Cardinal and deep uterosacral ligament lines of action: MRI based 3D technique development and preliminary findings in normal women

INTRODUCTION AND HYPOTHESIS

The cardinal ligament (CL) and deep uterosacral ligament (US) play a critical role in utero-vaginal support. This study aims to quantify their geometrical relationships in living women using a MRI-based 3D technique.

METHODS

The angles between ligaments, the ligaments length and curvature were assessed on 3D models constructed from twenty MRIs of volunteers with normal support. How angle variation theoretically affects ligament tension was investigated using a simplified biomechanical model.

RESULTS

The CLs are 18.1 ° ± 6.8 °(SD) from the cephalic-caudal body axis , and the USs are dorsally directed and 92.5 ° ± 13.5 from the body axis. The CLs are longer and more curved than US. The theoretical calculated tension on CL is 52 % larger than that on US.

CONCLUSIONS

The CL is relatively parallel to the body axis while the US is dorsally directed. The tensions on these ligaments are affected by their orientations.

Self-reported natural history of recurrent prolapse among women presenting to a tertiary care center

OBJECTIVE

To describe the characteristics of recurrent pelvic organ prolapse (POP).

METHODS

A convenience sample of patients presenting with recurrent POP symptoms between October 2007 and February 2010 completed questionnaires. The survey focused on timing of recurrence(s), symptoms, and demographics.

RESULTS

Ninety-seven women completed questionnaires. Thirty-four (35.1%) had undergone multiple prior treatments. Overall, 23 of 76 (30.3%) women had not informed their surgeon of the recurrence. Twenty-seven of 59 (45.8%) women reported that their symptoms were the same as before treatment, whereas 23 of 59 (39.0%) reported more severe symptoms. POP was considered to be persistent if symptoms returned within 3 months, and recurrent if symptom relief exceeded 3 months. After primary surgery, 28 of 79 (35.4%) cases were considered to be persistent, whereas 51 (64.6%) cases were recurrent. Similar percentages were seen after second and third treatments.

CONCLUSION

Overall, 35% of participants experienced early return of symptoms. Almost one-third of participants had not informed their surgeon of the recurrence, indicating that there may not be an accurate self-assessment of outcome in the absence of careful follow-up.

A comparison of the effect of age on levator ani and obturator internus muscle cross-sectional areas and volumes in nulliparous women

AIMS

Functional tests have demonstrated minimal loss of vaginal closure force with age. So we tested the null hypotheses that age neither affects the maximum cross-sectional area (CSA) nor the volume of the levator muscle. Corresponding hypotheses were also tested in the adjacent obturator internus muscle, which served as a control for the effect of age on appendicular muscle in these women.

METHODS

Magnetic resonance images of 15 healthy younger (aged 21-25 years) and 12 healthy older nulliparous women (aged >63 years) were selected to avoid the confounding effect of childbirth. Models were created from tracing outlines of the levator ani muscle in the coronal plane, and obturator internus in the axial plane using 3D Slicer v. 3.4. Muscle volumes were calculated using Slicer, while CSA was measured using Imageware™ at nine locations. The hypotheses were tested using repeated measures analysis of variance with P < 0.05 being considered significant.

RESULTS

The effect of age did not reach statistical significance for the decrease in levator ani muscle maximum CSA or the decrease in volume (4.3%, P = 0.62 and 10.9%, 0.12, respectively). However, age did significantly adversely decrease obturator internus muscle maximum CSA and volume (24.5% and 28.2%, P < 0.001, respectively). Significant local age-related changes were observed dorsally in both muscles.

CONCLUSIONS

Unlike the adjacent appendicular muscle, obturator internus, the levator ani muscle in healthy nullipara does not show evidence of significant age-related atrophy.

Measurement of the 3D geometry of the fascial arches in women with a unilateral levator defect and "architectural distortion"

INTRODUCTION AND HYPOTHESIS

The arcus tendineus fascia pelvis (ATFP) and arcus tendineus levator ani (ATLA) are elements of anterior vaginal support. This study describes their geometry in women with unilateral levator ani muscle defects and associated "architectural distortion."

METHODS

Fourteen subjects with unilateral defects underwent MRI. 3D models of the arcus were generated. The locations of these relative to an ilial reference line were compared between the unaffected and affected sides.

RESULTS

Pronounced changes occurred on the defect sides' ventral region. The furthest point of the ATLA lays up to a mean of 10 mm (p = 0.01) more inferior and 6.5 mm (p = 0.02) more medial than that on the intact side. Similarly, the ATFP lays 6 mm (p = 0.01) more inferior than on the unaffected side.

CONCLUSIONS

The ventral arcus anatomy is significantly altered in the presence of levator defects and architectural distortion. Alterations of these key fixation points will change the supportive force direction along the lateral anterior vaginal wall, increasing the risk for anterior vaginal wall prolapse.

Urethral closure pressures among primiparous women with and without levator ani muscle defects

INTRODUCTION AND HYPOTHESIS

Vaginal birth is an established risk factor for levator ani (LA) defects and incontinence. We hypothesized an association between urethral pressure profiles and LA defects.

METHODS

One hundred sixty primiparous women, 9-12 months postpartum, were assessed with MRI for LA defects, urodynamic testing, and instrumented speculum for vaginal closure force. Urodynamic testing included resting maximal urethral closure pressure (MUCP) and urethral closure pressure with a pelvic floor contraction or Kegel (KUCP). We examined the relationships between MUCP, KUCP, LA defect status, and vaginal closure force.

RESULTS

There was no significant association between MUCP or KUCP in women with and without LA defects (p = 0.94, p = 0.95). Additionally, there was no correlation between MUCP and vaginal closure force (r = 0.06, p = 0.41), and a weak correlation between KUCP and vaginal closure force (r = 0.20, p = 0.01).

CONCLUSIONS

In this population, urethral pressure profiles are unrelated to LA defect status after vaginal birth, indicating that the mechanism responsible for LA damage spares the urethra.

Levator defects affect perineal position independently of prolapse status

OBJECTIVE

The purpose of this study was to determine the effect of levator defects on perineal position and movement irrespective of prolapse status.

STUDY DESIGN

Forty women from an ongoing study were divided into 2 groups of 20 women with and without severe levator defects. Prolapse status was matched between groups, with 50% of the women having stage III or greater anterior wall prolapse. Perineal structure locations were measured against standard axes on magnetic resonance scans at rest, maximum contraction (Kegel), and maximum Valsalva maneuver. Differences in location were calculated and compared.

RESULTS

In women with levator defects, independently of prolapse status: (1) At rest, the perineal body was 1.3 cm, and the anal sphincter was 1.0 cm more caudal (P ≤ .01); at maximum contraction, the perineal body and the anal sphincter were both 1.2 cm more caudal (P ≤ .01); with maximum Valsalva maneuver, the perineal body was 1.3 cm more caudal, and the anal sphincter was 1.2 cm more caudal (P ≤ .01). (2) At rest, the levator hiatus was 0.8 cm larger, and the urogenital hiatus was 1.0 cm larger (P ≤ .01). (3) At rest, the bladder was 0.07 cm more posterior (P ≤ .02); with maximum contraction, it was 1.9 cm lower (P ≤ .02). (4) With maximum Valsalva maneuver, the bladder was 1.5 cm lower and displaced further caudally (P ≤ .03).

CONCLUSION

When we controlled for prolapse, the women with levator defects had a more caudal location of their perineal structures and larger hiatuses at rest, maximum contraction, and maximum Valsalva maneuver.

Structural position of the posterior vagina and pelvic floor in women with and without posterior vaginal prolapse

OBJECTIVE

The objective of the study was to compare pelvic structure location on magnetic resonance imaging (MRI) during maximal Valsalva among women with posterior prolapse and those with normal support.

STUDY DESIGN

Subjects (n=37) had posterior vaginal wall (PVW) prolapse of +1 cm or greater. All underwent midsagittal, dynamic MRI. Structure locations (distal vagina, apex, perineal body, external anal sphincter) were determined. PVW length, levator and urogenital hiatus diameters, and prolapse diameter were measured.

RESULTS

Subjects had more caudal structures (P<.001) and larger hiatus diameters (P<.005); the posterior wall was longer, whereas the straight-line distance between the apex and distal vagina was shorter. In enteroceles, the apex was more ventrally displaced compared with rectoceles (P=.003). Unlike apical descent (r=-0.3; P=.1), PVW length and point Bp were correlated with MRI prolapse size (r=0.5; P=.002; r=0.7; P<.001, respectively).

CONCLUSION

At maximal Valsalva on MRI, structures are more caudal in women with posterior prolapse. The posterior vaginal wall is longer; this length strongly correlates with prolapse size.

Fecal incontinence in older women: are levator ani defects a factor?

OBJECTIVE

We sought to compare pelvic floor structure and function between older women with and without fecal incontinence (FI) and young continent (YC) women.

STUDY DESIGN

YC (n=9) and older continent (OC) (n=9) women were compared to older women with FI (older incontinent [OI]) (n=8). Patients underwent a pelvic organ prolapse quantification, measurement of levator ani (LA) force at rest and with maximum contraction, and magnetic resonance imaging. Displacement of structures and LA defects were determined on dynamic magnetic resonance imaging.

RESULTS

LA defects were more common in the OI vs the YC (75% vs 11%, P=.01) and OC (22%, P=.14) groups; women with FI were more likely to have LA defects than women without (odds ratio, 14.0, 95% confidence interval, 1.8-106.5). OI women generated 27.0% and 30.1% less force during maximum contraction vs the OC (P=.13) and YC (P=.04) groups. During Kegel, OI absolute structural displacements were smaller than in the OC group (P=.01).

CONCLUSION

OI women commonly have LA defects, and cannot augment pelvic floor strength.

Pelvic floor consequences of cesarean delivery on maternal request in women with a single birth: a cost-effectiveness analysis

BACKGROUND

The potential benefit in preventing pelvic floor disorders (PFDs) is a frequently cited reason for requesting or performing cesarean delivery on maternal request (CDMR). However, for primigravid women without medical/obstetric indications, the lifetime cost-effectiveness of CDMR remains unknown, particularly with regard to lifelong pelvic floor consequences. Our objective was to assess the cost-effectiveness of CDMR in comparison to trial of labor (TOL) for primigravid women without medical/obstetric indications with a single childbirth over their lifetime, while explicitly accounting for the management of PFD throughout the lifetime.

METHODS

We used Monte Carlo simulation of a decision model containing 249 chance events and 101 parameters depicting lifelong maternal and neonatal outcomes in the following domains: actual mode of delivery, emergency hysterectomy, transient maternal morbidity and mortality, perinatal morbidity and mortality, and the lifelong management of PFDs. Parameter estimates were obtained from published literature. The analysis was conducted from a societal perspective. All costs and quality-adjusted life-years (QALYs) were discounted to the present value at childbirth.

RESULTS

The estimated mean cost and QALYs were $14,259 (95% confidence interval [CI] $8,964-$24,002) and 58.21 (95% CI 57.43-58.67) for CDMR and $13,283 (95% CI $7,861-$23,829) and 57.87 (95% CI 56.97-58.46) for TOL over the combined lifetime of the mother and the child. Parameters related to PFDs play an important role in determining cost and quality of life.

CONCLUSIONS

When a woman without medical/obstetric indications has only one childbirth in her lifetime, cost-effectiveness analysis does not reveal a clearly preferable mode of delivery.

Why do women have stress urinary incontinence?

This article reviews progress made in understanding the causes of stress urinary incontinence. Over the last century, several hypotheses have been proposed to explain stress urinary incontinence. These theories are based on clinical observations and focus primarily on the causative role of urethral support loss and an open vesical neck. Recently these hypotheses have been tested by comparing measurements of urethral support and function in women with primary stress urinary incontinence to asymptomatic volunteers who were recruited to be similar in age, race, and parity. Maximal urethral closure pressure is the parameter that differs the most between groups being 43% lower in women with stress incontinence than similar asymptomatic women having as effect size of 1.6. Measures of urethral support effect sizes range from 0.5 to 0.6. Because any one objective measure of support may not capture the full picture of urethrovesical mobility, review of blinded ultrasounds of movements during cough were reviewed by an expert panel. The panel was able to identify women with stress incontinence correctly 57% of the time; just 7% above the 50% that would be expected by chance alone, confirming that urethrovesical mobility is not strongly associated with stress incontinence. Although operations that provide differential support to the urethra are effective, urethral support is not the predominant cause of stress incontinence. Improving our understanding of factors affecting urethral closure may lead to novel treatments targeting the urethra and improved understanding of the small but persistent failure rate of current surgery.

Racial differences in bother for women with urinary incontinence in the Establishing the Prevalence of Incontinence (EPI) study

OBJECTIVE

The purpose of this study was to compare differences in degree of bother in black and white women with urinary incontinence (UI).

STUDY DESIGN

A population-based study was conducted in black and white women in Michigan. Participants completed an interview and the Incontinence Impact Questionnaire short form (IIQ-7). Statistical analysis included 2-way analysis of variance for post hoc comparisons of IIQ-7 scores between races at different frequencies, amounts, and types of UI.

RESULTS

Black women with moderate UI had significantly higher IIQ-7 scores than white women (31.4 +/- 3.5 vs 23.7 +/- 1.9; P = .03). Overall, black women with urge incontinence had higher scores than white women (30.5 +/- 4.0 vs 21.0 +/- 3.0; P = .05). After adjustment for severity, black women with urge and mixed incontinence tended to be more bothered (P = .06).

CONCLUSION

With moderate UI (not mild or severe), black women are more bothered than white women. At this discriminatory level of UI severity, racial differences are important, because they may dictate care-seeking behavior.

On the biomechanics of vaginal birth and common sequelae

Approximately 11% of U.S. women undergo surgery for pelvic floor dysfunction, including genital organ prolapse and urinary and fecal incontinence. The major risk factor for developing these conditions is giving vaginal birth. Vaginal birth is a remarkable event about which little is known from a biomechanical perspective. We first review the functional anatomy of the female pelvic floor, the normal loads acting on the pelvic floor in activities of daily living, and the functional capacity of the pelvic floor muscles. Computer models show that the stretch ratio in the pelvic floor muscles can reach an extraordinary 3.26 by the end of the second stage of labor. Magnetic resonance images provide evidence that show that the pelvic floor regions experiencing the most stretch are at the greatest risk for injury, especially in forceps deliveries. A conceptual model suggests how these injuries may lead to the most common form of pelvic organ prolapse, a cystocele.

Fecal incontinence in pregnancy and post partum

OBJECTIVE

To assess the prevalence of fecal incontinence (FI) during pregnancy and post partum, and to determine any associations with demographic and birth variables.

METHODS

Secondary analysis of 240 primiparous women conducted during pregnancy and post partum. Women were asked at various time points if they had lost control over their stool or bowel movements, and if they were practicing Kegel exercises. Associations of bowel symptoms with demographic and birth data were evaluated.

RESULTS

Most participants were white (87%), with a median age of 30 years (range, 18-42 years). Women who reported fecal incontinence at 1 year were more educated than those who did not report it. No other demographic or birth data were associated with fecal incontinence at 1 year.

CONCLUSIONS

Prevalence of FI during pregnancy and post partum is low and not linked to low-risk birth. Furthermore, when FI occurs it is often sporadic. This should be reassuring to patients and providers alike.

The association of Incontinence Symptom Index scores with urethral function and support

OBJECTIVE

The objective of this study was to establish categories of symptom severity based on Incontinence Symptom Index (ISI) scores and to show how these categories are associated with urethral function and support.

STUDY DESIGN

Women with stress incontinence (n = 97) and asymptomatic controls (n = 98) completed the ISI. Asymptomatic women's scores were between 0 and 6; this range was designated as absent/mild (n = 104). The median score for symptomatic women was 16; scores from 7 to 16 (n = 50) were designated as moderate, and scores of 17 or greater (n = 40) were designated as severe.

RESULTS

Urethral function differed in women with mild, moderate, and severe scores: Valsalva leak point pressure (162.3 vs 123.5 vs 101.9 cm H(2)O; P = .001), cough leak point pressure (202.0 vs 163.0 vs 134.3 cm H(2)O; P = .001), and maximum urethral closure pressure (69.1 vs 44.1 vs 35.3 cm H(2)O; P = .001). Loss of urethrovesical support (point Aa: -1.0 vs -0.6 vs -0.5 cm; P = .004) was found in women with moderate and severe symptoms, compared with those with mild symptoms.

CONCLUSION

Categories of symptom severity assessed by the ISI are associated with urethral function and support.

Complications requiring reoperation following vaginal mesh kit procedures for prolapse

OBJECTIVE

The objective of the study was to the characterize the symptoms and management of vaginal mesh-related complications requiring operative intervention.

STUDY DESIGN

This was a case series of patients undergoing excision of vaginal graft material. Only women who had vaginal mesh placement for the correction of pelvic organ prolapse (POP) were included. We describe the symptoms, complications, and management of women treated surgically for vaginal mesh-related complications.

RESULTS

Thirteen referred women underwent surgery for vaginal mesh-related complications. All meshes were Apogee and/or Perigee. Ten had symptomatic mesh exposures, 1 had an exposure with pelvic abscess, and 2 had pain syndromes without mesh exposure. Patients also had rectovaginal fistula, vesicovaginal fistula, recurrent POP, and persistent discharge. Five women had prior surgery for this problem. All patients underwent transvaginal mesh excision and other indicated procedures at our institution, and 6 women required a second surgery at our institution, with a median of 2 surgeries per patient.

CONCLUSION

Vaginal mesh placement for POP can be associated with pain, exposure, and fistula formation, requiring multiple operative interventions.

Effects of Aging on Lower Urinary Tract and Pelvic Floor Function in Nulliparous Women

OBJECTIVE

To evaluate the effects of aging, independent of parity, on pelvic organ and urethral support, urethral function, and levator function in a sample of nulliparous women.

METHODS

A cohort of 82 nulliparous women, aged 21-70 years, were recruited from the community through advertisements. Subjects underwent pelvic examination using pelvic organ prolapse quantification, urethral angles by cotton-tipped swab, and multichannel urodynamics and uroflow. Vaginal closure force was quantified using an instrumented vaginal speculum. Subjects were grouped into five age categories and analyses performed using t tests, Fisher exact tests, Kruskal-Wallace, and Pearson correlation coefficients. Multiple linear regression modeling was performed to adjust for factors that might confound the results of our primary outcomes.

RESULTS

Increasing age was associated with decreasing maximal urethral closure pressure (r=-0.758, P<.001) with a 15-cm-H(2)O decrease in pressure per decade. Pelvic organ support as measured by pelvic organ prolapse quantification did not differ by age group. Levator function as measured by resting vaginal closure force and augmentation of vaginal closure force also did not change with increasing age.

CONCLUSION

In a sample of nulliparous women between 21 and 70 years of age maximal urethral closure pressure in the senescent urethra was 40% of that in the young urethra; increasing age did not affect clinical measures of pelvic organ support, urethral support, and levator function.

LEVEL OF EVIDENCE

III.

Sexual function, quality of life, and severity of anal incontinence after anal sphincteroplasty

OBJECTIVE

The purpose of this study was to determine the severity of anal incontinence and its impact on quality of life and sexual function in women after anal sphincteroplasty.

STUDY DESIGN

Eighty-six women who underwent anal sphincteroplasty during the years 1993 to 2004 were mailed validated survey instruments to evaluate continence status, health-related quality of life, and sexual functioning. Demographic and perioperative data were obtained from patient charts.

RESULTS

At a mean follow-up time of 5.6 +/- 3.0 years, 6 women (11%) were totally continent; 8 women (15%) were incontinent of flatus only, and 41 women (75%) were incontinent of liquid and/or solid stool. Sexual function scores were not correlated with continence scores; 24% vs 4% of subjects who had undergone an overlapping sphincteroplasty versus an end-to-end sphincteroplasty reported pain during intercourse (P = .04).

CONCLUSION

Anal continence rates 5 years after anal sphincteroplasty are disappointing, adversely impact quality of life, yet do not appear to relate to sexual function.

Levator plate angle in women with pelvic organ prolapse compared to women with normal support using dynamic MR imaging

OBJECTIVE

The purpose of this study was to determine whether the levator plate is (1) horizontal in women with normal support, (2) different between women with and without prolapse, (3) related to levator hiatus and perineal body descent.

STUDY DESIGN

Cohorts of cases with prolapse at least 1 cm below the hymen and normal controls with all points 1 cm or more above the hymen were prospectively enrolled in a study of pelvic organ support to be of similar age, race, and parity. Subjects underwent supine midsagittal dynamic magnetic resonance imaging (MRI) during Valsalva. Levator plate angle (LPA) was measured relative to a horizontal reference line. Levator hiatus length (LH) and perineal body location (PB) were also measured. Student t tests and Pearson correlation coefficients (r) were performed.

RESULTS

Sixty-eight controls and 74 cases were analyzed. During Valsalva, controls had a mean LPA of 44.3 degrees . Cases, compared to controls, had 9.1 degrees (21%) more caudally directed LPA (53.4 degrees vs 44.3 degrees , P < .01), 15% larger LH length (7.8 cm vs 6.8 cm, P < .01), and 24% more caudal PB location (6.8 cm vs 5.5 cm, P < .01). Increases in LPA were correlated with increased LH length (r = 0.42, P < .0001) and PB location (r =.51, P < .0001).

CONCLUSION

The measured levator plate angle in women with normal support is 44.3 degrees . During Valsalva, women with prolapse have a modest (9.1 degrees) though statistically greater levator plate angle compared to controls. This larger angle showed moderate correlation with larger levator hiatus length and greater displacement of the perineal body in women with prolapse compared to controls.

Interrater reliability and physical examination of the pubovisceral portion of the levator ani muscle, validity comparisons using MR imaging

AIMS

Defects in the pubovisceral portion of the levator ani muscle are seen with MR imaging. This study aims to determine interrater reliability of physical examination in detecting these defects, and to validate findings from physical examination using comparisons with MR images.

METHODS

Two examiners palpated the pubovisceral muscles of 29 women to assess for defects in this muscle. Each examiner was blinded to the others findings. MR scans were acquired on a further 24 women after structured clinical examination by one examiner. These images were read to determine pubovisceral muscle defects, blinded to patient identifiers. Agreement between raters and between MR imaging and clinical examination were calculated.

RESULTS

The two examiners had positive agreement (presence of a defect) of 72.7% and negative agreement (absence of a defect) of 83.3%. The positive agreement between physical examination and MR imaging was 27.3% and the negative agreement 86.5%.

CONCLUSION

The structured physical examination to detect defects in the pubovisceral portion of the levator ani muscle can be learned as shown by good interrater agreement. However, examination alone underestimates these defects compared with MR imaging.

Vaginal thickness, cross-sectional area, and perimeter in women with and those without prolapse

OBJECTIVE

Use axial magnetic resonance imaging to test the null hypothesis that no difference exists in apparent vaginal thickness between women with and those without prolapse.

METHODS

Magnetic resonance imaging studies of 24 patients with prolapse at least 2 cm beyond the introitus were selected from an ongoing study comparing women with prolapse with normal control subjects. The magnetic resonance scans of 24 women with prolapse (cases) and 24 women without prolapse (controls) were selected from those of women of similar age, race, and parity. The magnetic resonance files were imported into an experimental modeling program, and 3-dimensional models of each vagina were created. The minimum transverse plane cross-sectional area, mid-sagittal plane diameter, and transverse plane perimeter of each vaginal model were calculated.

RESULTS

Neither the mean age (cases 58.6 years +/- standard deviation [SD] 14.4 versus controls 59.4 years +/- SD 13.2) nor the mean body mass index (cases 24.1 kg/m(2)+/- SD 3.3, controls 25.7 kg/m(2)+/- SD 3.7) differed significantly between groups. Minimum mid-sagittal vaginal diameters did not differ between groups. Patients with prolapse had larger minimum vaginal cross-sectional areas than controls (5.71 cm(2)+/- standard error of the mean [SEM] 0.25 versus 4.76 cm(2)+/- SEM 0.20, respectively; P = .005). The perimeter of the vagina was also larger in the prolapse group (11.10 cm +/- SEM 0.24) compared with controls (9.96 cm +/- SEM 0.22) P = .001. Subgroup analysis of patients with endogenous or exogenous estrogen showed prolapse patients had larger vaginal cross-sectional area (P = .030); in patients without estrogen group differences were not significant (P = .099).

CONCLUSION

Vaginal thickness is similar in women with and those without pelvic organ prolapse. The vaginal perimeter and cross-sectional areas are 11% and 20% larger in prolapse patients, respectively. Estrogen status did not affect differences found between groups.

Does vaginal closure force differ in the supine and standing positions?

OBJECTIVE

This study was undertaken to quantify resting vaginal closure force (VCF(REST)), maximum vaginal closure force (VCF(MAX)), and augmentation of vaginal closure force augmentation (VCF(AUG)) when supine and standing and to determine whether the change in intra-abdominal pressure associated with change in posture accounts for differences in VCF.

STUDY DESIGN

Thirty-nine asymptomatic, continent women were recruited to determine, when supine and standing, the vaginal closure force (eg, the force closing the vagina in the mid-sagittal plane) and bladder pressures at rest and at maximal voluntary contraction. VCF was measured with an instrumented vaginal speculum and bladder pressure was determined with a microtip catheter. VCF(REST) was the resting pelvic floor tone, and VCF(MAX) was the peak pelvic floor force during a maximal voluntary contraction. VCF(AUG) was the difference between VCF(MAX) and VCF(REST). T tests and Pearson correlation coefficients were used for analysis.

RESULTS

VCF(REST) when supine was 3.6 +/- 0.8 N and when standing was 6.9 +/- 1.5 N--a 92% difference (P < .001). The VCF(MAX) when supine was 7.5 +/- 2.9 N and when standing was 10.1 +/- 2.4 N--a 35% difference (P < .001). Bladder pressure when supine (10.5 +/- 4.7 cm H2O) was significantly less (P < .001) than when standing (31.0 +/- 6.4 cm H2O). The differences in bladder pressure when either supine or standing did not correlate with the corresponding differences in VCF at rest or at maximal voluntary contraction. The supine VCF(AUG) of 3.9 +/- 2.7 N, was significantly greater than the standing VCF(AUG) of 3.3+/-1.9 N.

CONCLUSION

With change in posture, vaginal closure force increases because of higher intra-abdominal pressure and greater resistance in the pelvic floor muscles.

Pudendal nerve stretch during vaginal birth: a 3D computer simulation

OBJECTIVE

The purpose of this study was to determine the increase in pudendal nerve branch lengths using a 3D computer model of vaginal delivery.

STUDY DESIGN

The main inferior rectal and perineal branches of the pudendal nerve were dissected in 12 hemi-pelves from 6 adult female cadavers. Their 3D courses were digitized in the 4 specimens with the most characteristic nerve branching pattern, and the data were imported into a published 3D computer model of the pelvic floor. Each nerve branch was then represented by a stretchable cord with a fixation point at the ischial spine. The length change in each branch was then quantified as the fetal head descended through the pelvic floor. The maximum nerve strains ([final length minus original length/original length] x 100) were calculated for 5 degrees of perineal descent: reference descent from the literature, 1.25 cm and 2.5 cm caudal and cephalad. The effect of alternative fixation points on resultant nerve strain was also studied.

RESULTS

The inferior rectal branch exhibited the maximum strain, 35%, and this strain varied by 15% from the scenario with the least perineal descent to that with the most perineal descent. The strain in the perineal nerve branch innervating the anal sphincter reached 33%, while the branches innervating the posterior labia and urethral sphincter reached values of 15% and 13%, respectively. The more proximal the nerve fixation point, the greater the nerve strain.

CONCLUSION

During the second stage: (1) nerves innervating the anal sphincter are stretched beyond the 15% strain threshold known to cause permanent damage in appendicular peripheral nerve, and (2) the degree of perineal descent is shown to influence pudendal nerve strain.

Can women without visible pubococcygeal muscle in MR images still increase urethral closure pressures?

OBJECTIVE

The purpose of this study was to determine if the ability to increase maximum urethral closure pressure (MUCP) with a pelvic muscle contraction is impaired in women without pubococcygeal muscle (PCM).

STUDY DESIGN

This was a cross-sectional study of continent women comparing those with (n=28) and those without (n=17) PCM as identified by MR scans. A pelvic muscle contraction was performed simultaneously with recordings of urethral and bladder pressures.

RESULTS

Eighty-six percent of the women with PCM compared with 41% of the women without could volitionally increase (>5 cm H(2)O) their MUCP. Those with PCM generated a mean intraurethral pressure rise of 14.0 (10.8) cm H(2)O, compared with 6.2 (8.7) cm H(2)O in those without (P=.015). Among women who could produce a visible pressure rise, there was not a statistically significant difference between groups (with PCM=17.2 [7.8] cm H(2)O; without PCM=14.7 [7.5] cm H(2)O; P=.457).

CONCLUSION

Selective women without visible PCM can increase MUCP.

Pathophysiology of adult urinary incontinence

The anatomic structures that prevent stress incontinence, urinary incontinence during elevations in abdominal pressure, can be divided into 2 systems: a sphincteric system and a supportive system. The action of the vesical neck and urethral sphincteric mechanisms at rest constrict the urethral lumen and keep urethral closure pressure higher than bladder pressure. The striated urogenital sphincter, the smooth muscle sphincter in the vesical neck, and the circular and longitudinal smooth muscle of the urethra all contribute to closure pressure. The mucosal and vascular tissues that surround the lumen provide a hermetic seal, and the connective tissues in the urethral wall also aid coaptation. Decreases in striated muscle sphincter fibers occur with age and parity, but the other tissues are not well understood. The supportive hammock under the urethra and vesical neck provides a firm backstop against which the urethra is compressed during increases in abdominal pressure to maintain urethral closure pressures above rapidly increasing bladder pressure. The stiffness of this supportive layer is presumed to be important to the degree to which compression occurs. This supporting layer consists of the anterior vaginal wall and the connective tissue that attaches it to the pelvic bones through the pubovaginal portion of the levator ani muscle and also the tendinous arch of the pelvic fascia. Activation of the levator muscle during abdominal pressurization is important to this stabilization process. The integrity of the connection between the vaginal wall and tendinous arch also plays an important role.

Differences in pelvic floor area between African American and European American women

OBJECTIVE

This study tests the null hypothesis that the size of the pelvic opening spanned by the pelvic floor is the same in African American and European American women.

STUDY DESIGN

Forty African American female pelvises were age matched with 40 European American female pelvises from the Hamann-Todd collection at the Cleveland Museum of Natural History. The distances between the anchoring points of the pelvic floor to the bony pelvis (pubis anteriorly, ischial spines laterally, and inferior lateral angle of the sacrum posteriorly) were measured on each half of the pelvis. Measurements from left and right halves were averaged. The cross-sectional area of the pelvic floor was calculated from these dimensions. The bi-ischial line divided the total area into anterior and posterior pelvic floor areas. Analyses taking into account differences in stature by dividing individual dimensions by height were also performed. Group differences were compared with the Student t test and the Mann-Whitney rank sum test.

RESULTS

African American women had a 5.1% smaller pelvic floor area than European American women (889.6 cm(2) vs 937.0 cm(2), 5.1% P =.037). This was attributable to a 10.4% smaller posterior area (365.3 cm(2) vs 407.6 cm(2), 10.4% P =.016), whereas the anterior areas were similar (524.3 cm(2) vs 529.3 cm(2), P =.61). The following measured distances were smaller in African American women: ischial spine to inferior sacral angle (5.4 cm vs 5.9 cm, P =.016) and bi-ischial diameter (10.0 cm vs 10.6 cm, P =.004). These distances remained significant after height was controlled.

CONCLUSIONS

In African American women, the posterior pelvic floor area is 10.4% smaller than in European American women, resulting in a 5.1% smaller total pelvic floor area.

Fascial and muscular abnormalities in women with urethral hypermobility and anterior vaginal wall prolapse

OBJECTIVE

Our purpose was to assess the structural integrity of individual elements of the urethral and anterior vaginal wall support system.

STUDY DESIGN

Notes were made during retropubic operations for cystourethrocele and stress incontinence in 71 women aged 52 +/- 12.4 (SD) years. Vaginal support was assessed with the Baden-Walker system with the following average findings: urethra 1.9 +/- 0.6, bladder 1.9 +/- 1.0, apex 0.8 +/- 1.1, upper posterior wall 0.3 +/- 0.8, and rectocele 1.1 +/- 0.7. The presence of the following features was noted: paravaginal defect, integrity of the pubic and ischial attachments of the arcus tendineus fascia pelvis (ATFP), appearance of the ATFP on the sidewall, and abnormalities in the pubococcygeal muscle.

RESULTS

Paravaginal defects were present in 87.3% on the left and in 88.7% on the right. Detachment of the ATFP from the pubic bone was present in 1.4% (left) and 2.8% (right). The ATFP was detached from the ischial spine in 97.6% (left) and 95.1% (right). Remnants of the ATFP were present on the sidewall in 62% (left) and 63% (right). Of these, 9% extended one fourth the distance to the spine, 21% one half the distance, 3% three fourths the distance, and 17% all the way to the spine. The pubococcygeal muscle was visibly normal in 45% (left) and 39% (right). It showed localized atrophy in 22% (left) and 30% (right) and generalized atrophy in 22.5% (left) 30.0% (right).

CONCLUSION

The ATFP usually detaches from the ischial spine, but not from the pubis; slightly less than half of these women have visibly abnormal levator ani muscles.