Plane Of Minimal Hiatal Dimensions Research Articles

Feasibility and reproducibility of new technique for measurement of transverse diameter of levator ani muscle hiatus using two-dimensional transperineal ultrasound in nulliparous women at term.

The aim of the present study was twofold; firstly to develop and describe the technique for measurement of the transverse diameter of the levator ani muscle hiatus (TD) in the coronal view using 2D transperineal ultrasound (TPUS) in nulliparous women at term of pregnancy. Secondly, we aimed to assess the feasibility and reproducibility of 2D TPUS assessment of TD, in addition to the inter-method agreement between 2D TPUS and the 3D measurement of TD on the axial plane, the latter considered as the gold standard in nulliparous women at term of pregnancy. For the aim of the study, we recruited a group of nulliparous women at term of pregnancy before the onset of labor. The study was conducted in two phases: phase 1 involved developing and describing the 2D TPUS technique for measuring TD, while phase 2 focused on assessing the technique's feasibility, reproducibility, and inter-method agreement. In phase 1, we enrolled 30 women. Each woman underwent the acquisition of a 3D TPUS volume, which was analyzed using the multiplanar mode to identify the appearance of the lateral borders of the levator ani muscle at the level of the plane of minimal hiatal dimensions in the coronal plane. These borders were used as landmarks for TD measurement. Additionally, we measured the distance between the line indicating TD and the center of the urethra in the axial view. Phase 2 involved recruiting 100 women. Each woman underwent the acquisition of three 2D TPUS clips in the coronal plane, each encompassing a sweep of the entire levator hiatus, and a 3D volume, all obtained during rest. On the 2D clips, TD was measured twice by one operator and once by another operator. TD was measured once in the 3D volume in the axial plane, considered the gold standard. Each operator was blinded to all other measurements during their assessments. We analyzed intraobserver, interobserver, and intermethod (2D vs. 3D) reproducibility. Bland-Altman analysis was conducted, and Levene's W0 and Student t-tests were performed to explore clinical factors that might contribute to systematic differences. In phase 1, we successfully identified the landmarks denoting the lateral borders of TD in the coronal view. These appeared as two symmetrical hypoechoic indentations located at the inner border of the hyperechoic structure of the levator ani muscle, at the point of maximum distance between the two sides of the levator ani muscle. Additionally, the distance between the urethra and the plane where TD was measured using 3D TPUS in the axial plane had a median of 4 mm and varied from 0 to 9 mm. This enabled us to describe the method for assessing TD in the coronal plane through the use of 2D TPUS. In phase 2, TD was successfully measured in all 2D and 3D acquisitions from the entire group of 100 women. The analyses for intraobserver, interobserver reproducibility, and intermethod comparison (2D vs. 3D) revealed almost perfect agreement in TD measurements using 2D TPUS, with Intraclass Correlation Coefficients (ICCs) of 0.95 (95% CI, 0.92 to 0.96), 0.87 (95% CI, 0.78 to 0.92), and 0.85 (95% CI, 0.78 to 0.90), respectively. The average differences between measurements were 0.1 mm for intraobserver, 1.0 mm for interobserver, and 0.2 mm for intermethod repeatability. No systematic differences were observed in any of the measurement sets, except in the inter-operator analysis, although the difference was clinically insignificant (38.2 vs. 37.1 mm, P= 0.01). None of the examined clinical factors (maternal body mass index and maternal age) exhibited a statistically significant impact on intraobserver, interobserver, or intermethod reliability. Utilizing our described technique to measure the transverse diameter of the levator hiatus in the coronal view using 2D TPUS is not only feasible but also highly reproducible and accurate in nulliparous women at term of pregnancy. Moreover, it yields measurements that are comparable to those obtained in the reconstructed axial plane generated by 3D TPUS. This article is protected by copyright. All rights reserved.

Ultrasound examination of the pelvic floor during active labor: A longitudinal cohort study.

There is limited evidence about changes in the pelvic floor during active labor. We aimed to investigate changes in hiatal dimensions during the active first stage of labor and associations with fetal descent and head position. We conducted a longitudinal, prospective cohort study at the National University Hospital of Iceland, from 2016 to 2018. Nulliparous women with spontaneous onset of labor, a single fetus in cephalic presentation, and gestational age ≥37 weeks were eligible. Fetal position was assessed with transabdominal ultrasound and fetal descent was measured with transperineal ultrasound. Three-dimensional volumes were acquired from transperineal scanning at the start of the active phase of labor and in late first stage or early second stage. The largest transverse hiatal diameter was measured in the plane of minimal hiatal dimensions. The levator urethral gap was measured as the distance between the center of the urethra and the levator insertion using tomographic ultrasound imaging. Measurements of the levator urethral gap were made in the plane of minimal hiatal dimensions and 2.5 and 5 mm cranial to this. The final study population comprised 78 women. The mean transverse hiatal diameter increased 12.4% between the two examinations, from 39.4 ± 4.1 mm (±standard deviation) at the first examination to 44.3 ± 5.8 mm at the last examination (p < 0.01). We found a moderate correlation between the transverse hiatal diameter and fetal station at the last examination (r = 0.44, r2 = 0.19; p < 0.01; regression equation y = 2.71 + 0.014x), and a weak correlation between the change in transverse hiatal diameter and change in fetal station (r = 0.29; r2 = 0.08; p = 0.01; regression equation y = 0.24 + 0.012x). Levator urethral gap increased significantly in all three planes on both the left and right sides. Head position was not associated with hiatal measurements after adjusting for fetal station. We found a significant, but only modest, increase of the hiatal dimensions during the first stage of labor. The risk of levator ani trauma will therefore be low during this stage. The change in transverse hiatal diameter was associated with fetal descent but not with head position.

Automatic Plane of Minimal Hiatal Dimensions Extraction From 3D Female Pelvic Floor Ultrasound.

There is an increasing interest in the applications of 3D ultrasound imaging of the pelvic floor to improve the diagnosis, treatment, and surgical planning of female pelvic floor dysfunction (PFD). Pelvic floor biometrics are obtained on an oblique image plane known as the plane of minimal hiatal dimensions (PMHD). Identifying this plane requires the detection of two anatomical landmarks, the pubic symphysis and anorectal angle. The manual detection of the anatomical landmarks and the PMHD in 3D pelvic ultrasound requires expert knowledge of the pelvic floor anatomy, and is challenging, time-consuming, and subject to human error. These challenges have hindered the adoption of such quantitative analysis in the clinic. This work presents an automatic approach to identify the anatomical landmarks and extract the PMHD from 3D pelvic ultrasound volumes. To demonstrate clinical utility and a complete automated clinical task, an automatic segmentation of the levator-ani muscle on the extracted PMHD images was also performed. Experiments using 73 test images of patients during a pelvic muscle resting state showed that this algorithm has the capability to accurately identify the PMHD with an average Dice of 0.89 and an average mean boundary distance of 2.25mm. Further evaluation of the PMHD detection algorithm using 35 images of patients performing pelvic muscle contraction resulted in an average Dice of 0.88 and an average mean boundary distance of 2.75mm. This work had the potential to pave the way towards the adoption of ultrasound in the clinic and development of personalized treatment for PFD.

Automatic Extraction of Hiatal Dimensions in 3-D Transperineal Pelvic Ultrasound Recordings.

The aims of this work were to create a robust automatic software tool for measurement of the levator hiatal area on transperineal ultrasound (TPUS) volumes and to measure the potential reduction in variability and time taken for analysis in a clinical setting. The proposed tool automatically detects the C-plane (i.e., the plane of minimal hiatal dimensions) from a 3-D TPUS volume and subsequently uses the extracted plane to automatically segment the levator hiatus, using a convolutional neural network. The automatic pipeline was tested using 73 representative TPUS volumes. Reference hiatal outlines were obtained manually by two experts and compared with the pipeline's automated outlines. The Hausdorff distance, area, a clinical quality score, C-plane angle and C-plane Euclidean distance were used to evaluate C-plane detection and quantify levator hiatus segmentation accuracy. A visual Turing test was created to compare the performance of the software with that of the expert, based on the visual assessment of C-plane and hiatal segmentation quality. The overall time taken to extract the hiatal area with both measurement methods (i.e., manual and automatic) was measured. Each metric was calculated both for computer-observer differences and for inter-and intra-observer differences. The automatic method gave results similar to those of the expert when determining the hiatal outline from a TPUS volume. Indeed, the hiatal area measured by the algorithm and by an expert were within the intra-observer variability. Similarly, the method identified the C-plane with an accuracy of 5.76 ± 5.06° and 6.46 ± 5.18 mm in comparison to the inter-observer variability of 9.39 ± 6.21° and 8.48 ± 6.62 mm. The visual Turing test suggested that the automatic method identified the C-plane position within the TPUS volume visually as well as the expert. The average time taken to identify the C-plane and segment the hiatal area manually was 2 min and 35 ± 17 s, compared with 35 ± 4 s for the automatic result. This study presents a method for automatically measuring the levator hiatal area using artificial intelligence-based methodologies whereby the C-plane within a TPUS volume is detected and subsequently traced for the levator hiatal outline. The proposed solution was determined to be accurate, relatively quick, robust and reliable and, importantly, to reduce time and expertise required for pelvic floor disorder assessment.

Levator-Urethra Gap: Normative Data in a Nonpregnant Nulliparous Population.

This study aimed to establish a normative range of the levator-urethra gap (LUG) measurement in nonpregnant, nulliparous women to be used as a standard against which assessments of injury or avulsion of the levator ani could be made. Nulliparous women in the Pacific Northwest who were planning pregnancy within the ensuing 12 months underwent high-resolution magnetic resonance imaging (MRI) and 3-dimensional transperineal ultrasonography. In the plane of minimal hiatal dimensions, the LUG was measured on both the right and left sides for 3 contiguous image slices. One hundred thirty-five participants underwent examinations, of which 134 had evaluable MRIs and 70 had evaluable ultrasounds. Mean (SD) age was 30.8 (4.0) years, and mean (SD) body mass index was 25.9 (6.4). The majority of the participants self-identified as White (80%) and non-Hispanic (89%). The 99th percentile was no greater than 2.39 cm on any slice for either MRI or US-based measurements. In the MRI set, the lowest LUG values at which all 3 measurements on a side were found to have exceeded a putative threshold value (for injury) were 2.1 cm for the right side and 2.05 cm for the left side. The corresponding LUG values in the ultrasound set were 2.2 cm on the right and 2.25 cm on the left. The LUG threshold in 3 successive slices in the minimal hiatal dimension suggestive of levator ani injury could be as low as 2.1 cm when using MRI and 2.25 cm when using ultrasound in a similar population.

Malmström vacuum or Kielland forceps: which causes more damage to pelvic floor?

To determine whether differences exist in the rate of levator ani muscle (LAM) avulsion between women who had undergone either Malmström vacuum delivery (MVD) or Kielland forceps delivery (KFD), allowing for potential confounding factors. This was a prospective observational study of nulliparous women undergoing instrumental delivery using Malmström vacuum extractor or Kielland forceps, at two hospital centers in Spain. Fetal head position (anterior, posterior or transverse) and fetal head station (low or mid) were assessed by ultrasound and digital examination, respectively. Avulsion was defined on tomographic ultrasound imaging as an abnormal insertion of the LAM in the three central slices from the plane of minimal hiatal dimensions. In total, 414 patients were included in the study (212 MVD and 202 KFD). We observed a higher rate of LAM avulsion in the KFD group (KFD 49.5% vs MVD 32.5%; P = 0.001). When the results were evaluated according to fetal head position and station, we observed no differences in LAM avulsion. The crude odds ratio (OR) for the difference in avulsion between women in the KFD and MVD groups was 2.03 (95% CI, 1.36-3.03). However, when adjusted for duration of second stage of labor, fetal head circumference and fetal head station, the OR was no longer statistically significant (OR, 2.14 (95% CI, 0.95-4.85); P = 0.068). When potential confounding factors are taken into account, the rate of LAM avulsion does not differ between women according to whether they have undergone KFD or MVD. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

A comparable rate of levator ani muscle injury in operative vaginal delivery (forceps and vacuum) according to the characteristics of the instrumentation.

Forceps delivery is associated with a high rate of levator ani muscle (LAM) trauma (avulsion) at 35%-65% whereas data on avulsion rates after vacuum delivery vary greatly. Nevertheless, a common characteristic of all previous studies carried out to evaluate the association between instrumental deliveries (forceps and vacuum) and LAM avulsion, is the fact that characteristics of the instrumentation have not been described or evaluated. The objective of this study is to compare the rate of LAM avulsion between forceps and vacuum deliveries according to the characteristics of the instrumentation. Prospective, observational study, including 263 nulliparous women, who underwent an instrumental delivery with either Malmström vacuum or Kielland forceps. The characteristics of the instrumentation, position (anterior position and other position) and height of the fetal head at the moment of instrumentation (low instrumentation [vertex at +2 station] and mid-instrumentation [head is involved but leading part above +2 station]) were assessed. Evaluation of LAM avulsion was performed at 6months postpartum by three-/four-dimensional transperineal ultrasound. Using the multi-view mode, a complete avulsion was diagnosed when the abnormal muscle insertion was identified in all three central slices, that is, in the plane of minimal hiatal dimensions and the 2.5-mm and 5.0-mm slices cranial to this one. To detect a 30% or 15% difference in the LAM injury rate, with 80% power and 5% α-error, we needed, respectively 42 and 99 women per study group. In all, 263 nulliparous individuals have been evaluated (162 vacuum deliveries, 101 forceps deliveries). Instrumentation in an occipito-anterior position was more frequent in vacuum deliveries (75.3% vs 56.4%, P=.002), whereas other positions were more frequent in the forceps deliveries group (24.7% vs 43.6%). No statistically significant differences were noted regarding the height of the fetal head at the moment of instrumentation. No statistically significant differences were found in the presence of LAM avulsion (41.4% vs 38.6%) between vacuum and forceps deliveries. The univariate analysis of the crude odds ratio was 1.17, 95% CI 0.67-1.98, P=.70 for the avulsion of the LAM and the multivariate of the adjusted OR 0.90, 95% CI; 0.53-1.55, P=.71. We consider that, in our population, LAM avulsion rate should not be a factor taken into account when choosing the type of instrumentation (Malmström vacuum or Kielland forceps) in an operative delivery.

Atraumatic normal vaginal delivery: how many women get what they want?

Trauma to the perineum, levator ani complex, and anal sphincter is common during vaginal childbirth, but often clinically underdiagnosed, and many women are unaware of the potential for long-term damage. In this study we use transperineal ultrasound to identify how many women will achieve a normal vaginal delivery without substantial damage to the levator ani or anal sphincter muscles, and to create a model to predict patient characteristics associated with successful atraumatic normal vaginal delivery. This is a retrospective, secondary analysis of data sets gathered in the context of an interventional perinatal imaging study. A total of 660 primiparas, carrying an uncomplicated singleton pregnancy, underwent an antepartum and postpartum interview, vaginal exam (Pelvic Organ Prolapse Quantification), and 4-dimensional translabial ultrasound. Ultrasound data were analyzed for levator trauma and/or overdistention and residual sphincter defects. Postprocessing analysis of ultrasound volumes was performed blinded against clinical data and analyzed against obstetric data retrieved from the local maternity database. Levator avulsion was diagnosed if the muscle insertion at the inferior pubic ramus at the plane of minimal hiatal dimensions and within 5 mm above this plane on tomographic ultrasound imaging was abnormal, ie the muscle was disconnected from the inferior pubic ramus. Hiatal overdistensibility (microtrauma) was diagnosed if there was a peripartum increase in hiatal area on Valsalva by >20% with the resultant area ≥25 cm2. A sphincter defect was diagnosed if a gap of >30 degrees was seen in ≥4 of 6 tomographic ultrasound imaging slices bracketing the external anal sphincter. Two models were tested: a first model that defines severe pelvic floor trauma as either obstetric anal sphincter injury or levator avulsion, and a second, more conservative model, that also included microtrauma. A total of 504/660 women (76%) returned for postpartum follow-up as described previously. In all, 21 patients were excluded due to inadequate data or intercurrent pregnancy, leaving 483 women for analysis. Model 1 defined nontraumatic vaginal delivery as excluding operative delivery, obstetric anal sphincter injuries, and sonographic evidence of levator avulsion or residual sphincter defect. Model 2 also excluded microtrauma. Of 483 women, 112 (23%) had a cesarean delivery, 103 (21%) had an operative vaginal delivery, and 17 (4%) had a third-/fourth-degree tear, leaving 251 women who could be said to have had a normal vaginal delivery. On ultrasound, in model 1, 27 women (6%) had an avulsion and 31 (6%) had a residual defect, leaving 193/483 (40%) who met the criteria for atraumatic normal vaginal delivery. In model 2, an additional 33 women (7%) had microtrauma, leaving only 160/483 (33%) women who met the criteria for atraumatic normal vaginal delivery. On multivariate analysis, younger age and earlier gestation at time of delivery remained highly significant as predictors of atraumatic normal vaginal delivery in both models, with increased hiatal area on Valsalva also significant in model 2 (all P ≤ .035). The prevalence of significant pelvic floor trauma aftervaginal child birth is much higher than generally assumed. Ratesofobstetric anal sphincter injury are often underestimated and levator avulsion is not included as a consequence of vaginal birth in most obstetric text books. In this study less than half (33-40%) of primiparous women achieved an atraumatic normal vaginal delivery.

Can pelvic floor trauma be predicted antenatally?

Levator trauma is a risk factor for the development of pelvic organ prolapse. We aimed to identify antenatal predictors for significant damage to the levator ani muscle during a first vaginal delivery. A retrospective observational study utilizing data from two studies with identical inclusion criteria and assessment protocols between 2005 and 2014. A total of 1148 primiparae with an uncomplicated singleton pregnancy were recruited and assessed with translabial ultrasound at 36 weeks antepartum and 871 (76%) returned for reassessment 3-6 months postpartum. The ultrasound data of vaginally parous women were analyzed for levator avulsion and microtrauma. The former was diagnosed if the muscle insertion at the inferior pubic ramus in the plane of minimal hiatal dimensions and within 5 mm above were abnormal on tomographic ultrasound imaging. Microtrauma was diagnosed in women with an intact levator and if there was a postpartum increase in hiatal area on Valsalva by >20% with the resultant area ≥25 cm2 . The complete datasets of 844 women were analyzed. Among them, 609 delivered vaginally: by normal vaginal delivery in 452 (54%), a vacuum birth in 102 (12%) and a forceps delivery in 55 (6%). Levator avulsion was diagnosed in 98 and microtrauma in 97. On multivariate analysis, increasing maternal age, lower body mass index and lower bladder neck descent were associated with avulsion. Increased bladder neck descent and a family history of cesarean section (CS) were associcated with microtrauma. Maternal age, body mass index, bladder neck descent and family history of CS are antenatal predictors for levator trauma.

The Association Between Levator-Urethra Gap Measurements and Symptoms and Signs of Female Pelvic Organ Prolapse.

Levator avulsion is associated with pelvic organ prolapse in women. It is diagnosed clinically by a widened gap on palpation between the insertion of the puborectalis muscle on the inferior pubic ramus and the urethra. This gap can also be assessed on imaging. This study aimed to determine the association between sonographically determined levator-urethral gap (LUG) measurements and symptoms and signs of prolapse. This is a retrospective study on 450 women seen in a tertiary urogynecological center for symptoms of pelvic floor dysfunction between January 2013 and February 2014. All had a standardized interview, International Continence Society Pelvic Organ Prolapse Quantification assessment and 4-dimensional translabial ultrasound. Post-imaging analysis of archived ultrasound volumes for LUG measurement was undertaken on tomographic slices at the plane of minimal hiatal dimensions and within 5-mm cranial to this plane, bilaterally at an interslice interval of 2.5 mm, blinded against all clinical data. A LUG of 25 mm or greater was considered abnormal. Mean LUG and maximum LUG in individuals were 22.5 mm (SD, 4.6) and 26.4 mm (SD, 6.0), respectively, with at least 1 abnormal LUG in 51% (n = 222). An abnormal LUG in all 3 slices involving the plane of minimal hiatal dimensions and within 5 mm cranial to this plane on at least 1 side was fulfilled in 24% (n = 103). The LUG measurements were strongly associated with bother, symptoms and signs of prolapse (P < 0.001 to 0.002). This remained significant on multivariate analysis controlling for potential confounding factors. Sonographically determined LUG is strongly associated with symptoms, symptom bother, and pelvic organ prolapse on clinical examination and imaging.

Assessment of pelvic floor muscle contraction with palpation, perineometry and transperineal ultrasound: a cross-sectional study.

To study the correlation between palpation, perineometry and transperineal ultrasound for assessment of pelvic floor muscle contraction and to define a contraction scale for ultrasound measurements. This was a cross-sectional study of 608 women examined with palpation of pelvic floor muscle contraction, using the Modified Oxford Scale, and measurement of the vaginal squeeze pressure with a vaginal balloon connected to a fiber-optic microtip transducer (perineometry). Transperineal ultrasound was used for measurements of levator hiatal area and anteroposterior (AP) diameter in the plane of minimal hiatal dimensions, at rest and on contraction. The pelvic floor muscle contraction was expressed as the percentage difference between values at rest and on contraction. Spearman's rank was used to test for correlation between the different methods of assessment. Significant correlations were found between all assessment methods (P < 0.001). Palpation correlated with perineometry (rs = 0.74) and with proportional change in hiatal area (rs = 0.67) and AP diameter (rs = 0.69) on ultrasound. Perineometry correlated with proportional change in hiatal area (rs = 0.60) and AP diameter (rs = 0.66) on ultrasound. We defined a contraction scale based on the proportional change in AP diameter. In this population, a change in AP diameter of < 7% corresponded to absence of contractions, 7-18% corresponded to weak contractions, 18-35% corresponded to normal contractions and > 35% corresponded to strong contractions. We found moderate to strong correlation between ultrasound measurements, palpation and perineometry for assessing pelvic floor muscle contraction. The proportional change in levator hiatal AP diameter was the ultrasound measurement with strongest correlation to palpation and perineometry and formed the basis for the contraction scale for ultrasound measurements. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Pelvic floor muscle variables and levator hiatus dimensions: a 3/4D transperineal ultrasound cross-sectional study on 300 nulliparous pregnant women.

The aims of the present study were to investigate the correlation among vaginal resting pressure and pelvic floor muscle (PFM) strength and endurance, and the correlation between the same variables and levator hiatus (LH) dimensions in nulliparous pregnant women. This was a cross-sectional study of 300 nulliparous pregnant women, mean age 28.7 years (SD 4.3) and pre-pregnancy BMI 23.9 kg/m(2) (SD 3.9), assessed at mean gestational week 20.8 (±1.4). Vaginal resting pressure and PFM strength and endurance were measured using a high precision pressure transducer connected to a vaginal balloon. LH dimensions (transverse and anterior-posterior diameters_ and LH area were assessed using 3/4D transperineal ultrasound in the axial plane of minimal hiatal dimensions using render mode. The Pearson correlation was used to analyze correlations among vaginal resting pressure and PFM strength and endurance, and between PFM variables and LH dimensions. Level of significance was set at 0.05. Pelvic floor muscle strength and vaginal resting pressure were significantly, but weakly correlated (r = 0.198, p < 0.001). PFM strength and endurance showed a strong correlation (r = 0.929, p < 0.001). High vaginal resting pressure was moderately correlated with a small LH area at rest (r = -0.451, p < 0.001), but there was no significant correlation neither between PFM strength and LH area at rest (r = -0.012, p = 0.84) nor between muscle endurance and LH area at rest (r = -0.014, p = 0.81). A strong PFM contraction correlated moderately with reduction of the LH area (r = -0.367, p < 0.001). Pelvic floor muscle strength and endurance are strongly correlated, butdo not correlate with a smaller LH area at rest.

Intra‐ and interobserver reliability of levator ani muscle biometry and avulsion using three‐dimensional endovaginal ultrasonography

To test intra- and interobserver reliability of assessment of levator ani muscle (LAM) biometry and avulsion using antenatal and postnatal three-dimensional (3D) endovaginal ultrasonography (EVUS), and to determine levator-urethra gap (LUG) values on EVUS. Primigravid women were scanned prior to delivery, early postpartum and 3 months postpartum, with EVUS performed at rest using a standardized protocol. During post-processing, measurements were taken in the plane of minimal hiatal dimensions by two independent investigators blinded to the clinical information and each other's results. LAM attachment to the pubic bone was assessed at the pubococcygeus and puborectalis levels using a score system: (1) intact; (2) partial avulsion (< 50%); (3) partial avulsion (≥ 50%); and (4) complete avulsion. Intraclass correlation coefficients (ICCs) and limits of agreement (LOAs) were calculated for each time point, with intraobserver analysis conducted in a random sample of 20 women scanned 3 months following delivery. One hundred and sixty-nine antenatal scans, 83 early postpartum scans and 75 scans at 3 months postpartum were performed. The intra- and interobserver ICCs, respectively, were 0.95 and 0.86-0.88 for hiatal area, 0.90 and 0.16-0.74 for hiatal transverse diameter, 0.91 and 0.73-0.80 for hiatal anteroposterior diameter, 0.50 and 0.32-0.52 for LAM thickness at the '9 o'clock position' and 0.55 and 0.33-0.45 for LAM thickness at the '3 o'clock position'. Both intra- and interobserver analysis revealed acceptable LOAs for hiatal measurements, but the LOAs were wide for thickness measurements. The correlation of LAM avulsion score was excellent on intra- and interobserver analysis. Antenatal mean ± SD LUGs were 18.8 ± 2.4 mm and 19.2 ± 2.3 mm on right and left sides, respectively; the intraobserver ICC was 0.82-0.91 but LOAs were wide, while interobserver ICC was 0.13-0.68 and also had wide LOAs. 3D-EVUS is a reliable tool for the assessment of hiatal measurements and LAM avulsion in women during pregnancy and after delivery, but performs less well for measurements of LAM thickness and LUG. EVUS can therefore be used in research studies involving childbirth and recurrent prolapse.

Prevalence of pubovisceral muscle avulsion in a general gynecology cohort: A computed tomography (CT) study

To calculate the prevalence of pubovisceral muscle (PM) avulsion in a cohort of women presenting at a university hospital for non-urogynecological conditions. Women with or without symptoms of PFD were studied in a tertiary referral urogynecology center between February and October 2010. Women were recruited from the Department of Radiology, where they were referred for a CT pelvis scan due to various pathologies. Assessment of participants included a detailed clinical interview, completion of King's Health and Prolapse-Quality of Life (P-QOL) questionnaires and spiral CT scan of the pelvis. Bilateral attachments of the PM to the pubic rami were identified in the plane of minimal hiatal dimensions, when present, and measurement of the levator symphysis gap (LSG) was taken in cases with PM complete detachment. Bivariate analysis between the PM maximum thickness and different obstetric variables was performed by using Spearman's correlation test (P < 0.05). One hundred ten women were included in the analysis. The overall prevalence of PM avulsion was 6.4% (7/110). In cases with confirmed avulsion, the levator sympysis gap (LSG) ranged from 17.30 to 25.40 mm. The left PM was found to be significantly thinner in parous women and in those with a history of prolonged second stage of labor. The prevalence of pubovisceral muscle avulsion using CT scanning in a general gynecology cohort is 6.4%. Thinning of the pubovisceral muscle occurs with parity and protracted labor and is more prominent on the left portion of the muscle.

Can we identify the limits of the puborectalis/pubovisceralis muscle on tomographic translabial ultrasound?

In order to determine the relative locations of puborectalis/pubovisceralis (PR/PV) and iliococcygeus (IC) muscles, we undertook an analysis of four-dimensional (4D) ultrasound datasets obtained after suburethral sling placement. This was a retrospective analysis of ultrasound volume data obtained in 110 women after undergoing the Monarc suburethral sling procedure. Tomographic ultrasound imaging (TUI) was performed with eight slices in the axial plane, from 5 mm below to 12.5 mm above the plane of minimal hiatal dimensions. Hyperechogenic tape material was rated as absent, present or as producing an anechoic acoustic shadow overlying the muscle in each slice. Slices 7 and 8 virtually always showed evidence of the implant or its acoustic shadow on the pelvic sidewall (98% for slice 8 and 96% for slice 7), suggesting that these slices are located at the level of the obturator foramen. This implies that these slices do not generally contain PR/PV muscle, but rather IC muscle. On standardized tomographic imaging of the levator hiatus and muscle, slices located ≥ 1 cm over the plane of minimal dimensions are very likely to contain IC muscle rather than PR/PV muscle.

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

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

Avulsion injury and levator hiatal ballooning: two independent risk factors for prolapse? An observational study

To study whether avulsion and ballooning are independent risk factors for symptoms and/or signs of pelvic organ prolapse. Retrospective analysis of data obtained in clinical practice. Tertiary urogynecology unit. Seven hundred and sixty-one consecutive women with symptoms of pelvic floor dysfunction. Evaluation included history, vaginal examination and four-dimensional translabial ultrasound. Ultrasound analysis was performed off-line, blinded against clinical data. Hiatal dimensions were measured at the plane of minimal hiatal dimensions. Puborectalis avulsion was identified using tomographic imaging. Symptoms and objective signs of prolapse (ICS POP-Q stage 2+). Owing to previous surgery 156 women were excluded, leaving 605, of whom 258 (43%) had prolapse symptoms. Significant prolapse (International Continence Society Prolapse Quantification System grade 2+) was identified as follows: cystocele in 222 (37%) women, rectocele in 159 (27%) and apical in 40 (8%), while 110 (18%) had an avulsion. There was a strong association between avulsion, hiatal ballooning and symptoms/signs of prolapse (p < 0.001). On multivariable backwards stepwise logistic regression, puborectalis avulsion was associated with an increased risk of symptoms and signs of prolapse, even after allowing for the degree of levator ballooning. The presence of avulsion did not modify the relation between hiatal area and symptoms of prolapse. Puborectalis avulsion injury and levator hiatal ballooning are independent risk factors for symptoms and signs of prolapse. The role of avulsion in the pathogenesis of prolapse is not fully explained by its effect on hiatal dimensions. It is likely that avulsion implies not only muscular trauma but also damage to structures impossible to assess clinically or by imaging, i.e. myofascial and connective tissue.

A simplified method for determining hiatal biometry

The levator hiatus is the largest potential hernial portal in the human body. Its dimensions are measured in the axial plane and are strongly associated with female pelvic organ prolapse. We aimed to compare two commonly used methods for measuring hiatal dimensions. We performed offline analysis of 100 consecutive 4D ultrasound volume datasets of women seen in a tertiary urogynecological clinic. Hiatal measurements were obtained in sectional planes (SP, Method A) and rendered volumes of 1-2 cm thickness (RV, Method B). A test-retest series in 20 women showed similar repeatability for both methods, with an intraclass correlation (ICC) of 0.85 (CI 0.81-0.88) for Method A (SP) and of 0.88 (CI 0.85-0.9) for Method B (RV). Measurements taken from rendered volumes were generally lower than those taken in axial plane slices, reaching significance for area on Valsalva (P=0.005), sagittal diameter and area on pelvic floor contraction (P=0.009 and 0.044). Method B seemed more strongly associated with symptoms of prolapse than Method A (P=0.008 vs P=0.027). We recommend that hiatal dimensions be measured in rendered volumes whenever possible because this method seems more valid and at least as repeatable. This is probably due to the fact that the plane of minimal hiatal dimensions is non-Euclidean, i.e., warped, which can be compensated for by measuring in a rendered volume of 1-2 cm thickness.

Can the Paula method facilitate co-contraction of the pelvic floor muscles? A 4D ultrasound study

The aim was to compare constriction of the levator hiatus (LH) and reduction of pelvic floor muscle (PFM) length during instruction of the Paula method (contraction of ring musculature of the mouth) and contraction of the PFM. Seventeen pregnant or postpartum women, mean age 28.6 (range 20-35) participated. A Voluson E8 ultrasound machine with 4-8 MHz curved array 3D/4D transducer (RAB 4-7l/obstetric) was used. Measurements were performed in the axial plane of minimal hiatal dimensions. Muscle length was calculated as circumference of the LH minus the suprapubic arch. Differences between groups were analyzed using Wilcoxon signed rank test. Significance level was set to 0.05. There was a significant reduction of the LH area (p<0.001) and muscle length (p<0.001) during PFM contraction, but not during contraction according to the Paula method, p=0.51 and p=0.31, respectively. The Paula method did not facilitate PFM contraction.

Measuring the levator hiatus with axial MRI sequences: Adjusting the angle of acquisition

We aimed to compare MRI measurements of the female levator hiatus and the most caudal "levator ani" muscles between image slices in a plane axial to the body (AxB) and an axial plane parallel to the direction of the puborectalis muscle (AxPRM). We performed high-resolution, T2-weighted axial magnetic resonance imaging (in two different planes) on 20 sequentially recruited asymptomatic nulliparous women. Levator hiatus measurements were compared between the two planes. The mean tilt angle of the AxPRM slices relative to the AxB slices was 18.9° (SD 8.5) and the area of the levator hiatus was 10% greater (P=0.04) in the AxPRM plane. By rotating the acquisition plane to be parallel to the puborectalis muscle (sometimes called the plane of minimal hiatal dimensions), some of the measurements of the distal and medial pelvic floor muscles (and the hiatus defined by them) are altered. This issue is important because both MRI and 3D ultrasound are increasingly being used to evaluate the pelvic floor hiatus, and its relationship to childbirth injury and pelvic floor disorders. To make meaningful comparisons, it is important that both modalities are measuring the same thing.