Lethal Effects of Tannic Acid in the Barium Enema

Abstract

The addition of tannic acid to barium sulfate suspensions employed in the roentgenographic examination of the colon has been recommended by a number of authors (1, 5, 7, 12, 16) and its use is widespread. The rationale is based on the following considerations: Tannic acid as an astringent stimulates contracture of the colon, inhibits the secretion of mucin, and causes precipitation of the protein of the superficial layers of the mucosa. It also makes barium sulfate adhere to the bowel wall (5, 7, 16) and is said to inhibit absorption of substances from the colon (16). The concentration of tannic acid recommended for use in barium enema examinations varies between 0.25 and 3.0 per cent (16). A variety of tannic acids are found in nature. They are water-soluble polymers of various hydroxybenzoic acids (10). Tannic acid in the form of baths, dressings, or jellies was utilized in the treatment of cutaneous burns for almost twenty years before its use was abandoned. Clinical evidence of its hepatotoxicity accumulated rapidly. This was confirmed in experimental animals (2–4, 6, 8, 10, 11, 13, 18). Albino rats given varying amounts of the substance showed microscopic changes of hepatocellular damage that could be correlated with the total amount of tannic acid solution injected subcutaneously (2, 18). The other organs were not specifically damaged. A patient at the St. Louis Children's Hospital died with acute hepatic failure, and a search for possible hepatotoxic agents uncovered only the tannic acid added to the barium sulfate suspension used in the roentgen examination of the colon and in the preparatory enemas for that examination. Tannic acid was demonstrated in the liver of this patient. We were unable to discover either experimental data on the absorption of tannic acid from the colon and terminal ileum or reports of fatalities or serious complications associated with its use in the gastrointestinal tract. This case is reported as an example of death due to liver failure as a result of the absorption of tannic acid from the intact bowel, together with 2 other cases with hepatic necrosis found in a review of sudden, unexplained deaths after the performance of a colon examination. These deaths occurred over a twelve-month span. In addition, experimental studies undertaken to confirm the absorption of tannic acid from the colon and to show its effect on the liver will be presented. Case Reports Case 1. Clinical Course: A 10-year-old white male was admitted to the St. Louis Children's Hospital because of abdominal cramping associated with urgency and fecal incontinence of several months duration. The patient had been seen previously in the Outpatient Department for bouts of intermittent diarrhea. A stool examination four months prior to admission showed the presence of ova and adult forms of Ascaris. The stool examination with the guaiac reagent was negative.