A Prospective, Randomized, Controlled, Single-Blinded Study to Assess the Effect of a 33-Gauge Needle Versus a 34-Gauge Needle on Pain Experienced During Injection of Local Anesthetic on the Face

Background: Most pain experienced by patients during Mohs micrographic surgery is associated with the initial injection. Previous studies have shown that a smaller gauge needle (33-gauge vs 30-gauge) is associated with less patient-reported pain. Objectives: To evaluate patient-reported pain levels following _Doinjection _{Not Copy} with a 33-gauge versus a 34-gauge needle. Methods: _{a 34-gauge} During _needle this _group. prospective, _{Pain levels} randomized, _following controlled, _{needle insertion Penalties} single-blinded _{wereApply recorded} study, 480 _using patients _{the validated} were randomized _numerical into _rating a 33-gauge _{scale (VNRS)-11} versus scale. Results: Injection of local anesthetic with a 34-gauge needle is associated with significantly less pain compared to a 33-gauge needle across all subgroups (P=0.007, average pain level 0.49 [34-gauge group] vs 0.79 [33-gauge group] rated on a 0-10 pain scale). Females, first time Mohs patients, patients under age 65, patients with basal cell carcinoma, and those with tumor locations on the nose experienced the most pain reduction with use of a 34-gauge needle. Limitations: This was a single-blinded study; thus, the injector was able to see which needle was being used. This knowledge could have subconsciously affected the angle, speed, or force used to insert the needle. Conclusions: Injections with a 33-gauge and a 34-gauge needle are both tolerated well and associated with minimal pain. While the pain reduction associated with using a 34-gauge needle is statistically significant, the use of a 34-gauge needle may be most clinically relevant for certain patient subgroups.