To the Editor: Impairment of microcirculation in the gastrointestinal mucosa is known to play an important role in cases of mucosal injury, not only from local ischemia resulting in cellular hypoxia (1) but also from over-production of oxygen radicals, eicosanoids, and platelet-activating factor (2,3). Developments in spectrophotometric techniques have made possible in vivo, noninvasive assessment of the concentration of hemoglobin and levels of oxygenation in the gastrointestinal mucosa in adult patients using gastrointestinal fiberscopy (4-6). However, there have been no reports of this kind of evaluation in children. We measured the mucosal microcirculation in colonic polyps and in the normal surrounding colon using reflectance spectrophotometry during colonofiberscopy in four children with juvenile polyps. Four patients aged from 1.5 to 6 years were studied. The patients had melena, and barium enema radiography revealed colonic polyps. All patients had a single polyp of maximum diameter 12-30 mm located between the transverse colon and the rectum. Colonofiberscopy was used to perform polypectomy under systemic anesthesia. During this operation, the mucosal microcirculation in the polyp and in the normal surrounding colon was evaluated using reflectance spectrophotometry. The hemoglobin concentration and the levels of oxygenation were measured in the mucosa using a tissue spectrum analyzer (TS-200, Sumitomo Electric Industries, Osaka, Japan). This was done using a fine optic bundle, whose tip was passed through the biopsy channel until it gently contacted the mucosal surface, following the method of Kamada et al. (4). The concentration of mucosal hemoglobin in the polyp mucosa was significantly higher (p < 0.05) than that in the normal surrounding mucosa. In contrast, the amount of mucosal oxygen in the polyp mucosa was typically less (p < 0.1) than that in the normal surrounding mucosa (Fig. 1). Histological examination of the polyps showed typical findings of juvenile polyps. Reflectance spectrophotometry can evaluate the concentration of hemoglobin in the gastrointestinal mucosa and the levels of oxygenation during endoscopical examination (4-6). These microcirculatory parameters are known to be indicators of mucosal ischemia, congestion, and other disturbances of the gastrointestinal mucosal microcirculation that can cause mucosal injury of the gastrointestinal tract. Our findings showed that the mucosal hemoglobin concentration in the juvenile polyp was markedly more than normal but the levels of oxygenation were typically less than normal. These findings indicate congestion in the mucosal microcirculation in juvenile polyps. This is in accordance with our histological findings, which showed hypervascularity in the veins and capillaries of the polyps. Further, this study suggests that it is feasible to assess the relationship between mucosal microcirculation and mucosal injury in children, as well as adults, using in vivo measurement of the gastrointestinal mucosal microcirculation with reflectance spectrophotometry (4-6). Toshiaki Shimizu, Yuichiro Yamashiro, Atsushi Unno, Kaoru Obinata, Keijiro Yabuta, and *Tatsuo Ogihara Department of Pediatrics *Division of Gastroenterology Department of Internal Medicine Juntendo University School of Medicine Tokyo, JapanFIG. 1.: Index of mucosal blood volume (•) and oxygenation (○) in the mucosa of colonic polyps and of normal surrounding colon in four children with juvenile polyps. Means were compared using a paired t test.