Effects of vaginal distension on urethral anatomy and function

Abstract

Objective To determine the effect of repeated and prolonged vaginal distension on the leak‐point pressure (LPP) and urethral anatomy in the female rat, as prolonged vaginal distension has been clinically correlated with signs of stress urinary incontinence (SUI). Materials and methods Sixty female rats were placed into one of five groups; four groups underwent one of four vaginal distension protocols using a modified 10 F Foley catheter, i.e. prolonged (1 h), brief (0.5 h), intermittent (cycling inflated/deflated for 0.5 h) or sham distension. All animals had a suprapubic bladder catheter implanted 2 days after and were assessed urodynamically 4 days after vaginal distension. The fifth group of rats acted as controls and did not undergo vaginal distension, but did have a suprapubic bladder catheter placed and urodynamics assessed. To measure LPP the rats were anaesthetized with urethane, placed supine and the bladder filled with saline (5 mL/h) while bladder pressure was measured via the bladder catheter. LPPs were measured three times in each animal by manually increasing the abdominal pressure until leakage at the urethral meatus, when the external abdominal pressure was rapidly released. Peak bladder pressure was taken as the LPP and a mean value calculated for each animal. Immediately after measuring LPP the urethra was removed and processed routinely for histology (5 µm sections, stained with haematoxylin/eosin and trichrome). The means ( sem ) were compared using a Kruskal–Wallis one‐way anova on ranks, followed by a Dunn's test, with P < 0.05 indicating a significant difference. Results Both LPP and the external increase in abdominal pressure were significantly lower after prolonged distension, at 31.4 (1.7) and 19.8 (1.2) cmH 2 O, than in the sham group, at 41.1 (3.2) and 32.0 (4.7) cmH 2 O, respectively. There were no significant differences in LPP or in the increase in abdominal pressure between the brief, intermittent and sham groups. Qualitative histology showed that prolonged distension resulted in extensive disruption and marked thinning of urethral skeletal muscle fibres. Brief and intermittent distension showed mild and focal disruptions, respectively. Conclusions As observed clinically, prolonged vaginal distension results in a lower LPP, greater anatomical injury and increased severity of SUI. These results suggest that ischaemia is important in the development of SUI after prolonged vaginal distension.

Animal Models of Female Stress Urinary Incontinence

“…In addition, they have previously reported that a lesser duration of VD or intermittent cycling VD does not result in changes in urethral resistance. 24 Active middle urethra sneeze induced reflex responses are present but decreased by approximately 50% after simulated childbirth injury (VD) in rats. 26 However, they were increased by intravenous nisoxetine and decreased by intrathecal phentolamine and prazosin, suggesting that this injury simulates clinical SUI and it may be treatable with a norepinephrine reuptake inhibitor.…”

Qualidade de vida de mulheres com incontinência urinária

“…Apresentam-se na Tabela Entre os fatores que podem estar associados à incontinência urinária por esforço é a deficiência esfincteriana uretral intrínseca, aumento da pressão intraabdominal, período gestacional, elevado número de partos, trauma obstétrico, obesidade, tabagismo, doenças neurológicas, doenças respiratórias crônicas e tratamentos cirúrgicos ginecológicos (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24) . A mulher incontinente, principalmente as casadas ou com vida sexual ativa, sofrem grande impacto na sua qualidade de vida, porque estão sempre com medo ou com receio de perder urina em certas situações como durante a relação sexual, quando sentem receio de As infecções urinárias de repetição provocam a urgeincontinência (3) .…”

“…Ainda, alterações anatômicas podem provocar a IU como a hipermobilidade da uretra e deficiência esfincteriana (3,14) , modificações do assoalho pélvico (15) , distensões nas fibras musculares da uretra (7) e instabilidade do músculo detrusor da bexiga urinária (4,16) .…”

Effect of vaginal distention on elastic fiber synthesis and matrix degradation in the vaginal wall: potential role in the pathogenesis of pelvic organ prolapse

“…A similar distention protocol was used as above, except 400 l of saline was injected in the balloon due to the animals' smaller size. The previously validated Mouse Pelvic Organ Quantification (MOPQ) exam was used to measure the degree of vaginal, perineal, and anal prolapse in all animals preoperatively and then on postoperative days 3,6,10,14, and continued weekly until postoperative day 98 (i.e., 14 wk after the distention, or 20 wk of age). The MOPQ was completed by having one investigator hold the animal by the scruff of the neck, which resulted in a prolonged, reflex valsalva (evidenced by defecation), while the other investigator performed the measurements using a caliper with the precision of 1/100th of a millimeter.…”