The Effects of TTNS, TTNS Combined With PHUS, and Conventional Therapy With PHUS in the Treatment of PFC.

This study is a randomized, controlled trial designed to evaluate the effects of transcutaneous tibial nerve stimulation (TTNS), TTNS combined with pocket-sized handheld ultrasound (PHUS), and conventional therapy with PHUS on children with functional constipation (FC). Participants will be stratified into three intervention arms (n=20 per group). FC will be defined based on the Rome IV diagnostic criteria, in the absence of organic or anatomical causes. Participants will be between 4 and 14 years old and will have experienced failure of conservative treatment for at least three months prior to enrollment. The primary outcomes include changes in rectal ultrasound parameters and symptom severity scores. Ultrasound assessments will be conducted by trained clinicians using standardized protocols. Monitoring for adverse events will be performed throughout the intervention phase. Safety considerations include predefined exclusion criteria, such as underlying neurological, metabolic, or cardiac conditions.

Inclusion Criteria Children aged 4 to 14 years Clinical diagnosis of functional constipation (FC), with no identifiable organic or anatomical cause (e.g., endocrine, metabolic, anatomical, or neuromuscular dysfunction) FC diagnosis established according to Rome IV criteria No additional tests required to confirm eligibility Ability to complete daily diaries and TTNS sessions (by participant or caregiver) Failure of conservative medical treatment (including toilet training and laxatives) after at least three months Exclusion Criteria Malformations of the digestive system and rectal anatomical anomalies (e.g., large intestinal atresia/stenosis, Hirschsprung's disease, congenital anorectal anomalies) Neurological or psychiatric disorders (e.g., cerebral palsy, spina bifida, intellectual disability, anorexia nervosa) Major cognitive impairment Metabolic conditions (e.g., diabetes mellitus, diabetes insipidus, scurvy, phenylketonuria) Endocrine disorders (e.g., hypothyroidism) Cardiac conditions (e.g., heart disease, arrhythmias, presence of pacemaker or ventriculoperitoneal shunt) due to possible interference with electrical stimulation History of thoracic or abdominal surgery Presence of skin lesions in the area of electrode application Presence of active electronic implants