Authors' Reply to "Comments on 'Association Between Urinary Stress Incontinence and Levator Avulsion Detected by 3D Transperineal Ultrasound'".

Abstract

We would like to thank the authors for the comments on our study [1], in which they expressed several concerns regarding terminology and the incidence rate of urinary stress incontinence in our nation. The following is our reply. First, with regard to the use of the term “USI”, we clearly stated in line 11 in the second paragraph of our study that “USI” was defined as urinary stress incontinence, which means it was used in this study as the abbreviation for the diagnosis of urinary stress incontinence, not “urodynamic stress continence”. In most recent studies, urodynamic investigations (UDS) are no longer the first and necessary tests for the diagnosis of urinary stress incontinence [2, 3, 4]. Moreover, the decline in the routine use of UDS is due to its invasive nature and high cost as stated in most recommendations by international guideline groups [3, 4]. Instead, the cough test, which in our study was presented as a “simple stress test” (in line 5, paragraph 4, section “materials and methods-3/4 D ultrasound image acquisition and clinical evaluation”), was verified as the best performing test with a sensitivity of 83% and specificity of 90% and best correlated with UDS findings [5]. Also, patients in our study who reported isolated symptoms and cases that were unclear underwent a urodynamic test to confirm the diagnosis (in line 5, paragraph 4, section “materials and methods-3/4 D ultrasound image acquisition and clinical evaluation”). In a word, patients in our study who were diagnosed with urinary stress incontinence were confirmed by symptoms, cough test, and UDS (if necessary), which means the object of study was reliable. Second, with regard to a repeatable test, we mentioned more than once in the section “materials and methods-3/4 D ultrasound image acquisition and clinical evaluation” that all collected data were acquired and measured more than 3 times (line 3, the second paragraph of this section& line 1, the third paragraph of this section). With regard to the figure legends, thank you for pointing out the mistakes in the legends. In the process of revising this article, figure 2 and figure 3 were added in the revised version, and the position of figure 3 and figure 4 were reversed, which may have resulted in the errors regarding one-to-one correspondence. The corrections of the figure legends are as follows: Figure 3 Measurement of hiatal area on pelvic floor muscle at rest in patient without avulsion of puborectalis muscle A, and on Valsalva B in patient with right-sided avulsion. Oblique axial plane in plane of minimal hiatal dimensions. Figure 4 Measurement of the levatorurethra gap (LUG) using tomographic ultrasound technique in a woman without levator avulsion. Figure 5 Measurement of levator-urethra gap (LUG) on tomographic ultrasound imaging in patients with right side A and left side B avulsion. We do not agree with the assessment of figure 6 in the authors’ letter. In this study, levator avulsion was diagnosed with LUG> 25mm (line 12, paragraph 2, in the section “3/4D ultrasonic image acquisition and clinical evaluation”) [6], and the LUG result confirmed that it showed bilateral avulsion of the levator ani in figure 6, regardless of whether it was partial or full avulsion. Third, with regard to sample selection bias, the authors of the letter figured out that pelvic organ prolapse was accompanied by levator avulsion in 38.9 % of Chinese women. This means that levator avulsion is the most common accompanying symptom in women diagnosed with POP, and it was confirmed by most of the literature that levator avulsion is a risk factor of POP [7, 8, 9, 10, 11, 12], which we also clearly mentioned in the article (line 5line 10, paragraph 1, in the section of discussion). However, this evidence about the prevalence of levator avulsion in Chinese women proved to be useless and the question of a higher incidence rate of levator avulsion in non-POP women was confused because there was no evidence showing that the rate was lower in the non-POP group. According to the strict inclusion and exclusion criteria, we excluded women diagnosed with pelvic floor dysfunction. In order to conduct a specific evaluation of isolated urinary stress incontinence, women complaining of symptoms of urinary urgency incontinence or prior pelvic organ prolapse were also excluded (in the section “materials and methodspatient population”, paragraph 1, line 11line 14). Moreover, more than 60 % of women recruited for our study had episiotomy surgery during delivery, which means the incidence of levator avulsion was predictably high. This may be related to the fundamental realities in our country regarding the prevalence of episiotomy in the 1980 s to 1990 s. Most of the literature showed a prevalence of levator avulsion of greater than 20 % after the first delivery, e. g. 21.8 % in Symphorosa SC Chan group [13] and 27.5 %–35.2 % in Youssef A group [14]. This evidence means that the prevalence of levator avulsion in our study is reasonable. Finally, with regard to the prevalence of urinary stress incontinence, this is uncertain in most studies. It depends on symptom tolerance and consultation rate of patients. The literature showed an incidence rate of 10–77% [15, 16, 17, 18, 19, 20]. Nearly 50 % of adult women may experience urinary incontinence, with 10 % to 20% of all women and up to 77% of elderly women residing in nursing homes being affected [21]. It should be noted that this was a single-center prospective study, with 3,130 patients being admitted to our center for physical examination or regular postpartum follow-up not because of lower urinary tract symptoms (LUTS). Patients with POP were excluded from this study in order to exclude an interference factor, which also may have lowered the prevalence rate because some urinary stress incontinence was accompanied by POP. In conclusion, we would like to thank the authors of the letter who pointed out the error in the figure legends. Their questions also make our study more interesting and meaningful. However, all of their questions can be answered by our article or by other publications. If they read our article and other excellent recent publicaLetter to the Editor