ARE THE SAME TAPES REALLY THE SAME?- ULTRASOUND STUDY OF LASER CUT AND MECHANICALLY CUT TVT-OPOST-OPERATIVE BEHAVIOR
Z. RUSAVY1, J. MASATA2, K. SVABIK 2, P. HUBKA 2, A.MARTAN 2;
1Dpt. of Obstet. and Gynecol.,Med. Faculty in Pilsen, Charles Univ., Prague, Czech Republic, 2Dpt.of Obstet. and Gynecol., 1st Faculty of Med., Charles Univ., Prague,Czech Republic.
Introduction: Tension freevaginal tape is currently considered the golden standard of surgicaltreatment for stress urinary incontinence. It has been demonstratedthat different polypropylene tapes may have different biomechanicalproperties and different outcomes. In order to prevent flaking at theedges of the mesh, the manufacturer of the TVT-O polypropylene tapemodified the production by laser cutting rather than mechanicalcutting. In spite of the fact that the elongation properties shouldbe identical according to the manufacturer, we have noticeddifferences in the TVT-O tape behavior after implantation onretrospective evaluation of two randomized controlled trials fromdifferent time periods. From medical records we found that in onestudy mechanically cut and in the second study laser cut tapes wereused.
Objective: To compare behavior of the laser cut andmechanically cut TVT-O tape using ultrasound at various time pointsafter the surgery.
Methods: This is a secondary analysis ofprospectively collected data from two previously published studiesusing TVT-O in one of the study arms. Mechanically cut TVT-O tapeswere implanted in a standardized manner between January 2007 andNovember 2009, while the laser cut TVT-O between May 2010 and May2012. Subsequently, the women were followed with ultrasound at day 1,2nd week, 3rd month, and 1st and 2nd year after the surgery. Theurinary bladder was filled to 300 ml with sterile saline prior toeach ultrasound examination. The measurements were taken in supineposition at rest and during maximal Valsalva. The position of thebladder neck and of the upper and lower tape margins was described bycoordinates in the orthogonal system, which were calculated frompolar coordinates. The tape mobility was assessed as the change inthe position of the upper and lower tape margin. The differencebetween the mobility of the laser cut and mechanically cut TVT-O wasstatistically evaluated. The fact that the two tape margins were notindependent was taken into consideration. A 2-year subjective andobjective surgery outcomes were additionally compared.
Results:A total of 68 mechanically-cut and 50 laser-cut TVT-O tapes wasimplanted in both studies. The women did not differ in any baselinecharacteristics including age, BMI, parity, mixed urinaryincontinence and urgency, urodynamic results, ICIQ, iQoL, bladderneck position and urethral mobility. A statistically significantlylower tape mobility was observed on day 1 and week 2 after thesurgery in the mechanically cut TVT-O, which subsequently increasedto comparable mobility as the laser cut TVT-O. Since the laser cutTVT-O was implanted more loosely, the tape mobility was comparablesince the 3-month follow-up visit (Table 1, Graph 1). The subjectiveand objective surgery outcomes were comparable.
Upperand lower TVT-O tape margin mobility
Uppertape margin mobility at day 1, [mm]
Lowertape margin mobility at day 1, [mm]
Uppertape margin mobility at week 2, [mm]
Lowertape margin mobility at week 2, [mm]
Uppertape margin mobility at month 3, [mm]
Lowertape margin mobility at month 3, [mm]
Uppertape margin mobility at year 1, [mm]
Lowertape margin mobility at year 1, [mm]
Uppertape margin mobility at year 2, [mm]
Lowertape margin mobility at year 2, [mm]
Conclusions: Our datademonstrate that even the same TVT-O tape from the same manufacturermay have different biomechanical properties after a modification inproduction occurs. Clinically it was observed that when a laser-cuttape was tensioned equally as the mechanically cut tape there was anincreased risk of urinary retention. Our data suggest that moreelastic mechanically-cut TVT-O would get stretched after implantationdue the load from the intraabdominal pressure. The less elasticlaser-cut TVT-O will keep its shape and will not undergo anyloosening in the first weeks after the surgery. The surgeon shouldbear in mind that elasticity of the tape in important for itsbehavior within the first three months after implantation and adjusttensioning accordingly to avoid urinary retention using the tape withlower elasticity or failure following the tape with higherelasticity.