A sterile device intended to be used in conjunction with an epidural needle to aid a user in locating the epidural needle tip within the epidural space. It is typically a small chamber made of synthetic polymers with Luer inlet and exit ports on opposing sides and an expandable membrane (diaphragm) as one of the sides between the ports. The device is inserted between the syringe and epidural needle and its diaphragm is inflated with air; the needle is inserted into the patient until the diaphragm collapses signalling entry into the epidural space. This is a single-use device.