Cadaveric Assessment of Synthetic Mid-Urethral Sling Placement

doi:10.4236/oju.2011.12006

Paper Menu >>

Journal Menu >>

Open Journal of Urology, 2011, 1, 19-24

doi:10.4236/oju.2011.12006 Published Online May 2011 (http://www.SciRP.org/journal/oju)

Cadaveric Assessment of Synthetic Mid-Urethral

Sling Placement

Scott Serels

Bladder Control Center of Norwalk, Norwalk CT, USA

E-mail:[email protected]

Received March 5, 2011; revised April 25, 2011; accepted Ma y 5, 2011

Abstract

Purpose: To determine if 3 types of mid-urethral synthetic slings are visually the same. Materials and Methods: A

retropubic, obturator, and single incision sling was individually placed in three cadavers. Tension was set using a spacer

(obturator and retropubic). Single incision sling (SIS) tension was set by visual inspection. Thirty physicians were asked

to determine placement method, tension, and location of the 3 slings. Results: Physicians were composed of 5 urolo-

gists, 7 urogynecologist, and 18 general gynecologists, with an average of 53 slings performed per year. Conclusions:

This study showed that after placement of a sling it is hard to tell how the sling was placed and that most physicians felt

the SIS was tensioned the best and most likely at the mid-urethra.

Retropubic Obturator SIS

% correctly identified sling 40% 43% 23%

% thought tension was just right 33% 47% 73%

% thought sling was at mid-urethra 50% 67% 83%

Keywords: Stress Incontin ence, Surgical Correction of Incontinence, Single Incision Slings

1. Introduction

Urinary incontinence is a common problem in adult

women, with a prevalence of approximately 35% [1].

Stress urinary incontinence (SUI), the most common form

of urinary incontinence in women, is an involuntary loss

of urine that occurs during physical activity, such as

coughing, sneezing, laughing, or exercise. Treatment

options for SUI in women are designed to prevent the

involuntary loss of urine from the urethra during increases

in intra-abdominal pressure. Nonsurgical therapies include

behavioral therapy (e.g. bladder training, fluid and dietary

modification) and l imit ed drug t herapy.

Surgical therapy for this condition has existed for over

100 years. The suburethral sling was first described in

1907 by von Giordano, and consisted of pl acing autol ogous

tissue underneath the bladder neck and suspending it

superiorly. Since then, over 200 different surgical

procedures have been described. Sling material has also

evolved from autologous fascia lata, muscle, and rectus

fascia to synthetic material. The majority of midurethral

slings now available u se type I polypropylene mesh. The

development of the mid-urethral slings and corresponding

placement methodologies have evolved to improve

efficacy, safety, cost-effectiveness, and to minimize

invasiveness. Currently, the three main approaches to

placement of synthetic mid urethral sling include

retropubic, transobturator, and the single incision mini

sling.

The Integral Theory of Female Urinary Incontinence

by Ulmsten and Petros in the early 1990’s challenged our

understanding of incontinence significantly and led to the

market introduction of the minimally invasive retropubic

midurethral sling known as tension-free vaginal tape

(TVT) [2]. The TVT procedure initiated in 1996

revolutionized the surgical manag ement of female SUI in

terms of its efficacy and minimal invasiveness. Although

80% - 89% cure rates, with durable cure rates up to 5

years post-procedure, have been reported, blind passage

through the retropubic space poses considerable risks.

[3,4] Pot enti al compli cati ons i ncl ude bowel i njury , bl adder

injury, major vascular injury, and nerve injury. Bladder

perforation in retropubic slings is a common complication

with a recent meta-analysis reporting rates of 3.2%, [5]

20 S. SERELS

and rates up to 15% have also been reported in at least

one multicenter study [6]. Bowel and vascular injuries

have also been reported, though less frequently than

bladder perforations, but are more serious and have

resulted in patient deaths.

The transobturator approach was first described by

Delorme in 2001 [7]. The major advantage of the

transobturator approach is the avoidance of the retropubic

space, decreasing complicatio ns such as bladder and bowel

perforation, and major vascular injury. Bladder perforation

using the transobturator approach have reported rates as

low as 0%, considerably less than those reported for the

retropubic procedure [5]. Recent studies report that the

transobturator method provides intermediate-term efficacy

results that are comparable to the retropubic method with

a reduction in major complication risks [8-10]. As a

result, the transobturator approach has increased in

popularity for midurethral sling placement in many

centers due to its efficacy and low morbidity.

In keeping with the trend of improving SUI treatment

options (less invasive, more efficacious, safer, improved

recovery), the single-incision method has recently been

introduced. Single-incision slings provide the latest

advance in midurethral tensionless sling technology and

require only one small vaginal incision placed beneath

the urethra. Proposed advantages of the single-incision

method over the retropubic and transobturator are less

postoperative pain and decreased incidence of

complications [11]. Currently however, there is minimal

data available on the long-term efficacy and safety of the

single-incisio n m e t hod [12].

Our experience indicates that many physicians are

hesitant to use the single-incision method as they think

the anchoring results in tensioning that is too tight. The

purpose of the current study was to determine if different

mid-urethral synthetic sling placements were visually

similar regardless of the placement methods, anchor sites,

and tension methods. We also evaluated which sling

placement was tensioned most correctly and was most

likely positioned at th e mid-urethr a. The impetus for this

study was the realization that visually all slings,

regardless of their approach for placement, look fairly

similar after being placed in live patients although the

means of placement may be different.

2. Materials and Methods

Three, fresh female cadavers, with mid-urethal slings

placed by either the retropubic, transobturator, or single

incision method, were used for this investigation. All

three slings used Advantage Mesh from Boston Scien-

tific, USA. Incisions for each of the 3 placement methods

were made on each cadaver so the method of placement

could not be determined by incisions alone. A single

surgeon performed all of the cadaveric sling placements.

This particular surgeon performs over 200 slings each

year. In his own practice, he performed, at the time of

this study in his live patient population, approximately

15% of his slings by the suprapubic approach, 50% by

the obturator approach, and 35% of his slings by the sin-

gle incision approach.

The retropubic sling procedure was performed by

making a 15 mm sagittal incision in the vaginal wall, at

the level of the mid-urethra, followed by a periurethral

dissection plane which was extended laterally toward the

ischiopubic rami. Two stab incisions were made in the

suprapubic region at the upper rim of the pubic bone, 2

cm lateral from the midline. Then, a trocar was placed

within the periurethral tunnel with the tip of the device

between the index finger and the lower rim of the pubic

ramus. The device was pushed upwards with controlled

pressure to exit the suprapubic incision, keeping the tip

of the tunneler in close contact with the pubic bone. The

procedure was repeated on the contralateral side (Figure

1(a)). The synthetic mesh was transferred from the sub-

urethral incision to the skin incisions on each side fol-

lowed by tension-free adjustment using a 12 Hagar dila-

tor as a spacer (Figure 2).

The transobturator technique used was based on

Delorme’s description. 5 An anterior, vertical 15 mm

vaginal incision was made at a point approximately 1 cm

below the urethral meatus. Dissection was then made

laterally toward the ischiopubic ramus. The entry point

was made at the junction of the adductor longus tendon

and inferior pubic ramus. The tip of the trocar was in-

troduced through this incision, initially in a direction

perpendicular to the cadaver, and then oriented upward

and inward in an oblique direction to reach the index

finger introduced in the periurethral space once the ob-

turator muscle and membrane had been punctured. The

introducer was exteriorized from the suburethral incision,

and the tape or the synthetic mesh was transferred from

this site to the skin incision (Figure 1(b)). The same pro-

cedure was performed on the contra-lateral side, and then

tension-free adjustment was set using a 12 Hagar dilator

as a spacer (Figure 2).

For the single-incision method, a 1 to 1.5 cm midure-

thral anterior vaginal wall incision was made. Dissection

was then made up to the inferior pubic ramus on either

side of the urethra. The single incision sling was placed

into the obturator internus muscle using the introducer

and repeated on both sides (Figure 1(c)). The tension of

the single incision sling was set so the sling lay against

the urethra such that pillowing of the periurethral tissues

were observ ed through the por es of the sling.

After placement of each sling, blinding incisions were

complet ed and 30 gynecologis t s and general urologists of

ifferent specializations visually inspected the sling d

S. SERELS

(a) (b) (c)

Figure 1. Placement of mid-urethal slings to alle viate stre ss urinary incontinence using the (a) re tropubic; (b) tr ansobturat or;

Figure 2. Tension-free adjustment for the retropub ic and transobtu rator techniques was set using a 12 Hagar dilator as a spacer.

1) How was the sling placed? placements. These were experienced surgeons who used

their own experience and knowledge to give their opin-

ion of the sling placement. This study was a visual as-

sessment. The physicians were not able to palpate the

slings. The rationale for not allowing patients to touch

the slings was that if people pulled on the slings then it

may change their position and/or allow people to figure

out how they wer e placed.

a. retropubic

b. obturator

c. single incision

2) Is the sling the right tension?

a. too tight

b. just right

c. too loose

3) Is the sling located at the mid-urethra or bladder neck? Each physician was asked to respond to 3 questions:

22 S. SERELS

3. Results

3.1. Physician Specialization and Characteristics

Reviewing physicians were gynecolgists or general

urologists of varying specializations. The average num-

ber of slings performed each year was 53, with obturator

and retropubic being the most favoured sling types (Ta-

ble 1). Most physicians preferred the obturator or retro-

pubic slings. Markedly fewer physicians used all three

techniques or a combination of obturator plus retropu-

bic/single incision techniques.

3.2. Physician Review

Less than half of the physicians (40%, 43%, 23%; Fig-

ure 3) were able to correctly identify the sling placement

used in each cad aver, and were least likely to id entify th e

single incision sling placement (23%). The single inci-

sion sling, in which the tension was not set with a spacer,

was thought to have the most appropriate tension (73%

tension just right versus 33% retropubic and 47% obtu-

rator). Furthermore, the single incision sling was identi-

fied more often (83%) as placed at the mid-urethra,

compared to the retropubic (50%) and the obturator

(67%) (Figure 3).

4. Discussion

Urinary incontinence is a common problem in adult

women, with SUI the most common form. Treatment

options for SUI in women are designed to prevent the

involuntary loss of urine during increases in intraab-

dominal pressure.

The retropubic sling has reported success rates of 80%

- 89%, but requires blind passage through the retropubic

space, posing risks for bowel injury, bladder injury, ma-

jor vascular injury, and nerve injury [3,4].The tran-

Table 1. Backgroud Information regarding the surgeons

that participated in this study.

Characteristics Reviewing Physicans

N = 30

Specialty, n (%)

General Urology 5 (17)

Gynecology 18 (60)

Urogynecology 7 (23)

Preferred Sling Type, n (%)

Retropubic 11 (37)

Transobturator 13 (43)

Single Incision 2 (7)

Retropubic and Transobturator 1 (3)

Retropubic and Single incisi o n 1 (3)

All Slings 1 (3)

No Preference 1 (3)

Number of Slings Placed per Year

Mean 53

Min 0

Max 200

Figure 3. Physician assessment of sling tec hnique , tension, and placement.

S. SERELS

sobturator, by contrast, avoids the retropubic space,

decreasing complications such as bladder and bowel

s being different than the retropu-

ferent than the other c

ten-

experience. Taken together, these data seem to initially

dispel some of the previously held misconceptions of

d the single-incision sling as tensioned

. Lose, D. Sykes, et al., “The Prevalence

continence in Women in Four European

he British Association of Urological

93, 2004, pp. 324-330.

ternational Urogynecology Journal and

injuries and is as efficacious as the retropubic method

with a reduction in adverse events [8-10]. Single inci-

sion slings provide the latest advance in midurethral

tensionless sling technology and require only one small

vaginal incision placed beneath the urethra thereby po-

tentially reducing post-operative pain and risk of com-

plications. However, minimal data are currently avail-

able on the long-term efficacy and safety of the sin-

gle-incision method.

Our ex per ie nce h as b een tha t most physicians view the

single incision sling a

c or transobturator slings. Furthermore, physicians of-

ten describe the single-incision as a “tight” sling. This

association of “tight” with the single-incision sling is

based primarily on perceived placement methodology,

and not on actual tensioning tests. For example, the ten-

sion of the single-incision sling is achieved by pushing

the sling into tissue rather than pulling up on it as is do ne

for the retropubic and transobturator slings. When the

coverings are taken off and any spacing devices are re-

moved from the multi-incision slings, there is further

retraction that occurs. Thus, the initial placement of the

multi-incision sling changes and the sling tightens a

small amount. In contrast, placement of the single inci-

sion sling does not change, and the site of the sling dur-

ing tensioning is where it remains. As a result, the sin-

gle-incision sling may seem slightly tighter on initial

placement, but appears the same as the others when the

sling is in its final position.

The purpose of this study was to determine if the sin-

gle-incision sling looks difom-

only used retropubic and obturator slings, and to de-

termine which of the three slings was identified by

trained physicians as being most correctly tensioned at

the mid urethra. The results showed that well-trained,

experienced incontinence surgeons could not visually

differentiate between sling placement methodologies.

Less than half of the physicians (40%, 43%, 23%) were

able to correctly identify the sling placement used, and

were least likely to be able to identify a single-incision

sling placement (23% correctly identified).

Furthermore, the results showed that the single inci-

sion sling was identified as having the most correct

on (73% tension just right versus 33% retropubic and

47% obturator) and the most correct mid-urethral posi-

tioning (83% versus 50%retropubic and 67% obturator).

Of note, 6 physicians who were highly experienced in

sling placement (> 100 procedures/year each). There

were no clear trends in the ability to appropriately iden-

tify the sling placement method used based on physician

how a single-incision sling differs from multi-incision

sling procedures and indicate that the biases toward the

single incision sling typically voiced by practicing phy-

sicians seem to be rooted in preconceived misconcep-

tions and not on actual results, regardless of experience

or specialty.

Conclusions: This study showed that after placement

of a midurethral synthetic sling it is difficult to deter-

mine the placement method used and that most physi-

cians assesse

ost appropriately and most likely positioned at the

mid-urethra.

5. Acknowledgements

This study was supported by an unrestricted grant from

Boston Scientific.

6. References

[1] S. Hunskaar, G

of Urinary In

Countries,” Journal of t

Surgeons, Vol.

[2] P.E Petros and U. Ulmsten, “An Integral Theory of

Female Urinary Incontinence,” Acta Obstetricia et

Gynecologica Scandinavica, Supplement 153, Vol. 69,

1990, pp. 7-31.

[3] C. G. Nilsson, N. Kuuva, C. Falconer, et al., “Long-Term

Results of the Tension-Free Vaginal Tape (TVT)

Pr oc ed ur e for Surgical Treatme nt of Female Stress Urinary

Incontinence,” In

Pelvic Floor Dysfunction, Supplement 2, Vol. 12, 2001,

pp. S5-S8. doi:10.1007/s001920170003

[4] K. L. Ward and P. Hilton, “UK and Ireland TVT Trial

Group. Tension-Free Vaginal Tape Versus Colposuspension

for Primary Urodynamic Stress Incontinence: 5-Year

Follow Up,” BJOG, Vol. 115, No. 2, 2008, pp. 226-233.

doi:10.1111/j.1471-0528.2007.01548.x

[5] V. W. Sung, M. D. Schleinitz, C. R. Rardin, et al.,

“Com parison of Retropubic versus Transobturator Approach

to Midurethral Slings: A Systematic Review and Meta-

Analysis,” American Journal of

Obstetrics and

Gynecology, Vol. 197, No. 1, 2007, pp. 3-11.

doi:10.1016/j.ajog.2006.09.025

[6] A. C. Wang, “The Techniques of Trocar Insertion and

Intraoperative Urethrocystoscopy in Tension-Free

Vaginal Taping: An Experience of 600 Ca

Obstetricia et Gynecologica Scases,” Acta

ndinavica, Vol. 83, No. 3,

6-1313.

2004, pp. 293-298.

[7] E. Delorme, “Transobturator Urethral Suspension: Mini-

Invasive Procedure in the Treatment of Stress Urinary

Incontinence in Women [in French],” Prog Urol, Vol. 11,

No. 6, 2001, pp. 130

9/000099337

S. SERELS

[8] W. Al-Singary, I. S. Shergill, S. E. Allen, et al.,

“Transobturator Tape for Incontinence: A 3-Year

Follow-Up,” Urologia Internationalis, Vol. 78, No. 3,

2007, pp. 198-201. doi:10.115

mplications,”

[9] P. M. Latthe, R. Foon and P. Toozs-Hobson,

“Transobturator and Retropubic Tape Procedures in

Stress Urinary Incontinence: A Systematic Review and

Meta-Analysis of Effectiveness and Co

BJOG, Vol. 114, No. 5, 2007, pp. 522-531.

doi:10.1111/j.1471-0528.2007.01268.x

[10] P. Grise, S. Droupy, C. Saussine, et al., “Transobturator

Tape Sling for Female Stress Incontinence with

Polypropy-Lene Tape and Outside-In Procedure:

Prospective Study with 1 Year of Min

and Review of Transob-Turator Tape Sling,” Urology,

Vol. 68, 2006, pp. 759-763.

doi:10.1016/j.urology.2006.04.020

[11] R. Moore, T. Erickson, S. Serels,

Review of Early Experience Usinet al., “Retrospective

g the AMS MiniArc

atment for Female Stress Urinary Inconti-

Single Incision Sling,” Journal of Minimally Invasive

Gynecology, Vol. 14, No. 6, 2007, pp. S129-130

(Abst.357).

[12] R. D. Moore, S. R. Serels and G. W. Davila, “Minimally

Invasive Tre

nence,” Expert Review of Obstetrics & Gynecology, Vol.

3, No. 2, 2008, pp. 257-272.

doi:10.1586/17474108.3.2.257

imal Follow-Up