During epidural analgesia the following points suggests that needle is in the extradural space

Loss of resistance technique, tactile feedback from the needle, and surface landmarks are traditionally used to guide the epidural needle tip into the epidural space (EDS). Number of newer techniques are now available like ultrasound - Ultrasound imaging with preacquired three-dimensional images of spine, Ultrasound through needle, Ultrasound imaging with preacquired three-dimensional images of spine Modifications of the loss of resistance techniqueMembrane in syringe technique, Epidural balloon, Epidrum, Episure Autodetect, Auditory and visual display of pressure wave