[Detection of obscure fistulas complicated with Crohn's disease by indocyanine green].

When treating patients with Crohn's disease (CD), external or internal fistulas connected to the intestine were encountered, and these were often difficult to diagnose correctly. In order to diagnose such fine fistulas, we modified a method of using indocyanine green (ICG) administration to the gut lumen. The subjects of this study comprised nine patients with CD who had an obscure fistula which could not be demonstrated by barium study, fistulography, or by urological or gynecological examinations. If the administrated ICG was detected by various ways from an external fistula or from the neighboring organs, a fistulous connection was thought to be evident. Following oral administration in nine patients, colonic fistulas became evident in seven and by ICG enema in three patients, colonic fistulas became evident in all three. In addition, since the fistulous connection was ameliorated following nutritional therapy, it would appear that ICG administration is a useful marker of such therapy for this condition. ICG administration was therefore thought to be a useful method of detecting obscure fistulas connected to the intestine.