All colonoscopies were performed by two experienced board-certificated attending endoscopists and gastroenterologists who had performed more than 10,000 colonoscopies.
Colonoscope insertion in the cecum was accomplished using standard maneuvers. Small shaking, jiggling, and right-turn shortening maneuvers have been frequently used for insertion
9 (link)
. We started the colonoscopy with the patients in the left lateral position. Then, we placed the patients in the supine position after observation of the lower rectum. Extra gas and liquid were aspirated and removed as much as possible. We conducted colonoscopies using water-aided techniques with a 20-mL syringe placed directly through the colonoscope accessory channel for patients in the 260 group; we used the OFP-2 for patients in the 290 group
10 (link)
. For colonic insufflation, air was used for patients in the 260 group and patients in the 290 group with chronic respiratory failure; CO
2was administered through the UCR for patients in the 290 group without chronic respiratory failure.
Colonoscopies were performed under conscious sedation with midazolam (0.5 to 10 mg) and/or pethidine hydrochloride (17.5 to 70 mg). In the absence of contraindications, when the colonoscope reached the cecum, we administered 10 to 20 mg of scopolamine butylbromide.
Observation time for withdrawal of the colonoscope was standardized as at least 6 minutes
11 (link)
. PCC involved pan-colonic spraying with 0.05 % indigo carmine by a 20-mL syringe placed directly through the colonoscope accessory channel. We repeated administration of 5 mL indigo carmine with 10 mL air-spraying 10 to 20 times during the withdrawal procedure, and pools of excess dye were suctioned before examination. The colonoscope was sequentially withdrawn as the prescribed position changed
12 (link)
13 (link)
: the ascending colon/hepatic flexure was examined in the left lateral decubitus position; the transverse colon was examined in the supine position; the splenic flexure, descending colon, and sigmoid-descending colon junction were examined in the right lateral position; and the sigmoid colon and rectum were examined in the right lateral position. Physicians were permitted to change the position if it was medically necessary.
To endoscopically diagnose colorectal polyps, we used the updated Paris Endoscopic Classification of superficial neoplastic lesions in the digestive tract and the NICE (NBI International Colorectal Endoscopic) classification
14 (link)
15 (link)
. Lesions diagnosed as adenomas or sessile serrated polyps (SSPs) were removed by using hot or cold polypectomy with a snare or forceps or by endoscopic mucosal resection on the examination day. We did not resect the polyps with a diameter of 20 mm or more because they should be resected in the hospitalization facility.
Patients involved in this study underwent colonic preparation using 2 L of polyethylene glycol solution administered orally 5 hours before the procedure. Polyethylene glycol solution or magnesium citrate was added when the stool was not clear liquid. Quality of the bowel preparation was graded as A (all colon segments empty and clean or minor amount of fluid in the gut that was easily removed by suction), B (at least one colon segment with residual amounts of brown liquid or semi-solid stool that could be easily removed or displaced), C (at least one colon segment with only partially removable stool preventing complete visualization of mucosa), or D (at least one colon segment that could not be examined due to presence of remaining solid stool). The following colon segments were rated: rectum, sigmoid colon, descending colon, transverse colon, and ascending colon/cecum
16 (link)
. Patients with a grade of D during colonoscopy were excluded.
Colonoscope insertion in the cecum was accomplished using standard maneuvers. Small shaking, jiggling, and right-turn shortening maneuvers have been frequently used for insertion
9 (link)
. We started the colonoscopy with the patients in the left lateral position. Then, we placed the patients in the supine position after observation of the lower rectum. Extra gas and liquid were aspirated and removed as much as possible. We conducted colonoscopies using water-aided techniques with a 20-mL syringe placed directly through the colonoscope accessory channel for patients in the 260 group; we used the OFP-2 for patients in the 290 group
10 (link)
. For colonic insufflation, air was used for patients in the 260 group and patients in the 290 group with chronic respiratory failure; CO
2was administered through the UCR for patients in the 290 group without chronic respiratory failure.
Colonoscopies were performed under conscious sedation with midazolam (0.5 to 10 mg) and/or pethidine hydrochloride (17.5 to 70 mg). In the absence of contraindications, when the colonoscope reached the cecum, we administered 10 to 20 mg of scopolamine butylbromide.
Observation time for withdrawal of the colonoscope was standardized as at least 6 minutes
11 (link)
. PCC involved pan-colonic spraying with 0.05 % indigo carmine by a 20-mL syringe placed directly through the colonoscope accessory channel. We repeated administration of 5 mL indigo carmine with 10 mL air-spraying 10 to 20 times during the withdrawal procedure, and pools of excess dye were suctioned before examination. The colonoscope was sequentially withdrawn as the prescribed position changed
12 (link)
13 (link)
: the ascending colon/hepatic flexure was examined in the left lateral decubitus position; the transverse colon was examined in the supine position; the splenic flexure, descending colon, and sigmoid-descending colon junction were examined in the right lateral position; and the sigmoid colon and rectum were examined in the right lateral position. Physicians were permitted to change the position if it was medically necessary.
To endoscopically diagnose colorectal polyps, we used the updated Paris Endoscopic Classification of superficial neoplastic lesions in the digestive tract and the NICE (NBI International Colorectal Endoscopic) classification
14 (link)
15 (link)
. Lesions diagnosed as adenomas or sessile serrated polyps (SSPs) were removed by using hot or cold polypectomy with a snare or forceps or by endoscopic mucosal resection on the examination day. We did not resect the polyps with a diameter of 20 mm or more because they should be resected in the hospitalization facility.
Patients involved in this study underwent colonic preparation using 2 L of polyethylene glycol solution administered orally 5 hours before the procedure. Polyethylene glycol solution or magnesium citrate was added when the stool was not clear liquid. Quality of the bowel preparation was graded as A (all colon segments empty and clean or minor amount of fluid in the gut that was easily removed by suction), B (at least one colon segment with residual amounts of brown liquid or semi-solid stool that could be easily removed or displaced), C (at least one colon segment with only partially removable stool preventing complete visualization of mucosa), or D (at least one colon segment that could not be examined due to presence of remaining solid stool). The following colon segments were rated: rectum, sigmoid colon, descending colon, transverse colon, and ascending colon/cecum
16 (link)
. Patients with a grade of D during colonoscopy were excluded.
