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abstract

111 - DISSECTING OF THE PARAVESICAL SPACE IN PELVIC SURGERY WOULD RESULT IN LOWER URINARY TRACT DYSFUNCTION - A RAT MODEL

111

DISSECTING OF THE PARAVESICAL SPACEIN PELVIC SURGERY WOULD RESULT IN LOWER URINARY TRACT DYSFUNCTION - ARAT MODEL

T. LO1, Y. LIN 2,M. UY-PATRIMONIO 3, W. HSIEH 4;
1ChangGung Mem. Hosp., Keelung, Taiwan, 2Obstetrics andgynecology, Chang Gung Mem. Hosp., Tao-Yuan, Taiwan, 3Dr.Pablo O. Torre Mem. Hosp., Talisay City, Philippines, 4ChangGung Mem. Hosp., Tao-Yuan Hsien,, Taiwan.

Introduction: Incidence ofpostoperative de novo SUI after extensive pelvic reconstructivesurgery (PRS) was reported to be 11 %.1 The odds ratiorelated to various types of surgical mesh procedures withsacrospinous ligament fixation (SSF) were: Perigee mesh 0.95,Avaulta A 0.91, Prolift T 3.50 and Elevate A 3.48.1High occurrence of post-operative de novo SUI was found in specifictype of surgeries involving opening of the paravesical fossaextending to the sacrospinous ligament bilaterally which may causemore tissue damage and denervation in comparison with SSF, Perigeeand Avaulta A. The latter surgeries only need limited area of tissuedissection that might explain why there were less de novo SUI. Ananimal model is necessary to test the hypothesis that opening theparavesical space causes lower urinary tract dysfunction (LUTS) afterprolapse surgery.
Objective: We hypothesize that opening ofthe paravesical space during dissection in pelvic surgeries wouldresult in lower urinary tract dysfunction especially de novoSUI.
Methods: Thirty five female Sprague Dawley (SD) ratswere divided into 5 groups of 7 rats each. The Group-1 was thecontrol group where no surgery was done but only has UDs andimmunohistochemical study. The Group-2 & -3 were Sham groups(Sham-F & Sham-H), wherein anterior colporrhaphy were done. TheGroup-4 & -5 were Study groups (Study-M-F & Study-M-H),wherein synthetic mesh were implanted between vagina and bladder ofSD rats. The difference between Sham-F & Sham-H, as well asStudy-M-F & Study-M-H was the opening of the paravesical space.Sham-H had anterior colporraphy only; Sham-F had anterior colporraphywith paravesical space opened; Study-M-H had vaginal mesh implanted;and Study-M-F had vaginal mesh implanted into paravesical space.Procedure starts with hydrodissection (normal saline, 0.5- 1.0cc) atthe anterior vaginal wall followed by a 1 cm midline incision, thenopening of the space between the vagina and bladder. A polypropylenemesh of 0.5 x 0.5 cm and 0.5 x 1.5 cm in size were inserted for theStudy-M-H and Study-M-F groups respectively. The Sham groups hadsimilar surgeries except that no mesh were implanted. Moreover, theparavesical space was opened and dissected on the Study-M-F andSham-F groups. The vaginal mucosa was closed with Polyglactin 5/0suture. The rats were sacrificed immediately after UDs on day 40 forsham and study groups. Mesh with the underlying vaginal and bladderwall was removed. The outcome measures were the density ofinflammatory reaction produced by the Interleukin-1 (IL-1), TumourNecrosis Factor-α (TNF-α), Nerve Growth Factor (NGF) and Matrixmetalloproteinases (MMPs) around the surgical site/area of implantsand their association with the functional urodynamic investigation ofthe SD rats. ANOVA and Fisher exact test were applied for comparisonof categorical data and periods. p <0.05 were consideredstatistically significant for all comparisons.
Results: Allrats survived with no complications observed during the postimplantation period. Both the Sham-F and Study-M-F groups on day 40had a significantly lower value on leak point pressure (LUPP) whencompared to Sham-H, Study-M-H and control groups. The Sham-F andStudy-M-F have similar features where paravesical space had beenopened bilaterally. Meanwhile, Study-M-F on day 40 had significantshorter voiding interval when compared to control (P = 0.005). Theother UDs data showed no difference in the voiding pressure (VP),voiding interval (VI) and voiding volume (VV) between groups on day40 and within the study groups. Histological examinations showedintense inflammatory reaction on day 40 in the study groups ascompared to control. The IL-1, TNF-α, MMP-2, NGF and CD31 on day 40in all group except Study-M-F were observed to return to almostnormal when compared to control.
Conclusions: The lowerlevels of LUPP and higher levels of immunohistochemical data afterparavesical space opening procedure imply greater incidence of denovo SUI surgery than those procedure that does not involve openingof the para-vesical space.
References: 1. Lo TS, Karim NB,Nawawi EA, Wu PY, Nusee Z. Predictors for de novo stress urinaryincontinence following extensive pelvic reconstructive surgery. IntUrogynecol J. 2015 Sep;26(9):1313-9