X-ray contrast preparation containing a hydrophilic polymer containing amino groups

A method of carrying out X-ray examination of the gastro-intestinal tract of a patient, which method comprises the oral or rectal administration to the patient of minute particles of a cross-linked hydrophilic polymer containing amino groups suspended in a physiologically acceptable aqueous liquid and finely divided barium sulphate and taking of pictures of the gastro-intestinal tract, said polymer being insoluble in water at body temperature and being a polyfunctional amine or a member selected from the group consisting of dextran, cellulose, starch and pollulan, which is substituted with amino groups and optionally with other ionizable groups which give rise to negative surface charges, said polymer having molecules held together to a water-insoluble, but water swellable threedimensional network by bridges comprising straight or branched aliphatic saturated hydrocarbon chains substituted by one or more hydroxyl groups and containing 3 - 30 carbon atoms and being non-broken or broken by one or more oxygen atoms and said polymer containing more than 0.1 and less than 15 milliequivalents of amino groups per gram of dry polymer, the swellability of the polymer in the presence of water is able to absorb more than 0.5 g and less than 50 g of water, the average particle size of the polymer particles in the presence of water being greater than 0.1 micro-meter and smaller than 300 micro-meter, and the ratio between the polymer particles and the barium sulphate being 2 to 100 g of said particles per 100 g of barium sulphate, the barium sulphate being used in an effective contrast-producing amount and the polymer particles being used in an effective amount for coating the surface of the parts of the gastro-intestinal tract to be examined.