Segmental Water Exchange Method in Patients With Unsedated Colonoscopy

• Pain Scores [ Time Frame: up to six months ] [ Designated as safety issue: No ]
  The subjects were asked to report the pain score during the insertion phase by using the visual analog pain scale (0=no pain and 10=most severe pain imaginable).
• Polyp detection rate [ Time Frame: up to six months ] [ Designated as safety issue: No ]
  The proportion of subjects with at least one polyp.
• Cecum intubation time [ Time Frame: up to six months ] [ Designated as safety issue: No ]
  Total time of colonoscope intubation from anus to cecum.

Colonoscopy is widely used for diagnosis and management of colorectal diseases. Conventional colonoscopy with air insufflation may distend, lengthen and distend the colon lead to increased discomfort of patients and difficulty of cecal intubation. The use of water infusion in lieu of air insufflation (water exchange method) obviates excessive lengthening of the colon, and facilitates completion of colonoscopy. Several studies revealed that the total colonic water exchange method can significantly reduce the pain score and enhance the success of cecal intubation in minimal-sedation or unsedated colonoscopy. However, this method was associate with long operation time. Due to the special anatomic structure of sigmoid and descending colon (the left side of the colon), passage through this region is more difficult during colonoscopy. The investigators hypothesized that the critical superiority of water-aided colonoscopy is avoiding of lengthening and looping of sigmoid and descending colon. So, compare with total colonic water exchange method, the segmental colonic water exchange method should get the same effect with less operation time.

• Polyp
• Pain

• Other: Air colonoscopy
  Colonoscopy will be performed without medications and with judicious air insufflation during colonoscope insertion. A successful cecal intubation was defined as insertion of the colonoscope tip into the cecal caput.
  Other Name: Air colonoscopy
• Other: Total water exchange colonoscopy
  The air pump was turned off before colonoscopy. Colonoscopy will be performed without medications and aided by water infusion in-lieu of air insufflation during insertion of the colonoscope. The water infusion involves putting 37°C warm sterile water into the colon to open up the colon for advancement of the colonoscope until the end of the colon (cecal caput) is reached.
  Other Name: Water aided colonoscopy
• Other: Segmental colonic water exchange colonoscopy
  The air pump was turned off before colonoscopy. Colonoscopy will be performed without medications and aided by water infusion in-lieu of air insufflation during insertion of the colonoscope. The water infusion involves putting 37°C warm sterile water into the colon to open up the colon for advancement of the colonoscope until the splenic flexure of colon is reached. A successful cecal intubation was defined as insertion of the colonoscope tip into the cecal caput.
  Other Name: Water aided colonoscopy

• Active Comparator: Air colonoscopy
  Colonoscopy will be performed without medications and with judicious air insufflation during colonoscope insertion. A successful cecal intubation was defined as insertion of the colonoscope tip into the cecal caput.
  Intervention: Other: Air colonoscopy
• Experimental: Total water exchange colonoscopy
  The air pump was turned off before colonoscopy. Colonoscopy will be performed without medications and aided by water infusion in-lieu of air insufflation during insertion of the colonoscope. The water infusion involves putting 37°C warm sterile water into the colon to open up the colon for advancement of the colonoscope until the end of the colon (cecal caput) is reached.
  Intervention: Other: Total water exchange colonoscopy
• Experimental: Segmental colonic water exchange colonoscopy
  The air pump was turned off before colonoscopy. Colonoscopy will be performed without medications and aided by water infusion in-lieu of air insufflation during insertion of the colonoscope. The water infusion involves putting 37°C warm sterile water into the colon to open up the colon for advancement of the colonoscope until until the splenic flexure of colon is reached. A successful cecal intubation was defined as insertion of the colonoscope tip into the cecal caput.
  Intervention: Other: Segmental colonic water exchange colonoscopy

Inclusion Criteria:

• Outpatients with unsedated colonoscopy

Exclusion Criteria:

• history of colon resection
• severe colonic stricture or obstructing tumor
• hemodynamic instability
• inability to provide informed consent