Sir,

We thank Drs. Hsin-Yi, Chin-Ru and Cheng-Yu for their interest in our recent paper about pelvic organ prolapse and detrusor underactivity (DU) published in this journal [1]. In their letter to the editor, the authors highlighted the importance of postoperative urodynamic evaluations to evaluate the impact of prolapse surgery on detrusor underactivity.

We are in complete agreement with their observation. We confirm that only urodynamic study is capable of assessing the postoperative bladder contractility index, post-void residual and maximum cystometric capacity and the subsequent prevalence of detrusor underactivity.

However, the primary aim of this study was to evaluate the prevalence of DU in a cohort of patients with POP and its association with symptoms, anatomy and urodynamic findings for the first time. We were able to demonstrate a high prevalence (40.9%) of detrusor underactivity in patients with prolapse. The presence of detrusor underactivity was directly related to the presence of voiding symptoms and inversely related to referral for urge incontinence. Moreover, detrusor underactivity was associated with more severe cystocele. On preoperative urodynamic evaluation, detrusor underactivity was associated with a higher postvoid residual.

Postoperative evaluation was only conducted as a secondary outcome. We agree that it was flawed by the absence of routine postoperative urodynamics, and this limitation was acknowledged in the article. We found that after surgical repair, voiding symptoms became equal between DU and non-DU patients. Based on this finding, we suggested that DU may not be an irreversible mechanism in these patients. Nevertheless, without postoperative urodynamic evaluation, it is not possible to draw any conclusion. Still, we wanted to report this preliminary finding to take the first step and draw the attention of clinicians and researchers to this neglected topic.

This is why we appreciated your letter, because we do think that we have achieved our purpose. With time and high-quality studies, the relationship among pelvic organ prolapse, surgical repair and detrusor underactivity should become more clear. Still, now a stone has been cast into the pond.