The Midurethral Sling

Contents

1. Why the middle of the urethra
2. Tension free tape, 1995
3. Variations on a strip of mesh
4. How it became the standard
5. A look inside the bladder
6. Who it is meant for
7. Complications and sexual function
8. The historical echo

Bladder suspension procedures and cystoscopy both appear in Candace Cooley’s surgical experience, and the operation that came to dominate bladder suspension is named for a place. Midurethral means the middle of the urethra, the short tube that carries urine out of the bladder. The name marks the sling’s difference from its predecessors: an older generation of slings sat higher, at the bladder neck, while this one is a strip of tape laid beneath the midpoint of the urethra, as a clinical update in The Hospitalist describes.²

Why the middle of the urethra

The traditional pubovaginal sling is fixed at the bladder neck, and it has been considered the gold standard for women whose urethral sphincter itself is weak.² Moving the support to the midurethra changed the side effects. An MDedge column by a gynecologic surgeon observes that, compared with bladder neck slings, midurethral slings cause less trouble emptying the bladder after surgery and fewer new urgency symptoms.¹ The operation treats leakage with coughing, laughing or exertion, the pattern the Office on Women’s Health calls stress incontinence.⁸

Tension free tape, 1995

Ulf Ulmsten introduced the tension free vaginal tape in 1995, and it has since been used in millions of women with good long term results.¹ In the original technique a small trocar carries a strip of permanent polypropylene mesh from a small vaginal incision up through the space behind the pubic bone, exiting through two small incisions above it, and the strip settles under the midportion of the urethra. The Hospitalist update cited eleven years of follow up supporting the method and credited its quick adoption to a minimally invasive approach, high effectiveness and rare serious adverse events.²

Variations on a strip of mesh

Success brought imitators. Manufacturers produced kits with smaller trocars, some passed in the same bottom up direction and others top down from the abdomen into the vagina. A later generation went through the obturator openings of the pelvis to avoid blind passage behind the pubic bone, and some newer slings needed only one vaginal incision. Transobturator tapes can be passed from inside to out or from outside in, and they lie at a slightly different angle beneath the urethra.² Route matters most for women with a weak sphincter: in one comparison, the retropubic tape cured more of them than the transobturator tape but caused more prolonged voiding trouble and new urgency, suggesting it presses more firmly on the urethra.² A 2009 Cochrane analysis favored the bottom up retropubic route over top down, with higher cure rates and less bladder perforation, mesh erosion and voiding trouble.¹

Figure

Two routes for the tape

	Retropubic	Transobturator
Path of the needles	From the vagina up through the space behind the pubic bone	Out through the obturator openings toward the groin
Bladder perforation	7%	0%
Symptoms much better at one year	79%	82%

How it became the standard

Ten years after it appeared, the tape had overtaken the Burch colposuspension as the operation surgeons used most for stress leakage.² Level 1 trials showed it as effective as bladder neck slings and colposuspension with less morbidity and shorter operations, sometimes under local anesthesia, and a trial of 660 women found that starting with the sling beat starting with physiotherapy at one year.¹ A 2019 review abstracted by UroToday found good subjective cure in the short and longer term and low overall complication rates.³ Earlier guidance summarized in American Family Physician already reported similar success for the tape and the open Burch operation.⁷

A look inside the bladder

The retropubic needles pass close to the bladder, and perforation is an injury the trials track closely. In one comparison of two retropubic slings it was the primary outcome, occurring in 0.7 and 1.9 percent of women; in another, 7 percent of retropubic operations and none of the transobturator ones perforated the bladder.² Cystoscopy is how the bladder wall is seen directly. The National Institute of Diabetes and Digestive and Kidney Diseases describes a long, thin instrument with a lens and light that is passed through the urethra while saline fills the bladder, so the urethral and bladder linings can be examined on a monitor. It can be done in an office, an outpatient center or a hospital, and a simple look takes about 15 to 30 minutes including preparation. The same instrument is also used to treat leakage in another way, by injecting bulking material into the wall of the urethra.⁹ Its own risks include infection, bleeding and injury to the urethra or bladder.⁹

Figure

What happens in a cystoscopy

1. 01
   NumbingAn anesthetic gel or injection numbs the urethra; sedation or general anesthesia is used for some procedures.
2. 02
   EntryThe urologist passes a thin, lighted cystoscope through the urethra into the bladder.
3. 03
   FillingSterile saline slowly fills the bladder so its wall can be seen clearly.
4. 04
   InspectionThe linings of the urethra and bladder are examined, and small instruments can treat problems or take a biopsy.
5. 05
   AfterwardMild burning or a little blood in the urine is common and should settle within about a day.

Who it is meant for

Surgery for stress incontinence is indicated after nonsurgical care has fallen short and the woman wishes to go further. Not every candidate needs formal bladder pressure testing first; the guidance exempts women who leak only with exertion, void normally, have no neurologic findings or earlier incontinence surgery, and show a mobile urethra on examination.⁷ The MDedge author argued that for severe stress leakage the sling may reasonably come first, while physiotherapy keeps a stronger case in mild disease.¹ A multicenter trial tested a preventive sling at the time of vaginal prolapse repair in women without leakage beforehand: it cut the rate of leakage at three months and at a year at the cost of more bladder perforations, infections and bleeding.⁴ For the condition as a whole, see stress urinary incontinence.

Complications and sexual function

Mesh brought scrutiny. The 2019 review noted concern over mesh implants generally, while finding low complication rates for the sling and support from major urogynecological societies.³ Certain kits proved more prone to mesh problems and left the market.² A review of 98 studies, reported by Medical Dialogues, found that most women kept or improved their sexual function after the sling, probably because leaking stopped, but that a subset had mesh exposure or recurrent leakage, managed with pelvic floor training, injections, sling adjustment or removal, bulking or repeat surgery.⁵

The historical echo

The sling’s story keeps repeating its own pattern. The bladder neck sling was once the standard for the hardest cases; the midurethral tape displaced it and then the Burch operation; and the 2019 review called the midurethral sling the gold standard just as the mesh debate reopened the question.²³ Now the tape itself is the comparator. A trial of 596 women in the New England Journal of Medicine judged mini slings placed through a single incision noninferior on patient reported success at 15 and 36 months, though tape or mesh exposure and painful intercourse were more frequent with them, and its authors opened by noting that standard slings had been the worldwide standard only until recently.⁶ Whether any sling suits one woman’s leakage is for her and her own surgeon to weigh. Leakage driven by urgency rather than effort follows different rules, described under overactive bladder.