Korean J Pediatr 2010;53(9):817-823 • DOI: 10.3345/kjp.2010.53.9.817 821 pediatric endoscopist, complication occurs in less than 1%33). It is important for the endoscopist to anticipate the possibility of complication and be prepared for appropriate management. During the procedure, desaturation below 90% occurs in about 10% of children34). Nasal oxygen application is sufficient to correct this desaturation. Most complications in children have been related to percutaneous gastrostomy, esophageal dilation, variceal sclerotherapy, and foreign body removal. Major complications are bowel perforation and hemorrhage. Minor complications are nausea, transient hypoxemia, and transient odynophagia. To minimize the risk, it is very important to never proceed scope if the endoscopic view is not clear. Fleischer et al.35) reported prospective data collected over 1 year, including 3,287 procedures. The overall complication rate was 1.9%, 2 deaths (0.06%) and 3 bowel perforations (0.09%). Six patients required surgical intervention (0.18%), and 16 patients had cardiopulmonary problems (0.49%). Duodenal hematoma has been reported in children following routine diagnostic endoscopic biopsies. This complication is rare, but seems to occur more often in children36). Infections can occur due to the patient’s own microbial flora and those from other patients through a contaminated endo- scope. The most frequent microorganisms are Salmonella species,Pseudomanas aeruginosa ,Mycobacterium species, and Helicobacter pylori 37). These infectious complications can be seen in cardiac-risk groups. Bacteremia is rare in patients with no risk; thus, prophylactic antibiotics are required only for selected patients. Advances in pediatric endoscopy 1. Wireless capsule endoscopy (WCE) The use of WCE in children was approved by the FDA in 2003. More than 500,000 patients, including children, have been safely evaluated by this unique modality. PillCam® SB video capsule is vitamin sized, measures 11-26 mm, and weighs less than 4 g. It provides resolution down to 0.1 mm; an upper GI typically identifies lesions 0.5 mm or larger. The general indication for WCE is evaluation of suspected small bowel diseases-abdominal pain, celiac disease, inf lammatory bowel diseases, and obscure GI bleeding. This tool can be used to monitor the treatment status of small bowel diseases such as small bowel lesion in Henoch-Schöenlein purpura38) or graft-versus-host diseases39). WCE can be also applied in the surveillance of polyposis of the small bowel40). Thomson et al.41) reported the clinical application of WCE in 28 pediatric patients with suspected small bowel disease. They found WCE to be more sensitive than radiographic or endoscopic investigations, and led to management alteration in 64% of the patients evaluated. In a prospective study by Sharmir et al.42) in 10 children with functional abdominal pain, significant abnormalities were diagnosed in 4 children whose radiologic and laboratory results showed no specific abnormality. The capsule is either swallowed or placed endoscopically, and the patient can then resume daily activities. The recording device is removed after 8 hours, and the recorded pictures are downloaded. The capsule moves down with bowel movement and is usually passed out within 24 hours. Patients older than 10 years can often swallow the capsule with only water. Endoscopic placement of capsule has been reported in patients as young as 2.5 years old, weighing 12 kg43, 44). The main complication of WCE is retention in the bowel; that is, the capsule does not pass out for a minimum of 2 weeks. This event occurs in patients with obscure GI bleeding (1.5%), Crohn’s disease (5%), and previous small bowel obstruction or surgery. When compared with barium studies, WCE was considered diagnostic in 45% of patients versus 27%, with 31% versus 5% of the causes of obscure bleeding being found45). The current contraindications of capsule endoscopy are pregnancy; GI stricture or f istula; and implanted cardiac pacemaker, defibrillator, or any medical devices in the body. 2. Narrow band imaging This procedure is a high-resolution endoscopic imaging technology that utilizes optical filters and light wavelengths of narrow bands to enhance the microvasculature of mucosal surfaces. The white light goes through a XENON lamp and is dispersed into a narrow band blue light that is absorbed by hemoglobin and displays the superficial capillary network, while the green light penetrates the deeper tissue. This technology is used simultaneously with endoscopy, with no limitation of the visual field and no requirement for a dye. It is helpful to detect early changes in the microvasculature and mucosal abnormalities in dysplastic lesions, such as high-grade dysplasia in patients with ulcerative colitis (UC), and in early detection of Barrett’s esophagus46). 3. Chromoendoscopy This is an endoscopic technique that uses dyes to enhance visualization of abnormal-appearing mucosa during endoscopy. No special equipment is required. The dye and a spray catheter are used. The dyes or stains are Lugol’s solution, toludine blue, methylene blue, crystal violet, indigo carmine, Congo red, and phenol red. This endoscopic method is useful in pediatric patients for detection of villous atrophy in celiac disease47), early detection of high-grade