethral muscosal apposition and closure of the lumen. In women, 2-4 injections are recommended (depending on agent) while in men, 3-4 circumferential injections are administered. Overall success rates are variable, depending on both the agent and patient selection (reported in ranges of 50-80%).1, 2, 3 and 4 Results tend to deteriorate with time and repeat treatments are often needed.

Surgery is considered after conservative methods have failed. There are three main operations, all of which can be performed open via a Pfannenstiel or lower midline abdominal incision to approach the bladder neck and develop the retropubic space. Burch colposuspension can also be performed laparoscopically. Better results are seen in patients with pure stress incontinence and primary repair (as opposed to ‘re-do’ surgery).

This is the most widely used technique with the best durability. Patients that are selected require good vaginal mobility as the vaginal wall is elevated and attached to the lateral pelvic wall where the formation of adhesions over time will secure its position. It is also considered an option for patients with concurrent SUI and anterior vaginal wall prolapse. This operation involves exposing the paravaginal fascia and approximating it to the iliopectineal (Cooper’s) ligament of the superior pubic rami. Initial success rates for open repair are about 85-90% at 1y and 70% at 5y.1 Success rates when used for recurrent incontinence are 83% at 1y.2 Overall success rates are slightly higher for open repair over the laparoscopic approach.3, 4 Open repair has a shorter operating time and the laparoscopic approach is more costly, but has a shorter hospital stay.

A variant of the Burch procedure. Sutures are placed by the vaginal wall and paravaginal fascia and then passed through the obturator fascia to attach to part of the parietal pelvic fascia below the tendinous arch (arcus tendoneus fascia). It aims to disperse tension on the paravesical tissues laterally to reduce the risk of prolapse. Cure rates are up to 85%, although it is considered less effective than the Burch colposuspension.