Histology of the vaginal wall in women with pelvic organ prolapse: a literature review

Introduction and hypothesis

The pathophysiology of pelvic organ prolapse (POP) is incompletely understood. The purpose of this study is to describe the current knowledge about histology of the vaginal wall and its possible involvement in the pathogenesis of pelvic organ prolapse.

Methods

Eligible studies were selected through a MEDLINE search covering January 1986 to December 2012. The research was limited to English-language publications.

Results

Investigations of changes in the vaginal tissue that occur in women with genital prolapse are currently still limited and produced contrary results. The heterogeneity of the patients and the control groups in terms of age, parity and hormonal status, of the localization of biopsies and the histological methods as well as the lack of validation of the quantification procedures do not allow clear and definitive conclusions to be drawn.

Conclusions

This review shows that current knowledge of the histological changes observed in women with POP are inconclusive and relatively limited. More studies are needed in this specific field to better understand the mechanisms that lead to POP.     

Elastin density: Link between histological and biomechanical properties of vaginal tissue in women with pelvic organ prolapse?

Introduction and hypothesis

The aim of the study was to correlate histological and biomechanical characteristics of the vaginal wall in women with pelvic organ prolapse (POP).

Methods

Tissue samples were collected from the anterior [point Ba; POP Questionnaire (POP-Q)] and/or posterior (point Bp; POP-Q) vaginal wall of 15 women who underwent vaginal surgery for POP. Both histological and biomechanical assessments were performed from the same tissue samples in 14 of 15 patients. For histological assessment, the density of collagen and elastin fibers was determined by combining high-resolution virtual imaging and computer-assisted digital image analysis. For biomechanical testing, uniaxial tension tests were performed to evaluate vaginal tissue stiffness at low (C₀) and high (C₁) deformation rates.

Results

Biomechanical testing highlights the hyperelastic behavior of the vaginal wall. At low strains (C₀), vaginal tissue appeared stiffer when elastin density was low. We found a statistically significant inverse relationship between C₀ and the elastin/collagen ratio (p?=?0.048) in the lamina propria. However, at large strain levels (C₁), no clear relationship was observed between elastin density or elastin/collagen ratio and stiffness, likely reflecting the large dispersion of the mechanical behavior of the tissue samples.

Conclusion

Histological and biomechanical properties of the vaginal wall vary from patient to patient. This study suggests that elastin density deserves consideration as a relevant factor of vaginal stiffness in women with POP.

     

Biomechanical properties of prolapsed or non-prolapsed vaginal tissue: impact on genital prolapse surgery

Introduction and hypothesis  

Our aim is to characterize prolapsed and non-prolapsed vaginal tissue, and thus offer a better understanding of the genital prolapse physiopathology and an improvement of surgical treatments.     

Biomechanical properties of vaginal tissue. Part 1: new experimental protocol

PURPOSE: We established a reliable experimental protocol to characterize the biomechanical properties of vaginal tissue and guarantee good test repeatability. MATERIALS AND METHODS: Because of the large quantities of tissue required to establish the protocol, we worked on ewes according to animal ethics laws. To study the mechanical properties of ewe vaginal tissue we used unidirectional tension tests at a constant deformation rate. Rupture tests were performed under different experimental conditions to analyze the influence of each condition. RESULTS: Tissue underwent exhaustive tests. The parameters studied were sampling, freezing, preservation conditions, hygrometry and temperature during vaginal tissue tests, and the rate of deformation during tests. As previously noted, vaginal tissue is anisotropic and the collection has been tested previously. We noted that freezing tissue had no consequences on the mechanical response of tissue during unidirectional tension testing. The experimental conditions that we defined (temperature, hygrometry and rate of deformation) allowed us to have reproducible tests. CONCLUSIONS: Results and analyses allowed us to determine the best reference protocol.     

Pulse transit time improves detection of sleep respiratory events and microarousals in children

OBJECTIVES: To evaluate the additional information provided by pulse transit time (PTT), a noninvasive tool, when using during polysomnography for the diagnosis of sleep breathing disorders in a pediatric population. MAIN FINDINGS: Respiratory and microarousals events were scored twice. The first scoring was performed using nasal pressure, thermistors, thoracic and abdominal movements, and oxygen saturation. The second scoring, blinded to the first scoring, was performed using PTT in combination with all the other signals. Microarousals were scored once visually on the EEG trace (cortical arousals [CAs]) and once using the PTT signal (autonomic arousals [AAs]) blinded to EEG. For the whole group of 16 children studied (mean age, 9.5 years), there was no significant difference between the respiratory disturbance index (RDI) with or without PTT analysis (22.4 +/- 13.5/h vs 20.4 +/- 14.3/h; not significant [mean +/- SD]). Among the children exhibiting a "without PTT" RDI < 30/h, 5 of 12 children (41.66%) showed a clinically significant >/= 5/h increase in RDI when using PTT. AAs detected by PTT were significantly more frequent than CAs during rapid eye movement (REM) sleep (7.4 +/- 3.9/h vs 3.2 +/- 2.3/h; p < 0.001) and slow wave sleep (SWS) [6.0 +/- 4.3/h vs 0.6 +/- 0.5/h; p < 0.0001]. CONCLUSIONS: The quantification of respiratory effort using PTT improves the detection of respiratory events in children. The detection of microarousals is improved particularly in REM and SWS.     

Feasibility and benefits of the ewe as a model for vaginal surgery training

Introduction and hypothesis

The objective was to evaluate the ewe as an animal model for teaching and training in vaginal surgery.

Methods

Twenty-nine postgraduate surgeons attended a training course on vaginal prolapse surgery. After a review of human and sheep anatomy, the participants performed transvaginal meshes, vaginal hysterectomy, SSLF (Richter), and OAS repair in ewes and human cadavers. Participants completed questionnaires on the whole course.

Results

Questionnaires showed the significant superiority of ewes over human cadavers for all items evaluated regarding surgical dissections. Only identification of the sacrospinous ligament and the spine were judged to be similar in ewes and human cadavers. Participants noticed that ewe model is appropriate for vaginal prolapse surgery training for resident and for postgraduate surgeons. Two vaginal hysterectomies were also performed. Operating time, surgery, and anatomy were nearly identical to that of humans. The same conclusions were made while performing sacrospinous ligament fixation (Richter) and obstetric anal sphincter injury repair.

Conclusion

This series indicates that the ewe is a useful animal model for teaching vaginal surgery.