Endoscopic India ink injection: a method for preparation, sterilization, and administration.

India ink tattooing of the colon has been used to mark lesions for subsequent surgical identificationl -3 and to identify polypectomy sites to facilitate followUp.4 In animal studies, endoscopic injection of dyes in the colon has been shown to be an effective and welltolerated method for mucosal marking.5 Unfortunately, several side effects have been attributed to the injection of India ink. Reports include influenza infection in mice pre-treated with India ink,6 phlegmonous gastritis after injection into the stomach,7 fat necrosis,s inflammatory pseudotumor (which appeared to consist of inflammatory cells and fibroblast proliferation),S and abscess.9 Possible causes of these complications may be an inflammatory reaction to the ink (carbon particles) or diluent (either via a direct irritant effect ofthe undiluted ink or secondary to a hypersensitivity reaction), or inadequate sterilization. For example, in the case of phlegmonous gastritis7 and the cases of infection in mice,5 the ink was not sterilized. In the report of pseudotumor,s the ink (Higgins, Faber-Castell, Lewisberg, Tenn.), comprising about 7 % carbon pigment, 5% propylene glycol, and smaller concentrations of shellac, ammonium hydroxide, and surfactant, was used in a very concentrated form (approximately equal parts India ink and bacteriostatic water). Anyone ofthe multiple diluents or the carbon pigments may have caused this inflammatory response. In addition, post-autoclave contamination of the ink may have occurred. Similar reasons might account for the case offat necrosis,s in which the type of ink was unknown but was injected in concentrated form (approximately equal parts India ink and bacteriostatic water). The same possible causes could account for the abscess9 found incidentally during operative resection for tumor. The India ink used was Pelikan brand (Pelikan, Hanover, Germany), containing ethylene glycol, sodium tetraborate decahydrate, and ammonia in 1:10 dilution with sterile water. This for-