The sling procedure, or suburethral sling procedure, refers to a particular kind of surgery using ancillary material to aid in closure of the urethral sphincter function of the bladder. It is performed as a treatment of severe urinary incontinence. The sling procedure, also known as the suburethral fascial sling or the pubovaginal sling, has many forms due to advances in the types of material used for the sling. Some popular types of sling material are Teflon (polytetrafluoroethylene), Gore-Tex ® , and rectus fascia (fibrous tissue of the rectum). The surgery can be done through the vagina or the abdomen and some clinicians perform the procedure using a laparoscope—a small instrument that allows surgery through very small incisions in the belly button and above the pubic hairline. The long-term efficacy and durability of the laparoscopic suburethral sling procedure for management of stress incontinence are undetermined. A new technique, the Tension-Free Vaginal Tape Sling Procedure (TVT), has gained popularity in recent years and early research indicates high success rates and few postoperative complications. This procedure is done under local anesthetic and offers new opportunities for treatment of stress incontinence. However, TVT has not been researched for its long-term effects. Finally, there are many surgeons who use the sling procedure for all forms of incontinence.
Incontinence is very common and not fully understood. Generally defined as the involuntary loss of urine, incontinence comes in many forms and has many etiologies. Four established types of incontinence, according to the Agency for Health Care Policy and Research, affect approximately 13 million adults—most of them older women. Actual prevalence may be higher because incontinence is widely underreported and underdiagnosed. The four types of incontinence are: stress incontinence, urge incontinence (detrusor overactivity or instability), mixed incontinence, and overflow incontinence. There are also other types of incontinence tied to specific conditions, such as neurogenic bladder in which neurological signals to the bladder are impaired.
Stress incontinence is the most frequently diagnosed form of incontinence and occurs largely with physical activity, laughter and coughing, and sneezing. The inability to hold urine can be due to weakness in the internal and external urinary sphincter or due to a weakened urethra. These two conditions, intrinsic sphincter deficiency (ISD) and urethral hypermobility or genuine stress incontinence (GSI), pertain to the inability of the "gatekeeper" sphincter muscles to stay taut and/or the urethra failing to hold urine under pressure from the abdomen. In women, as the pelvic structures relax due to age, injury, or illness, the uterus prolapses and the urethra becomes hypermobile. This allows the urethra to descend at an angle that permits loss of urine and puts pressure upon the sphincter muscles, both internal and external, allowing the mouth of the bladder to stay open.
Urge incontinence, the other frequent type of incontinence, pertains to overactivity of the sphincter in which the muscle contracts frequently, causing the need to urinate. Stress incontinence is often allied with sphincter overactivity and is often accompanied by urge incontinence.
Severe stress incontinence occurs most frequently in women younger than 60 years old. It is thought to be due to the relaxation of the supporting structures of the pelvis that results from childbirth, obesity, or lack of exercise . Some researchers believe that aging, perhaps due to estrogen deficiency, is a major cause of severe urinary incontinence in women, but no link has been found between incontinence and estrogen deficiency. Surgery for stress or mixed incontinence is primarily offered to patients who have failed, are not satisfied with, or are unable to comply with more conservative approaches. It is often performed during such other surgeries as urethra prolapse, cystocele surgery, urethral reconstruction, and hysterectomy .
The sling procedure gets its name from the tissue attached under the mid- or proximal urethra and sutured at its ends onto a solid structure like the rectus sheath, pubic bone, or pelvic side walls. The procedure is used in the severest cases of stress incontinence, particularly those that have a concomitant sphincter inadequacy (ISD). The sling supports the urethra as it receives pressure from the abdomen and helps the internal sphincter muscles to keep the urethral opening closed. The procedure is the most popular because it has the highest success rate of all surgical remedies for severe stress incontinence related to sphincter inadequacies in both men and women.
Urinary incontinence (UI) plagues 10–35% of adults and at least half of the million nursing home residents in the United States. Other studies indicate that between 10% and 30% of women experience incontinence during their lifetimes, compared to about 5% of men. One reason that more women than men have incontinent episodes is the relatively shorter urethras of women. Women have urethras of about 2 in (5 cm) and men have urethras of 10 in (25.4 cm). Studies have documented that about 50% of all women have occasional urinary incontinence, and as many as 10% have regular incontinence. Nearly 20% of women over age 75 experience daily urinary incontinence. Incontinence is a major factor in individuals entering long term care facilities. Women at highest risk are those who have given birth to more than three children and women who were given oxytocin to induce labor. Oxytocin puts more pressure on the pelvic muscles than does ordinary labor. Women who smoke have twice the rate of incontinence, according to one study of 600 women. Those women who do high-impact exercises are at much higher risk for incontinence. According to the medical literature, those at highest risk for urinary leakage are gymnasts, followed by softball, volleyball, and basketball players. Finally, women who have diabetes or are obese have higher rates of incontinence. Women who require sling procedures have often had other surgeries for incontinence, necessitating sling procedure to treat intrinsic sphincter deficiency caused by operative trauma. A rarer cause of stress incontinence in older women is urethral instability. In men, stress incontinence is usually caused by sphincter damage after surgery on the prostate.
Anti-incontinence surgery is used to address the failure of two parts of female urinary continence: loss of support to the bladder neck or central urethra and intrinsic sphincter deficiency (ISD). The surgery does not restore function to the urethra or to the ability for closure to the sphincter. It replaces the mechanism for continence with supporting and compressive aids. Stabilizing the supporting elements of the urethra (ligaments, fascia, and muscles) was thought for many years to be the most important factor in curing incontinence. Called anatomic or genuine stress urinary incontinence (SUI), retropublic procedures, like the Burch procedure, sought only to restore the urethra to a fixed position. However, it became clear with the high failure rate of these procedures that ISD was present and unless surgery could confer some added compressive ability to the closure of the bladder, SUI would persist.
The urethral sling procedure is effective in the treatment of the severest types of incontinence (Types II and III) by re-establishing the "hammock effect" of the proximal or central point of the urethra during abdominal straining. The surgery involves the placement of a piece of material under the urethra at its arterial or vesical juncture and anchoring it on either side of the pubic bone or to the abdominal wall or vaginal wall. This technique involves the creation of a sling from a strip of tissue from the patient's own abdominal fascia (fibrous tissue) or from a cadaver. Synthetic slings also are used, but some are prone to break down over time.
The urethral sling procedure is most often performed as open surgery, which involves entering the pelvic area from the abdomen or from the vagina while the patient is under general or regional anesthesia. Broad-spectrum antibiotics are offered intravenously. If the patient is fitted with a urethral catheter, ampicillin and gentamicin are administered instead. The patient is placed in stirrups. Surgery takes place as a 6-to-9-cm by 1.5-cm sling is harvested from rectal tissue and sutured under the urethra at each end within the retropubic space (the area that undergirds the urethra). Synthetic tissue or fascia from a donor may also be used.
The goal of the surgery is to create a compression aid to the urethra. This involves an individualized approach to the tension needed on the sling. While the sling procedure is relatively easy to complete, the issue of tension on the sling is hard to determine and involves the use of tests during surgery for determining the compression effect of the sling on the urethra. Some manual tests are performed or a more sophisticated urodynamic test, like cystourethrography, may determine tension. It is important for the surgeon to test tension during surgery because of the high rate of retention of urine (inability to void) after surgery associated with this procedure and the miscalculation of the required tension.
Candidates for surgical treatment of incontinence must undergo a full clinical, neurological, and radiographic evaluation before there can be direct analysis of the condition to be treated and the desired outcome. Both urethral and bladder functions are evaluated and there is an attempt to determine the conditions associated with stress incontinence. In many women, incontinence may be due to vaginal prolapse. Stress incontinence can be identified by observation of urine during pelvic examination or by a sitting or standing stress test where patients are asked to cough or strain and evidence of leakage is obtained. Gynecologists often use a Q-tip test to determine the angle and change in the position of the urethra during straining. Other tests include subtracted cystometry to measure how much the bladder can hold, how much pressure builds up inside the bladder as it stores urine, and how full it is when the patients feels the urge to urinate.
The frequency of stress incontinence as measured by typical symptoms ranges between 33% and 65%. The frequency of stress incontinence is around 12% when measured or defined by cystometric findings. The ability to distinguish SUI as the cause of incontinence, as opposed to ISD, becomes more complicated; but it is a very important factor in the decision to have surgery. A combination of pelvic examination for urethral hypermoblity and leak point pressure as measured by coughing or other abdominal straining has been shown to be very effective in distinguishing ISD, and identifying the patient who needs surgery.
IV ketorolac and oral and intravenous pain medication are administered, as are postoperative antibiotics. A general diet is available usually on the evening of surgery. When the patient is able to walk, usually the same day, the urethral catheter is removed. The patient must perform self-catheterization to check urine volume every four hours to protect the urethral wall. If the patient is unwilling to perform catheterization, a tube can be placed suprapubically (in the back of the pubis) for voiding. Catheterization lasts about eight days, with about 98% of patients able to void at three months. Patients are discharged on the second day postoperatively, unless they have had other procedures and need additional recovery time. Patients may not lift heavy objects or engage in strenuous activity for approximately six weeks. Sexual intercourse may be resumed in the fourth week following surgery. Follow-up visits are scheduled for three to four weeks after surgery
Although the sling treatment has a very high success rate, it is also associated with a prolonged period of voiding difficulties, intraoperative bladder or urethra injury, infections associated with screw or staple points, and rejection of sling material from a donor or erosion of synthetic sling material. Patients should not be encouraged to undergo a sling procedure unless the risk of long-term voiding difficulty and the need for intermittent self-catheterization are understood. Fascial slings seem to be associated with the fewest complications for sling procedure treatment. Synthetic slings have a greater risk of having to be removed due to erosion and inflammation.
Regardless of the procedure used, a proportion of patients will remain incontinent. Results vary according to the type of sling procedure used, the type of attachment used for the sling, and the type of material used for the sling. Normal results for the sling procedure overall are recurrent stress incontinence of 3–12% after bladder sling procedures. In general, reported cure rates are lower for second and subsequent surgical procedures. A recent qualitative study published in the American Journal of Obstetrics and Gynecology of 57 patients who underwent patient-contributed fascial sling procedures indicates good success with fascial sling procedures. At a median of 42 months after the procedure, the postoperative objective cure rate for stress urinary incontinence was 97%, with 88% of patients indicating that the sling had improved the quality of their lives. Eighty-four percent of patients indicated that the sling relieved their incontinence long term, and 82% of patients stated that they would undergo the surgery again. The study also found that voiding function was a common side effect in 41% of the patients.
The most common complications of sling procedures are voiding problems (10.4%), new detrusor instability (7–27%), and lower urinary tract damage (3%). Some of the complications depend upon tension issues as well as on the materials used for the sling. There are recent and well-designed studies of patient fascia and donor fascia used for slings in five centers with follow-up from 30 to 51 months that report no erosions or vaginal wall complications in any patients. Prolonged retention or voiding issues occurred in 2.3% of patients and de novo or spontaneous urge incontinence developed in 6%. These figures relate only to a large study utilizing patient or donor fascia and one that did not control for other factors like techniques of anchoring. In general, studies of the sling procedure are small and have many variables. There are no long term studies (over five years) of this most popular procedure.
Alternatives to anti-incontinent sling procedure surgery depend upon the severity of the incontinence and the type. Severe stress incontinence with intrinsic sphincter deficiency can benefit from bulking agents for the urethra to increase compression, as well as external devices like a pessary that is placed in the vagina and holds up the bladder to prevent leakage. Urethral inserts can be placed in the urethra until it is time to use the bathroom. The patient learns to put the insertion in and take it out as needed. There are also urine seals that are small foam pads inserted in garments. Milder forms of incontinence can benefit from an assessment of medication usage, pelvic muscle exercises, bladder retraining, weight loss, and certain devices that stimulate the muscles around the urethra to strengthen them. For mild urethral mobility, procedures for tacking or stabilizing the urethra at the neck called Needle Neck Suspension, as well as procedures to hold the urethra in place with sutures, like the Burch method, are alternative forms of surgery.
"Urologic Surgery." In Campbell's Urology, edited by M. F. Campbell, et al., 8th ed. Philadelphia: W. B. Saunders, 2002.
Lobel, B., A. Manunta, and A. Rodriguez. "The Management of Female Stress Urinary Incontinence Using the Sling Procedure." British International Journal of Urology 88, no. 8 (November 2001): 832.
Melton, Lisa. "Targeted Treatment for Incontinence Beckons." Lancet 359, no. 9303, (January 2002): 326.
Richter, H. R. "Effects of Pubovaginal Sling Procedure on Patients with Urethral Hypermobility and Intrinsic Sphincteric Deficiency: Would They Do it Again?" American Journal of Obstetrics and Gynecology 184, no. 2 (January 2001): 14–19.
American Foundation for Urologic Disease/The Bladder Health Council. 1128 North Charles St., Baltimore, MD 21201. (410) 468-1800. Fax: (410) 468-1808. admin@ afud.org. http://www.afud.org .
The Simon Foundation for Continence. P.O. Box 835, Wilmette, IL 60091. (800) 23-simon or (847) 864-3913. http://www.simonfoundation.org/html/ .
National Kidney and Urological Diseases Information Clearinghouse. Bladder Control in Women. Intellihealth. April 17, 2003 [cited June 25, 2003]. http://www.intelihealth.com/IH/ihtIH/WSIHW000/9103/24149/35872.html?d=dmtContent .
"Urinary Incontinence." MD Consult Patient Handout. [cited June 25, 2003]. http://www.MDConsult.com .
Nancy McKenzie, Ph.D.
The surgery is performed by a urological surgeon who has trained specifically for this procedure. The surgery takes place in a general hospital.