PURPOSE: To obtain a vessel (spitze) for inspecting blood which clots satisfactorily the blood of a patient receiving heparin dose, can reduce considerably the time for clotting and permits sampling of the serum with good separability by allowing polyamine sulfone to exist on the inside wall surface of said vessel.

CONSTITUTION: This vessel for inspecting blood is constituted by allowing the polyamine sulfone expressed by the general formula shown in the figure to exist as an accelerator for blood clotting on the inside wall of a vessel consisting of various materials such as a thermoplastic resin, thermosetting resin, modified natural resin, glass, etc. The polyamine sulfone when brought into contact with the blood contg. heparin adsorbs and neutralizes the heparin and settles together with the heparin to deprive the hetarin of its effect and to restore the normal clotting function of the blood according to the above-mentioned vessel for inspection and therefore the serum is obtd. with good separability by clotting the blood in the vessel in short time and separating the blood-clot and the serum by a means such as centrifugal sepn.