The ReVo Study: Low-volume vs High-volume Rectal Irrigation

Rectal irrigation, which is the introduction of warm tap water through the anal canal into the rectum to initiate defaecation, is recommended to be considered in patients with chronic constipation, which is refractory to conservative measures such as lifestyle modification, laxatives, nurse-led bowel retraining programmes which focuses on bio-feedback as well as psychosocial support. Two systems of rectal irrigation are available based on volume delivered, low and high volume. It is unknown if one type of irrigation is superior to the other and whether one type has better outcomes in patients with a particular pathology. Therefore, a comparison is required between the two types of irrigation to assess their acceptability as a therapy and response rates in patients with chronic constipation secondary to difficulty emptying rectum. This trial/research aims to compare low-volume rectal irrigation with high-volume rectal irrigation in patients with chronic constipation secondary to disorders of difficulty emptying rectum. The main questions it aims to answer are: * if one type of rectal irrigation is superior to the other * whether one type of rectal irrigation has better outcomes in patients with a particular pathology on pelvic floor ultrasound * assess the acceptability and response rates to rectal irrigation. Participants upon recruitment will be allocated to either low-volume rectal irrigation or high volume rectal irrigation groups. This will purely be by chance where the possibility of being in either of the groups will be 50%. They will then undergo a baseline assessment with four quality-of-life questionnaires and clinical examination. Following this a pelvic floor ultrasound will be performed to assess the cause of their symptoms. Lastly they will be provided training on using rectal irrigation (the type they have been assigned to). They will then be asked to commence irrigation at home from the next day. Participants will continue to use irrigation for