Comparison of a New Non-invasive Device With the Invasive Gold-standard Investigation to Assess Function of the Large Bowel in Children

The goal of this clinical trial is to learn if the new non-invasive device (Body Surface Colonic Mapping) works to accurately assess colonic movement and function in children.The main questions it aims to answer are: * Are Body Surface Colonic Mapping (BSCM) recordings comparable with gold-standard colonic manometry recordings (HRCM - High Resolution Colonic Manometry) in the paediatric population? * What are the effects of bowel preparation on colonic function assessed using BSCM? Children with clinical recommendation of colonic and/or anorectal manometry (clinical tests used to assess colonic function) for investigation of persistent bowel dysfunction symptoms will be invited to participate. We will perform and compare simultaneous recordings of manometry and BSCM in children, in order to demonstrate same colonic function measurements recorded by the two devices in this population. Eligible participants who consent to inclusion in the study will undergo colonoscopy and placement of a large bowel catheter, according to usual Royal Children's Hospital (RCH) practice. These involve administration of oral laxatives for bowel preparation and maintaining a clear fluids diet 24 hours prior to the investigation. Ahead of the simultaneous devices recordings, patients will also be invited to attend the hospital 2-4 weeks prior to have non-invasive BSCM recording only. The aim of this part of the study is to have a BSCM recording in the same patient once with the "physiological state" colon (early hospital visit without any bowel preparation administration) and once with the "non-physiological state" colon (time of colonoscopy, colonic manometry and BSCM with bowel preparation).

Inclusion Criteria: 1. Is aged 18 years or less at enrolment. 2. Has undergone a repeat rectal biopsy to exclude a retained segment of aganglionic colon (Hischsprung disease (HD) cohort only). Exclusion Criteria: 1. Has undergone primary surgical repair of HD or (anorectal malformation (ARM) within 12 months of the study. Is less than twelve months following primary surgical correction of HD or ARM (HD or ARM cohorts only). 2. Has a prior diagnosis of: i. Intellectual disability or a spinal abnormality, such that continence is unlikely to be attainable; ii. Malignant (cancer) conditions, receiving chemotherapy; iii. GMFCS IV or V. 3. Is unable to attend for and/or engage in consent process or assessments, including due to language restriction.