How best to measure the levator hiatus: evidence for the non-Euclidean nature of the 'plane of minimal dimensions'

Validation of shear wave elastography as a noninvasive measure of pelvic floor muscle stiffness

OBJECTIVES

To investigate the validity of shear wave elastography (SWE) as a measure of stiffness of the puborectalis muscle by examining: (1) the relationship between puborectalis muscle stiffness and pelvic floor muscle (PFM) activation at different intensities; and (2) the relationship between puborectalis stiffness and pelvic floor morphometry during contractions at different intensities.

METHODS

Fifteen healthy asymptomatic women performed 6-s isometric PFM contractions at different intensities (0, 10%, 20%, 30%, 50%, 75%, and 100% of maximal voluntary contraction) guided by intravaginal electromyography (EMG). Stiffness of the puborectalis muscle was measured using SWE by calculating the average shear modulus in regions of interest that contained puborectalis muscle fibers parallel to the transducer. Pelvic floor morphometry was assessed in the mid-sagittal plane using transperineal B-mode ultrasound imaging. Shear modulus, EMG (root mean square amplitude) and pelvic floor morphometry parameters were normalized to the value recorded during maximal voluntary contraction. To assess the relationship between stiffness and pelvic floor activation/morphometry, coefficient of determination (r² ) was calculated for each participant and a group average was computed.

RESULTS

Shear modulus and EMG were highly correlated (average r² ; left 0.90 ± 0.08, right 0.87 ± 0.15). Shear modulus also strongly correlated with bladder neck position (x-axis horizontal coordinates relative to the pubic symphysis), anorectal rectal angle and position, levator plate angle, and antero-posterior diameter of the levator hiatus (average r² : range 0.62-0.78).

CONCLUSIONS

These findings support the validity of SWE to assess puborectalis muscle stiffness in females. Stiffness measures were strongly associated with PFM EMG and pelvic floor morphometry and may be used to indirectly assess the level of activation of the puborectalis muscle without the use of more invasive techniques. By overcoming limitations of current assessment tools, this promising noninvasive and real-time technique could enable important breakthrough in the pathophysiology and management of pelvic floor disorders.

Deep learning-based pelvic levator hiatus segmentation from ultrasound images

Purpose

To automatically segment and measure the levator hiatus with a deep learning approach and evaluate the performance between algorithms, sonographers, and different devices.

Methods

Three deep learning models (UNet-ResNet34, HR-Net, and SegNet) were trained with 360 images and validated with 42 images. The trained models were tested with two test sets. The first set included 138 images to evaluate the performance between the algorithms and sonographers. An independent dataset including 679 images assessed the performances of algorithms between different ultrasound devices. Four metrics were used for evaluation: DSC, HDD, the relative error of segmentation area, and the absolute error of segmentation area.

Results

The UNet model outperformed HR-Net and SegNet. It could achieve a mean DSC of 0.964 for the first test set and 0.952 for the independent test set. UNet was creditable compared with three senior sonographers with a noninferiority test in the first test set and equivalent in the two test sets collected by different devices. On average, it took two seconds to process one case with a GPU and 2.4 s with a CPU.

Conclusions

The deep learning approach has good performance for levator hiatus segmentation and good generalization ability on independent test sets. This automatic levator hiatus segmentation approach could help shorten the clinical examination time and improve consistency.

Levator ani avulsion: a Systematic evidence review (LASER)

BACKGROUND

There is variation in the reported incidence rates of levator avulsion (LA) and paucity of research into its risk factors.

OBJECTIVE

To explore the incidence rate of LA by mode of birth, imaging modality, timing of diagnosis and laterality of avulsion.

SEARCH STRATEGY

We searched MEDLINE, EMBASE, CINAHL, AMED and MIDIRS with no language restriction from inception to April 2019.

STUDY ELIGIBILITY CRITERIA

A study was included if LA was assessed by an imaging modality after the first vaginal birth or caesarean section. Case series and reports were not included.

DATA COLLECTION AND ANALYSIS

RevMan v5.3 was used for the meta-analyses and SW SAS and STATISTICA packages were used for type and timing of imaging analyses.

RESULTS

We included 37 primary non-randomised studies from 17 countries and involving 5594 women. Incidence rates of LA were 1, 15, 21, 38.5 and 52% following caesarean, spontaneous, vacuum, spatula and forceps births, respectively, with no differences by imaging modality. Odds ratio of LA following spontaneous birth versus caesarean section was 10.69. The odds ratios for LA following vacuum and forceps compared with spontaneous birth were 1.66 and 6.32, respectively. LA was more likely to occur unilaterally than bilaterally following spontaneous (P < 0.0001) and vacuum-assisted (P = 0.0103) births but not forceps. Incidence was higher if assessment was performed in the first 4 weeks postpartum.

CONCLUSIONS

LA incidence rates following caesarean, spontaneous, vacuum and forceps deliveries were 1, 15, 21 and 52%, respectively. Ultrasound and magnetic resonance imaging were comparable tools for LA diagnosis.

TWEETABLE ABSTRACT

Levator avulsion incidence rates after caesarean, spontaneous, vacuum and forceps deliveries were 1, 15, 21 and 52%, respectively.

Ultrasound in the assessment of pelvic organ prolapse

Imaging is increasingly being used in urogynaecology. Because of low cost and universal availability, ultrasound (US) is the most commonly used diagnostic modality, which allows the observation of manoeuvres such as Valsalva and pelvic floor muscle contraction in real time. The ability to see beyond surface anatomy is particularly important in the posterior compartment and in obstructed defecation where this method may replace defecation proctography. Imaging is especially useful in the form of 3D/4D multiplanar and tomographic translabial US, as these modalities give access to the axial plane and the levator ani. This allows assessment of both avulsion, i.e. major maternal birth trauma, and hiatal overdistension, i.e. ballooning. Both are major risk factors for both prolapse and prolapse recurrence. This review will outline current clinical utility, introduce recent research in the respective field and provide an overview of likely future utility of imaging in the investigation of pelvic organ prolapse.

Pelvic floor muscle dysfunction on 3D/4D transperineal ultrasound in patients with deep infiltrating endometriosis: a pilot study

OBJECTIVE

Pelvic floor muscle (PFM) dysfunction seems to play an important role in the pathophysiology of pelvic pain, including that associated with deep infiltrating endometriosis (DIE). The aim of this study was to evaluate the static and dynamic morphometry of the PFM using three-dimensional (3D) and four-dimensional (4D) transperineal ultrasound in women with DIE compared with asymptomatic healthy women.

METHODS

This was a pilot, prospective study conducted at our tertiary center between March and November 2015. Fifty nulliparous women with DIE (study group) and 35 nulliparous asymptomatic healthy women (control group) were included. 3D/4D transperineal ultrasound examination of the PFM was performed in both groups. Levator hiatal area (LHA) and anteroposterior and left-right transverse diameters were evaluated at rest, on maximum PFM contraction and on maximum Valsalva maneuver. Persistent levator ani muscle (LAM) coactivation during Valsalva maneuver was investigated.

RESULTS

Compared with the control group, women with DIE had a smaller LHA at rest (P = 0.03) and during Valsalva maneuver (P < 0.01). Furthermore, reduction in LHA during PFM contraction (P < 0.001) and enlargement in LHA during Valsalva maneuver (P = 0.01) were significantly less marked. In comparison with controls, women with DIE presented a higher frequency of LAM coactivation during Valsalva maneuver, although this difference did not reach statistical significance (P = 0.05).

CONCLUSIONS

3D and 4D transperineal ultrasound is an objective and non-invasive method for PFM morphometry and may have a role in detecting PFM dysfunction in women with DIE. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Quality of reporting of diagnostic accuracy studies on pelvic floor three-dimensional transperineal ultrasound: a systematic review

OBJECTIVE

In recent years, a large number of studies have been published on the clinical relevance of pelvic floor three-dimensional (3D) transperineal ultrasound. Several studies compare sonography with other imaging modalities or clinical examination. The quality of reporting in these studies is not known. The objective of this systematic review was to determine the compliance of diagnostic accuracy studies investigating pelvic floor 3D ultrasound with the Standards for Reporting of Diagnostic Accuracy (STARD) guidelines.

METHODS

Published articles on pelvic floor 3D ultrasound were identified by a systematic literature search of MEDLINE, Web of Science and Scopus databases. Prospective and retrospective studies that compared pelvic floor 3D ultrasound with other clinical and imaging diagnostics were included in the analysis. STARD compliance was assessed and quantified by two independent investigators, using 22 of the original 25 STARD checklist items. Items with the qualifier 'if done' (Items 13, 23 and 24) were excluded because they were not applicable to all papers. Each item was scored as reported (score = 1) or not reported (score = 0). Observer variability, the total number of reported STARD items per article and summary scores for each item were calculated. The difference in total score between STARD-adopting and non-adopting journals was tested statistically, as was the effect of year of publication.

RESULTS

Forty studies published in 13 scientific journals were included in the analysis. Mean ± SD STARD checklist score of the included articles was 16.0 ± 2.5 out of a maximum of 22 points. The lowest scores (< 50%) were found for reporting of handling of indeterminate results or missing responses, adverse events and the time interval between tests. Interobserver agreement for rating the STARD items was excellent (intraclass correlation coefficient, 0.77). An independent t-test showed no significant mean difference ± SD in total STARD checklist score between STARD-adopting and non-adopting journals (16.4 ± 2.2 vs 15.9 ± 2.6, respectively). Mean ± SD STARD checklist score for articles published in 2003-2009 was lower, but not statistically different, compared with those published in 2010-2015 (15.2 ± 2.5 vs 16.6 ± 2.4, respectively).

CONCLUSION

The overall compliance with reporting guidelines of diagnostic accuracy studies on pelvic floor 3D transperineal ultrasound is relatively good compared with other fields of medicine. However, specific checklist items require more attention when reported. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Is curved three-dimensional ultrasound reconstruction needed to assess the warped pelvic floor plane?

OBJECTIVES

Caudal distension of the female pelvic floor is common and results in perineal descent and a caudally curved levator hiatus (warping). Image reconstruction of the pelvic floor using currently available ultrasound techniques involves a linear approach (flat-plane reconstruction). We aimed to evaluate the feasibility, reproducibility and potential usefulness of a new three-dimensional (3D) technique capable of reconstructing a curved plane of the levator hiatus.

METHODS

Primiparous women were recruited to undergo a 3D/four-dimensional transperineal ultrasound examination 3-6 months after delivery. Levator ani muscle warping was evaluated on Valsalva maneuver by measuring the distance between the plane extending from the pubic rami to the anorectal angle and the plane of minimal hiatal dimensions on the coronal plane. Warping distance was used to reconstruct a curved plane of the levator hiatus using the curved OmniView volume contrast imaging (VCI) technique (C-OV). Intra- and interobserver reproducibility of the C-OV technique were assessed, as was intermethod agreement between the C-OV technique and the linear OmniView-VCI (L-OV) technique, for the measurement of levator hiatal area on Valsalva maneuver.

RESULTS

Measurement of the levator hiatal area using C-OV was feasible in all 84 women recruited. The warping distance ranged from -3.5 to 9.7 mm, confirming that the 1-2-cm slice thickness traditionally used for linear reconstruction was adequate for proper assessment of levator hiatal area in our population. C-OV showed excellent intra- and interobserver reproducibility, as well as excellent agreement with the L-OV technique for measuring levator hiatal area. No systematic difference was demonstrated in any of the reproducibility studies performed.

CONCLUSIONS

3D reconstruction of the warped levator hiatal plane is feasible and highly reproducible. In our population, reconstruction of a curved plane to correct for levator hiatal warping did not offer any benefit over the traditionally performed linear reconstruction. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Warping of the levator hiatus: how significant is it?

OBJECTIVES

The levator hiatus is the largest potential hernial portal in the human body. Excessive distensibility is associated with female pelvic organ prolapse (POP). Distension occurs not just laterally but also caudally, resulting in perineal descent and hiatal deformation or 'warping'. The aim of this study was to quantify the warping effect in symptomatic women, to validate the depth of the rendered volume used for the 'simplified method' of measuring hiatal dimensions and to determine predictors for the degree of warping.

METHODS

This was a retrospective study utilizing records of patients referred to a tertiary urogynecological service between November 2012 and March 2013. Patients underwent a standardized interview, clinical assessment using the POP quantification system of the International Continence Society and four-dimensional translabial ultrasound. The craniocaudal difference in the location of minimal distances in mid-sagittal and coronal planes was determined by offline analysis of ultrasound volumes, and provided a numerical measure of warping. We tested potential predictors, such as demographic factors, signs and symptoms of prolapse, levator avulsion and levator distensibility, for an association with warping.

RESULTS

Full datasets were available for 190 women. The mean craniocaudal difference in location of minimal distances in mid-sagittal and coronal planes was -1.26 mm (range, -6.7 to 4.6 mm; P < 0.001). This measure of warping was associated with hiatal area on Valsalva maneuver (r = - 0.284; P < 0.0001) and signs of significant prolapse on clinical and ultrasound examination (both P < 0.0001).

CONCLUSIONS

The plane of minimal dimensions of the levator ani hiatus is non-Euclidean, i.e. warped, and the degree of warping is associated with hiatal distension, or 'ballooning', and with POP. However, the degree of warping is minor, the largest difference we found in the location of the plane of minimal dimensions being 6.7 mm. Hence, our results support the determination of hiatal area in a rendered volume of 1-2 cm in depth. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Agreement and reliability of pelvic floor measurements during rest and on maximum Valsalva maneuver using three-dimensional translabial ultrasound and virtual reality imaging

OBJECTIVES

Imaging of the levator ani hiatus provides valuable information for the diagnosis and follow-up of patients with pelvic organ prolapse (POP). This study compared measurements of levator ani hiatal volume during rest and on maximum Valsalva, obtained using conventional three-dimensional (3D) translabial ultrasound and virtual reality imaging. Our objectives were to establish their agreement and reliability, and their relationship with prolapse symptoms and POP quantification (POP-Q) stage.

METHODS

One hundred women with an intact levator ani were selected from our tertiary clinic database. Information on clinical symptoms were obtained using standardized questionnaires. Ultrasound datasets were analyzed using a rendered volume with a slice thickness of 1.5 cm, at the level of minimal hiatal dimensions, during rest and on maximum Valsalva. The levator area (in cm(2) ) was measured and multiplied by 1.5 to obtain the levator ani hiatal volume (in cm(3) ) on conventional 3D ultrasound. Levator ani hiatal volume (in cm(3) ) was measured semi-automatically by virtual reality imaging using a segmentation algorithm. Twenty patients were chosen randomly to analyze intra- and interobserver agreement.

RESULTS

The mean difference between levator hiatal volume measurements on 3D ultrasound and by virtual reality was 1.52 cm(3) (95% CI, 1.00-2.04 cm(3) ) at rest and 1.16 cm(3) (95% CI, 0.56-1.76 cm(3) ) during maximum Valsalva (P < 0.001). Both intra- and interobserver intraclass correlation coefficients were ≥ 0.96 for conventional 3D ultrasound and > 0.99 for virtual reality. Patients with prolapse symptoms or POP-Q Stage ≥ 2 had significantly larger hiatal measurements than those without symptoms or POP-Q Stage < 2.

CONCLUSIONS

Levator ani hiatal volume at rest and on maximum Valsalva is significantly smaller when using virtual reality compared with conventional 3D ultrasound; however, this difference does not seem clinically important. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Comparison of translabial three-dimensional ultrasound with magnetic resonance imaging for measurement of levator hiatal biometry at rest

OBJECTIVES

To compare translabial three-dimensional (3D) ultrasound with magnetic resonance imaging (MRI) for the measurement of levator hiatal biometry at rest in women with pelvic organ prolapse, and to determine the interobserver reliability between two independent observers for ultrasound and MRI measurements.

METHODS

Data were derived from a multicenter prospective cohort study in which women scheduled for conventional anterior colporrhaphy underwent translabial 3D ultrasound and MRI prior to surgery. Intraclass correlation coefficients (ICCs) were calculated to estimate interobserver reliability between two independent observers and determine the agreement between ultrasound and MRI measurements. Bland-Altman plots were created to assess the agreement between ultrasound and MRI measurements.

RESULTS

Data from 139 women from nine hospitals were included in the study. The interobserver reliability of ultrasound assessment at rest, during Valsalva maneuver and during contraction and of MRI assessment at rest were moderate or good. The agreement between ultrasound and MRI for the measurement of levator hiatal biometry at rest was moderate, with ICCs of 0.52 (95%CI, 0.32-0.66) for levator hiatal area, 0.44 (95%CI, 0.21-0.60) for anteroposterior diameter and 0.44 (95%CI, 0.22-0.60) for transverse diameter. Levator hiatal biometry measurements were statistically significantly larger on MRI than on translabial 3D ultrasound.

CONCLUSIONS

The agreement between translabial 3D ultrasound and MRI for measurement of the levator hiatus at rest in women with pelvic organ prolapse was only moderate. The results of translabial 3D ultrasound and MRI should therefore not be used interchangeably in daily practice or in clinical research. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Reliability of new three-dimensional ultrasound technique for pelvic hiatal area measurement

OBJECTIVE

To assess the reproducibility of a new technique for three-/four-dimensional (3D/4D) ultrasound imaging of the pelvic floor: OmniView™ volume contrast imaging (VCI) for measurement of the pelvic hiatal area on maximum contraction and Valsalva maneuver. In addition, we aimed to study the intermethod agreement between the new technique and the 3D/4D render method.

METHODS

We acquired one static 3D and two dynamic 4D transperineal volumes (one obtained during contraction and one during Valsalva maneuver) from 35 nulliparous asymptomatic healthy volunteers and 35 women with symptoms of pelvic floor dysfunction. Each 3D dataset was analyzed using the OmniView-VCI technique to measure the pelvic hiatal area at rest, on maximum contraction and on maximum Valsalva. Analysis was performed twice by the same operator and once by another operator in order to assess intra- and interobserver reproducibility. All measurements were repeated by one operator using the 3D/4D render method to evaluate the intermethod agreement. Reproducibility and intermethod agreement were studied by means of intraclass correlation coefficients (ICC) and the Bland-Altman method.

RESULTS

Measurement of hiatal area using the OmniView-VCI technique showed excellent intraobserver and interobserver reproducibility in both asymptomatic and symptomatic women at rest, on contraction and on Valsalva maneuver. In addition, excellent agreement was demonstrated between OmniView-VCI and 3D/4D render in both groups (ICCs on Valsalva in asymptomatic and symptomatic women were 0.894 and 0.975, respectively). No systematic difference was noted in any of the reliability studies performed.

CONCLUSIONS

OmniView-VCI is a reliable method for pelvic hiatal area measurement. Both rendering mode and OmniView-VCI can be used interchangeably for assessing pelvic hiatal area. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Persistence of levator ani sonographic defect detected by three-dimensional transperineal sonography in primiparous women

OBJECTIVES

Correlation of the sonographic appearance of levator ani muscle (LAM) injury soon after delivery with that at long-term follow-up has not been described fully. We aimed to compare results of three-dimensional (3D) transperineal sonographic (TPS) evaluation of the LAM from the period immediately postpartum with long-term follow-up, to determine whether sonographic findings persist over time.

METHODS

Primiparous women (n = 210) who had been examined by 3D-TPS in a previous study to determine LAM trauma 24-72 hours after delivery were invited to participate in a follow-up examination 3-21 months postpartum. We included in this study only women who were not pregnant when approached and who had not given birth in the interim. LAM trauma was diagnosed with 3D-TPS when we observed discontinuity and distortion of the most anteromedial part of the pubovisceral muscle in the coronal C-plane or rendered image. Initial and follow-up 3D-TPS results were compared using Cohen's kappa test for inter-rater agreement.

RESULTS

Among the 87 women included in this study we found strong correlation between earlier and later sonographic appearance of LAM: 17/21 women with a sonographic finding of LAM injury in the period immediately postpartum were positive in the follow-up examination, and only 2/66 women negative for LAM damage at the first examination were found to have sonographic evidence of LAM defect at follow-up (Cohen's kappa, 0.805 (95% CI, 0.656-0.954), P < 0.001).

CONCLUSIONS

Our findings suggest that 3D-TPS of the LAM is a reliable examination. A sonographic finding of LAM defect identified in the period immediately postpartum persists months or years after delivery; therefore, this test may be performed following delivery, or may be delayed without impacting the result. It is likely that this sonographic defect represents real anatomical disruption and is not an imaging artifact.

Detection of Subpubic Tumor Causing Bladder Outlet Obstruction by 3D Perineal Ultrasound

This case report shows that 3D perineal ultrasound can be superior to clinical examination and routine 2D perineal ultrasound in the detection of an unusual subpubic tumor. A 73-year-old female patient was referred to our urogynecological outpatient unit complaining of over-active bladder symptoms and voiding dysfunction for 3 years. Gynecological examination found no signs of pelvic organ prolapse or abnormality in the vaginal cavity. Routine 2D perineal ultrasound showed substantial residual urine (ca. 300 ml on catheter) and limited bladder neck mobility, but no signs of pelvic organ prolapse. Use of standardized 3D perineal ultrasound revealed a 24 × 26 × 32 mm spherical, hypoechoic tumor below the pubic symphysis between the distal urethra and the pubic bones. This structure was mistaken for the pubic symphysis in the midline on 2D ultrasound performed earlier. At surgery, the tumor was completely excised through a vaginal incision between the urethra and the pubic symphysis. After an uneventful postoperative recovery the patient developed de-novo stress urinary incontinence, which was corrected successfully by the insertion of a retropubic tension-free suburethral sling after an interval of 8 weeks. After a further follow-up of 8 weeks the patient reported well-being, urinary continence and no voiding dysfunction; no abnormalities were found on examination. In conclusion, 3D perineal ultrasound is a useful additional tool for the diagnostic workup of bladder outlet obstruction.

A new simple technique for 3-dimensional sonographic assessment of the pelvic floor muscles

OBJECTIVES

The purpose of this study was to assess the reproducibility of a new technique for 3-dimensional (3D) pelvic floor sonography: OmniView combined with Volume Contrast Imaging (VCI; GE Healthcare, Kretz Ultrasound, Zipf, Austria) for pelvic hiatal area measurement. In addition, we aimed to study the intermethod agreement between the new technique and the standard 3D rendering method.

METHODS

We acquired a static 3D sonographic transperineal volume from 124 nulliparous asymptomatic women and 118 women with symptoms of pelvic floor dysfunction. Each 3D data set was analyzed by the OmniView-VCI technique to measure the pelvic hiatal area twice by one operator and once by another to assess intraobserver and interobserver reproducibility. The first operator later measured the hiatal area using the 3D rendering method to evaluate intermethod agreement. Reproducibility and intermethod agreement were studied by the intraclass correlation coefficient and Bland-Altman method.

RESULTS

Hiatal area measurements by the OmniView-VCI technique showed high intraobserver and interobserver reproducibility in both asymptomatic and symptomatic women. In addition, high agreement was shown between the new technique and 3D rendering in both groups. No systematic differences were noted in any of the reliability studies performed. The new technique took slightly less time to calculate the hiatal area than the standard rendering method in both asymptomatic and symptomatic women.

CONCLUSIONS

OmniView-VCI is a reliable method for pelvic hiatal area measurement. Further studies are needed to assess its reliability under contraction and the Valsalva maneuver and to evaluate its usefulness and reproducibility for diagnosis of levator ani lesions.

Levator hiatus dimensions in late pregnancy and the process of labor: a 3- and 4-dimensional transperineal ultrasound study

OBJECTIVE

The objectives of the investigation were to study the association between levator hiatus dimensions in late pregnancy and both the length of second stage of labor and also the delivery mode in women delivering their first child.

STUDY DESIGN

In this cohort study, 231 nulliparous women were examined with 3- and 4-dimensional transperineal ultrasonography at 37 weeks of gestation. The anteroposterior, transverse diameter, and the area of levator hiatus were measured at rest, during levator ani muscle contraction, and during Valsalva maneuver. The second stage of labor was divided into passive and active second stage and delivery modes into normal vaginal or instrumental deliveries. Spearman correlation coefficient, independent-sample t test, and standard logistic regression were used for analysis.

RESULTS

Larger levator hiatus dimensions at rest and during contraction at 37 weeks of gestation correlated with a shorter duration of the active second stage in women with normal vaginal delivery (Spearman correlation coefficient, -0.13 to -0.35, P ≤ .08). Women having normal vaginal deliveries had significantly larger transverse diameter at rest, during contraction, and during Valsalva maneuver compared with women having instrumental deliveries (mean difference, 0.29; 95% confidence interval (CI), 0.16-0.41; mean difference, 0.33; 95% CI, 0.21-0.44 and mean difference, 0.24; 95% CI, 0.06-0.42; P < .05). The same was true for the levator hiatus area at rest and during contraction (mean difference, 1.22; 95% CI, 0.37-2.07 and mean difference, 0.84; 95% CI, 0.22-1.46; P < .01). These estimates were unchanged by adjustments in the logistic regression analysis.

CONCLUSION

Larger levator hiatus dimensions in late pregnancy had a significant association with a shorter active second stage of labor and normal vaginal delivery.

Can hiatal ballooning be determined by two-dimensional translabial ultrasound?

INTRODUCTION

Imaging of the levator hiatus, the largest potential hernial portal in the human body, requires axial plane imaging by ultrasound or magnetic resonance imaging. The aim of this study is to determine whether 2D translabial ultrasound may identify excessive hiatal distensibility by measuring the anteroposterior (AP) diameter of the hiatus. This may become clinically relevant for risk stratification of women prior to prolapse surgery.

METHODS

This is a retrospective analysis of 577 women seen at a tertiary urogynaecological unit between May 2008 and September 2010. All women underwent a standardised interview, clinical prolapse assessment (ICS POP-Q) and translabial ultrasound. The hiatal AP diameter was measured at rest, on Valsalva and during pelvic floor muscle contraction. All analyses were performed offline, blinded against clinical data.

RESULTS

There was a strong statistical relationship between reported prolapse symptoms/pelvic organ descent and hiatal AP diameter on Valsalva (P < 0.001 on chi-squared test for trend). A cut-off of 6 cm of the AP hiatal diameter on Valsalva yielded a specificity of 0.64 and a sensitivity of 0.7 for detecting significant prolapse on ultrasound.

CONCLUSION

Hiatal ballooning can be diagnosed with 2D translabial ultrasound. We propose that an AP hiatal diameter on Valsalva of up to 5.99 cm be regarded as normal, with 6-<6.5 cm defined as mild, 6.5-<7 cm as 'moderate', 7-<7.5 cm as 'marked' and 7.5 or more as 'severe' ballooning.

Agreement and reliability of pelvic floor measurements during contraction using three-dimensional pelvic floor ultrasound and virtual reality

OBJECTIVES

Virtual reality is a novel method of visualizing ultrasound data with the perception of depth and offers possibilities for measuring non-planar structures. The levator ani hiatus has both convex and concave aspects. The aim of this study was to compare levator ani hiatus volume measurements obtained with conventional three-dimensional (3D) ultrasound and with a virtual reality measurement technique and to establish their reliability and agreement.

METHODS

100 symptomatic patients visiting a tertiary pelvic floor clinic with a normal intact levator ani muscle diagnosed on translabial ultrasound were selected. Datasets were analyzed using a rendered volume with a slice thickness of 1.5 cm at the level of minimal hiatal dimensions during contraction. The levator area (in cm(2)) was measured and multiplied by 1.5 to get the levator ani hiatus volume in conventional 3D ultrasound (in cm(3)). Levator ani hiatus volume measurements were then measured semi-automatically in virtual reality (cm(3) ) using a segmentation algorithm. An intra- and interobserver analysis of reliability and agreement was performed in 20 randomly chosen patients.

RESULTS

The mean difference between levator ani hiatus volume measurements performed using conventional 3D ultrasound and virtual reality was 0.10 (95% CI, - 0.15 to 0.35) cm(3). The intraclass correlation coefficient (ICC) comparing conventional 3D ultrasound with virtual reality measurements was > 0.96. Intra- and interobserver ICCs for conventional 3D ultrasound measurements were > 0.94 and for virtual reality measurements were > 0.97, indicating good reliability for both.

CONCLUSION

Levator ani hiatus volume measurements performed using virtual reality were reliable and the results were similar to those obtained with conventional 3D ultrasonography.

Tomographic ultrasound imaging of the pelvic floor in nulliparous pregnant women: limits of normality

OBJECTIVES

To define normal appearance of the puborectalis muscle on tomographic ultrasound imaging in pregnant nulliparous women, establishing limits of normality.

METHODS

This was a subanalysis of consecutive ultrasound volume datasets of 497 pregnant nulliparous women recruited in the context of two studies. All participants were carrying a singleton pregnancy at a mean gestation of 36.4 (range, 33-38) weeks. Tomographic ultrasound imaging was performed by subsequent post-processing on volumes obtained at maximal pelvic floor contraction at 2.5-mm slice intervals, from 5 mm below to 12.5 mm above the plane of minimal hiatal dimensions, producing eight slices per patient.

RESULTS

Apparent abnormalities of the insertion of the puborectalis muscle were commonly seen in slices 1 and 2, but were uncommon in slice 3 (< 8%), very uncommon in slice 4 (1%) and rare elsewhere. They were not associated with bladder neck descent. Considering published minimal criteria for diagnosing an avulsion of the puborectalis muscle (slices 3 to 5 all abnormal), this diagnosis was made in three women. On reviewing those cases, one of which was rated abnormal on both sides, two were false positive as judged by the two senior authors. However, one was judged to be highly abnormal by both senior authors, with a full avulsion diagnosed on the left.

CONCLUSIONS

Published minimal criteria for the diagnosis of avulsion of the puborectalis muscle by tomographic pelvic floor ultrasound imaging are highly unlikely to result in a false-positive diagnosis and appear to be sufficiently robust for clinical practice.

Dynamic magnetic resonance imaging to quantify pelvic organ prolapse: reliability of assessment and correlation with clinical findings and pelvic floor symptoms

Introduction and hypothesis

The aim of this study was to assess the interobserver agreement of magnetic resonance imaging (MRI)-based staging of pelvic organ prolapse (POP) and to quantify associations between MRI-based POP staging, findings at pelvic examination, and pelvic floor symptoms.

Methods

This was a cross-sectional study of ten symptomatic POP patients, ten symptomatic patients without POP, and ten nulliparous asymptomatic women. Three different observers performed MRI-based POP staging using the pubococcygeal line (PCL), midpubic line (MPL), perineal line, and H line as references.

Results

The interobserver agreement of MRI-based staging of the anterior and middle compartment was good to excellent. In symptomatic women without prolapse, MRI-based and pelvic-examination-based POP staging were poorly correlated. In none of the women were MRI-based POP Quantification (POP-Q) staging and pelvic floor symptoms strongly associated.

Conclusion

The interobserver agreement of MRI-based POP staging is excellent, but the added clinical value of such staging is questionable due to poor association with clinical findings and pelvic floor symptoms.

Female pelvic floor dysfunction--an imaging perspective

Female pelvic floor dysfunction encompasses a range of morbidities, including urinary incontinence, female pelvic organ prolapse, anal incontinence and obstructed defecation. Patients often present with symptoms covered by several specialties including gastroenterology, colorectal surgery, urology and gynecology. Imaging can therefore bring clinicians from multiple specialties together by revealing that we frequently deal with different aspects of one underlying problem or pathophysiological process. This article provides an interdisciplinary imaging perspective on the pelvic floor. Modern pelvic floor imaging comprises defecation proctography, translabial and endorectal ultrasound, and static and dynamic MRI. This Perspectives focuses on the potential use of translabial ultrasound, including 3D and 4D applications, for diagnosis of pelvic floor disorders. Over the next decade, pelvic floor imaging will most likely be integrated into mainstream diagnostics in obstetrics and gynecology and colorectal surgery. Using imaging to facilitate communication between different specialties has the potential to greatly improve the multidisciplinary management of complex pelvic floor disorders.

Ultrasound imaging of the pelvic floor: where are we going?

We produced a non systematic review of ultrasound imaging of the pelvic floor in women with urinary incontinence (UI) and/or pelvic organ prolapse (POP). We have searched the PubMed and Embase databases for the following PICO question: women; imaging; urinary incontinence, pelvic organ prolapse, pelvic floor, pelvic floor muscle, pelvic floor muscle training; physical examination, no imaging; diagnosis, prognosis, outcome. The production of a systematic review was deemed impossible based on the type and quality of the published evidence. Clinical research focused on the pathophysiology of the UI and POP looking relation between anatomic abnormalities, childbirth, the risk of UI or POP, the outcome of conservative treatment and reconstructive surgery. Published papers fall into the remits of diagnostic studies but often fail to comply with the recommendations of the STARD initiative. Most published evidence remains the product of a single institution effort and confirmatory studies are rarely found. Imaging studies in patients with UI did not provide evidence of any clinical benefit in the management of patients. In patients with POP, interesting correlations have been identified such as between childbirth, dimension of levator hiatus, avulsion of levator ani and risk of prolapse, but the non clinical benefit of pelvic floor imaging could still not be identified. Research on pelvic floor imaging requires a coordinated, international, multicentre effort to improve internal and external validity of imaging techniques, confirm observations published by single institutions and provide health technology assessment of imaging in the management of UI or POP patients.