An analysis of methods in which barium enemas are performed in some departments of radiology will usually show that complete asepsis is lacking. In most, the enema tip is disposable, but the enema set (can, all tubing, glass connecting rods, and tips) is autoclaved or disposed of after each examination in very few, if any, departments.
Recently M. H. Nathan1 demonstrated sudden rapid increases in rectal pressure, which he interpreted as mass peristalsis. He observed that pressures above 75 cm. H2O (55.5 mm. Hg) resulted in backflow of fecal matter into the enema container which was suspended at a height of 2.5 ft. above the table; this occurred in 12 of 14 patients who exhibited mass peristalsis.
It is the purpose of this paper to demonstrate the pressure changes during barium enema examination which may result in contamination of the apparatus and to prevent possible contamination by