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Research Reports |
MP FitzGerald, MD, is Associate Professor, Division of Female Pelvic Medicine and Reconstructive Pelvic Surgery, Loyola University Medical Center, 2160 S First Ave, Bldg 103, Room 1004, Maywood, IL 60153 (USA)
KL Burgio, MD, is Professor of Medicine, Division of Gerontology, Geriatrics, and Palliative Care, University of Alabama at Birmingham, Birmingham, Ala, and Associate Director for Research, Geriatric Research, Education, and Clinical Center, Department of Veterans Affairs, Birmingham, Ala
DF Borello-France, PT, PhD, is Associate Professor, Department of Physical Therapy, Duquesne University, Pittsburgh, Pa
SA Menefee, MD, is Associate Clinical Professor, Department of Reproductive Medicine, University of California–San Diego, San Diego, Calif, and Director, Division of Female Pelvic Medicine & Reconstructive Surgery, Kaiser Permanente, San Diego, Calif
J Schaffer, MD, is Professor, Chief of Gynecology and Urogynecology, Department of Obstetrics/Gynecology, University of Texas Southwestern Medical Center, Dallas, Tex
S Kraus, MD, is Assistant Professor, Department of Surgery, Division of Urology, and Head, Section of Female Urology, Neuro-Urology and Voiding Dysfunction, University of Texas Health Services Center at San Antonio, San Antonio, Tex
VT Mallett, MD, is Professor and Chair, Department of Obstetrics and Gynecology, University of Tennessee Health Science Center, Memphis, Tenn
Y Xu, MS, is Statistician, New England Research Institute, Watertown, Mass
The Urinary Incontinence Treatment Network is funded by the National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Md, and the National Institute of Child Health and Human Development, Rockville, Md
Address all correspondence to Dr FitzGerald at: Mfitzg8{at}lumc.edu
Submitted March 6, 2006;
Accepted May 21, 2007
 | Abstract |
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Subjects: Data were obtained from 643 women who were participating in a randomized surgical trial for treatment of stress urinary incontinence.
Methods: Patient demographic variables, baseline urinary and fecal incontinence symptom questionnaires, urodynamic data and urinary diary data, pad test results, and standardized assessment of pelvic organ support were compared with PFM strength as described by the Brink scoring system. Bivariate analysis of factors associated with the Brink scale score was done using analysis of variance and linear regression. Multivariate analysis included patient variables that were significant on bivariate analysis.
Results: The mean Brink scale score was 9 (SD=2) and did not vary widely in this large, but highly select, patient sample. We found a weak, but statistically strong, relationship between age and Brink score. Brink scores were not related to diary and pad test measures of incontinence severity.
Discussion and Conclusion: Overall, PFM strength was good in this sample of women with stress incontinence. Scores tended to be similar, and it is possible that the Brink scale does not reflect real clinical differences in PFM strength.
| Introduction |
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 TopAbstract Introduction MethodResultsDiscussionConclusionReferences |
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Clinical assessment of PFM strength is by transvaginal or transrectal digital palpation of the PFMs during contraction, and PFM strength is scored according to several validated methods,13 none of which is generally accepted as the gold standard. Although studies with small numbers of subjects1–6 suggest that PFM strength is altered in women with urinary and fecal incontinence, the association of PFM strength and pelvic symptoms has not been well studied using validated measures in a large sample of women. The purpose of this article is to describe the relationship among patient characteristics, symptoms, and a clinical measure of PFM strength in a large cohort of women whose pelvic strength and symptoms were well characterized using validated clinical instruments.
| Method |
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TopAbstractIntroductionMethodResultsDiscussionConclusionReferences |
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Subjects
A total of 655 women were enrolled in the SISTEr study. We present data for the 643 women with complete baseline Brink scale scores. Of these women, 197 (31%) reported that they had undergone a prior hysterectomy, and 92 women (14%) reported that they had undergone prior incontinence surgery. Table 1 describes the sample by ethnicity, stage of pelvic organ prolapse, genital hiatus size, and Brink scale scores.
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The Urogenital Distress Inventory (UDI), with its stress symptoms, irritative symptoms, and obstructive symptoms subscales,16 also was included at baseline. The UDI contains 19 questions about lower urinary tract symptoms and the degree to which they are bothersome. The UDI has been shown to be valid, reliable, and responsive in a community-dwelling population of women with incontinence.16 The stress symptoms subscale describes bother with symptoms of SUI. The irritative symptoms subscale describes bother with urinary urgency, frequency, and urge incontinence. The obstructive symptoms subscale describes bother related to bladder emptying and symptoms of pelvic heaviness or discomfort.
We also determined whether women experienced fecal incontinence by asking them "Do you have leaking or loss of control of gas?" (and, if so, how often?) and similar questions concerning lost control of liquid and solid stool. Subjects underwent urodynamic testing in the standing position, with urodynamic diagnoses made according to International Continence Society definitions.17 Subjects completed a urinary diary for 1 week (recording number and type of incontinence episodes) and completed a standardized pad test. Pelvic organ support was assessed using the Pelvic Organ Prolapse Quantification (POP-Q) system.18
Pelvic-floor muscle strength was determined through transvaginal digital palpation during the performance of a voluntary PFM contraction and rated using the Brink scoring system,19 which has been reported to yield scores with reasonable interrater reliability, test-retest reliability, and validity.19 Pelvic-floor muscle strength was assessed with each subject in the dorsal lithotomy position, while the tester placed 1 or 2 lubricated fingers 4 to 6 cm into the subject's vagina with the palm facing down. The subject was instructed that the tester would be counting to 3 and would then ask her to "squeeze your pelvic muscles, the ones that you use to stop your urine stream, as strong as you can. I want you to hold the contraction for as long as possible or until I tell you to stop. As you do this, I want you to try to avoid contracting your tummy, bottom, or thigh muscles." Once the subject demonstrated the ability to contract her PFMs, formal assessment took place. The expected co-contraction of the abdominal wall and PFMs was permitted.
The Brink scale evaluates 3 PFM contraction variables: vaginal pressure or muscle force, elevation or vertical displacement of the examiner's fingers, and duration of contraction. Each muscle contraction variable is rated on a 4-point ordinal scale. The pressure felt by examining fingers is rated 1 ("no response"), 2 ("weak squeeze"), 3 ("moderate squeeze"), or 4 ("strong squeeze"). The vertical displacement is rated 1 ("none"), 2 ("finger base moves anteriorly"), 3 ("whole length of fingers move anteriorly"), or 4 ("whole fingers move anteriorly, are gripped and pulled in"). Duration of contraction (in seconds) is timed and scored 1 ("none"), 2 ("<1 second"), 3 ("1–3 seconds"), or 4 (">3 seconds"). Ratings are summed to obtain total scores, with a possible range of scores of 3 to 12.
The PFM strength testers were certified in the assessment using the Brink scale by the principal investigator at each site. All testers were either physicians or registered nurses, and several testers were certified at each clinical site.
Data Analysis
A priori, we predicted that PFM strength would be related to subject characteristics (including age, race, parity, hysterectomy status, and history of prior surgery for urinary incontinence) and to subject symptoms of urinary and fecal incontinence. After descriptive statistics were tabulated for all variables, bivariate analysis of factors associated with the Brink scale score was done using analysis of variance with categorical variables and simple linear regression with continuous measures, with results considered significant at the .05 level. For inclusion in the multivariate analysis, we selected subject variables that were statistically significant on bivariate analysis and that could reasonably be thought to predict PFM strength. Subjects’ symptoms that were likely to be a result of altered PFM strength, rather than a cause of altered PFM strength, were not included in the multivariate analysis.
| Results |
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TopAbstractIntroductionMethodResultsDiscussionConclusionReferences |
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Table 2 details descriptive statistics for continuous measures. In summary, the women had a mean age of 51.9 years (SD=10.3) and had a mean of 2.6 (SD=1.6) vaginal deliveries. As expected in this sample of women who were incontinent with stress-predominant symptoms, MESA stress incontinence subscale scores were higher than the urge incontinence subscale scores. A higher degree of distress associated with stress compared with overactive bladder syndrome symptoms also was reflected in the UDI subscale scores.
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The presence of incontinence of flatus (P=.01) or liquid stool (P=.001) was related to lower Brink scale scores. Incontinence of flatus at least once a month was present in 19 (58%) of the subjects with Brink scale scores in the lowest quartile and in 133 (47%) of the subjects with Brink scale scores in the highest quartile. Similarly, incontinence of liquid stool at least monthly was present in 9 (27%) and 37 (13%) of those subjects with low quartile and high quartile Brink scale scores, respectively. Finally, although incontinence of solid stool was seldom reported and thus we could find no statistical relationship, it was present at least monthly in 5 (15%) of the subjects with Brink scale scores in the lowest quartile and in 13 (5%) of the subjects with Brink scale scores in the highest quartile.
As detailed in Table 4, multivariate analysis confirmed age (P<.001) as a subject characteristic that significantly predicted Brink scale score after correcting for other factors, but the model explained only 7% of the variability seen and did not add to our understanding of factors influencing Brink scale score.
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| Discussion |
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Although our large sample size allowed us to discern several statistically important relationships, it is clear from Tables 2 and 3 that the variation in absolute Brink scale scores was very small. We were able to support the findings of Rizk et al,20 who demonstrated racial differences in PFM morphology in women who were nulliparous and healthy, and our findings also confirmed the results of prior studies that suggested there is weakening and thinning of the PFMs with aging.11,21
We found no relationship between PFM strength and the number of vaginal deliveries after controlling for age and other factors. The relationship between PFM strength and vaginal parity has been examined previously with mixed results. Electromyographic evidence of denervation at the time of vaginal delivery has been found, with longer second stage of labor and larger birth weight associated with more evidence of denervation.7 One study of postpartum Brink scale scores in a small number of primigravidas22 showed that PFM strength was highest in women who delivered by Cesarean section and was incrementally lower in women with vaginal delivery without episiotomy, followed by vaginal delivery with episiotomy and vaginal delivery with laceration. Another study2 also showed a reduction in PFM strength 3 to 8 days postpartum and lower scores in women who were multiparous than in women who were primiparous. However, follow-up testing 6 to 10 weeks postpartum showed resolution of function to antepartum levels. Conversely, a study using the Oxford Digital Rating Scale23 did not show differences in PFM strength between women who were nulliparous and women who were parous.
The UDI obstructive symptoms subscale measures symptoms related to lower abdominal pressure or pain, heaviness or dullness in the pelvic area, dysuria, or the need to push on the vaginal walls to have a bowel movement. Our finding of a weak relationship between decreased PFM strength and those symptoms is pathophysiologically reasonable, as many women with a weakened pelvic floor may have a widened genital hiatus and feel pelvic pressure. Again, because this relationship is weak and the multivariate model was able to explain only 7% of the variability in Brink scale scores, we are anxious not to overinterpret this finding.
In the present study, all women had stress incontinence, yet we did not find the expected negative relationship between PFM strength and measures of SUI severity, including Valsalva leak point pressure, pad test weight, and number of incontinence episodes recorded in the urinary diary. Our lack of ability to show this relationship may have been due to the relative homogeneity of the study sample, with a relatively small range of Brink scale scores and lack of a continent control group. However, other studies investigating the relationship between PFM strength and urinary symptoms are divided in their results. Some studies have shown differences in PFM strength measured by digital palpation between women with and without incontinence.22 Other studies have not found associations between subjects’ perception of urine loss and PFM strength determined by vaginal digital palpation or the Oxford Digital Rating Scale.24
Several factors may have interfered with the ability to show stronger associations between Brink scale scores and these demographic and clinical variables. Although the Brink method of muscle testing has been found to be a fairly reliable clinical measure,19,25 like other current measures of PFM strength, it cannot fully characterize PFM function. It does provide the clinician with a crude measure of a woman's ability to contract her PFMs over a brief time period, but it does not determine whether the woman's muscle function is adequate to fulfill its role in maintaining continence. The sphincteric and supportive roles of the PFMs require that they have good endurance and the ability to contract with adequate force and sufficient timing to anticipate increases in intra-abdominal pressure. Additionally, to prevent urine leakage during a functional task, such as standing from a sitting position, adequate recruitment of the PFMs must be coordinated with that of other muscles needed for that specific task.
It is probably unrealistic to expect that a simple digital measure of PFM strength could strongly predict whether these motor control and coordination demands can be met to prevent stress incontinence or urge incontinence when encountered during a functional task. The finding that this sample of women with incontinence had fairly good PFM strength, as defined by a mean Brink scale score of 9 out of a possible 12 points, provides support for the notion that adequate muscle function depends on several factors, including the ability to perform a muscle contraction under a variety of environmental circumstances. For example, a woman may have good PFM strength but lack the skill to activate her muscles under certain situations, such as during a sneeze as she runs to her car in the rain while carrying her child. Support for this notion is provided by the finding of Devreese and colleagues26 that women who were continent had significantly better coordination between the PFMs and the lower abdominal muscles during coughing compared with women who were incontinent.
Another variable that limits the functional generalizability of digital strength test results is the test condition itself. Both tactile and verbal examiner feedback is provided to the patient during the assessment. This feedback has the potential to enhance the patient's ability to understand the task and thus contract her muscles. In real life, without feedback and instruction, the woman's ability to use her PFMs to prevent a stress incontinence or urge incontinence episode may be more limited.
The fact that the Brink scale scores of women in our sample fell within a narrow range also may have limited our ability to find stronger associations between PFM strength and symptoms of pelvic dysfunction. To further explore these relationships, additional studies may need to include women with a broader range of PFM strength and with a greater diversity of clinical symptoms. Other strength rating systems also may better reflect the diversity of clinical findings and allow more sophisticated exploration of this interesting relationship.
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TopAbstractIntroductionMethodResultsDiscussionConclusionReferences |
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| Footnotes |
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The institutional review boards at all participating clinical centers approved the study.
This work was presented orally at the 26th Annual Scientific Meeting of the American Urogynecologic Society; September 15–17, 2005; Atlanta, Ga. An abstract of this research was published in Journal of Pelvic Surgery (2005;11[suppl 1]:15).
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| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
