Female urology

Petrou, Steven P.

doi:10.1590/S1677-55382004000200022

UROLOGICAL SURVEY

Female urology

The tensile properties of tension-free vaginal tape and cadaveric fascia lata in an in vivo rat model

Spiess PE, Rabah D, Herrera C, Singh G, Moore R, Corcos J

Department of Urology, McGill University, Montreal, Canada

BJU Int. 2004;93: 171-3

OBJECTIVE: To examine the tensile properties (break load and maximum average load), after in vivo implantation in a rat animal model, of tension-free vaginal tape (TVT) and cadaveric fascia lata (CFL), as pubovaginal slings of these materials have become popular for treating stress urinary incontinence.

MATERIALS AND METHODS: Twenty Sprague-Dawley rats (300-400 g) had 1 x 2 cm strips of commercially available TVT and CFL implanted on the right and left anterior abdominal wall, respectively. Half of the animals were then killed at 6 weeks and the remainder at 12 weeks, after which the strips of TVT and CFL were removed and their tensile properties measured using a tensiometer. The tensile strength of TVT and CFL strips maintained only in normal saline served as controls.

RESULTS: The TVT strips had a mean break load of 0.740 kg in the control and only 0.390 kg for CFL (P < 0.05). At 6 weeks the TVT material had a mean (sd) maximum average load of 0.634 (0.096) kg and a mean break load of 0.589 (0.249) kg, whereas the respective values for the CFL were 0.323 (0.198) and 0.167 (0.063) kg (P < 0.05). Similarly at 12 weeks, TVT had a greater mean maximum average and break load than CFL, at 0.742 (0.052) and 0.274 (0.126), and 0.737 (0.056) and 0.185 (0.128) kg, respectively.

CONCLUSION: This is the first study to assess the tensile properties of the currently used sling materials, TVT and CFL, in an in vivo model. TVT has a greater break load and maximum average load than CFL; the tensile strength of these materials does not decrease with time.

Editorial Comment

The authors measure and compare the tensile properties of commercially available synthetic polypropylene mesh and cadaveric fascia lata after 6-12 weeks of in vivo implantation. Their description and quantification of the temporally associated comparative changes of these materials help shed light on one of the potential causes of failures of suburethral slings using cadaveric fascia lata. The implantation site was abdominal which does raise the spector of a possible different induced tissue change or alteration had the materials been placed in the suburethral area (a site oft plagued with postoperative bleeding). This study does highlight the long-term durability of the polypropylene mesh without an associated potential genetic contamination. The interested urologist looks forward to the author's promised further long-term studies utilizing this clinical, experimental model.

Dr. Steven P. Petrou

Associate Professor of Urology

Mayo Medical School

Jacksonville, Florida, USA

Cesarean section: does it really prevent the development of postpartum stress urinary incontinence? A prospective study of 363 women one year after their first delivery

Groutz A, Rimon E, Peled S, Gold R, Pauzner D, Lessing JB, Gordon D

Urogynecology and Pelvic Floor Unit, Department of Obstetrics and Gynecology, Lis Maternity Hospital, Tel Aviv Sourasky Medical Center, affiliated to the Sackler School of Medicine, Tel Aviv University, Israel

Neurourol Urodyn. 2004; 23: 2-6

AIMS: Stress urinary incontinence (SUI) in young women is usually the result of pelvic floor injury during vaginal delivery. Whether cesarean section delivery may prevent such injury is questionable. We undertook a prospective study to compare the prevalence of SUI among primiparae 1 year after spontaneous vaginal delivery versus elective cesarean section, or cesarean section performed for obstructed labor.

METHODS: Three hundred and sixty-three consecutive primiparae were recruited immediately after delivery and were followed for 1 year. Women were asked upon recruitment whether they had ever experienced SUI before pregnancy. Those who had SUI before pregnancy were excluded. Thus, only cases of de novo childbirth-associated SUI were analyzed. Patients were divided into three subgroups according to the mode of delivery: spontaneous vaginal delivery (n = 145), elective cesarean section (n = 118), and cesarean section performed for obstructed labor (n = 100). Patients who underwent elective cesarean section were not given a trial of labor. Cesarean sections for obstructed labor were performed at a mean cervical dilatation of 8.7 +/- 1.6 cm and arrest of 184 +/- 24 min. Prevalence, frequency, and severity of postpartum SUI, as well as demographic and obstetric parameters, were analyzed in each subgroup.

RESULTS: The three subgroups were comparable with respect to maternal age, weight, and height. Prevalence of postpartum SUI was similar after spontaneous vaginal delivery (10.3%) and cesarean section performed for obstructed labor (12%). However, SUI was significantly less common following elective cesarean section with no trial of labor (3.4%, P < 0.05). Approximately half of the symptomatic patients in each subgroup reported either moderate or severe symptoms, however, only 15-18% expressed their desire for further evaluation.

CONCLUSIONS: Prevalence of postpartum SUI is similar following spontaneous vaginal delivery and cesarean section performed for obstructed labor. It is quite possible that pelvic floor injury in such cases is already too extensive to be prevented by surgical intervention. Conversely, elective cesarean section, with no trial of labor, was found to be associated with a significantly lower prevalence of postpartum SUI. Whether the prevention of pelvic floor injury should be an indication for elective cesarean section is yet to be established.

Editorial Comment

The authors attempt to illuminate the timing and role of cesarean section with regard to postpartum stress urinary incontinence by examining a study population divided into three subgroups. The first group being 145 primiparae women who underwent spontaneous vaginal delivery, the second group being 118 primiparae women who underwent selective cesarean section and a the third group of 100 primiparae women who underwent cesarean section for obstructed labor. The authors, in their paper, come to a clearly defined conclusion that childbirth induced stress urinary incontinence is best prevented through elective cesarean section prior to the onset of labor. In addition, it is noted in the report that cesarean section performed for obstructed labor was not associated with a diminished incidence of postoperative stress urinary incontinence. They also found that patients who have new onset stress urinary incontinence during pregnancy will have an increased risk of stress urinary incontinence at one year postpartum measurements.

The authors should be commended for this excellent paper for it is noteworthy in that it compares cesarean section performed before and after obstructed labor and contrasts the results of same. Urologists are often asked by female patients whether having a cesarean section may help them avoid incontinence later in life; this paper answers that question.