Pubococcygeal Line Versus H-line as MR Defecography Reference for Bladder Descent

INTRODUCTION AND HYPOTHESIS

Magnetic resonance defecography imaging techniques have been used widely to study pelvic floor function and diagnose pelvic organ prolapse (POP). The aim of this study was to investigate the diagnostic accuracy of the H-line to detect bladder descent compared with the current landmark, the pubococcygeal line (PCL).

METHODS

In this retrospective cohort study, patients who underwent MR defecography in our medical center and were diagnosed with moderate to severe cystocele by radiological measurements were recruited. One rest image and one maximum evacuation image for each subject were used for the following measurements: bladder base perpendicular distance from the genital hiatus (GH), indicative of clinically significant bladder descent, PCL as the current radiological reference line, and the H-line, or minimal levator hiatus line, indicative of pelvic floor muscle and connective tissue support. Subjects were categorized as having clinically significant cystocele if the "bladder base" reached within 1 cm or lower of the GH (stage II or higher cystocele). A comparison was performed to assess differences and predictive capabilities of the reference lines relative to the GH measure.

RESULTS

Seventy subjects were included, 30 with clinically significant bladder descent based on distance to GH. Women with bladder descent were older (64.0 ± 11.8 vs 51.2 ± 15.6, p < 0.001), had increased parity (3 [1-7] vs 2 [0-5], p = 0.009), and had a bladder that descended lower than the H-line at rest (1.9 ± 0.5 vs 2.2 ± 0.4, p = 0.003) and evacuation (-2.4 ± 1.6 vs -0.7 ± 1.1, p < 0.001). Multivariate regression analysis confirmed that age, length of the H-line at evacuation, the perpendicular distances between the H-line and the lowest bladder point at rest, and the PCL to the lowest bladder point at evacuation significantly correlated with bladder descent. Receiver operating characteristic analysis was used to identify a measurement threshold to diagnose clinically significant cystocele for both measurements, bladder base to the H-line: -1.2 (80.0, 72.5) area under the curve (AUC) 0.82, and bladder base PCL: -3.3 (77.8, 79.5) AUC 0.86.

CONCLUSION

Our data support the application of using the minimal levator hiatus plane and specifically the H-line as a reliable landmark to diagnose bladder descent using MR defecography imaging.

Quantifying the effect of an endo-vaginal probe on position of the pelvic floor viscera and muscles

INTRODUCTION AND HYPOTHESIS

Endovaginal ultrasound has long been hypothesized to have a significant effect on locations of what it visualizes. However, little work has directly quantified its effect. This study aimed to quantify it.

METHODS

This cross-sectional study consisted of 20 healthy asymptomatic volunteers who underwent both endovaginal ultrasound and MRI. The urethra, vagina, rectum, pelvic floor, and pubic bone were segmented in both ultrasound and MRI using 3DSlicer. Then, using 3DSlicer's transform tool the volumes were rigidly aligned based on the posterior curvature of the pubic bone. The organs were then split into thirds along their long axis to compare their distal, middle, and proximal sections. Using Houdini, we compared the location of the centroid of each of the urethra, vagina, and rectum and the surface-to-surface difference of the urethra and rectum. The anterior curvature of the pelvic floor was also compared. Normality of all variables was assessed by Shapiro-Wilk test.

RESULTS

The largest amount of surface-to-surface distance was observed in the proximal region for the urethra and rectum. Across all three organs, the majority of the deviation was in the anterior direction for geometries obtained from ultrasound versus those from MRI. For each subject, the trace defining the midline of the levator plate was more anterior for ultrasound compared to MRI.

CONCLUSIONS

While it has often been assumed that placing a probe in the vagina probably distorts the anatomy, this study quantified the distortion and displacement of the pelvic viscera. This allows for better interpretation of clinical and research findings based on this modality.

Multimodal measurements of levator bowl volume in nulligravid asymptomatic women: endovaginal ultrasound versus MRI

INTRODUCTION AND HYPOTHESIS

Measurements of levator bowl volume using advanced imaging, may be predictive of pelvic floor muscle function. The aim of this study was to compare the volume of the levator bowl using both magnetic resonance imaging (MRI) and endovaginal ultrasound (EVU) of healthy asymptomatic women.

METHODS

All participants underwent a comprehensive interview including completion of the Pelvic Floor Distress Inventory Questionnaire-20 questionnaire, pelvic examination with a pelvic organ prolapse quantification evaluation, MRI, and EVU. The pelvic floor was segmented using Slicer and the MRI segmentations were trimmed using two methods: soft-tissue landmarks and the field of view (FOV) of the ultrasound volume. The levator bowl volume of the 3D segmented shapes was measured using Blender's 3D printing toolkit. Normality was tested using the Shapiro-Wilks test and comparisons were made using self-paired t tests.

RESULTS

The final analysis included 19 patients. Levator bowl volume measured via MRI was larger than that measured in EVU (46.1 ± 7.9 cm3 vs 27.4 ± 5.9 cm3, p<0.001). Reducing the FOV of the MRI to that of EVU caused the MRI volume to be much closer to the EVU volume (35.5 ± 3.3 cm3 vs 27.4 ± 5.9 cm3, p<0.001); however, it remained significantly larger.

CONCLUSION

Levator bowl volume measured using MRI was larger than that measured using EVU no matter the method of delineation of the levator muscles. Although EVU is safe, cheap, and easy to perform, it captures a smaller volume of levator bowel than MRI.

Immediate postpartum assessment of the anal sphincter by endovaginal ultrasound: An experimental study

INTRODUCTION AND HYPOTHESIS

Obstetric anal sphincter injuries are frequently missed and carry a significant risk for the development of anal incontinence. Immediate postpartum endoanal ultrasound increases identification of these injuries but is rarely employed. We hypothesize that endovaginal ultrasound could be a feasible and easily available alternative sonographic tool to improve early diagnosis of anal sphincter tears.

METHODS

We conducted a prospective experimental study including 160 primiparous women. Shortly after vaginal delivery, patients underwent clinical and sonographic perineal examinations. We analyzed the feasibility of anal sphincter assessment by endovaginal ultrasound and its potential contribution in the early diagnosis of anal sphincter injuries.

RESULTS

Sonographic assessment of the anal sphincter was analyzable for 136 patients (85.0%). Causes of non-analyzability included air artifacts (6.9%), lack of distinction between the external anal sphincter and surrounding tissues (9.4%) and distortion artifacts (9.4%). Patients in the non-analyzable ultrasound subgroup were less likely to have delivered in a dorsal lithotomy position (62.5% vs. 85.3 %) and more likely to have had an episiotomy (33.3% vs. 14.0%), and their risk of sphincter injury was more frequently classified as "improbable" on clinical examination (91.7% vs. 61.0%). Ultrasounds were analyzable for 96.4% of patients clinically reported as having "possible" or "certain" sphincter injuries. The incidence of anal sphincter injury was 16.9% for clinical observation and 20.0% with associated sonographic examination.

CONCLUSIONS

Endovaginal ultrasound could be used as a complementary tool in assessment of the anal sphincter in high-risk patients. Its feasibility and easy availability make this technique a promising tool for improving the management of anal sphincter tears.

Immediate postpartum assessment of the anal sphincter by endovaginal ultrasound: a new technical approach

INTRODUCTION AND HYPOTHESIS

In this study we described a new technical approach to adapt endovaginal ultrasound scanning of the anal sphincter complex to the immediate postpartum period.

METHODS

We analyzed the clinical and ultrasonographic examinations of 18 primiparous women presenting deep perineal tears with potential or clearly identified lesions of the anal sphincter. Potential anal sphincter lesion was defined as a second degree perineal tear extending close to the anal sphincter with exposition of its capsule or muscular fibers. We reported interesting ultrasonographic images explaining our technique in a video.

RESULTS

We reported clinical and ultrasonographic features in nine cases of grade 2, four cases of grade 3a, four cases of grade 3b and one case of grade 3c perineal tears. The ultrasonographic examination confirmed the intact state of the anal sphincter complex in all patients with clinical grade 2 tears except one in which a grade 3b lesion was detected. We were not able to identify external anal sphincter lesions on ultrasound in any of the patients with clinical grade 3a tears. In patients with clinical grade 3b tears, the ultrasound confirmed the external anal sphincter lesion in all cases, but revealed additional involvement of the internal anal sphincter in 1 case (grade 3c).

CONCLUSION

Immediate postpartum endovaginal ultrasound could be a promising technique to improve the management of perineal traumas after vaginal delivery.

Urethral support in female urinary continence part 1: dynamic measurements of urethral shape and motion

INTRODUCTION AND HYPOTHESIS

Urethral closure mechanism dysfunction in female stress urinary incontinence (SUI) is poorly understood. We aimed to quantify these mechanisms through changes in urethral shape and position during squeeze (voluntary closure) and Valsalva (passive closure) via endovaginal ultrasound in women with varying SUI severity.

METHODS

In this prospective cohort study, 76 women who presented to our tertiary center for urodynamic testing as preoperative assessment were recruited. Urodynamics were performed according to International Continence Society criteria. Urethral pressures were obtained during serial Valsalva maneuvers. Urethral lengths, thicknesses, and angles were measured in the midsagittal plane via dynamic anterior compartment ultrasound. Statistical shape modeling was carried out by a principal component analysis on aligned urethra shapes.

RESULTS

Age, parity, and BMI did not vary by SUI group. Ultrasound detected a larger retropubic angle, urethral knee-pubic bone angle (a novel measure developed for this study), and infrapubic urethral length measurements at Valsalva in women with severe SUI (p = 0.016, 0.015, and 0.010). Shape analysis defined increased "c" shape concavity and distal wall pinching during squeeze and increased "s" shape concavity and distal wall thickening during Valsalva (p < 0.001). It also described significant urethral shape differences across SUI severity groups (p < 0.001).

CONCLUSIONS

Dynamic endovaginal ultrasound can visualize and allow for quantification of voluntary and passive urethral closure and variations with SUI severity. In women with severe SUI, excessive bladder neck and distal urethra swinging during Valsalva longitudinally compressed the urethra, resulting in a proportionally thicker wall at the mid-urethra and urethral knee.

Vaginal ultrasound-guided Pouch of Douglas robotic entry in a live ovine model and human female cadaveric specimens

We aimed to determine whether intraoperative ultrasound is a feasible tool for visualization of the pouch of Douglas (POD) to facilitate a safe vaginal entry for direct robotic vaginal trocar insertion for pelvic floor surgery. Endovaginal ultrasound-guided needle insertion of a trocar into the POD was performed in six fresh frozen female cadavers and a live sheep animal model. Using an endovaginal probe the POD was identified as a fluid-filled space clear of bowel or adhesions, then a Veress needle was also used to confirm POD localization. Access to the POD was achieved using a robotic trocar designed for this purpose. The animal study was approved by the Ethics Committee of Asaf-Harofe hospital. Direct visualization during laparoscopy in cadavers and open cadaveric dissections confirmed safe POD entry and accurate trocar placement. This method was found feasible in the development of a safe vaginal entry in both the animal and cadaveric model, possibly negating the need for laparoscopic umbilical observation.

Vascularity of the urethra in continent women using colour doppler high-frequency endovaginal ultrasonography

Objectives

To assess the urethral vascularity in continent women using colour doppler high frequency endovaginal ultrasonography (EVUS).

Methods

We recruited 61 continent women attending gynaecology clinics between July and October 2009. Exclusion criteria included symptoms of urinary incontinence, voiding dysfunction, pelvic organ prolapse or urinary tract infection. The participants underwent EVUS using high frequency (9-12 MHz) biplane transducer (type 8848 BK Medical), according to a standardised protocol. Colour Doppler US was performed in sagittal plane and in transverse plane at the level of the mid-urethra. Ten seconds video files were recorded and following vascular parameters: flow velocity (V_mix), area of the vessels (A_mix), intensity of vascularity (I_mix), pulsatility index (PI_mix) and resistance index (RI_mix) was evaluated.

Results

There were 30 nulliparous (49.2%) women and 31 multiparous women (50.8%) with a mean (±SD) age of 32 (±4) and 46 (±6) years respectively. Significant impairment of vascularity was observed in multiparous patients as compared to nulliparous and was reflected by increased values of RI_mix (p < 0.001) and PI_mix (p < 0.001), and decreased values of V_mix (p < 0.001), A_mix (p < 0.001), I_mix (p < 0.001) in axial and midsagittal sections of the midurethra. A significant decrease of mean value ± SD of I_mix- from 0.02 ± 0.02 in nulliparous to 0.005 ± 0.01 in multiparous was observed.

Cronbach alpha, used to assess vascular correlations and parity demonstrated a reduction when expressed only for vascular parameters, indicating that number of deliveries is an important factor while assessing urethral vascularity.

Conclusions

Compared to continent nulliparous women, continent multiparous women demonstrated a significant reduction in the vascularity parameters in all measured variables when parity was accounted for.

Advances in knowledge

This study provides the basis for further research in assessing urethral vascularity in women.