Inclusion Criteria:  Children aged 7 - 18 years old Able to give assent/consent or have a parent/carer able to give informed consent Willing to allow his or her General Practitioner and consultant, if appropriate, to be notified of participation in the clinical investigation.  Children diagnosed with clinical diagnosis of constipation  Exclusion Criteria:  The participant may not enter the clinical investigation if ANY of the following apply:  Female participants who are pregnant, lactating or planning pregnancy during the course of the clinical investigation. This will be self-reported.  Any history of gastrointestinal surgery that could affect gastrointestinal function, such as colectomy or small bowel resection.  Existing ACE procedure before the first MRI scan. Contraindications for MRI scanning i.e. metallic implants, pacemakers, history of metallic foreign body in eye(s) and penetrating eye injury.  Inability to lie flat and relatively still for less than 5 minutes Poor understanding of English language Current diagnosis of COVID 19. The following disease or disorder; Bowel Stricture disease, Crohn's or any difficulty in swallowing (Dysphagia) Hirschsprung disease, congenital anorectal malformations, Paediatric Pseudo-obstruction syndrome  Currently using the following drugs influencing motility:  Opioid analgesics (tramadol, morphine, fentanyl, oxycodone, co-codamol and codydramoland) Antispasmodic Buscopan (hyoscine butylbromide, also known as scopolamine butylbromide) Participants who have participated in another research clinical investigation involving an investigational product in the past 12 weeks.  4 or more bowel movements in one week and no episodes of bowel incontinence in one week (if these are reported in the participant's medical notes. Absence of this information should not warrant exclusion)