Letter to “Risk Factors for de Novo Postoperative Urinary Retention in Posterior Lumbar Spine Surgery”

To the Editor,

We read with great interest the recent article by Nakajima et al. investigating predictors of de novo postoperative urinary retention (POUR) following lumbar decompression surgery for lumbar spinal canal stenosis (LSCS). ¹ The authors should be congratulated for addressing this often under-recognized yet clinically significant complication and for identifying Cobb angle, ventral or dorsal compression of the dura mater, and curve-type cauda equina morphology as independent radiographic risk factors.

We would like to highlight several areas of interest and offer suggestions for further clarification. First, the study defines POUR as urinary retention persisting for at least one week post-catheter removal. While this helps exclude transient postoperative voiding dysfunction, it may lead to underestimation of clinically relevant short-term retention. Could the authors elaborate on the rationale behind this threshold, and whether patients with brief but symptomatic POUR (e.g., <7 days) were analyzed separately?

Second, the identification of curve-type dural compression and non-midline (ventral/dorsal) stenosis morphology as key predictors is highly informative. However, these morphologies may reflect underlying differences in neural mobility or decompression dynamics. Have the authors considered whether intraoperative neuromonitoring or advanced imaging (e.g., cine MRI ² )could provide further insight into dynamic neural flow impairment?

Third, it is noteworthy that factors traditionally associated with POUR, such as sex, comorbidities (for example, diabetes and benign prostatic hyperplasia), or intraoperative fluid volume, were not significant in this cohort. This raises an important question: could the specific exclusion of patients with perioperative complications have biased the identification of systemic vs local anatomical risk factors?

Lastly, considering that nearly half of patients with de novo POUR had not recovered by 3 months postoperatively, greater emphasis should be placed on effective postoperative treatment and management. It would be helpful if the authors could clarify whether specific measures such as early bladder training, use of medications like alpha-blockers or cholinergic agents, ³ or standardized intermittent catheterization protocols were applied, and whether these influenced recovery. Future studies exploring structured rehabilitation programs or neuromodulation techniques, such as sacral nerve stimulation, ⁴ may help promote earlier bladder function recovery and reduce long-term complications.

In conclusion, this study makes a valuable contribution to the spine literature by highlighting preoperative imaging features as key predictors of de novo POUR. Future prospective studies validating these findings across institutions and surgical techniques would be highly beneficial.