ORIGINAL ARTICLE. Judith A. Thompson & Peter B. O Sullivan & N. Kathryn Briffa & Patricia Neumann

Transcription

1 Int Urogynecol J (2007) 18: DOI /s ORIGINAL ARTICLE Comparison of transperineal and transabdominal ultrasound in the assessment of voluntary pelvic floor muscle contractions and functional manoeuvres in continent and incontinent women Judith A. Thompson & Peter B. O Sullivan & N. Kathryn Briffa & Patricia Neumann Received: 14 November 2005 / Accepted: 6 July 2006 / Published online: 17 October 2006 # International Urogynecology Journal 2006 Abstract Transperineal (TP) and transabdominal (TA) ultrasounds were used to assess bladder neck (TP) and bladder base (TA) movement during voluntary pelvic floor muscle (PFM) contraction and functional tasks. A sonographer assessed 60 asymptomatic (30 nulliparous, 30 parous) and 60 incontinent (30 stress, 30 urge) women with a mean age of 43 (SD=7) years, BMI of 24 (SD=4) kg m 2 and a median parity of 2 (range, 0 5), using both ultrasound methods. The mean of three measurements for bladder neck and bladder base (sagittal view) movement for each task was assessed for differences between the groups. There were no differences in bladder neck (p=0.096) or bladder base (p=0.112) movement between the four groups during voluntary PFM contraction but significant differences in bladder neck (p<0.004) and a trend towards differences in bladder base (p=0.068) movement during Valsalva and abdominal curl manoeuvre. During PFM contraction, there was a strong trend for the continent women to have greater bladder neck elevation (p=0.051), but no difference in bladder base movement (p=0.300), when compared to the incontinent women. The incontinent women demonstrated increased bladder neck descent during Valsalva and abdominal curl (p<0.001) and bladder base descent during Valsalva (p=0.021). The differences between the groups were more marked during functional activities, suggesting that comprehensive assessment of the J. A. Thompson (*) : P. B. O Sullivan : N. K. Briffa School of Physiotherapy, Curtin University of Technology, GPO Box U1987, Perth 6845 Western Australia, Australia judiththompson@bigpond.com P. Neumann School of Physiotherapy, University of South Australia, Adelaide 5000 South Australia, Australia PFM should include functional activities as well as voluntary PFM contractions. TP ultrasound was more reliable and takes measures from a bony landmark when compared to TA ultrasound, which lacks a reference point for measurements. TA ultrasound is less suitable for PFM measures during functional manoeuvres and comparisons between subjects. Few subjects were overweight so the results may not be valid in an obese population. Keywords Physiotherapy. Transperineal ultrasound. Transabdominal ultrasound. Pelvic floor muscles. Stress urinary incontinence. Urge urinary incontinence Introduction Evaluation of pelvic floor muscle (PFM) activity and function is necessary to give feedback about the ability to perform PFM exercises and to document changes in PFM function after intervention [1]. Real-time ultrasound provides direct visualisation of a PFM contraction and has been used to assess and give feedback about PFM exercise performance [2, 3]. The amount of movement occurring at the bladder neck and bladder base during voluntary PFM contractions can be quantified [3 5] and has been shown to correlate with other measures of PFM strength [6, 7]. Wijma et al. [8], using transperineal (TP) ultrasound, compared the amount of movement occurring at the bladder neck during voluntary PFM contraction in women with stress urinary incontinence (SUI) and continent controls. The authors found no difference between the groups during voluntary PFM contraction. However, they observed the women with SUI had increased bladder neck descent during coughing. Barbic et al. [9] demonstrated that increased

2 780 Int Urogynecol J (2007) 18: bladder neck mobility during coughing is associated with a delayed onset of the PFM in women with SUI compared with continent controls. The ability to voluntarily contract the PFM may not reflect the activation of PFM during functional manoeuvres [10]. To date, clinical measurement tools used by physiotherapists to assess the PFM have focused primarily on assessment of the voluntary activation of the PFM [1]. It is important to develop clinical tests that investigate the activation of PFM during functional manoeuvres as well as the capacity to consciously contract the PFM. TP ultrasound has been established as a reliable method to assess bladder neck movement during voluntary PFM contraction and functional manoeuvres [11, 12]. More recently, transabdominal (TA) ultrasound has been used by physiotherapists as biofeedback during PFM exercises to observe bladder base movement as a marker for the PFM [4, 5, 7, 13 16]. Good intra- and inter-rater reliability for the measurement of bladder base movement (transverse and sagittal view) during PFM contraction [5, 16, 17] and good intra-rater reliability (transverse view) during functional active straight-leg-raise testing has been reported [18]. TA ultrasound has several clinical advantages for physiotherapists using this method for biofeedback training. For example, the patient does not need to undress (which may be important in specific populations, e.g. children), observing bladder movement is easy for the patient, the measurement is quick and easy to perform and the position of the probe on the abdomen does not limit functional manoeuvres [16]. It is of interest to compare both TP and TA ultrasound as clinical methods to assess both the voluntary activation of the PFM and the mobility of the bladder neck and bladder base during functional manoeuvres known to increase intra-abdominal pressure (IAP) in a mixed subject population. The first aim of the study was to use TP and TA ultrasound to assess the amount of bladder neck (using TP) and bladder base (using TA) movement occurring during voluntary PFM contraction and functional manoeuvres in four groups of women: nulliparous asymptomatic, parous asymptomatic, SUI and urge urinary incontinence (UUI). The second aim was to compare TP and TA ultrasound methods for clinical utility and assessment of between group differences. Materials and methods A cross-sectional study design was used to compare four groups of women: nulliparous asymptomatic, parous asymptomatic, SUI and UUI. Female volunteers were recruited from the local Perth metropolitan community. All gave written informed consent. Inclusion criteria were ages years and pre-menopausal status or on hormone replacement therapy. General exclusion criteria were pregnancy, urinary tract infection, vaginal infection, known neurological disorders and an inability to understand English. In the asymptomatic group, in order to obtain a naive sample, women were excluded if they were physiotherapists or had previously had any individual PFM training. In an effort to obtain two distinct symptomatic groups, women with incontinence were excluded if they had symptoms of mixed urinary incontinence as defined by the urinary symptoms questionnaire [19]. Some of the symptomatic women recruited had previously received some PFM training. In order to avoid the effects of recent training, women were excluded if they had undergone any individual PFM training within the last 2 years. All women were interviewed by telephone and questioned regarding any urinary leakage using the incontinence severity index questionnaire [20]. Urinary incontinence was assessed using a urinary symptoms questionnaire [19]. The study received ethical approval from the Human Research Ethics Committee, Curtin University of Technology. Before commencing testing, all women filled in a questionnaire regarding general and PFM exercise habits and a history of disorders that might result in the subjects generating high levels of IAP on an ongoing basis such as chronic cough, sinusitis and constipation. The results of the questionnaire have previously been reported [7]. Equipment Ultrasound All women were assessed by the same qualified sonographer for all the tests. Ultrasound imaging was performed using high-definition imaging (Philips HDI Sono 5000CT) with two-curved linear array probes (5 2, 7 4 MHz) using both the TA and TP approach. The women were not able to observe the ultrasound screen in order to avoid a training biofeedback effect. The reliability of the ultrasound measurements [intra-class correlations (ICC) and standard error of measurements (SEM)] for PFM contraction [TP 0.91 (0.11), TA 0.93 (0.13)] and Valsalva manoeuvre [TP 0.87 (0.16), TA 0.51 (0.38)] for this study and a detailed description of the methodology has previously been reported [16]. Ten asymptomatic women were tested on two occasions, 1 week apart, for reliability of the measurement of abdominal curl-up exercise [TP 0.79 (0.33), TA 0.53 (0.41)]. TP imaging was performed with the ultrasound transducer placed in the mid-sagittal plane at the perineum. A measure of the position of the bladder neck was taken at

3 Int Urogynecol J (2007) 18: rest, and the change from the resting position was measured using the standardised method described by Schaer [12]. The measurements were entered in a computer spreadsheet, and the cranio-ventral bladder neck lift or dorso-caudal descent was calculated using the method described by Dietz [3]. TA ultrasound was performed by placing the probe supra-pubically, on the lower abdomen, in the mid-sagittal plane. The transducer was angled in a caudal/posterior direction to obtain a clear image of the inferior posterior aspect of the bladder. A marker was placed at the bladder base on the junction of the hyper- and hypo-echoic areas in the region of the greatest displacement visualised during a PFM contraction. The marker was placed at rest and at the end of PFM contraction to mark the point of maximal displacement of the bladder base from the resting position. The same point used during the PFM contraction test was used as the start point for the other manoeuvres. The difference between the rest position and position of the bladder base at the end of the manoeuvre was measured using the on-screen callipers. Three tasks were performed: a PFM contraction, a Valsalva manoeuvre and an abdominal curl-up exercise. (1) PFM contraction: Instructions were to draw in and lift the PFM, breathing normally whilst holding the PFM contraction. (2) Valsalva manoeuvre: Instructions were to strain downwards with maximal effort. A Valsalva was defined as a forced expiration against a closed glottis. The degree of effort during Valsalva was not standardised as attempts to standardise Valsalva have resulted in limiting maximal descent of the bladder neck [11, 21]. (3) Abdominal curl-up manoeuvre: Instructions were to place the arms across the chest and lift the head and shoulders until the edge of the shoulder blades just came off the bed. Computer-generated random numbers determined the order in which the three test manoeuvres were performed. The tests were repeated three times, and a mean measurement was calculated for each test. Evidence of prolapse visualised using TP ultrasound was recorded. Following the ultrasound assessment, the same continence physiotherapist assessed all women vaginally to assess for the presence of prolapse. Valsalva and abdominal curl tests were chosen as tasks, as these tasks have previously been shown to result in an increase in IAP [9, 15, 21, 22] and an increase in reflex PFM activity [23, 24]. During Valsalva, the IAP is increased as a conscious straining effort; while during the abdominal curl manoeuvre, IAP is increased unconsciously. Often, reflex PFM activity is assessed during coughing, but coughing is difficult to standardise, and the movement observed is rapid and transient and difficult to measure using TA ultrasound. Statistical analysis of the data Statistical analysis of the data was performed using SPSS (V10). The reliability of the measurements during abdominal curl was assessed using ICC (2,3) and the SEM from the duplicate measures on the 10 volunteers tested 1 week apart. The minimal detectable change was calculated to determine the magnitude of difference between serial measurements required to be 95%, confident that the difference was more than simply a manifestation of measurement error [25]. A two-way repeated-measures ANOVA was performed using the mean measurement for each task to assess for interactions between the groups (task group). Although a negative movement of the bladder neck and bladder base was recorded in some subjects, all subjects were included in these analyses. A one-way ANOVA was performed for each separate task using the mean ultrasound measurement during each test as the dependent variable. Where there was a significant main effect for groups, post hoc comparisons were made using linear contrasts. A primary analysis was performed on the four groups followed by a secondary analysis to compare the differences between the continent and incontinent groups. Results One hundred and twenty women with a mean age of 43 (SD=7) years, BMI of 24 (SD=4) kg m 2 and a median parity of 2 (range 0 5) were assessed. The demographic data, results of the urinary symptoms questionnaires and number of women in each group assessed to have prolapse is displayed in Table 1. The mean (SD) values for bladder neck and bladder base movement for each of the tasks for the four groups are displayed in Table 2 (Fig. 1) and for the continent and incontinent women in Table 3. Minimal detectable change The minimal detectable change between serial measurements was less using TP ultrasound than TA ultrasound for all the tasks (PFM TP=0.30, TA=0.36; Valsalva TP=0.44, TA=0.97; abdominal curl TP=0.91, TA=1.14). Amount of bladder neck and bladder base movement on ultrasound The results of the two-way ANOVA showed that there was a significant difference in the bladder neck movement measured using TP ultrasound occurring during the three tasks between the four groups (task group, TP p<0.001). There was a trend towards a difference in bladder base

4 782 Int Urogynecol J (2007) 18: Table 1 Demographic data; the mean (SD) for age, BMI, parity, ISI score, the stress and urge score [19] Continent Incontinent Nulliparous Parous SUI UUI p value Age 39.7 (9) a 41.8 (5) a,b 46.4 (5) b,c 43.3 (8) a,b 0.011* Parity 0 a 2(1to4) b,c,d 2(1to4) b,d 2(0to4) b,c <0.001* BMI 23 (3) 22 (3) 24 (4) 24 (4) ISI score 0 a 0 a 4 (2) b 5 (2) b <0.001* Stress score 0 a 0 a 23 (2) b 2 (2) c <0.001* Urge score 0 a 0 a 5 (1) b 18 (2) c <0.001* Prolapse 3 a 6 a,c 20 b 13 b,c 0.002* Post hoc comparisons: values with different superscripts are significantly different at p<0.05. p values for the differences between the four groups: (1) nulliparous asymptomatic (2) parous asymptomatic (3) SUI (4) UUI *Indicates significance alpha <0.05 movement measured using TA ultrasound occurring during the three tasks between the four groups (task group, TA p= 0.089). Voluntary PFM contraction When considering bladder neck movement (TP), there was no difference in the amount of movement occurring during PFM contraction between the four groups (p=0.096) (Fig. 2). There was a strong trend towards greater bladder neck elevation in the continent women compared to the incontinent women [0.58 (0.56) vs 0.39 (0.52); p=0.051]. The results of bladder neck movement measured using TP ultrasound during voluntary PFM contraction have previously been reported [16]. When considering bladder base movement (TA), there was no significant difference in the amount of movement between the four groups (p=0.112) or between continent and incontinent women (0.50 [0.50] vs 0.39 [0.58]; p=0.300; Table 2). Valsalva When considering bladder neck descent (TP), there was a significant difference between the four groups during Valsalva (p<0.001). Post hoc linear comparisons showed that the SUI group [1.76 (0.88)] had increased bladder neck descent compared with the nulliparous [0.92 (0.69); p<0.001] and parous [0.97 (0.47); p=0.001] asymptomatic groups. There was no difference between the UUI group [1.40 (0.78)] and nulliparous (p=0.097) or parous (p=0.160) asymptomatic groups. There was no difference between the nulliparous and parous asymptomatic groups (p=0.996) or SUI and UUI groups (p=0.277). The incontinent women had greater bladder neck descent than the continent women during Valsalva [1.58 (0.84) vs 0.95 (0.58); p<0.001]. When considering bladder base movement (TA), there was a trend towards a difference in the amount of movement between the four groups during Valsalva (p= 0.068). The incontinent women displayed a greater amount of bladder base descent compared with the continent women [2.17 (0.98) vs 1.77 (0.88); p=0.021; Table 2]. Table 2 Primary analysis, comparison between the four groups: (1) nulliparous asymptomatic (2) parous asymptomatic (3) SUI (4) UUI Nulliparous Parous SUI UUI p value Transperineal ultrasound % of group BN descent PFM contraction (cm) 0.57 (0.59) 0.59 (0.54) 0.50 (0.50) 0.27 (0.53) Abdominal curl (cm) 0.44 (0.59) 0.54 (0.32) 0.87 (0.48) 0.77 (0.52) Valsalva manoeuvre (cm) 0.92 (0.69) 0.97 (0.47) 1.76 (0.88) 1.40 (0.78) <0.001 Transabdominal ultrasound % of group bladder base descent PFM contraction (cm) 0.50 (0.49) 0.49 (0.50) 0.55 (0.51) 0.26 (0.61) Abdominal curl (cm) 1.48 (0.68) 1.74 (0.67) 1.96 (0.71) 1.78 (0.68) Valsalva manoeuvre (cm) 1.64 (0.90) 1.90 (0.83) 2.27 (1.00) 2.13 (0.97) The mean (SD) for measurements of bladder neck (BN) movement using transperineal (TP) ultrasound and bladder base movement transabdominal ultrasound (TA) during (1) PFM contraction (2) maximal Valasalva and (3) abdominal curl-up exercise.

5 Int Urogynecol J (2007) 18: Fig. 1 The mean and standard deviation (cm) for the ultrasound measurements of bladder neck (a transperineal) and bladder base (b transabdominal) movement from rest during (1) voluntary pelvic floor muscle (PFM) contraction (2) abdominal curl-up, (3) Valsalva manoeuvre, for the four groups: nulliparous asymptomatic, parous asymptomatic, stress urinary incontinence (SUI), urge urinary incontinence (UUI). a Transperineal, there was no difference in the amount of movement occurring during PFM contraction (TP p=0.096), but significant difference for abdominal curl (p=0.004) and Valsalva (p<0.001) between the four groups. b Transabdominal, there was no difference in the amount of movement occurring during PFM contraction (p=0.112), abdominal curl (p=0.068) and Valsalva (p=0.068) between the four groups Abdominal curl-up manoeuvre When considering bladder neck movement (TP), there was a significant difference between the four groups during abdominal curl (p=0.004). Post hoc linear comparisons showed that the SUI group [0.87 (0.48)] had increased bladder neck descent compared with the nulliparous asymptomatic group [0.44 (0.59); p=0.023], and there was a trend towards the SUI having increased bladder neck movement compared with the parous asymptomatic group [0.97 (0.47); p=0.068]. There was no difference between the UUI group [0.77 (0.52)] and the nulliparous and parous asymptomatic groups (p>0.112). There was no difference between the nulliparous and parous asymptomatic groups (p=0.979) or between the SUI and UUI groups (p=0.919). The incontinent women displayed greater bladder neck descent than the continent women during abdominal curl [0.82 (0.50) vs 0.49 (0.47); p<0.001]. When considering bladder base movement (TA), there was a trend towards a difference in movement between the four groups during abdominal curl (p=0.068) and a strong trend towards the incontinent women having a greater amount of bladder base descent compared with the continent women [1.85 (0.69) vs 1.61 (0.69); p=0.056; Table 2].

6 784 Int Urogynecol J (2007) 18: Table 3 Secondary analyses, comparison between the continent and incontinent groups Continent (TP) Incontinent p value Continent (TA) Incontinent p value PFM contraction (cm) 0.58 (0.56) 0.39 (0.52) (0.50) 0.39 (0.58) Abdominal curl (cm) 0.49 (0.47) 0.82 (0.50) < (0.69) 1.85 (0.69) Valsalva manoeuvre (cm) 0.95 (0.58) 1.58 (0.84) < (0.88) 2.17 (0.98) The mean (SD) for measurements of bladder neck movement using transperineal (TP) ultrasound and bladder base movement transabdominal ultrasound (TA) during (1) PFM contraction (2) maximal Valasalva and (3) abdominal curl-up exercise. Discussion Both methods of ultrasound used in this study were noninvasive and gave objective measures of the amount of movement occurring at the bladder neck and bladder base during voluntary PFM contractions and functional manoeuvres. Comparisons between the four groups and the continent and incontinent women demonstrated that there were no statistical differences in the amount of bladder neck or bladder base movement during voluntary PFM contraction in these untrained subjects. These results support two smaller studies that found no difference in the amount of bladder neck elevation during voluntary PFM contraction in asymptomatic women compared to women with SUI [8, 26]. These findings suggest that conscious muscle contraction may not be a sensitive measure of PFM function and may have limited value in identifying PFM dysfunction. These findings are consistent with other authors [8, 10]. There was no statistical difference between the groups in the ability to perform an elevating PFM contraction, but the higher proportion of women in the UUI group, unable to elevate the bladder neck [7] and base, would appear to be clinically significant and warrants further investigation. These findings are consistent with the clinical observational Fig. 2 The mean and standard deviation (cm) for the ultrasound measurements of bladder neck (TP transperineal) and bladder base (TA transabdominal) movement from rest during voluntary pelvic floor muscle (PFM) contraction for the four groups: nulliparous asymptomatic, parous asymptomatic, stress urinary incontinence (SUI), urge urinary incontinence (UUI). There was no difference in the amount of movement occurring during PFM contraction between the four groups (TP p=0.096; TA p=0.112) study [13]. During PFM contraction, although there was no significant difference between the groups, there was a trend towards greater bladder neck elevation in the continent women; these continent women were previously reported as stronger [7]. The ability to elevate the pelvic floor and degree of movement occurring at the bladder neck and bladder base during voluntary PFM contraction is dependent on a variety of factors, such as fascial laxity, resting PFM tone, force of the PFM contraction as well as the levels of intra-abdominal pressure and activity of the other muscles of the abdomino-pelvic cavity [15]. Therefore, it needs to be interpreted in combination with data obtained from a full clinical assessment to determine the clinical relevance. In contrast, during both the functional manoeuvres, Valsalva and abdominal curl, measurements of bladder neck movement made using TP ultrasound demonstrated significant differences in bladder neck movement between the four groups and the continent and incontinent women. The women with SUI showed increased bladder neck movement compared with both groups of continent women, although there were no differences found between the continent women and the women with UUI. Increased bladder neck mobility during Valsalva has previously been reported in women with SUI [21] and has been shown to have a strong association with urodynamic SUI [27]. It is hypothesised that the increased mobility demonstrated in the incontinent women in this study may be due to increased laxity of the passive support structures, a deficit in the recruitment of the PFM during functional manoeuvres or a lack of strength to accommodate the increase of IAP associated with these manoeuvres or, most likely, a combination of all three. Although the electromyogram and timing of recruitment of the PFM was not directly assessed in this study, the incontinent women were previously recorded to be significantly weaker than the continent women [7] supporting this notion. The measurements of bladder base movement made using TA ultrasound showed similar movement patterns to TP ultrasound but were less discriminative for the assessment of between-group differences. The lack of a fixed bony reference point and the lower (moderate) reliability and increased measurement error during the functional

7 Int Urogynecol J (2007) 18: manoeuvres are likely to have affected these results. In this study, 43 women were assessed as having some degree of prolapse, and this is likely to have affected the bladder base size and position. The sagittal view was used in this study as initial reliability testing (abstract) demonstrated improved reliability of the sagittal view for measuring bladder base movement during voluntary PFM contraction [17]. However, the point of measurement chosen (region of greatest displacement during PFM contraction) was not found to be very reliable during functional activities. From these results, the use of TA ultrasound (sagittal view) during these functional manoeuvres cannot be recommended. As previous studies have reported good reliability of the transverse view during functional manoeuvres such as active straight-leg-raise testing [18], further research is required to investigate if the transverse view would be a more reliable measure of bladder base movement during functional manoeuvres. There were several possible limitations of this study. The different probe placements may have altered the behaviour of the patients and altered the measurements. Measurement error could have occurred due to movement of the probe with both methods; however, greater probe movement is more likely with TA ultrasound due to outward movement of the abdominal wall. The possibilities of measurement error are more likely using TA ultrasound, as this method lacks a fixed bony reference point. In this study, the ultrasound probe was held firmly against the abdominal wall in order to limit probe movement. It is acknowledged that the presence of prolapse can affect the measurements made using the TA method and is likely to be a confounding factor. Although the measurement of bladder neck and bladder base were taken immediately following one another and the subjects were not given any feedback about performance, the fact that the measurements are taken at two different anatomical points at different times limits the measurement comparison [16]. The method of grouping the women into symptoms of SUI and UUI was made using a questionnaire by telephone interview and not by standard urodynamic diagnosis. Attempts were made to create homogenous groups by excluding all women with symptoms of mixed UI. The SUI group were significantly different from the UUI group in terms of stress score and urge score (p<0.001; Table 1), but it is acknowledged that this is a symptom score that may not reflect the urodynamic diagnosis. In this study, IAP was not directly monitored, as the purpose of the study was to assess the clinical utility of both methods of ultrasound as non-invasive measurement techniques. The functional tasks were assumed to result in an increase in IAP based on previous data [9, 15, 21, 22]. A good view of the bladder base was obtained in all women using the abdominal approach; few of the women in this study were overweight. It is acknowledged that TA scanning may be difficult in obese women. The study was powered for a larger effect size based on a 4-mm difference between asymptomatic and incontinent women during PFM contraction found by Bo et al. [26] using MRI. As there was considerable variability and overlap between the groups, a non-significant result for some of the comparisons between groups may be due to type II error, and a larger sample size may be needed to detect any differences. Clinical implications Differences in the amount of bladder neck and bladder base movement were more marked between groups during functional activities than during the voluntary PFM contractions. This highlights the importance of including an assessment of the PFM during functional activities. The ability to elevate the pelvic floor may not in itself be evidence of good PFM function and should be interpreted in combination with data obtained from a full clinical assessment including functional manoeuvres known to generate IAP to assess the ability of the PFM to resist depression under load. TA ultrasound (sagittal view) for the clinical assessment of bladder base movement during functional manoeuvres cannot be recommended. Conclusion Ultrasound is useful to objectively assess the direction of movement of the bladder neck and bladder base during voluntary PFM contraction to ensure a correct technique of performing an elevating PFM contraction. There were no differences between the four groups in the amount of bladder neck and bladder base movement during voluntary PFM contraction. Differences were found in bladder neck movement between groups during functional manoeuvres known to increase IAP. Simply observing PFM movement on ultrasound during voluntary PFM contraction may not identify PFM dysfunction. The differences in the voluntary and functional activation of the PFM suggest that comprehensive assessment of the PFM should include functional activities as well as voluntary PFM contractions. TP ultrasound was more reliable than TA ultrasound during the functional manoeuvres, which, in addition to the fact that the measurements are taken from a fixed bony marker, make it more suitable for comparisons between subjects. The measurements made using TA ultrasound showed similar movement patterns to TP ultrasound, but the reduced reliability during the functional manoeuvres combined with the potential for confounding by the presence of prolapse and probe movement suggest that TA ultrasound

8 786 Int Urogynecol J (2007) 18: (sagittal view) cannot be recommended for comparison between subjects during these functional manoeuvres. Acknowledgments We thank the Curtin University Postgraduate Scholarship Awards and the Physiotherapy Research Foundation of Australia for financial assistance, Dr. Anthony Murphy for the use of ultrasound equipment, Sarah Court for research assistance, Nicole David for the preparation of the graphics and Ritu Gupta for statistical advice. References 1. Bo K, Sherburn M (2005) Evaluation of female pelvic-floor muscle function and strength. Phys Ther 85(3): Dietz HP, Steensma AB, Vancaillie TG (2003) Levator function in nulliparous women. Int Urogynecol J Pelvic Floor Dysfunct 14 (1): Dietz HP, Wilson PD, Clarke B (2001) The use of perineal ultrasound to quantify levator activity and teach pelvic floor muscle exercises. Int Urogynecol J Pelvic Floor Dysfunct 12 (3): Bo K, Sherburn M, Allen T (2003) Transabdominal ultrasound measurement of pelvic floor muscle activity when activated directly or via a transversus abdominis muscle contraction. Neurourol Urodyn 22(6): Sherburn M et al (2005) Investigation of transabdominal real-time ultrasound to visualize the muscles of the pelvic floor. Aust J Physiother 51(3): Dietz HP, Jarvis SK, Vancaillie TG (2002) The assessment of levator muscle strength: a validation of three ultrasound techniques. Int Urogynecol J Pelvic Floor Dysfunct 13(3): , discussion Thompson J et al (2006) Assessment of voluntary pelvic floor muscle contraction in continent and incontinent women using transperineal ultrasound, manual muscle testing and vaginal pressure measurements. Int Urogynecol J Pelvic Floor Dysfunct (in press) 8. Wijma J, Tinga D, Visser H (1991) Perineal ultrasound in women with stress incontinence and controls: the role of the pelvic floor muscles. 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