Patent ID: 7331943

Claim:
An injection needle for piercing the skin and entering the vein of a patient particularly adapted for sclerotherapy comprising: a cannula, including a tubular member having an outer wall and an inner wall, a first end and a skin piercing second end, and a central main axis extending therebetween, said cannula being formed with a central duct defined by said inner wall extending between the first and second ends, said duct having an inlet at the first end and an outlet at the second end, said inlet and outlet being in fluid communication through the duct for carrying a sclerosing substance to be injected into a vein along a flow direction between the inlet and the outlet; said inner wall having an inner diameter and a continuous circumferential deformation formed in the outer wall proximate to the second end of the duct, said deformation extending inwardly of the cannula forming a corresponding continuous circumferential constriction in the inner wall for reducing the inner diameter of the duct thereat; said outlet formed as a central opening along the central main axis at the second end of the duct and transverse thereto, and at least two through holes formed in the wall of the cannula upstream of and proximate to the constriction, said two through holes being disposed in the wall in a longitudinal direction on a plane orthogonal to said central main axis according to the flow direction of said flow direction of the sclerosing substance; said constriction causing die sclerosing substance to undergo a decrease in the flow through the duct and out of the central opening downstream of the constriction, and to increase the flow of the sclerosing substance through the two through holes upstream of the constriction.