MIDURETHRAL SLINGS: RETROPUBIC MIDURETHRAL SLING
For many years, gynecologic surgeons awaited a primarily vaginal procedure that yielded cure rates and low complications comparable to the Burch colposuspension. The entire paradigm of surgery for stress urinary incontinence (SUI) underwent a significant change with the introduction of the retropubic tension-free vaginal tape (TVT) polypropylene mesh sling.1 This procedure is now the most commonly performed surgical treatment modality for SUI in women. The retropubic midurethral sling has also served as a prototype for a variety of modifications including transobturator tape slings, single-incision mini-slings, and adjustable slings. Objective cure rates vary depending on the definition of cure, but approximate 80% with follow-up times ranging from 1 to 11.5 years postoperation.2,3
Retropubic midurethral slings are indicated for primary or recurrent stress incontinence, for patients with intrinsic sphincter deficiency (ISD), for patients with or without urethral hypermobility, and for patients with stress-predominant mixed urinary incontinence.
The TVT retropubic procedure involves placing a 40 cm × 10 mm polypropylene mesh strip beneath the midurethra via a blind passage of a metal trocar through the retropubic space. The sling is covered by a plastic sheath that is removed after placement and final adjustment. The sling is placed loosely around the urethra without tension, making its initial attachment to the tissues by friction due to the design of the mesh. Cystoscopy is performed after each passage of the trocar to rule out unintentional perforation of the bladder or urethra. Bleeding in the retropubic space usually responds to external compression with or without use of local hemostatic agents. Some synthetic retropubic slings have dilators over the shaft of the trocar that allow a single cystoscopy to be performed after passage of bilateral trocars.
The primary indication for a retropubic midurethral sling is symptomatic stress incontinence. Patient symptoms alone have been shown to correlate poorly with the urodynamic diagnosis of stress or urgency urinary incontinence. Therefore, a multichannel urodynamic evaluation demonstrating involuntary loss of urine with increases in abdominal pressure in the absence of detrusor overactivity may be performed in patients prior to scheduling surgery as indicated. For patients with uncomplicated SUI without significant vaginal prolapse, a cough stress test may be all that is indicated.4 Patients with pelvic organ prolapse may not leak urine when prolapse is present due to the kinking effect on the urethra, particularly with a prolapsed bladder. Reduction of the prolapse during urodynamic testing may serve to unmask occult incontinence.
Patients should be advised that no anti-incontinence procedure is effective 100% of the time. By definition, midurethral slings should be tensioned loosely so as to avoid postoperation voiding dysfunction. Even with ideal placement, patients may experience transient incomplete bladder emptying requiring intermittent self-catheterization or an indwelling catheter. De novo detrusor overactivity is also seen in ...