Background: Current needle-catheter assemblies are designed so that a flexible catheter is threaded through a larger diameter needle towards a target nerve. These catheter-through-needle (CTN) assemblies suffer from several fundamental problems, including leakage at the insertion site and dislodgement of the catheter. The underlying problem of this design is that the needle puncture hole is wider in diameter than the catheter diameter. An alternative catheter-over-needle (CON) design, in which the catheter diameter is larger than that of the needle puncture hole, may be a potential solution to the problems of leakage and dislodgement. We wish to evaluate the ease of use and effectiveness of the CON method in the clinical setting by having anesthesiologists perform and rate the two techniques during and after administration of local anesthesia at various block sites on the body.