The Role of Transperineal Ultrasound for the Assessment of the Anorectal Angle and Its Relationship with Levator Ani Muscle Avulsion

Round 1

Reviewer 1 Report

This is an interesting study, demonstrating that there is a change in the ARA when an avulsion LAM is 11 present after vaginal delivery. By transperineal ultrasound, the presence of avulsion was assessed when there was abnormal insertion of the LAM in 3 central slices. In addition, the ARA was 14 assessed in the midsagittal plane (at rest, in Valsalva and at maximum contraction) as the angle 15 between the posterior border of the distal part of the rectum and the central axis of the anal canal. This study found that LAM avulsion produces an increase in ARA at rest, at contraction and 196 in Valsalva, especially in cases of bilateral LAM avulsion.

Some specific comments for this study.

1. It is not clear if the subjects have dyssynergia, anismus, fecal incontinence or anal prolapse. If they have, how long it took to get recovered?
2. What is the accuracy, sensitivity and specificity of transperineal ultrasound.
3. How about using intrarectal ultrasound for this study?
4. The comparisons between the two groups rendered no significant difference. How to explain these results? What is the clinical significance for the differences?
5. This study used the data from three previous studies. What is the difference between them?
6. How is the LAM avulsion defined using ultrasound imaging data?
7. For the figure, please mark the key anatomic structures.
8. Do you have the functional evaluation of the muscles?

Author Response

Reviewer 1:

This is an interesting study, demonstrating that there is a change in the ARA when an avulsion LAM is 11 present after vaginal delivery. By transperineal ultrasound, the presence of avulsion was assessed when there was abnormal insertion of the LAM in 3 central slices. In addition, the ARA was 14 assessed in the midsagittal plane (at rest, in Valsalva and at maximum contraction) as the angle 15 between the posterior border of the distal part of the rectum and the central axis of the anal canal. This study found that LAM avulsion produces an increase in ARA at rest, at contraction and 196 in Valsalva, especially in cases of bilateral LAM avulsion.

Some specific comments for this study.

1. It is not clear if the subjects have dyssynergia, anismus, fecal incontinence or anal prolapse. If they have, how long it took to get recovered?

Re: These patients were not included in the study.

Text: Subjects with dyssynergia, anismus, fecal incontinence or anal prolapse were not included.

2. What is the accuracy, sensitivity and specificity of transperineal ultrasound.

Re: Currently, we do not have studies exploring the accuracy, sensitivity and specificity of transperineal ultrasound for the evaluation of ARA.

3. How about using intrarectal ultrasound for this study?

Re: Assessing these findings with intrarectal ultrasound, as you suggest, would be very interesting. However, we do not have these data, since we do not have specific ultrasound probes to perform endoanal ultrasound.

4. The comparisons between the two groups rendered no significant difference. How to explain these results? What is the clinical significance for the differences?

Re: The appropriate explanation has been included in the text.

Text: No differences were observed between the different groups; therefore, the variations in the ARA between the different groups were determined by the presence of LAM avulsion.

5. This study used the data from three previous studies. What is the difference between them?

Re: The appropriate explanation has been included in the text.

Text: In these studies, LAM avulsion during operative vaginal delivery (10,11) and the changes that occur after physical therapy in patients with LAM avulsion (9) were studied.

6. How is the LAM avulsion defined using ultrasound imaging data?

Re: This information has been included in the text.

Text: Three volume measurements were taken for each patient: at rest, with the Valsalva maneuver and with maximum contraction. Avulsion was defined based on maximum contraction in the multislice mode described above (14,15). Complete avulsion was diagnosed when abnormal insertion of the LAM (LAM detachment) was observed in 3 central slices. In unclear cases, a levator–urethra gap >2.5 cm was used to define abnormal insertion (16).

7. For the figure, please mark the key anatomic structures.

Re: The image has been changed as you have suggested.

8. Do you have the functional evaluation of the muscles?

Re: With apologies, we do not have functionality data based on clinical examination or manometry.

Reviewer 2 Report

Dear Editor, thank you so much for inviting me to revise this manuscript.

This study addresses a current topic.

The manuscript is quite well written and organized. English could be improved.

Figures and tables are comprehensive and clear.

The introduction explains in a clear and coherent manner the background of this study.

We suggest the following modifications:

• Methods and Statistical Analysis: nothing to add.
• Discussion section: Very interesting and timely discussion. Of note, the authors should expand the Discussion section, including a more personal perspective to reflect on. For example, they could answer the following questions – in order to facilitate the understanding of this complex topic to readers: what potential does this study hold? What are the knowledge gaps and how do researchers tackle them? How do you see this area unfolding in the next 5 years? We think it would be extremely interesting for the readers.

However, we think the authors should be acknowledged for their work. In fact, they correctly addressed an important topic, the methods sound good and their discussion is well balanced.

One additional little flaw: the authors could better explain the limitations of their work, in the last part of the Discussion.

We believe this article is suitable for publication in the journal although some revisions are needed. The main strengths of this paper are that it addresses an interesting and very timely question and provides a clear answer, with some limitations.

We suggest a linguistic revision. Moreover, the authors should better clarify some points.

Author Response

Reviewer 2:

Dear Editor, thank you so much for inviting me to revise this manuscript.

This study addresses a current topic.

The manuscript is quite well written and organized. English could be improved.

Re: The manuscript has been re-edited.

Figures and tables are comprehensive and clear.

The introduction explains in a clear and coherent manner the background of this study.

We suggest the following modifications:

• Methods and Statistical Analysis: nothing to add.
• Discussion section: Very interesting and timely discussion. Of note, the authors should expand the Discussion section, including a more personal perspective to reflect on. For example, they could answer the following questions – in order to facilitate the understanding of this complex topic to readers: what potential does this study hold? What are the knowledge gaps and how do researchers tackle them? How do you see this area unfolding in the next 5 years? We think it would be extremely interesting for the readers.

Re: This information has been included in the text.

Text: The main strengths of this paper are that it addresses an interesting and very timely question and provides a clear answer, with a sufficient number of cases included to support the objectives of the study. The influence of LAM avulsion on the ARA was established, which may indicate that in the future, the LAM should be studied in clinical cases of anal incontinence.

However, we think the authors should be acknowledged for their work. In fact, they correctly addressed an important topic, the methods sound good and their discussion is well balanced.

One additional little flaw: the authors could better explain the limitations of their work, in the last part of the Discussion.

We believe this article is suitable for publication in the journal although some revisions are needed. The main strengths of this paper are that it addresses an interesting and very timely question and provides a clear answer, with some limitations.

Re: This information has been included in the text.

Text: The main strengths of this paper are that it addresses an interesting and very timely question and provides a clear answer, with a sufficient number of cases included to support the objectives of the study. The influence of LAM avulsion on the ARA was established, which may indicate that in the future, the LAM should be studied in clinical cases of anal incontinence. The imaging technique used (transperineal ultrasound) for the study of the ARA may be a limitation, since most studies that define the ARA are performed with defecography or MRI (17-22). Nevertheless, ultrasound has been previously shown to be comparable to defecography for the study of the ARA (28). Currently, the intraobserver and interobserver variability for ARA measurement by transperitoneal ultrasound remains undescribed, which presents an opportunity for possible future publications.

We suggest a linguistic revision. Moreover, the authors should better clarify some points.

Re: The manuscript has been re-edited.

Reviewer 3 Report

Introduction

You may consider adding an anatomical illustration.

Line 50 ref 5, 10-35% of women. I read it is the most cited paper about LAM avulsion after childbirth, do you think you can add also newer references supporting this data?

Ultrasound assessment

Subjects

Symptoms? Why do these patients perform US?

83-84, the mode acquisition was described in previous studies… Please rewrite, for readers, it’s better if you describe the mode instead to invite them to read another article.

88 levator-urethra gap (ref 16), Please describe the qualitative criteria.

You may consider adding a normal exam (rest, Valsalva, max contrac.) images with measurements.

Figure 1, please describe as you see images, first left and then right or invert them

Images are blurry (scan artifact of too magnify?), can you improve them?Also the green asterix is not readable and you have to cite in the legend.

Results

Is there any clinical difference between patients with bilateral LAM avulsion and unilateral?

I cannot understand the clinical impact, that I think you should improve.

On the other hand, you are proposing transperineal ultrasound to assess ARA, that is very interesting. You may consider underlining this concept also in the title, f.e. The role of transperineal ultrasound in….

Author Response

Reviewer 3:

Introduction

You may consider adding an anatomical illustration.

Re: A reference for Figure 1 has been included as you have suggested.

Text: The ARA is the angle demarcating the junction between the rectum and the anal canal, which is produced by the puborectalis muscle (a component of the levator ani) to form a sling around this level, creating a soft posterior rectal impression demarcating this anorectal junction (2) (FIGURE 1).

Line 50 ref 5, 10-35% of women. I read it is the most cited paper about LAM avulsion after childbirth, do you think you can add also newer references supporting this data?

Re: Another reference (Ref. 6) has been added to the text that you have indicated.

Text: On the other hand, childbirth is also the main risk factor for levator ani muscle (LAM) avulsion, which is present in 10-35% of women after a vaginal delivery (5,6), with instrumental vaginal delivery being the main risk factor (6).

Ultrasound assessment

Subjects

Symptoms? Why do these patients perform US?

Re: The patients were asymptomatic. The ultrasound control was performed because they belonged to studies analyzing LAM avulsion after childbirth.

Text:

In these studies, LAM avulsion during operative vaginal delivery (10,11) and the changes that occur after physical therapy in patients with LAM avulsion (9) were studied.

… Subjects with dyssynergia, anismus, fecal incontinence or anal prolapse were not included.

83-84, the mode acquisition was described in previous studies… Please rewrite, for readers, it’s better if you describe the mode instead to invite them to read another article.

Re: This information has been included in the text.

Text: The mode of acquisition and offline analysis of volumes have been described in previous studies (13); the volumes were acquired in the midsagittal plane of the pelvic floor with the woman in the lithotomy position after voiding.

88 levator-urethra gap (ref 16), Please describe the qualitative criteria.

Re: This information has been included in the text.

Text: Complete avulsion was diagnosed when abnormal insertion of the LAM (LAM detachment) was observed in 3 central slices. In unclear cases, a levator–urethra gap >2.5 cm was used to define abnormal insertion (16).

You may consider adding a normal exam (rest, Valsalva, max contrac.) images with measurements.

Figure 1, please describe as you see images, first left and then right or invert them

Images are blurry (scan artifact of too magnify?), can you improve them?Also the green asterix is not readable and you have to cite in the legend.

Re: The image has been changed as you have suggested.

Results

Is there any clinical difference between patients with bilateral LAM avulsion and unilateral?

Re: No clinical difference was note in any of the patients. They were all asymptomatic. The differences identified were in the ARA.

Text: The ARA was higher in patients with bilateral LAM avulsion than in patients with unilateral LAM avulsion at rest (129.4±12.5 vs. 136.2±13.8), in Valsalva (127.9±13.5 vs. 136.5±14.4) and at maximum contraction (130.2±13.5 vs. 132.3±13.2). The differences were statistically significant when studying the ARA at rest and in Valsalva, and the ORs adjusted for maternal age were 1.044 (95 % CI, 1.003-1.088; P=0.037) and 1.052 (95 % CI, 1.010-1.096; P=0.014), respectively.

I cannot understand the clinical impact, that I think you should improve.

Re: This information has been included in the text.

Text: The main strengths of this paper are that it addresses an interesting and very timely question and provides a clear answer, with a sufficient number of cases included to support the objectives of the study. The influence of LAM avulsion on the ARA was established, which may indicate that in the future, the LAM should be studied in clinical cases of anal incontinence.

On the other hand, you are proposing transperineal ultrasound to assess ARA, that is very interesting. You may consider underlining this concept also in the title, f.e. The role of transperineal ultrasound in….

Re: The title has been changed as you suggested.

Text: The role of transperineal ultrasound for the assessment of the anorectal angle and its relationship with levator ani muscle avulsion

Round 2

Reviewer 2 Report

Acceptance.