Pelvic Floor Mobility measured by Transperineal Ultrasound Imaging in Women with and without Urgency and Frequency Predominant Lower Urinary Tract Symptoms

Abstract

Background

Women with urgency/frequency predominant lower urinary tract symptoms (UF-LUTS) may have elevated pelvic floor muscle (PFM) position at rest and limited mobility with PFM contraction and bearing down, but this has not been quantified.

Objectives

To compare PFM position and mobility using transperineal ultrasound (TPUS) at rest, maximal PFM contraction (perineal elevation), and bearing down (perineal descent) in women with and without UF-LUTS. We hypothesized that women with UF-LUTS would demonstrate elevated resting position and decreased excursion of pelvic landmarks during contraction and bearing down as compared to women without UF-LUTS.

Study Design

Case-control study

Methods

Women with UF-LUTS were matched 1:1 on age, body mass index and vaginal parity to women without UF-LUTS. TPUS videos were obtained during 3 conditions: rest, PFM contraction, and bearing down. Levator plate angle (LPA) and puborectalis length (PR length), were measured for each condition. Paired t-tests or Wilcoxon signed rank tests compared LPA and PR length between cases and controls.

Results

21 case-control pairs (42 women): Women with UF-LUTS demonstrated greater LPA at rest (66.8 ± 13.2 degrees vs 54.9 ± 9.8 degrees; P=0.006), and less PR lengthening from rest to bearing down (0.2 ± 3.1 mm vs 2.1 ± 2.9 mm; P=.03).

Conclusion

Women with UF-LUTS demonstrated more elevated (cranioventral) position of the PFM at rest and less PR muscle lengthening with bearing down. These findings highlight the importance of a comprehensive PFM examination and possible treatment for women with UF-LUTS to include PFM position and mobility.

INTRODUCTION

Urinary urgency and frequency are the most common lower urinary tract symptoms (LUTS) in women¹ and present a substantial burden on patients’ activities and quality of life.² Literature to guide physical therapist-led intervention of women with urgency- and frequency- predominant LUTS (UF-LUTS) is sparse. While studies report successful treatment of urinary incontinence with PFM training,^3,4 literature specific to improvement of UF-LUTS is limited. In several clinical trials reporting urgency or frequency as an outcome, PFM training alone was unable to produce significant improvements in most participants.^5–7 Because no tests of PFM strength were conducted as outcomes for these trials^5–7 we cannot be certain whether their protocol was ineffective at improving urgency for a large percentage of those participants because it was ineffective at improving PFM strength and endurance, or because strength and endurance are not the appropriate targets for patients with UF-LUTS. We have demonstrated that a marker of PFM strength (vaginal squeeze pressure) did not differ between women with and without UF-LUTS,⁸ suggesting other parameters of PFM performance should be considered in patients with UF-LUTS.

PFM mobility may be one such parameter of interest. Many have theorized that, rather than poor strength and/or endurance, patients with UF-LUTS have PFM overactivity or impaired mobility.^9–12 Clinical observations, documented in the 2017 Diagnosis Dialog for Women’s Health Conditions,¹¹ suggest women with UF-LUTS have excessively elevated PFM position at rest and limited mobility with PFM contraction and bearing down. The PFMs must have sufficient mobility to move in parallel motion with the respiratory diaphragm during breathing¹³ and sufficient relaxation to allow for complete voiding of bladder and bowel.¹⁰ During expiration and voluntary PFM contraction, the PFMs should move cranially (perineal elevation).^13–16 During inspiration and bearing down, the PFMs should move caudally (perineal descent).^13,16

One theoretical mechanism linking impaired PFM mobility to UF-LUTS is mechanically stimulated alterations to neural afferent signals. For example, PFM mobility impairment may influence urinary afferent signals at the level of 1) the urothelium, and/or 2) peripheral nerves innervating the bladder, urethra and pelvic floor (e.g., branches of the pelvic, hypogastric, and pudendal nerves). The urothelium responds to mechanical stresses including tension, torsion, and movement of visceral organs.²² The urothelium may produce signals that are interpreted by the brain as bladder filling when the bladder, urethra and associated connective tissues move abnormally within the pelvic cavity. Impaired mobility of the PFMs and/or elevated position of the pelvic floor may reduce the degrees of freedom in which the bladder, urethra, neural and connective tissues are able to move in response to changes in body position and body movement. Similarly, if impaired PFM position and mobility reduce degrees of freedom for sliding and gliding of peripheral afferent nerves that transmit information about bladder volume to the central nervous system, the result can be hyperestheia²³ of the sensation of the need to urinate. Inflammatory factors induced by ischemia, infection, aging or other inflammatory processes may also contribute to reduced freedom of movement by creating mechanical cross-linking between urinary tract and pelvic floor tissues that would normally be permitted to slide and glide during everyday movement.

Clinical assessment of PFM function includes assessment of mobility and quality of motion during PFM contraction, relaxation, and bearing down. In women, this assessment is often completed by the practitioner palpating vaginally to determine the resting position of the PFMs,²⁴ and the direction and quantity of motion during contraction and bearing down.²⁵ However, PFM vaginal palpation is not always feasible or ideal for a variety of reasons: not all patients are comfortable with vaginal palpation; practitioner’s palpating digit may provide tactile feedback that causes the patient’s PFMs to perform differently than they might otherwise; and vaginal palpation does not allow for measurement of PFM mobility. Ultrasound imaging of pelvic landmark excursions during contraction (perineal elevation) and bearing down (perineal descent) may provide a noninvasive quantitative method to assess PFM mobility.²⁶

Two-dimensional (2-D) dynamic ultrasound is inexpensive and increasingly available in physician and physiotherapist offices. Transperineal ultrasound (TPUS) has long been used for biofeedback in training volitional PFM contractions, primarily in patients with urinary incontinence.²⁷ Transperineal ultrasound measurement during voluntary PFM contraction is reliable and associated with both PFM manual muscle testing and vaginal squeeze pressure measurements.²⁸ However, research is lacking in the use of TPUS to examine resting position and mobility of the PFMs in patients with conditions in which PFM mobility is suspected to be reduced, such as UF-LUTS.

The objective of our study was to compare PFM position and mobility in women with and without UF-LUTS via 2-D dynamic TPUS imaging at rest, with a maximal PFM contraction, and with bearing down. Based on clinical observations,¹¹ we hypothesized that women with UF-LUTS would demonstrate elevated resting position and decreased muscle excursion in relation to pelvic landmarks during contraction and during bearing down when compared to women without UF-LUTS.

MATERIALS AND METHODS

Participants

Participants were recruited as part of a 1:1 matched cross-sectional, case-control study to examine hip and pelvic floor muscle strength differences in women with and without UF-LUTS. ⁸ This study was approved by the Human Research Protection Office of [INSTITUTION REDACTED FOR REVIEW] and conducted in accordance with the Declaration of Helsinki. Participants gave written informed consent prior to participation. From April to December 2019, female participants 18–60 years of age were recruited from the community via paper and social media advertisements, emails, and research recruitment fairs. Participants with UF-LUTS (“cases”) were included if they experienced bothersome urinary urgency (sudden need to rush to urinate) and/or frequency (0–2 hours between needing to empty your bladder), during a typical day in the past 4 weeks as reported during a phone screen. Women without UF-LUTS (“controls”) were matched 1:1 to cases based on age ± 5 years, body mass index (BMI) ± 5 kg/m² and vaginal parity (0, 1, >1). These matching criteria were selected to reduce potential confounding by factors known to influence pelvic floor muscle function. Potential participants were excluded if they reported stress urinary incontinence more than once per month; current or recurrent urinary tract or gynecologic infection or cancer; previous surgery for prolapse or incontinence; hip, pelvic, or trunk trauma or cancer; abdominal or pelvic surgery in the past year; or implanted devices in the pelvis that impair the ability to visualize structures of interest on ultrasound. Detailed exclusion criteria are listed in TABLE 1.

TABLE 1.

Inclusion and exclusion criteria for study participants

Inclusion Criteria

All:

• Women ages 18–60 able to speak and understand English

Urgency and Frequency Lower Urinary Tract Symptoms (UF-LUTS):

• Bothersome urgency or frequency in the past 4 weeks

Controls:

• No UF-LUTS in the past 6 months

• Age, BMI, & vaginal parity matched to cases

Exclusion Criteria

• Stress urinary incontinence or mixed incontinence more than once per month

• Current or recurrent urinary tract infectiona or gynecologic infection or cancer

• Symptomatic pelvic organ prolapsea

• Previous surgery for pelvic organ prolapse or incontinence

• Hip, pelvic, or trunk trauma or cancer

• Abdominal or pelvic surgery in the past year

• Current injury that would limit their ability to participate in testing

• Onabotulinum toxin injections to the bladder, pelvic floor or hip muscles

• Vulvovaginal dermatological conditions associated with UF-LUTS

• Diabetes

• Current pregnancya or birth/termination/miscarriage in the past 12 weeks

• Neurological involvement that would influence their coordination or balance

• Implanted devices that impair the ability to visualize / make ultrasound measures

^aItems ruled out during final eligibility exam

Self-Report Questionnaires

Study data were collected and managed using REDCap electronic data capture tools.²⁹ Prior to examination, participants completed questionnaires including the UCLA Activity Score, the LUTS Tool³⁰ for a comprehensive assessment of participants’ LUTS, and the Pelvic Floor Impact Questionnaire short form (PFIQ-7)³¹ for a general overview of impact of symptoms on daily activities and quality of life. LUTS Tool subscales are reported as raw scores for each respective domain with zero indicating no symptoms or bother. PFIQ-7 scores represent percentages of worst possible score, with zero indicating no impact and 100 indicating maximum impact.

Final Eligibility Exam

A single assessor, a physiotherapist trained in vaginal pelvic floor examination, completed all exams. To determine final eligibility, a urine screen for current urinary tract infection and pregnancy and a pelvic organ prolapse screen were completed.⁸ After urine screening, a transabdominal ultrasound scan confirmed whether the bladder was empty. If postvoid residual urine was evident, participants were asked to void again until the bladder was empty as viewed on the scan prior to vaginal exam.

Transperineal Ultrasound Acquisition Procedure

Transperineal ultrasound (TPUS) images were acquired by a physiotherapist trained in pelvic floor imaging using a Clarius C3 curvilinear scanner (Clarius Mobile Health Corp, Burnaby BC) with a disposable cover and conducting gel applied above and below the cover. With participants positioned supine with knees bent and feet flat on the exam table, the probe was placed on the perineum in a midsagittal plane oriented cranially. The image acquisition angle was set at 73 degrees in the midsagittal plane and the image was optimized to visualize from the pubis to the deepest region of interest, the anorectal angle (ARA) vertex. Multiple settings were trialed, and the FOV of 73 degrees was chosen based on the image quality. Participants were instructed in the motion sequence and cued during each trial to “relax 1, 2, 3, squeeze and lift the PFMs as if you’re stopping your urine stream or trying to hold back gas, relax 1, 2, 3, then bear down as if you’re trying to have a bowel movement.” A practice trial was performed and imaged to ensure the participant understood the instructions and that all regions of interest remained in frame throughout the sequence. Three study trials of the entire sequence were video recorded with no identifying annotations. Study trials were recorded back-to-back during the same study session with one minute rest between each trial. Trials with equipment or examiner errors were noted during the exam, and up to 2 additional trials were completed to obtain 3 valid trials. Videos were stored on a secure server. Prior to image measurement, ultrasound video files were given a random code and the key was inaccessible to the blinded study assessor.

Transperineal Ultrasound Measurement Methods

Measurements were developed by two experts in pelvic health physiotherapy (S.N.F. and T.M.S.), adapted from 4D ultrasound methods.³² Measurement protocol specified that each reviewer watch all ultrasound videos from peak contraction to peak bearing down to select images. For each selected image, Fiji image analysis platform³³ was used to measure the ARA, the levator plate angle (LPA), and the puborectalis muscle length (PR length) (FIGURE 1). The ARA was defined as the angle between the rectal ampulla and the anal canal³⁴ using the posterior edge of the hypoechogenic lumen as a guide. The LPA was determined by one line from the posterior-inferior pubis to the vertex of the ARA and another from the pubis horizontally across the image (perpendicular to the transducer).³⁴ Motion of clitoris and connective tissue was used to distinguish the stationary border of the posterior/inferior pubis.³⁵ Levator plate angle excursion values were computed by subtracting the LPA at rest from the LPA with contraction and bearing down. A positive LPA value indicated PFM motion in the cranioventral direction, while a negative LPA value indicated motion in a caudodorsal direction. Bearing down results in PFM motion in the caudodorsal direction, thus decreasing LPA. The PR length was recorded as a 2-D representation of the length of the puborectalis muscle. The vertices of the ARA and LPA were identified and the distance between them in millimeters was defined as the PR length. (Figure 1) PR length change was computed by subtracting the length at rest from the length at peak contraction and bearing down. A decrease in the PR length (negative excursion) represented PFM shortening, while an increase in PR length (positive excursion) represented muscle lengthening. For each measure (LPA, and PR length) of each frame (at rest, peak contraction, and peak bearing down), the mean of 3 participant trials was used for analysis.

FIGURE 1.

Transperineal Ultrasound Midsagittal View and Measurements PS, pubic symphysis; U, urethra; V, vagina; REF, horizontal reference line perpendicular to sound head; LPA, levator plate angle; B, bladder; PR, puborectalis length; A, anus; R, rectum

Rater reliability and measurement selection

A research assistant, trained in the standardized procedures, was blinded to participant symptom status and other exam data throughout the study and completed all official study measures. Prior to obtaining official study measures, a training period served to ensure that the research assistant and trainer agreed on their measurements. During this training period and subsequent protocol refinement, it was discovered that the ARA vertices were easy to identify but due to indistinct margins of the posterior anus and rectum, it was difficult to measure ARA reliably at 73 degree field of view. Though interrater intraclass correlation coefficients (ICCs) improved after training and refinement (post-training ICCs reported in TABLE 2), the ARA remained a difficult measurement to make reliably and a decision was made to not include the ARA in further analysis. In advance of future studies, we were also interested to know how much between-session variability existed in participant performance for LPA and PR length. To compute test-retest reliability for LPA and PR length, we repeated the ultrasound data collection on 10 participants during a second reliability session scheduled 1–2 weeks after their first study appointment. The research assistant completed blinded image measurements from recorded videos for both sessions for computation of test-retest reliability (reported in TABLE 2). Official study results and interrater ICCs are reported from the first study appointment’s measures (n=42), and test-retest reliability includes data from those who also attended a second session (n=10). Test-retest reliability ICCs were moderate to good for LPA (0.563 to 0.748) and good for PR length (0.803 to 0.831) (TABLE 2). We recommend caution in interpreting these measures over multiple sessions in a cohort study or trial due to notable systematic bias observed in some variables from session 1 to session 2 (Supplemental Figure 1): LPA excursion during contraction tended to decrease, LPA excursion during bearing down tended to increase, and PR length tended to decrease.

TABLE 2.

Reliability of Dynamic Transperineal Ultrasound Measurements from Saved Videos

Transperineal Ultrasound Measure	Interrater ICC	Test-Retest ICC
ARA at rest / baseline	0.671	N/A
ARA from rest to contraction	0.466	N/A
ARA from rest to bearing down	0.534	N/A
LPA at rest / baseline	0.805	0.748
LPA from rest to contraction	0.795	0.725
LPA from rest to bearing down	0.831	0.563
PR length at rest / baseline	0.804	0.831
PR length from rest to contraction	0.932	0.803
PR length from rest to bearing down	0.692	0.831

ARA, Anorectal angle; LPA, Levator Plate Angle; PR, Puborectalis; Interrater ICC, two-way random effects absolute agreement; Test-Retest ICC, two-way mixed effects absolute agreement measured between two participant testing sessions; N/A, not applicable as ARA measures were not made at the second testing session.

Statistical Analysis

The sample size was predetermined based on our previously reported study that enrolled both women with and without UF-LUTS.⁸ Statistical analyses were computed using SAS software, version 9.4 of the SAS System for Windows (SAS Institute Inc., Cary, NC, USA). Descriptive statistics were computed for participant characteristics and questionnaire scores. Case and control participants were matched 1:1 on key variables, therefore paired-samples two-tailed t-tests were used to compare LPA and PR length at rest, during contraction, and excursion during bearing down. Assumptions were checked graphically with histograms and quartile-to-quartile plots and statistically with the Shapiro Wilk test. Where t-test assumptions were violated, Wilcoxon signed-rank tests are reported.

RESULTS

A total of 21 case-control pairs (42 women) were enrolled with adherence to 1:1 matching rules. (TABLE 3). Mean age of our participants was 28.5 years and all but one pair were nulliparous. There were no differences between cases and controls by age, BMI, vaginal parity and activity. Women with UF-LUTS had significantly worse LUTS Tool Storage and Voiding Symptom and Bother scores and significantly worse PFIQ-7 Urogenital Impact scores. Median LUTS Tool Scores for those with LUTS represented mild to moderate symptoms and bother, and median PFIQ scores indicated mild to moderate urogenital impact. None of our sample had ever used medications for LUTS.

TABLE 3.

Participant characteristics in women with and without urgency and frequency predominant lower urinary tract symptoms (UF-LUTS)

Characteristic	UF-LUTS (n=21)	Control (n=21)	Paired Differences	P
Age (years, mean ± SD [range])	28 ± 10 [19–56]	29 ± 9 [21–57]	−0.9 ± 3 [−5 – 4]	0.12*
BMI (kg/m2, mean ± SD [range])	24 ± 4 [18–35]	25 ± 4 [19–33]	−0.4 ± 2 [−4 – 4]	0.40*
Vaginal parity (%)
0	95	95		1.00
2–3	5	5
LUTS Tool (Median [IQR])
LUTS Storage Symptom	9 [3]	1 [2]	7 [3]	<0.0001
LUTS Storage Bother	8 [4]	0 [0]	8 [5]	<0.0001
LUTS Voiding Symptom	6 [4]	0 [1]	5 [4]	<0.0001
LUTS Voiding Bother	2 [3]	0 [0]	2 [3]	<0.0001
Pelvic Floor Impact Questionnaire - 7 (median [IQR])
PFIQ-7 Urogenital	24 [24]	0 [0]	24 [24]	<0.0001
PFIQ-7 Colorectal	0 [5]	0 [0]	0 [5]	0.004
PFIQ-7 Vagina/Pelvis	0 [5]	0 [0]	0 [5]	0.02
UCLA Activity Score (Median [IQR])	9 [5]	6 [5]	0.3 [3.6]	0.64

LUTS=Lower Urinary Tract Symptoms; SD=standard deviation; IQR=interquartile range defined as the 75th minus the 25th percentile.

^*P value from two-tailed paired samples t-test (all others from two-tailed Wilcoxon signed rank test)

The UCLA Activity Score is an ordinal self-report scale from 1 (No activity) to 10 (Regularly participates in high impact activity)

LUTS Tool scores were obtained by summing the frequency of LUTS (0–5) within each respective domain. The number of component items summed for each scale is: Storage Symptom 5 (worst score = 25), Storage Bother 4 (worst score = 20), Voiding Symptom 8 (worst score = 40), Voiding bother 7 (worst score = 35).

Transperineal Ultrasound Measurement Results

Compared to those without UF-LUTS, women with UF-LUTS demonstrated significantly greater LPA at rest (66.8 ± 13.2 degrees vs 54.9 ± 9.8 degrees; P=0.006), indicating a more cranial and ventral resting position of the pelvic floor (TABLE 4). Those with UF-LUTS also had less PR lengthening during bearing down (0.2 ± 3.1 mm vs 2.1 ± 2.9 mm; P=0.03). We did not find differences in excursion during contraction for any variable between women with and without UF-LUTS (TABLE 4).

TABLE 4.

Differences between women with and without UF-LUTS in transperineal ultrasound

		n=21 pairs
Transperineal Ultrasound Measure	UF-LUTS	Control	Paired Differences	P
LPA at rest / baseline	66.8 ± 13.2	54.9 ± 9.8	11.9 ± 17.8	0.006
LPA excursion rest to contract	10.6 ± 9.2	14.8 ± 5.6	−4.1 ± 11.2	0.10
LPA excursion rest to bear down	−4.0 ± 7.8	−6.8 ± 8.4	0.5 ± 10.5	0.49a
PR length at rest / baseline	40.6 ± 6.2	43.2 ± 6.4	−2.6 ± 8.7	0.19
PR length excursion rest to contract	−2.7 ± 3.1	−4.4 ± 3.9	1.7 ± 4.6	0.11
PR length excursion rest to bear down	0.2 ± 3.1	2.1 ± 2.9	−2.7 ± 4.7	0.02a

LPA, Levator plate angle; PR, Puborectalis

^aPaired differences (UF-LUTS minus Control) are expressed as median ± interquartile range and P values from two-tailed paired Wilcoxon Signed Rank test, all other paired differences expressed as mean ± standard deviation with P values from paired t-tests

DISCUSSION

We sought to compare PFM position and mobility in women with and without UF-LUTS. Women with UF-LUTS had relatively elevated PFMs at rest and less lengthening during bearing down compared to women without UF-LUTS, consistent with our stated hypothesis. Our present results, together with our previous finding that PFM strength is similar between women with and without UF-LUTS,⁸ suggest that PFM strengthening alone may not improve UF-LUTS. Clinically it has been reported that women with UF-LUTS commonly present with a non-relaxing pelvic floor muscle, which is thought to contribute to irritative voiding symptoms and potentially reduce the ability to empty the bladder; thus driving frequency of urination. ⁽¹¹⁾ This lack of ability to relax and lower the muscle is associated with reduced endurance, increased muscle stiffness and impaired coordination. ⁽³⁶⁾ These results highlight that women with UF-LUTS may present with reduced ability to lengthen the PFM. In addition, these results further highlight the importance of a comprehensive PFM examination for women with UF-LUTS including assessment of PFM position and mobility. Further studies are needed to understand the underlying mechanistic connection between the observed PFM position and mobility impairments and UF-LUTS. Future research is also warranted to assess how interventions to optimize PFM position and mobility might improve UF-LUTS and quality of life.

We were unable to find studies that measured PFM position and mobility in patients with UF-LUTS; however, studies have assessed PFM position and mobility in participants with pelvic pain. Similar to our findings, Morin et al described elevated PFM position and poorer PFM mobility in participants with pelvic pain compared to those without.³² The authors compared unmatched women with and without provoked vestibulodynia and reported larger LPA and shorter PR length at rest, and smaller LPA excursion during contraction in women with vestibulodynia. Our study did not find differences in excursion during contraction, possibly due to insufficient power. See Supplemental Table 1 for post-hoc power analysis. Previous studies have demonstrated an association between myofascial pelvic pain and LUTS,^12,36 particularly in younger patients.³⁷ One can postulate that this association may be due in part to similar impaired PFM position and mobility in individuals suffering from pelvic pain or UF-LUTS conditions.¹¹

Our findings suggest that PFM position and mobility may be important components of PFM function to consider in the assessment of patients with UF-LUTS. Dynamic TPUS allows for measurements not captured by PFM manometry, electromyography and manual palpation for pain. Existing clinical manual assessment methods of PFM function such as the PERFECT scheme³⁸ do not measure mobility. Unlike manual assessment, TPUS does not require invasive vaginal or rectal palpation and allows for quantitative measurements. Transperineal ultrasonography provides more detailed muscle visualization compared to transabdominal ultrasound of bladder base elevation and allows visualization of anterior-posterior PFM motion or muscle length change. Future studies are needed to determine how to maximize TPUS capability in the assessment of patients with UF-LUTS.

Using our methods, measurements of LPA and PR length determined from saved videos demonstrated reasonable test-retest reliability estimates. We recommend caution in interpreting these measures over multiple sessions in a cohort study or trial due to notable systematic bias observed in some variables from session 1 to session 2 (Supplemental Figure 1): LPA excursion during PFM contraction tended to decrease, LPA excursion during bearing down tended to increase, and PR length tended to decrease. We hypothesize test-retest differences may be due to early motor learning despite no feedback, standardized cuing and no known intervention between sessions. Future studies comparing measures of LPA and PR length between dynamic 2-D and 3-D/4-D TPUS would aid in validating the use of 2-D when 3-D/4-D is not available or financially feasible. Given the poor interrater reliability estimates for the ARA, we choose not to report these values. However, we were able to reliably select the X and Y coordinates of the ARA vertex, allowing for acceptable agreement of LPA and PR length. We believe our transducer’s 73 degree acquisition angle, in many participants, precluded our ability to maintain the pubis in view while obtaining clear images of the posterior wall of the anal canal without an acoustic shadow. Using a larger acquisition angle might have allowed improved measurement agreement. We would also recommend equipment that allows simultaneous viewing of the entire pubis cross-section and ARA so that the measurement axis could be standardized by a line bisecting the length of the pubic symphysis. We were also limited by the number of participants willing to return for a second testing session and included both cases and controls in our test-retest estimates. Future studies would benefit from comparing test-retest agreement both in symptomatic and asymptomatic participants separately to determine whether one group is more consistent or reliable in their performance of these cued tasks.

A disadvantage specific to the use of 2-D TPUS in our study is that we cannot be certain we captured the absolute minimum hiatal dimensions.³⁹ We were also unable to view the entire levator hiatus at once and measure or document any defects in the levator ani muscle. However, levator ani defects are likely more pertinent to patients with prolapse and incontinence than patients with UF-LUTS without incontinence. Finally, our participant sample was young and mostly nulliparous so our results may not be generalizable to other clinical populations. However, we sought to clearly assess the differences between women with and without UF-LUTS without the confounding effect of continence before broadening this inquiry to a larger and more clinically complex sample.

Future studies are needed to further investigate assessment using TPUS to inform possible treatment directed at PFM position and mobility in those with UF-LUTS. One potential therapeutic use of TPUS in UF-LUTS is as biofeedback to assist patients in learning to fully relax and coordinate their PFMs during physiotherapist led treatment sessions. Currently, transabdominal ultrasound is often used as biofeedback to teach PFM contraction, but the transabdominal bladder view of bladder base elevation does not allow measurement or reference to specific landmarks such as the pubic symphysis. With larger studies to obtain normative data, clinicians can also take measurements with TPUS to compare to normative values and aid in monitoring patient progress with treatment.

CONCLUSION

We found that women with UF-LUTS compared to women without demonstrated more cranioventral position of the PFM and less PR muscle lengthening with a cue to bear down. Treatment to improve PFM position and mobility may improve symptoms in women with UF-LUTS, but further studies are needed. Dynamic 2-D TPUS may be an appropriate noninvasive assessment method yielding novel information in patients with UF-LUTS, and potentially functioning as biofeedback and/or a clinical measurement tool, but further studies are needed.

Supplementary Material

Test-retest reliability of TPUS measures

Supplemental Figure 1: Test-retest scatterplots for ten participants’ TPUS LPA and PR length measures Ten participants returned for a second testing session to assess test-retest reliability of the measures.

Supplemental Table I

Supplemental Table 1: Post-hoc power analysis