Underactive bladder (UAB) in children is a voiding dysfunction characterized by impaired detrusor contractility, leading to incomplete bladder emptying, elevated postvoid residual (PVR) urine volumes, and associated complications such as urinary tract infections. While clean intermittent catheterization (CIC) is commonly used. To the best of our knowledge, there are few similar study that evaluates effects of TPTNS in management of UAB in children. To evaluate the effectiveness of TPTNS in improving bladder function in pediatric patients with UAB who failed conservative management.

This retrospective, non-randomized observational study included 52 pediatric patients with UAB treated with TPTNS between 2013 and 2022. Patients underwent 12 weekly sessions of TPTNS, and outcomes were assessed using bladder diary, urodynamic study, and PVR measurement. Patients with recent bladder surgery, pelvic floor interventions, or active infections were excluded.

Patients were divided into neurogenic and non neurogenic groups. In the nonneurogenic group, TPTNS significantly reduced PVR (248 mL to 84 mL, p < 0.0001) and CIC frequency (6 to 2.4 times/day, p < 0.001). Night-time incontinence episodes also decreased significantly. In terms of urodynamic parameters it showed improvement although not statistically significant.  However, minimal improvements were also observed in the neurogenic group, with no significant changes in spontaneous voiding or voided volume for either group.

Incontinence significantly decreased in non-neurogenic children after TPTNS, while neurogenic patients showed minimal changes. Improvements in PVR and CIC frequency were notable in the non-neurogenic group. Voided volume and urodynamic parameters showed limited impact. Non-neurogenic patients likely benefited more from TPTNS due to the presence of functional sacral nerve pathways, enabling better neuromodulation effects. While other studies have noted significant outcomes with techniques like sacral neuromodulation (SNM) or intravesical electrical stimulation (IFES), this study suggests TPTNS may be less effective for neurogenic UAB due to compromised sacral pathways. Despite promising results in nonneurogenic cases, the study has several limitations. A small sample size of 52 patients, lack of a control group, and short follow-up duration (2 years) limit statistical power and long-term assessments.

While TPTNS shows potential as a non-pharmacological treatment for improving bladder function in children with UAB, particularly in reducing PVR, night-time incontinence and frequency of CIC, further studies with larger sample sizes, long-term follow-up, and control groups are needed to confirm its efficacy and determine the optimal patient populations for this therapy.