Cross-sectional Area of Pubovisceral Muscle in Nulliparous and Primiparous Women

Study Overview
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Brief Summary
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Pelvic-floor disorders (PFD), including pelvic organ prolapse, urinary and fecal incontinence, decrease quality of life of every fourth women. 1 The main known risk factor for PFD is vaginal delivery 2,3 causing pelvic floor muscle avulsion, ischemia or denervation.4 Ultrasound (US) and magnetic resonance imaging (MRI) are frequently used to investigate structural changes in pelvic floor muscles. The investigators aimed to focus on structural changes (atrophy) caused by muscle denervation. 5 The pubovisceral muscle (PVM) is the part of the levator ani muscle (LAM) which is most frequently injured and it is thought to be possibly denervated by overstretching 6 Recently, the most precise measurement of PVM cross-sectional area was performed by the group of DeLancey. 7 In our study, the investigators aimed to describe which are the normal values of PVM volume in nulliparous women. The investigators performed a measurement of PVM volume in women after the first vaginal delivery. The investigators hypothesized that there will be a decrease of the cross-sectional area of the PVM developed after denervation trauma.

Detailed Description
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Two groups of women were recruited. First, the nulliparous group served as a control. The second group was women after their first vaginal delivery. Personal characteristics, anamnestic and delivery data were collected, and clinical examination, ultrasound (US) and magnetic resonance imaging (MRI) was performed. The number of women to reach significance in the study was 40/per group. The investigators did not expect a transfer of patients between the two groups. Volunteers were recruited from a general gynecological outpatient clinic. They were thoroughly informed and informed consent was provided. In nulliparous women, all examinations (clinical, US, MRI) were performed only once. In women after vaginal delivery, first US was performed within 72h after childbirth, in order to detect LAM avulsion and exclude these women. In women without avulsion, 6 weeks after delivery, during a general postpartum checkup, the clinical evaluation of pelvic floor muscle contraction was performed. In those where the score is 0-3 the 3D US was performed to confirm no change of hiatal area during contraction. Those scans were recorded as investigated data. Those women underwent MRI within 4 months US images were obtained with a GE Voluson E10 system (General Electric Healthcare, Chicago, IL) by one investigator. US data acquisition was performed translabial as already described.9 Volumes were acquired at rest, during Valsalva and contraction. From acquired volume was assessed PVM avulsion, size of urogenital hiatus. Decrease of hiatal area at contraction proves muscle function. The assessment of US scans was performed off-line at axial plane using the 4D View v 2.1-5.0 software (GE Medical Systems) by two investigators blinded against all clinical data. MRI images were obtained with a 3-T scanner (AchievaTM, Philips Healthcare). MRI included coronal, axial, and sagittal proton density-weighted sequences performed at rest, Valsalva and contraction. Primary outcome evaluated by MRI will be the cross-sectional area of the PVM. The precise MRI technique was already defined by the group of DeLancey and is in detail described in recent publication.7 Evaluation was performed off-line by two investigators blinded against all clinical data using ImageJ software. Intra- and interobserver variability was calculated.

Official Title
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Comparison of Cross-sectional Area of Pubovisceral Muscle in Nulliparous and Primiparous Women

Conditions
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Pelvic Floor Disorders

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: reproductive age vaginal birth Exclusion Criteria: history of gynecological surgery or disorder with possible impact on pelvic floor forceps, vaccumextraction) labour induction pregnancy-related disorders perineal tear grade III-IV (women with episiotomy were included) suspicion of LAM avulsion by ultrasound or palpation Oxford score 4 or 5 after delivery
Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| nulliparous<br>inclusion: reproductive age exclusion: history of gynecological surgery or disorder with possible impact on pelvic floor | |
| primiparous<br>Inclusion: reproductive age, vaginal birth exclusion: history of gynecological surgery or disorder with possible impact on pelvic floor assisted vaginal delivery (forceps, vaccumextraction) labour induction pregnancy-related disorders perineal tear grade III-IV (women with episiotomy were included) suspicion of LAM avulsion by ultrasound or palpation Oxford score 4 or 5 after delivery | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| cross-sectional area of pubovisceral muscle | The PVM CSA was measured as previously described by Masteling et al.. Briefly, the MR images were imported into 3D Slicer, where slices containing the volume of interest were identified in a plane perpendicular to the muscle direction. To identify a plane perpendicular to the PVM, the PVM fibres direction was first established between origin and insertion, namely the inner surface of the pubic bone and its insertion into the perineal structures. In the coronal plane perpendicular to the muscle direction, the boundaries of the PVM were identified and images of this region were taken. The captured images were then exported into ImageJ for measurement of CSA. | in nulliparous group measurements performed imediately after MRI. In primiparous group the MRI was performed within 3-6 months after delivery | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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magnetic resonance imaging, levator ani muscle, denervation