A comparison of the biocompatibility of three absorbable hemostatic agents in the rat middle ear.

Absorbable gelatin sponge (Gelfoam) has been used for many years in middle ear surgery. Although the sponge is generally well tolerated, fibrosis occasionally forms in the mesotympanum; some studies indicated that the absorbable gelatin sponge may be responsible. Many of these studies lack statistical analysis. We prospectively studied three absorbable hemostatic agents in the middle ear of adult male Sprague-Dawley rats to determine which promotes fibrosis to the greatest degree: absorbable gelatin sponge (Gelfoam), absorbable gelatin sheet (Gelfilm), or absorbable collagen sheet (Instat). The materials were implanted in the middle ear through a post-auricular approach and the temporal bones were serially harvested at different time intervals so we could examine histologic changes. The nonimplanted ear served as surgical control. Examination of the specimens at 6, 8, and 10 weeks by light microscopy revealed that although absorbable gelatin film and collagen-absorbable hemostat are well tolerated in this animal model, absorbable gelatin sponge promoted the presence of fibrosis to a significantly greater degree, (p = 0.0344). We conclude that absorbable gelatin sponge promotes fibrosis more frequently than do collagen-absorbable hemostat and absorbable gelatin film in this animal model.