Resumen

Objectives: This study aims to compare the precision, safety, and clinical outcomes of in-plane versus out-of-plane ultrasound-guided botulinum toxin injections in facial aesthetic applications. Introduction: Ultrasound-guided botulinum toxin injections are increasingly adopted in aesthetic medicine to improve accuracy and reduce complications. However, there is limited comparative data on the efficacy and safety of in-plane versus out-of-plane techniques. Materials / method: A prospective, observational study was conducted involving 60 patients undergoing botulinum toxin treatment for upper facial and lower facial indications. Each patient was randomly assigned to receive injections using either the in-plane or out-of-plane technique, depending on the anatomical target. Outcome measures included needle visualization score, targeting accuracy, procedure time, patient-reported discomfort, and the incidence of adverse events (vascular injury, diffusion-related complications, or asymmetry). Secondary outcomes assessed the learning curve and operator confidence. Results: The in-plane technique demonstrated superior needle visualization (p < 0.01) and targeting accuracy, particularly in deeper or more complex anatomical regions. Procedure time was slightly longer with the in-plane approach but correlated with fewer repositioning attempts. The out-of-plane method offered practical advantages in superficial targets but was associated with a higher incidence of needle tip misidentification (p = 0.03). No serious adverse events occurred in either group, though minor diffusion-related complications were slightly more common with the out-of-plane method. Conclusion: Both ultrasound-guided in-plane and out-of-plane techniques are effective for botulinum toxin injections in aesthetic practice. However, the in-plane approach offers greater precision and needle control, particularly in high-risk or deep anatomical areas, while the out-of-plane technique may be suitable for superficial targets with proper operator expertise. These findings support tailored technique selection to enhance both safety and clinical outcomes in aesthetic injections.