Lara brings her 4 year old son Toby to the GP as she is concerned he has had little response to 1 sachet twice daily of Movicol which was prescribed 5 days ago for constipation. She admits he has a poor diet and drinks little fluids whilst at school. He last opened his bowels 5 days ago and usually opens his bowels every 2-3 days. Today he has soiled his underwear which has prompted her to make the appointment.
On examination today his observations are normal and you palpate a mass in the left lower quadrant.
What is the most appropriate next step in management?