Title: A modified surgical approach to women with obstetric anal sphincter tears

Transcription

1 Reviewer's report Title: A modified surgical approach to women with obstetric anal sphincter tears Version: 3 Date: 27 January 2010 Reviewer: Stig S Norderval Reviewer's report: Review on manuscript entitled: A modified surgical approach to women with obstetric anal sphincter tears General comments: Anal incontinence is common after primary repair of obstetric anal sphincter injuries (OASI). There are many studies addressing this problem, and even some randomized studies comparing different mode of repairs. Repairing a torn internal anal sphincter (IAS) when injured has also been described in several studies (see below). The strength of the present study is that it has a fair long follow-up time (at least one year). Furthermore it shows an incidence reduction of incontinence following the change in the treatment. However, as the authors mention, it is not possible to identify a single factor responsible for this improvement. It may be due to selection of the two experienced and interested surgeons, to the method of repair, better peri-operative conditions (improved assistance, anaesthesia) or a combination of these factors. It is nevertheless important to document that the results after OASI can be improved! The main problem with the study is the number of included women in the study group; why 26? You state that this is a pilot study in advance of a randomized trial. Nevertheless the defined aim of the present study is to find out if an impaired technique will significantly improve outcome compared with another technique. As long as this is the defined aim, a power calculation should have been performed prior to the inclusion of patients, based on the incidence of incontinence following the old way of repair and the anticipated incidence following the new technique. If such a power calculation was not performed, you would be at a risk of not being able to identify a difference although present (type 2 error). Now, you found a significant difference between the groups, but this seems to be due to luck and not to a good study design! If no power calculation was performed, you should stress that your study is a pilot with the aim to obtain low incidence of incontinence. The next problem is the categorisation of incontinence. You state correctly that it is difficult to compare the results from different study. Unfortunately, the present study itself is a good example why!

2 While most studies on this topic published in international journals the last 10 years have classified incontinence according to scoring systems where symptoms occurring less frequent than once a week are recorded (especially Wexner score or St Mark s score), you have chosen to record only symptoms present once a week or more often. This has several implications: First, when a woman who experiences leakage episodes once or twice a month, she might check the box never as likely as the box once a week. Hence, your real incidence of women with symptoms could be higher than reported. Second, the score used does not take into consideration gas incontinence occurring once a week. This means that women with Wexner score or St Mark s score 1 or 2 is not counted. You define incontinence present not before symptoms corresponds to Wexner score or St Mark s score 3! We know that women with mild (but new) symptoms following primary repair of OASI represent a substantial part. Excluding this group makes your result look good. In fact, they are quite average. In a study where a similar operating technique was used, the authors report only 15% with symptoms if your classifications had been used (se below). It is therefore essential that you clearly report the number of women with symptoms. Doing so, incontinence was reported by 38.5% in the study group, by 39% in the vaginal delivery control group, and by 65.8% in the sphincter group. The reference list is clearly deficient. In the introduction page 3 you state that: the overlap procedure has been advocated, neither approach has been shown to be better than the other. This statement should be followed by references. Later on you refer to a randomised study (Fernando R et al); showing better outcome after overlap vs end-to-end repair of the external anal sphincter (EAS). There exists at least 4 randomised trials comparing end-to-end primary repair with overlap repair of the EAS, and 3 of them include separate repair of the internal sphincter when injured (ref 1-3). The results form these studies are diverting. Another case control study (like your own) (Ref 4) shows beneficial outcome in the overlap group. Furthermore, a study reporting the results in 71 women after end-to-end repair of the EAS combined with separate repair of IAS when injured (quite similar to your technique) was published some years ago (ref 5). These studies should be mentioned. 1 A randomized clinical trial comparing primary overlap with approximation repair of third-degree obstetric tears. Fitzpatrick M, Behan M, O'Connell PR, O'Herlihy C. Am J Obstet Gynecol Nov;183(5): How to repair an anal sphincter injury after vaginal delivery: results of a randomised controlled trial. Williams A, Adams EJ, Tincello DG, Alfirevic Z, Walkinshaw SA, Richmond DH. BJOG Feb;113(2): Primary repair of obstetric anal sphincter laceration: a randomized trial of two surgical techniques.

3 Garcia V, Rogers RG, Kim SS, Hall RJ, Kammerer-Doak DN. Am J Obstet Gynecol May;192(5): Overlap technique improves results of primary surgery after obstetric anal sphincter tear. Lepistö A, Pinta T, Kylänpää ML, Halmesmäki E, Väyrynen T, Sariola A, Stefanovic V, Aitokallio-Tallberg A, Ulander VM, Molander P, Luukkonen P. Dis Colon Rectum Apr;51(4): Epub 2008 Jan Anal incontinence after obstetric sphincter tears: outcome of anatomic primary repairs. Norderval S, Oian P, Revhaug A, Vonen B. Dis Colon Rectum May;48(5): Specific comments: Heading: Should state more precisely the most important element of the technique. Background: Page 3, phrase 1: The incidence of AST varies considerably, wit a clear rise in the Scandinavian countries over the last 20 years, but not in Finland. You should emphasise the Swedish incidence. Furthermore, mediolateral episiotomy has, as far as I know, not been shown to affect the OASI incidence rate in any direction. Phrase 2: Please refer to the randomised trials as mentioned abow, What do you mean with the profound part of the EAS? Is it the proximal part? If so, this is the part of the EAS most likely to be injured in any case (based on several ultrasound studies). Phrase 3: It might be of interest to mention that separate repair of the IAS and EAS is the standard method for secondary reconstruction in women with incontinence after OASI! Methods: Page 5, number 4: Move the background information to the discussion chapter. Page 6: Last phrase: nulliparous is wrong, and the sentence is OK when the word is deleted. Results: Regarding presentation of incontinence symptoms, se comments above.

4 Page 9: Should be rephrased to: and the last woman had a left mediolateral episiotomy.. What about dyspareunia? In table 3 it is shown that 50% experienced this in the study group compared to 28.6% in the control sphincter group. This finding is significant and should be discussed. Might it be du to your extensive exposition during surgery? Discussion: Page 10, second phrase: The reason to perform overlap sphincteroplasy in secondary repair is not because it is difficult to identify the IAS. The IAS us usually repaired separately when defect. Short-term outcome after overlap repair has been shown beneficial. The somewhat disappointing long-term result after secondary reconstruction is not believed to be due to the overlap, but to other long-term changes (ex. general loss of muscle mass and hormonal changes). Page 11, first phrase: The correlation between sphincter length and symptoms is shown in Ref 5 above. Second phrase: Did your new technique involve levatoroplasty in any way? If so, please describe under methods Table 3: Many of the numbers in the columns for control group and control AST group are incorrect. I.e.: the sum is sometimes not equal to the number of patients in the two groups. Were some data not available for all women? Please correct. Please change experience to experience A last question without the scoop of this review: How do you plan to perform a randomised study comparing the presented technique with the old technique where the IAS was not repaired intentionally? Once the obstetrician has learned to identify a torn IAS she will most likely not leave the IAS torn? There is a correlation between defects at EAUS after primary repair and symptoms (also shown by your own Marianne Starck) supporting the importance of an exact primary repair. I just wondered. With best regards Conclusion: reconsider after major revision. Level of interest: An article whose findings are important to those with closely

5 related research interests Quality of written English: Acceptable Statistical review: No, the manuscript does not need to be seen by a statistician. Declaration of competing interests: I declare that I have no competing interests