Constipation in children is a common problem. Managing these children is difficult, partly because they do not respond to laxatives and partly because their bowel problem cannot be defined. A "gut transit time" test can add information to help choose the best therapy but this is often not carried out because of the unsuitable radiation dose involved in the current methods such as X-ray. A new Magnetic Resonance Imaging (MRI) method to measure gut transit time using inert mini-capsules, the size of small pine nuts, has recently been developed.

This study is the first feasibility test of the new mini-capsules in paediatric constipation. 25 patients and 25 healthy controls will participate. The study will measure gut transit time using MRI and the mini-capsules before and after the young patients receive standard treatment.

One in ten children worldwide has constipation and it becomes chronic in 30% of these children, affecting their and their families' well-being. Managing these children is difficult, partly because they do not respond to laxatives and partly because their bowel problem cannot be defined. If the doctors could send the children for a quick test that indicates the time that food takes to travel through the gut (the "gut transit time"), they could use this information to help choose the best therapy, for example to decide if a patient needs surgery. The test could also be used to follow up the effects of different treatments. Gut transit time is often not tested due to the unsuitable radiation dose involved in the current methods such as X-ray. Doctors' decisions have to rely mostly on symptoms, leading to repeated appointments, frustration and a waste of NHS money.

A new method to measure gut transit time using mini-capsules, the size of small pine nuts, has recently been developed. The mini-capsules are swallowed but do not dissolve and their journey through the gut is imaged using Magnetic Resonance Imaging (MRI). From the images doctors can determine the gut transit time. MRI is harmless and can be used repeatedly to follow up the response to treatment.

This study will test these new mini-capsules to determine their suitability for paediatric use. Areas of interest are ease of imaging in the gut using MRI and whether they are small enough such that their emptying from the stomach and transit through the gut are similar to food. The study will test the mini-capsules in children with constipation, to measure gut transit time before and after they receive their usual treatment from their doctors. This will assess if the mini-capsules can detect changes in treatment and will make them clinically useful.

Inclusion Criteria:

• Aged 7 - 18 years old
• Male or female
• Able to give assent or have a parent able to give informed consent
• Willing to allow their GP or consultant, if appropriate, to be notified of participation in the clinical investigation
• Presenting with intractable constipation at secondary or tertiary care and considered for possible treatment which may include new drugs or procedures (Group1 only)
• Healthy bowel habit and does not suffer from constipation or diarrhoea (Group 2 only)

Exclusion Criteria:

• Female participants who are pregnant, lactating or planning pregnancy during the course of the investigation.
• Any history of gastrointestinal surgery such as colectomy or small bowel resection.
• Existing ACE procedure before the first MRI scan (Group 1 only)
• Significant renal or hepatic impairment
• Contraindications for MRI scanning such as metallic implants and penetrating eye injury.
• Inability to lie flat and relatively still for less than 5 minutes
• Poor understanding of English language
• Any other significant disease or disorder (other than intractable constipation for Group 1)
• Participation in another research clinical investigation involving an investigational product in the past 12 weeks.