Several transabdominal electrical stimulation studies have been reported for constipation in childhood. This study aims to assess the efficacy of this technique in adults with chronic constipation and compare two different electrical therapies.

Patients with Rome III defined constipation unresponsive to medical and behavioural treatment will be randomised in a double-blind prospective trial to receive either four weeks of transabdominal electrical stimulation (TENS) or Interferential stimulation (IFC). Treatment will be self-administered at home for sixty minutes a day. The response to treatment will be assessed with the Patient Assessment of Constipation Quality of Life questionnaire (PAC-QOL), the Patient-Assessment of Constipation Symptoms (PAC-SYM) tool and a bowel visual analogue scale (VAS). A bowel diary will be kept a week before and during the final week of stimulation, recording daily bowel frequency.

IFC stimulation is an effective, cheap and low risk intervention which has demonstrated efficacy for dysphagia, urinary incontinence, overactive bladder syndromes and chronic pain. The precise mechanism of its analgesic and pro-kinetic effect is unknown. The intervention is delivered by two separate continuous alternating electrical currents. Two pairs of pad electrodes are arranged in a quadripolar manner where each pair delivers a different frequency of current. It is suggested that this arrangement of stimulation improves colonic propagation. However as direct massage of the abdomen has demonstrated benefit in constipation it is argued that IFC is not a specific requirement and that non-IFC electrical stimulation over the abdomen is sufficient to evoke the same colonic and clinical responses. Owing to these questions the efficacy of this intervention will be further evaluated in adults.

This study has two aims. The primary aim is to evaluate the effectiveness of transabdominal electrical nerve stimulation (TENS) in adult patients with chronic constipation. The secondary aim is to establish whether IFC was superior to non-IFC (TENS) electrical stimulation in adults with chronic constipation.

Inclusion Criteria:

• Age over 18 years
• Rome III defined constipation (frequency of defecation of less than three times a week, straining or sense of incomplete emptying associated with at least 25% of defecations. Lumpy, hard stools or anal digitation for at least 25% of defecations
• Failed Biofeedback
• Competent and willing to complete stimulation at home
• Competent and willing to complete the questionnaires and bowel diaries

Exclusion Criteria:

• Rectal prolapse
• Active inflammatory bowel disease
• Pregnancy or intention to become pregnant during trial
• Spinal cord injuries/cauda equina syndrome
• Other implanted electrical devices
• Allergy to device components
• Neurological disorders