A medical syringe which is suitable for dispensing and injecting medical foams is described and claimed. The syringe has a standard syringe plunger and barrel arrangement but comprises a flexible annular flange on the inner surface of the barrel. The annular flange extends inwards and forwardly from a base portion, affixed to the inner surface of the barrel to contact the plunger shaft and form a seal. The shape and orientation of the annular flange enables injection of medical foam with reduced sputtering of the syringe contents which make administration of sclerosing foams more controllable.