Stress Urinary Incontinence

Introduction

Stress urinary incontinence (SUI) is defined as involuntary loss of urine on effort or physical exertion or on sneezing or coughing. It is one of the most common lower urinary tract disorders for which women seek medical attention. SUI is uncommon in men and, when present, is usually associated with prostate surgery. In young girls or adolescents it may be related to a congenital neurologic abnormality or to high levels of physical activity such as competitive gymnastics. In the majority of postmenopausal women with urinary incontinence, SUI and urgency urinary incontinence coexist and the combination is known as mixed urinary incontinence.

SUI in adult women is attributed to one or more defects in urethral support, urethral coaptivity, urethral composition, or neurologic innervation. Although distinctions are made between SUI due to urethral hypermobility (support defect) and SUI due to intrinsic sphincter deficiency (tissue and/or neurologic factors), most believe that both are present to one degree or another and that SUI represents a spectrum of urethral pathology. Predisposing factors in women include childbearing, obesity and constipation. Because SUI largely derives from the effects of parturition, it is commonly associated with pelvic organ prolapse (POP).

Symptoms

Patients affected by SUI will complain of lack of urinary control that results in leakage of variable volumes of urine. Often the leakage will necessitate the use of absorbent pads to protect undergarments and clothing. In general, the greater the level of exertion, the more leakage occurs. Often patients will restrict water intake to maintain low urine volumes thereby reducing incontinence episodes. Secondary effects of incontinence may be present such as excoriation of the skin or fungal skin infections. Patients are particularly embarrassed by the odour from the liberated urine.

Assessment

A thorough medical history and detailed pelvic examination are essential to the diagnosis of SUI. The sine qua non of SUI is a positive cough stress test on pelvic examination: loss of urine is visually confirmed by having the patient cough and observing expulsion of urine through the urethra. Coincident POP should be quantified using one of the established systems such as the POP-Q. (Please see the POP fact sheet.) A urinalysis is necessary to rule out infection as this can sometimes cause transient SUI.

If the preliminary evaluation confirms SUI +/- POP and there are no complicating factors such as coincident urgency urinary incontinence or failed prior surgery for SUI, no further evaluation is required and one can then establish a plan of care based on the patient’s preferences and goals. However, if there is any question regarding the validity of the SUI diagnosis, if there are complicating factors, or if mixed incontinence is present, then further assessment in the form of urodynamic testing is indicated. Urodynamics consists of a collection of studies that assess the function of the bladder and urethra and their interaction during the storage and voiding phases of micturition (urination). The testing is tailored to each individual and it attempts to reproduce the symptoms that the patient experiences. The studies therefore confirm the nature of the patient’s voiding dysfunction and provide guidance for the choice of therapy.

Treatment

There are no approved pharmacologic agents for SUI. First line therapy, particularly for mild SUI, consists of pelvic floor physiotherapy; primarily instruction in and reinforcement of exercises for strengthening of the pelvic floor. Adjunctive physiotherapeutic techniques include the use of electrical stimulation, vaginal cones and biofeedback. Passive electromagnetic stimulation of the pelvic floor was utilised in the past for treatment of SUI, but the results were neither reliably effective nor durable. A very well-established and effective treatment for SUI is the use of injectable agents for urethral bulking. These are injected directly into the urethra under vision producing coaptation of the urethral wall. The procedure can be performed in the office setting. The most significant issues are durability and cost, as the bulking materials degrade or migrate over time with loss of effect and the requirement for repeated injections to maintain continence.

Definitive therapy for SUI is surgical and involves restoring urethral support through use of a sling. Worldwide, midurethral slings comprised of synthetic mesh have become the treatment of choice for SUI. Long-term data are robust and demonstrate durable efficacy with a very low complication rate, particularly in experienced hands. Various techniques for sling placement and different meshes are employed according to physician preference, but all appear to be equally effective. An additional benefit of the slings is that they are easily combined with procedures for the repair of POP. In complex cases such as those involving prior failed anti-incontinence sling procedures, before any decision concerning further treatment is made, ultrasonography should be performed in order to localise tape position. When ultrasound demonstrates that the sling is malpositioned, a second sling should be placed at the midurethra.

Male SUI can also be treated with synthetic slings with few complications, though success rates are not as high as for procedures performed on women. Definitive therapy for male SUI is an artificial urinary sphincter. The device consists of a saline-filled silicone cuff that surrounds and compresses the urethra. When the patient wishes to void, he compresses a pump placed in the scrotum discharging the fluid from the cuff. This allows the urethra to open and the bladder to empty. The cuff then passively refills from a reservoir of fluid placed in the abdomen.

Conclusion

SUI remains a common and distressing condition that adversely affects quality of life. Unfortunately, many patients and some physicians continue to regard SUI as an inevitable consequence of aging. The availability of effective non-invasive interventions, minimally invasive procedures and definitive surgical approaches means that all patients with SUI can be successfully treated, or, at the very least, their condition significantly ameliorated.

References

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