The gastric contents are sometimes mixed with some abnormal products, which may be of importance with regard to diagnosis. They may contain mucus, bile and intestinal juice, blood, and pus.

Mucus, if present in considerable quantity, is easily recognized. It usually occupies the upper part of the fluid, presents a more watery color, and can be partly lifted from the surface by means of a glass rod on account of its adhesive quality. If it is present only in small quantities, its existence in the gastric filtrate is best revealed by adding a few drops of dilute acetic acid, which then forms a characteristic precipitate, settling on the bottom of the vessel.

Bile And Intestinal Juice

Small quantities of bile and intestinal juice in the stomach are often met with, even normally in examination of the patient in the fasting condition. The tube probably produces a slight regurgitation of the duodenal contents into the stomach. The frequent occurrence of considerable quantities of bile and intestinal juice within the stomach is always due to some abnormal condition, either to a relaxation of the pylorus or to a stenosis of the duodenum, situated below the mouth of the bile duct. The presence of bile is easily noticed, either by its golden-yellow color or (if mixed with gastric juice) by its more greenish aspect. Whenever there is doubt as to the presence of bile, the usual test which serves for its detection in the urine may be applied.

The presence of intestinal juice is recognized by the characteristic ferments, amylopsin, steapsin, trypsin.

1. The filtrate is mixed with one-per-cent solution of carbonate of sodium until it has a decidedly alkaline reaction. A flake of fibrin is then added to the filtrate, which is kept in a warm place for quite a while. The fibrin will then dissolve by the action of the trypsin.

2. Starch will be changed into maltose by the action of the amylopsin.

3. To a small portion of milk add a drop of blue litmus tincture and a few cubic centimetres of the neutralized filtrate and keep at blood temperature. The presence of steapsin very soon changes the blue color, and the milk becomes slightly reddish (caused by the decomposition of the fat into the fatty acids through the steapsin).

Blood

Blood, if present in considerable quantities in the gastric contents, is very easily recognized. Fresh blood can hardly be mistaken for anything else, if present even in small quantities. The gastric contents mixed with blood present either a reddish or (if the blood is not fresh) a slightly brownish or coffee-ground color. Occasionally, if the blood is present in large quantities, the contents may appear black. The detection of blood in gastric contents which do not present the appearances just mentioned must be made in the following manner:

1. A drop of the contents may be examined under the microscope for the presence of red blood corpuscles.

2. By The Spectroscope

If the presence of fresh blood is suspected the filtrate of the gastric contents may be directly examined with the spectroscope. Blood, if present, will show the two lines of the oxyhemoglobin. If the blood is not fresh, or if the gastric contents include a considerable quantity of free hydrochloric acid, then, according to Weber1 and Boas,2 the ordinary examination with the spectroscope would not show the presence of blood, as the haematin is not soluble in the filtrate. H. Weber therefore suggested the following procedure:

3. To the gastric filtrate add a few cubic centimetres of concentrated acetic acid, and shake thoroughly with sulphuric ether. The latter presents a Tokay-wine color if haemoglobin or haematin is present.