The role of pudendal nerve damage in the aetiology of genuine stress incontinence in women

Weakness of the pelvic floor: urological consequences

The pelvic floor comprises three compartments: anterior, posterior and middle. Weakness of the pelvic floor can lead to prolapse, urinary or faecal incontinence. This article deals with the defects in the anterior compartment which lead to urological consequences. The anatomy and management of stress incontinence are discussed.

Differential effects of cough, valsalva, and continence status on vesical neck movement

OBJECTIVE

We tested the null hypothesis that vesical neck descent is the same during a cough and during a Valsalva maneuver. We also tested the secondary null hypothesis that differences in vesical neck mobility would be independent of parity and continence status.

METHODS

Three groups were included: 17 nulliparous continent (31.3 +/- 5.6; range 22-42 years), 18 primiparous continent (30.4 +/- 4.3; 24-43), and 23 primiparous stress-incontinent (31.9 +/- 3.9; 25-38) women. Measures of vesical neck position at rest and during displacement were obtained by ultrasound. Abdominal pressures were recorded simultaneously using an intravaginal microtransducer catheter. To control for differing abdominal pressures, the stiffness of the vesical neck support was calculated by dividing the pressure exerted during a particular effort by the urethral descent during that effort.

RESULTS

The primiparous stress-incontinent women displayed similar vesical neck mobility during a cough effort and during a Valsalva maneuver (13.8 mm compared with 14.8 mm; P =.49). The nulliparous continent women (8.2 mm compared with 12.4 mm; P =. 001) and the primiparous continent women (9.9 mm compared with 14.5 mm; P =.002) displayed less mobility during a cough than during a Valsalva maneuver despite greater abdominal pressure during cough. The nulliparas displayed greater pelvic floor stiffness during a cough compared with the continent and incontinent primiparas (22.7, 15.5, 12.2 cm H(2)O/mm, respectively; P =.001).

CONCLUSION

There are quantifiable differences in vesical neck mobility during a cough and Valsalva maneuver in continent women. This difference is lost in the primiparous stress-incontinent women.

Behavioral intervention for urinary incontinence in women: evidence for practice

In the past, clinicians have relied heavily on pharmacologic and surgical interventions for urinary incontinence in women. However, evidence now exists that less invasive, behavioral therapies can be extremely effective in helping women become continent; thus, strategies that involve bladder and pelvic floor muscle training should generally be the first line of treatment. Before behavioral intervention is initiated, it is important to assess for any medical or associated conditions that should be treated first. Bladder training enables women to accommodate increasingly greater volumes of urine in the bladder and gradually to extend the interval between voiding. Pelvic floor muscle training increases awareness of function and strengthens these voluntary muscles, promoting continence.

Effects of pudendal nerve injury in the female rat

To test a neurogenic hypothesis for external urethral sphincter (EUS) dysfunction associated with urinary incontinence, the proximal pudendal nerve was crushed in anesthetized retired breeder female rats (n = 5) and compared with a sham lesion group (n = 4). Outcome measures included concentric needle electromyograms (EMGs) from the target EUS, voiding patterns during a 2-hour dark period, and micturition data over a 24-hour period. Fast Blue (FB) was introduced to the crush site at the time of injury and Diamidino Yellow (DY) to the EUS at the time the rats were killed (3 months post-operative), when histological analysis of the nerve and urethra was also performed. EMG records indicated the EUS motor units undergo typical denervation changes followed by regeneration and recovery. Voiding patterns from the crush group show a significant increase of small urine marks in the front third of the cage. At 1-2 weeks post-op, the frequency of voids was significantly increased in the crush group compared to pre-op and late post-op time periods. The mean volume voided in the light phase at the early post-op time was significantly increased in the sham group. Light and electron microscopic patterns seen in nerve and muscle suggest the regenerating motor units maintain a structural integrity. Motoneurons in the lower lumbar cord were labeled with either DY (14. 5 +/- 6.8), FB (31.7 +/- 23.7), or both (35.0 +/- 17.5) tracers, indicating approximately 54% of the crushed pudendal neurons regenerated to the EUS. In conclusion, several measures suggest this reversible crush lesion induces mild urinary incontinence. This animal model is promising for further development of hypotheses regarding neural injury, the pathogenesis of incontinence, and strategies aimed at prevention and treatment. Neurourol. Urodynam. 19:53-69, 2000.

Female stress, urge, and mixed urinary incontinence are associated with a chronic and progressive pelvic floor/vaginal neuromuscular disorder: An investigation of 317 healthy and incontinent women using vaginal surface electromyography

Reduction of the maximum vaginal surface electromyography (EMG) activity has previously been demonstrated in women with stress, urge, and mixed incontinence in comparison with healthy volunteers [Gunnarsson and Mattiasson, Scand J Urol Nephol 157:89-95, 1994]. The present study was performed to investigate if these EMG changes are age dependent and whether healthy parous women in general might show an age-related decrease of vaginal and pelvic neuromuscular activity. A total of 317 women, 144 with urinary incontinence and 173 healthy volunteers, 20 to 76 years of age, were investigated. The maximum EMG activity during repeated short contractions (2 s) was measured. We found that parous women who have maintained continence through the years had a normal pelvic floor function as estimated with vaginal surface EMG. In contrast, all three groups of incontinent women showed a successive decrease of the EMG activity with increasing age. This difference was highly significant (P < 0.001) in women above the age of 50. No significant differences could be seen between groups when stress, urge, and mixed incontinent women were compared. Even though any convincing correlation between the amount of urinary leakage and the reduction of EMG activity was not found, we conclude that a chronic and progressive deterioration of the pelvic-vaginal neuromuscular function occurs in women who develop urinary incontinence. The results support the view that a common pathophysiological mechanism in patients with stress, urge, and mixed incontinence might exist. The findings might help to establish a new perspective for the understanding of the pathophysiology, diagnosis, treatment, and prevention of female incontinence. Neurourol. Urodynam. 18:613-621, 1999.

Cortical magnetic stimulation in patients with genuine stress incontinence: correlation with results of pelvic floor exercises

Pelvic floor training is an established conservative method of treatment in patients with genuine stress incontinence. It is not known why only a proportion of patients benefit from this form of treatment, while others with a comparable degree of incontinence do not. Since muscle awareness is of vital importance in pelvic floor training, we decided to investigate whether differences in outcome might be explained by differences in cortical control of the pelvic floor muscles. The function in the total motor pathway to the pelvic floor muscles was examined with cortical magnetic stimulation and circumvaginal EMG recording. Since lesions of the peripheral motor pathway have been demonstrated in patients with genuine stress incontinence, possible differences at this level were investigated by means of terminal pudendal motor latencies, using electrical nerve stimulation and anal recording EMG. We found that patients who succeeded with pelvic floor exercises for genuine stress incontinence had a significantly higher probability of response to cortical magnetic stimulation and significantly larger response amplitudes than the patients who did not benefit from training. The findings in the latter group did not differ from those of a healthy control group. No differences between the groups were found in the terminal pudendal motor latencies. We conclude that women with genuine stress urinary incontinence, successfully alleviated by a physiotherapeutic training program, have a higher degree of corticofugal control of their perineal muscles than women who do not succeed with the same treatment program and healthy controls. Neurourol. Urodynam. 18:437-445, 1999.

The supine stress test: a simple method to detect intrinsic urethral sphincter dysfunction

PURPOSE

A new clinical test for intrinsic urethral sphincter dysfunction is proposed and compared to abdominal leak point pressure determination by video urodynamics.

MATERIALS AND METHODS

Patients were prospectively included in the study if they had stress urinary incontinence symptoms and were to undergo video urodynamic testing. Patients with urinary tract infection, cystocele, rectocele and vaginal vault prolapse were excluded from study. A supine stress test using cough and Valsalva's maneuvers was performed after bladder filling to 200 ml. with sterile normal saline solution by gravity. Efflux of the bladder solution from the meatus coinciding with the cough or Valsalva maneuver indicated a positive clinical test. A video urodynamic study, including abdominal leak point pressure, was performed. Intrinsic urethral sphincter dysfunction was diagnosed if abdominal leak point pressure was less than 100 cm. water. Test indexes were calculated based on the results of the supine stress test and the abdominal leak point pressure measurements.

RESULTS

Results were positive in 30 of 41 consecutive patients and negative in 11. Using abdominal leak point pressure measurement, the supine stress test had 93.5% sensitivity, 90.0% specificity, 96.7% positive predictive value and 81.8% negative predictive value for detecting intrinsic urethral sphincter dysfunction.

CONCLUSIONS

The supine stress test is easy, quick and inexpensive, and a positive test is a reliable predictor of intrinsic urethral sphincter dysfunction. A negative test is highly correlated with the absence of intrinsic urethral sphincter dysfunction during video urodynamic testing. This test is more reliable in diagnosing intrinsic urethral sphincter dysfunction than other nonurodynamic tests reported in the literature. The supine stress test can be a useful supplement to cotton swab testing for urethral hypermobility in determining the appropriate management for stress urinary incontinence.

Fecal incontinence in women

Pelvic floor disorders are common in women. Most gynecologists are well versed in the management of urinary incontinence and uterovaginal prolapse; however, knowledge of disorders involving the anorectum is often lacking. This review will discuss the issue of anorectal incontinence in women, attempt to provide a logical outline for evaluation and treatment, and offer potential methods of prevention.

Is antenatal bladder neck mobility a risk factor for postpartum stress incontinence?

OBJECTIVE

To assess the contribution of constitutional factors, as demonstrated by antenatal bladder neck mobility, in the development of postpartum urinary stress incontinence.

DESIGN

A prospective investigational study.

SETTING

General district hospital.

POPULATION

One hundred and three primigravid women with no pre-existing urinary incontinence or neurological disorder.

METHODS

Antenatal and postnatal measurement of bladder neck mobility using perineal ultrasound.

MAIN OUTCOME MEASURE

Urinary stress incontinence at 10-14 weeks postpartum.

RESULTS

Women with postpartum urinary stress incontinence have significantly greater antenatal bladder neck mobility than those women continent postpartum. There were no significant differences in any labour or delivery variables, including mode of delivery, between the postpartum continent and incontinent women.

CONCLUSIONS

There is evidence for a constitutional risk factor (eg, defective pelvic floor connective tissue in the development of postpartum stress incontinence).

Normal pelvic floor anatomy

The anatomy of the pelvic floor includes structures responsible for active and passive support of the urethrovesical junction, vagina, and anorectum. Intrinsic and extrinsic properties of the urethrovesical neck and anorectum allow maintenance of urinary and anal continence at rest and with activity. Damage to these structures may lead to loss of support and loss of normal function of the urethra, bladder, and anorectum. Over time, this damage can result in isolated or combined pelvic organ prolapse, urinary incontinence, and anal incontinence.

Prevalence of faecal incontinence among women with urinary incontinence

Four hundred and sixty-five women attending a urodynamic clinic were interviewed, and completed a detailed bowel questionnaire, about their urinary and bowel symptoms. All the women underwent video-cystourethrography with pressure and flow studies. The reported incidence of faecal incontinence was 15.3% (n = 71) on direct questioning and 26% (n = 121) on the postal questionnaire. Faecal incontinence was more common in women with a urodynamic diagnosis of detrusor instability (30% (n = 26)) than among women diagnosed as having genuine stress incontinence (21% (n = 38)). Denervation and myogenic injuries sustained during childbirth have been suggested as a common cause for genuine stress and faecal incontinence, but there may be an alternative mechanism to explain why women with detrusor instability suffer from faecal incontinence.

Epidemiology, pathophysiology, and evaluation of urinary incontinence and overactive bladder

OBJECTIVES

To present an overview of current knowledge regarding the epidemiology, pathophysiology, and evaluation of urinary incontinence (UI) with a focus on the problem of the overactive bladder.

METHODS

The most recent data on the epidemiology of UI are presented. The literature on the pathophysiology of urinary urge incontinence (UUI) is reviewed, and key concepts related to patient evaluation are summarized.

RESULTS

The prevalence of UI depends on the population being surveyed. The overactive bladder constitutes a substantial percentage of the overall problem, ranging from > 50% of incontinent men to only 10% to 15% of incontinent younger women. Few data are available on the incidence of the disorder or on racial/ethnic trends. Overactive bladder or urge incontinence is called detrusor hyperreflexia when a neurologic cause is known and detrusor instability when there is no neurologic abnormality. Although the pathophysiology of idiopathic instability is not well understood, some evidence suggests that this condition may result from subclinical neurologic disease or primary smooth muscle disease. Most patients with UUI can be adequately evaluated with a history, physical examination, determination of postvoid residual volume, and urinalysis. When neurologic disease or other complicating factors are present, or if initial treatment fails, sophisticated urodynamic testing is appropriate.

CONCLUSIONS

Urinary incontinence is prevalent in all strata of the population, although it affects women and the elderly disproportionately. With the exception of cases in which a neurologic lesion can be demonstrated, the etiology of UUI remains elusive. A thorough history, physical examination, determination of postvoid residual, and urinalysis will be adequate to classify and treat the majority of patients.

Electrical stimulation for the treatment of urinary incontinence

OBJECTIVES

To describe the rationale for the use of electrical stimulation (ES) for the treatment of urinary incontinence, and to summarize the results of clinical studies assessing these techniques.

METHODS

The effect of ES on the lower urinary tract (LUT) is explained, and the literature on clinical application of this technique is reviewed.

RESULTS

The use of ES is aimed at altering LUT function by stimulation of the sacral autonomic or somatic nerves. Two types of ES have been used: chronic stimulation and acute maximal functional electrostimulation. The frequency used depends on the clinical diagnosis. In patients with stress incontinence, uncontrolled studies suggest that high frequency and high amperage are required to obtain a 50% success rate, although success does not necessarily equate with cure. The only placebo-controlled trial in this population found that 62% of patients experienced significant improvement on provocative pad test determinations, but only 20% were dry. Researchers agree that low frequency and moderate amperage are required in patients with detrusor instability. The reported effectiveness of ES in this population has ranged widely, from 45% to 91%, but all studies agree that approximately one-third of patients will obtain a good long-term results. A review of multiple studies found that 20% of patients were reported as dry and 37% were significantly improved with functional ES.

CONCLUSIONS

Although nearly all studies of ES have been uncontrolled, a substantial body of "soft" data attests to the efficacy and safety of this technique.

The pathophysiology of stress urinary incontinence in women and its implications for surgical treatment

Stress urinary incontinence is a symptom that arises from damage to the muscles, nerves, and connective tissue of the pelvic floor. Urethral support, vesical neck function, and function of the urethral muscles are important determinants of continence. The urethra is supported by the action of the levator ani muscles through their connection to the endopelvic fascia of the anterior vaginal wall. Damage to the connection between this fascia and muscle, loss of nerve supply to the muscle, or direct muscle damage can influence continence. In addition, loss of normal vesical neck closure can result in incontinence despite normal urethral support. Although the traditional attitude has been to ignore the urethra as a factor contributing to continence, it does play a role in determining stress continence since in 50% of continent women, urine enters the urethra during increases in abdominal pressure, where it is stopped before it can escape from the external meatus. Perhaps one of the most interesting yet least acknowledged aspects of continence control concerns the coordination of this system. The muscles of the urethra and levator ani contract during a cough to assist continence, and little is known about the control of this phenomenon. That operations cure stress incontinence without altering nerve or muscle function should not be misinterpreted as indicating that these factors are unimportant.

The incidence of low-pressure urethra as a function of prolapse-reducing technique in patients with massive pelvic organ prolapse (maximum descent at all vaginal sites)

OBJECTIVE

Our aims were to compare several prolapse-reducing techniques during urodynamic evaluation and prospectively evaluate their usefulness in identifying the incidence of low urethral closure pressure in continent patients with massive prolapse.

STUDY DESIGN

This preoperative, prospective, repeated-measures urodynamic study evaluated the maximum urethral closure pressure with the use of four different techniques in 30 consecutive continent patients with grade 4 prolapse at all vaginal sites. Twenty patients with grade 0 prolapse served as the control group. All patients from the prolapse group underwent surgical treatment and were followed up clinically for a minimum of 1 year.

RESULTS

Use of the Scopette (Birchwood Laboratories, Eden Prairie, Minn.) reduction technique to reduce the prolapse in a linear orientation during multichannel urodynamics revealed a 56% incidence of low-pressure urethra and an overall genuine stress urinary incontinence of 83% in patients with massive pelvic organ prolapse but without clinical urinary incontinence.

CONCLUSIONS

There may be an increased indication for sling urethropexy in patients with massive prolapse.

Analysis of collagen status in premenopausal nulliparous women with genuine stress incontinence

OBJECTIVE

To determine if differences exist in the collagen status of premenopausal nulliparous women with genuine stress incontinence compared with continent controls.

DESIGN

Thirty-six premenopausal nulliparous women with urodynamically-proven genuine stress incontinence were compared with 25 controls. All the women studied had a periurethral vaginal biopsy taken of approximately 30-50 mg in wet weight. This biopsy was then analysed to determine the collagen content, the type I:III collagen ratio and the collagen cross-link content.

SETTING

A tertiary referral urodynamic unit.

RESULTS

The nulliparous women with genuine stress incontinence had significantly less collagen in their tissues (P < 0.0001) compared with the continent controls. In addition, there was a decreased ratio of type I to type III collagen (P = 0.0008), and the cross-link content was also significantly reduced in the women with genuine stress incontinence (P < 0.0001).

CONCLUSION

Genuine stress incontinence is present in a significant number of women before childbirth. The aetiology of their incontinence appears to be due to a defect in their connective tissue, with both a quantitative and qualitative reduction in their collagen.

Vaginal pudendal nerve stimulation: a new technique for assessment of pudendal nerve terminal motor latency

BACKGROUND

To evaluate vaginal stimulation of the pudendal nerve, a new method for investigation of pudendal nerve terminal motor latency (PNTML) and to assess the reproducibility of the method.

METHODS

Thirteen healthy women and 11 female patients, median age 31 years (range 21-53 years), participated in the study. Ten patients had sustained an anal sphincter rupture and one had idiopathic anal incontinence. Pudendal nerve terminal motor latency was measured after vaginal stimulation of the pudendal nerve with motor response from the pelvic floor and rectal stimulation with motor response from the anal sphincter using the St. Marks pudendal electrode. The women were stimulated by two observers both vaginally and by the rectum.

RESULTS

Vaginal PNTML for observer 1 was 2.06 msec (0.50 msec, 2 s.d.) and 2.04 msec (0.55 msec, 2 s.d.) for observer 2, while rectal PNTML was 1.99 msec (0.56 msec, 2 s.d.) and 1.97 msec (0.54 msec, 2 s.d.) respectively. The difference between vaginal and rectal PNTML was 0.065 msec for observer 1 (p = 0.106) and 0.070 msec for observer 2 (p < 0.05). Degree of agreement between vaginal and rectal PNTML was 80%-116% for observer 1 and 84%-12% for observer 2 (100% represent total agreement between measurements). Interobserver reproducibility for vaginal PNTML was 90%-109% and 86%-113% for rectal PNTML.

CONCLUSION

In clinical practice vaginal PNTML may replace rectal PNTML in women. Reproducibility is in the same range as for rectal PNTML.

Decreased innervation of the paraurethral epithelium in stress urinary incontinent women

OBJECTIVE

To determine whether there is a difference in the innervation of the paraurethral vaginal epithelium between stress urinary incontinent women of fertile age and comparable controls.

METHODS

Transvaginal biopsies close to the external orifice of the urethra were obtained from 11 stress urinary incontinent women and from ten comparable controls. The specimens were processed for indirect immunohistochemistry using protein gene product 9.5 (PGP 9.5) as a general neuronal marker. From each biopsy, ten randomly selected fields of 1 mm2 projected area were investigated and nerve fibre profiles were quantificated in a microscope equipped with light- and dark-field optics.

RESULTS

Nerve fibre profiles/mm2 of projected epithelial area were significantly lower in the incontinent group than in the control group (P < 0.01).

CONCLUSION

Our study indicates that stress urinary incontinent women have a significantly lower total innervation of the paraurethral vaginal epithelium than continent controls.

Effect of trauma and pelvic fracture on female genitourinary, sexual, and reproductive function

OBJECTIVES/HYPOTHESIS

To evaluate the impact of a pelvic fracture on a woman's physical, sexual, and reproductive functioning.

DESIGN

Retrospective review.

SETTING

Level one trauma center.

PATIENTS

Two groups of female multitrauma patients: those with pelvic fractures (subjects) and those with extremity fractures but no pelvic fracture (controls).

MAIN OUTCOME MEASUREMENTS

Of the 302 women eligible for participation in this study, 255 (80%; 123 subjects, 118 controls) were interviewed by blinded professional interviewers regarding genitourinary symptoms, sexual function, and reproductive history.

RESULTS

Urinary complaints occurred significantly more frequently in subjects than in controls (21 versus 7%, respectively; p = 0.003), in subjects with residual pelvic fracture displacement > or = 5 mm than in those without displacement (33 versus 14%, respectively; p = 0.018), and in subjects with residual lateral (60%) or vertical (67%) displacement than in those with medially displaced fractures (21.4%) (p = 0.04). Although both groups reported increased rates of cesarean section, this increase was statistically significant only in the subject group: 14.5% preinjury versus 48% postinjury (p < 0.0001). Adjusting for previous cesarean sections, cesarean section was significantly more frequent in subjects with fractures initially displaced > or = 5 mm (80%) than in those with fractures initially displaced < 5 mm (15%) (p = 0.02). There was no difference in the incidence of miscarriage or infertility between the groups. Problems with physiologic arousal or orgasm were rare. Pain during sex (dyspareunia) was more common in subjects with fractures displaced > or = 5 mm than in those with nondisplaced fractures (43 versus 25%, respectively; p = 0.04).

CONCLUSIONS

We found that pelvic trauma negatively affected the genitourinary and reproductive function of female patients. The increased rate of cesarean section in women after pelvic trauma may be multifactorial in origin and warrants further investigation.

Neurophysiology of micturition and continence in women

Micturition and continence involve the coordination of complex neural events between the central and peripheral nervous systems. An understanding of these events provides a foundation for the treatment of voiding disorders in women such as stress urinary incontinence, urge incontinence and interstitial cystitis. The purpose of this paper is to comprehensively review the neuroanatomy, neurophysiology and neuropharmacology of micturition and continence. However, a brief section discussing clinical correlations will follow each of these topics to help integrate the basic science with clinical observations.

Pelvic floor neuropathy in relation to the outcome of Burch colposuspension

The aim of the study was to determine the role of neurogenic damage to pelvic floor muscles on the outcome of Burch colposuspension. Thirty women objectively continent after Burch colposuspension and 18 women with recurrent stress urinary incontinence (RSUI) were investigated with concentric needle electrode electromyography (EMG) in both pubococcygeus muscles and the external anal sphincter muscle. Neurogenic EMG patterns were significantly more often seen in the pubococcygeus muscles in women with RSUI than in women continent after the colposuspension (P < 0.05). The distribution of neurogenic EMG patterns in the investigated muscles was significantly more pronounced in women with RSUI than in continent women: at least one pubococcygeus muscle with neurogenic EMG pattern, 72% vs. 34% (P < 0.05); both pubococcygeus muscles, 50% vs. 13% (P < 0.05); and all three investigated muscles 41% vs. 10% (P < 0.05). In conclusion, the results imply an association between the outcome of the Burch colposuspension and the occurrence of neuropathy in the pelvic floor muscles. Occurrence of neurogenic damage in the pubococcygeus muscles seems to impair the outcome of Burch colposuspension.

Stress urinary incontinence: where are we now, where should we go?

Stress urinary incontinence results from specific damage to the muscles, fascial structures, and nerves of the pelvic floor. Scientific data are accumulating about the nature of each of these injuries. As we begin to define the damage occurring in each element of the continence mechanism, we should be able to precisely select treatment plans on the basis of the abnormality found in individual patients. For example, a woman who has lost all neural control of her pelvic muscles could be saved the useless frustration of attempting pelvic muscle strengthening, whereas a woman with intact but weak muscles can be made continent with exercise. Before these advances can be realized, we must change our current empiric approach that assigns women to treatment because they have stress urinary incontinence to one that asks about the status of each part of the continence mechanism.

Obstetric practice and the prevalence of urinary incontinence three months after delivery

OBJECTIVE

To examine the relation between obstetric factors and the prevalence of urinary incontinence three months after delivery.

DESIGN

2134 postal questionnaires sent between August 1989 and June 1991.

SETTING

Teaching hospital in Dunedin, New Zealand.

SUBJECTS

All women three months postpartum who were resident in the Dunedin area.

MAIN OUTCOME MEASURE

Prevalence of urinary incontinence.

RESULTS

1505 questionnaires were returned (70.5% response rate). At three months postpartum 34.3% of women admitted to some degree of urinary incontinence with 3.3% having daily or more frequent leakage. There was a significant reduction in the prevalence of incontinence for women having a caesarean section, in particular in primiparous women with a history of no previous incontinence (prevalence of incontinence following a vaginal delivery 24.5%, following a caesarean section 5.2% P = 0.002). There was little difference between elective caesarean sections and those carried out in the first and second stages of labour. The odds ratios for women having a caesarean section were 0.4 (95% confidence interval (CI) 0.2.-0.7) (all women and all primiparae) and 0.2 (95% CI 0.0-0.6) (primipara with no previous incontinence) in comparison with those having a normal vaginal delivery. The prevalence of incontinence was also significantly lower in women having had two caesarean sections (23.3%; P = 0.05) but similar in those women having three or more caesarean sections (38.9%) in comparison with those women who delivered vaginally (37.7%). Other significant independent odds rations were found for daily antenatal pelvic floor exercises (PFE) (0.6, 95% CI 0.4-0.9), parity > or = 5 (2.2, 95% CI 1.0-4.9) and pre-pregnancy body mass index (1.07, 95% CI 1.04-1.10).

CONCLUSIONS

Adverse risk factors for urinary incontinence at three months postpartum are vaginal delivery, obesity and multiparity (> or = 5). Caesarean section and daily antenatal PFE appear to be protective, although not completely so.

Levator ani muscle in women with genitourinary prolapse: indirect assessment by muscle histopathology

The objective of this study was to assess the state of innervation in levator ani muscle sites using muscle histopathology. Asymptomatic women and patients with genitourinary prolapse were included. Histopathologic analysis allows indirect assessment of a muscle's innervation. Therefore, levator ani muscle was collected in a standardized fashion during abdominal surgery and frozen in the operating room using isopentane slush cooled by liquid nitrogen. Serial sections of levator ani muscle in cross-section were studied with standard histochemical and immunohistochemical techniques. The staining patterns from these histochemical techniques allowed quantitative determination of the ratios of fiber types I, IIA, and IIB and their fiber diameters. Objective assessment of fiber type grouping was performed. The distribution of both fiber type percentage and diameter were non-parametric. Therefore, the Mann-Whitney U-test was used to analyze the data for statistical differences between the means for these variables. There was no statistical difference in levator ani muscle fiber type percentage and diameter in patients with prolapse and/or urinary incontinence when compared to asymptomatic women. Levator ani muscles have a higher proportion of slow fibers (66%) than found in other human female muscle (48%). There was no evidence for denervation/reinnervation in any of the biopsy specimens. In this study, levator ani muscle biopsies from incontinent and/or prolapse patients were neither denervated nor reinnervated.

Benefits and risks of episiotomy: a review of the English-language literature since 1980. Part II

Mediolateral and, to a lesser degree, midline episiotomies substantially increase the amount of blood loss at delivery; in fact, simple avoidance of episiotomy may be the most powerful means the delivery attendant has to prevent excessive intrapartum hemorrhage. The long-term morbidity of the anal sphincter damage induced by episiotomy, particularly midline, has generally been underestimated in both its frequency and severity. Other potential fetal and maternal complications of episiotomies, although rare, are numerous and serious. The overall degree of risk that accompanies this procedure could only be justified by a clear and overriding benefit, which, as discussed under "Benefits" earlier in this review, does not appear to exist.

Benefits and risks of episiotomy: a review of the English-language literature since 1980. Part I

The professional literature on the benefits and risks of episiotomy was last reviewed critically in 1983, encompassing material published through 1980. This paper reviews the evidence accumulated since then. (Part II follows in this issue.) It is concluded that episiotomies prevent anterior perineal lacerations (which carry minimal morbidity), but fail to accomplish any of the other maternal or fetal benefits traditionally ascribed, including prevention of perineal damage and its sequelae, prevention of pelvic floor relaxation and its sequelae, and protection of the newborn from either intracranial hemorrhage or intrapartum asphyxia. In the process of affording this one small advantage, the incision substantially increases maternal blood loss, the average depth of posterior perineal injury, the risk of anal sphincter damage and its attendant long-term morbidity (at least for midline episiotomy), the risk of improper perineal wound healing, and the amount of pain in the first several postpartum days.

Lower urinary tract dysfunction in pregnancy: a review

It has long been observed that pregnancy may influence the development and course of urinary tract disorders. The physiological and anatomical changes inherent in normal pregnancy and the changing hormonal environment are generally assumed to play a role in the pathogenesis of urinary tract symptomatology. The purpose of this review is to examine the reported effect(s) of pregnancy on the lower urinary tract and to evaluate the possible role of pregnancy and delivery in lower urinary tract dysfunction.

Valsalva leak point pressures in women with genuine stress incontinence: reproducibility, effect of catheter caliber, and correlations with other measures of urethral resistance. Continence Program for Women Research Group

OBJECTIVES

The Valsalva leak point pressure has been promoted as an alternative to urethral pressure profilometry as a measure of urethral resistance in women with genuine stress incontinence. Our aims were to evaluate the reproducibility of the Valsalva leak point pressure, to assess the effect of catheter caliber on the Valsalva leak point pressure, and to compare vesical Valsalva leak point pressure to other measures of urethral resistance.

STUDY DESIGN

Sixty consecutive women with genuine stress incontinence underwent duplicate Valsalva leak point pressure determinations by use of 8F and 3F vesical and 8F vaginal catheters. Subjects also underwent a standard resting urethral pressure profilometry, cough leak point pressure determinations, and pressure-flow micturition studies.

RESULTS

Leakage was demonstrated on both Valsalva maneuvers in approximately 80% of subjects with both catheters. In subjects who leaked with both strains there was an extremely high correlation between the test-retest Valsalva leak point pressure within both catheters. The intercatheter correlation between the 8F and 3F Valsalva leak point pressures was significant but much weaker than the intracatheter correlations; 8F Valsalva leak point pressures were significantly higher than 3F Valsalva leak point pressures, although there were individual exceptions to this observation. Urethral pressure profilometry measures and micturition opening pressures were poorly correlated with Valsalva leak point pressure. Cough and vaginal Valsalva leak point pressures were significantly correlated with vesical Valsalva leak point pressure, but cough leak point pressures were significantly higher and vaginal Valsalva leak point pressures were significantly lower than the vesical Valsalva leak point pressure.

CONCLUSIONS

Valsalva leak point pressure is a simple and reproducible technique for evaluating urethral resistance in women with genuine stress incontinence. However, variations in Valsalva leak point pressure measurement must be precisely described, standardized, and validated before a technique can be advocated for clinical use.

Pelvic floor activity patterns: comparison of nulliparous continent and parous urinary stress incontinent women. A kinesiological EMG study

OBJECTIVE

To introduce neurophysiological methods to search for damage to neuromuscular structures involved in sustaining continence in women who experienced stress urinary incontinence during pregnancy and/or after delivery.

PATIENTS AND METHODS

Eight stress urinary incontinent parous women (mean of 2.75 vaginal deliveries [range 2-4] median age 45.3 years [range 31-60]) were examined using simultaneous electromyogram recordings of the left and right pubococcygeus muscle via wire electrodes. Comparisons were made with 10 nulliparous continent women (median age 27.2 years [range 22-32]).

RESULTS

Individual muscle activation patterns in stress urinary incontinent parous women were in principle similar to those observed in the continent nulliparous women, with two significant exceptions: (i) voluntary 'squeeze' showed significant differences in the holding time between the parous stress urinary incontinent patients and the nulliparous continent controls, with an empty bladder (49.0 s versus 193.9 s median value) and a full bladder (39.2 s versus 198.4 s); (ii) asymmetrical and uncoordinated levator activation patterns were demonstrated in four of eight parous stress incontinent women, i.e. inhibition of motor unit firing on coughing (n = 3) and dissociated recruitment of motor units during voluntary and reflex activation (n = 1).

CONCLUSION

Childbirth appeared to induce both quantitative and qualitative changes in the pelvic floor which jeopardized the continence mechanism. Sphincter weakness appeared to result not only from the loss of motor units but also from altered activation patterns in the remaining units: shorter activation periods, lack of response or paradoxical inhibition. Kinesiological EMG recordings revealed behavioural abnormalities which appeared relevant for planning treatment.

Bowel dysfunction: a pathogenic factor in uterovaginal prolapse and urinary stress incontinence

OBJECTIVE

To investigate the aetiological importance of bowel dysfunction in patients with uterovaginal prolapse and urinary stress incontinence.

DESIGN

Observational study using a questionnaire about obstetric history and bowel function, and anorectal physiological studies.

SETTING

Physiology unit and gynaecological outpatients departments of two teaching hospitals.

SUBJECTS

Twenty-three women with uterovaginal prolapse (mean age 57 years), 23 women with urinary stress incontinence (mean age 52 years) and 27 control women (mean age 52 years).

RESULTS

There was no statistically significant difference between the three groups in their parity, age or birthweight of their children. However, straining at stool as a young adult prior to the development of urogynaecological symptoms was significantly more common in women with uterovaginal prolapse (61% vs 4%, P < 0.001) and women with urinary stress incontinence (30% vs 4%, P < 0.05), compared with controls. A bowel frequency of less than twice per week as a young adult was also more common in women with uterovaginal prolapse than in control women (48% vs 8%, P < 0.001). At the time of consultation, 95% of the women with uterovaginal prolapse were constipated, compared with only 11% of control women. Many of these women also needed to digitate to achieve rectal evacuation. Compared with controls, women with uterovaginal prolapse had a prolonged pudendal nerve terminal motor latency (1.9 ms vs 2.2 ms, respectively, P = 0.003). Women with stress incontinence of urine had a normal pudendal nerve latency (2.0 ms). Other tests of anorectal function were normal.

CONCLUSIONS

Constipation, in addition to obstetric history, appears to be an important factor in the pathogenesis of uterovaginal prolapse.

Denervation and re-innervation of the urethral sphincter in the aetiology of genuine stress incontinence: an electromyographic study

OBJECTIVE

To investigate the role of altered innervation of the urethral sphincter in the genesis of genuine stress incontinence.

DESIGN

Prospective observational study.

SETTING

Tertiary referral centre urodynamics unit.

SUBJECTS

Sixty-eight women, 33 with urodynamically proven pure genuine stress incontinence and 35 controls without urinary symptoms.

INTERVENTIONS

Concentric needle electromyography of the urethral striated sphincter.

MAIN OUTCOME MEASURES

The means of motor unit potential duration, number of changes in polarity and the amplitude of individual motor unit potentials were compared between the two groups.

RESULTS

There was no statistically significant difference in motor unit potential duration (P = 0.87) or in the number of changes in polarity (P = 0.85). There was a trend towards a higher amplitude of motor unit potentials in the control group (P = 0.07).

CONCLUSIONS

Our findings suggest that denervation and re-innervation of the striated urethral sphincter following trauma to the pelvic floor, such as that occurring during childbirth, is not a major aetiological factor in the development of genuine stress incontinence.

A comparison of bioelectrical and mechanical activity of the female urethra

OBJECTIVE

To determine the relationship between mechanical function and innervation of the urethra in order to clarify the effect of denervation and reinnervation on urethral function.

DESIGN

Prospective observational study.

SETTING

Tertiary referral urodynamics unit.

SUBJECTS

Thirty-six women, 21 with urinary symptoms and urodynamically proven genuine stress incontinence and 15 without urinary symptoms.

INTERVENTIONS

All women underwent concentric needle electromyography of the urethral sphincter and urethral pressure profilometry at rest and during cough induced stress.

RESULTS

Significant correlations were found between variables indicating denervation and reinnervation and improved resting urethral function. No correlation was found between these variables and urethral function under stress.

CONCLUSIONS

Our findings contradict current opinion that denervation of the urethral sphincter is associated with a reduction in the sphincteric function of the urethra, at rest or during stress, and suggest that denervation cannot therefore be a major aetiological factor in the development of genuine stress incontinence.

Temporal separation of cough-induced urethral and bladder pressure spikes in women with urinary incontinence

The time separation of cough-induced urethral and bladder pressure spikes were studied in 32 female patients: 16 with urinary incontinence due to sphincter incompetence, 9 with urinary incontinence and a competent urethral closure mechanism, and 7 after incontinence surgery. There were no significant differences in time separation between the three groups at different positions in the urethra. Age and menopausal status did not affect time separation of pressure spikes. It is concluded that time separation of pressure spikes during cough cannot be used as a discriminator of the etiology of urinary incontinence. Surgery does not restore the latency seen in normal continent women and may restore continence by a mechanism different from that of normal continent women.