Study of Cadaveric Posterior Circumflex Humeral Artery Variations

Purpose: There are concerns regarding the sequelae of blood clots post-vaccination due to suboptimal administration techniques with the ongoing incentive for vaccination against the Coronavirus Disease 2019 (COVID-19). Specifically, the risk of administering the intramuscular (IM) vaccine into an artery in the deltoid region. The posterior circumflex humeral artery (PCHA) is a small branch originating from the third part of the axillary artery, classically traveling with the axillary nerve, through the quadrangular space, to run along the inferior aspect of the deltoid muscle. This study investigates the presence and prevalence of variations of the PCHA not traversing in its classical path. Methods: Detailed dissection was performed on bilateral shoulders of 10 (n=20) human cadavers. The PCHA was identified in all 20 shoulders and their anatomic locations were assessed and categorized. Results: Of the 20 shoulders studied, 15% had anatomical variations of the posterior circumflex humeral artery traveling superiorly into the upper deltoid. Conclusions: Recent studies have highlighted the possibility of erroneous injection of the COVID-19 vaccine into the bloodstream as a risk of post-vaccination blood clots. The high prevalence of arterial variations revealed in this study provides an impetus for further research investigating the relationship between the variation in arterial anatomy and injection site "safe zones."