Colonoscopy is a stressful and unpleasant procedure especially during the passage of the endoscope through angulations of colon. Electro-acupuncture is one of the alternative to reduce colorectal discomfort. However acupuncture is invasive. This present study explored the effectiveness of a non-invasive treatment modality, Transcutaneous Electrical Nerve Stimulation over Acupuncture points in reduction of colorectal discomfort during barostat-induced rectal distension.

Early colonoscopy screening is encouraged in prevention of development of colorectal cancer as the colonoscopy procedure allows removal of pathological polyps and reduces the risk of cancerous development. While colonoscopy is regarded a minimally invasive procedure, the procedure itself is often associated with abdominal pain and discomfort, especially when the colonoscope is passed through a colonic angulation. The unpleasant feeling during colonoscopy may affect the patient's overall tolerance to the procedure and thereby jeopardizing the accuracy of outcome findings. A combination of narcotic analgesia and benzodiazepines is often used to decrease the abdominal pain and colorectal discomfort during colonoscopy. However these medications are also associated with side effects such as nausea and vomiting. Although uncommon, respiratory and cardiac arrests during colonoscopy were reported. Colonoscopy is now an outpatient day-procedure, unwanted side effects however could prolong recovery time and increase demands of post-intervention nursing care, thereby affecting the cost-effectiveness of the medical model. Undesirable pharmacological side effects have recently led to exploration of alternative management strategies to minimize patient discomfort during colonoscopy.

Electroacupuncture (EA) is widely accepted in China and is considered worldwide a possible treatment option for acute and chronic pain of various origins. The role of acupuncture in managing pain and anxiety during colonoscopy however is unclear. A randomized sham-controlled study (involving 30 patients) suggested that patients receiving EA to acupoints including Zusanli (stomach meridian ST-36) and Hegu (large intestine meridian LI-4) had lower pain level during colonoscopy than those receiving sham acupuncture (SA), but the difference was non-significant statistically. Recently the investigators have shown that application of 45 minutes of EA to Hegu (LI4), Neiguan (PC6) and Zusanli (ST36) was able to effectively reduce colorectal discomfort during Barostat-induced rectal distension. Acupuncture however is invasive, and its application requires an experienced acupuncturist.

Application of Transcutaneous electrical nerve stimulation (TENS) over acupuncture points (Acu-TENS) is a non-invasive modality and a novel analgesic therapy that combines the advantages of acupuncture and TENS in management of painful conditions. Acu-TENS has been shown to be more effective in reducing postoperative analgesic requirement when compared with TENS at nonacupoints. It is postulated that TENS possibly modulates the noxious stimulus of pain via the control of the 'pain-gate' or through the release of β-endorphin. The efficacy of Acu-TENS in pain-relief during colonoscopy has not been reported.

This current study aims to investigate the effect of Acu-TENS on barostat-induced rectal discomfort. A dual drive barostat device was used to mimic colonoscopy in order to control for the nature, intensity and duration of isobaric distension.

Inclusion Criteria:

1. Ages of 18-65 undergoing elective colonoscopy
2. Patients with American Society of Anaesthesiologists grading I-II
3. Informed consent available

Exclusion Criteria:

1. Previous history of colorectal resection and abdominal surgery
2. Patients with irritable bowel syndrome (Rome II classifications)
3. Previous experiences of colonoscopy
4. American Society of Anaesthesiologists grading III or above
5. Renal impairment
6. Emergency colonoscopy
7. Pregnancy
8. Allergy to acupuncture needles or electrode pads
9. Refuse to enroll into the study