title: Cadaveric Assessment of Lip Injections: Locating the Serious Threats.
abstract: BACKGROUND
  Lip augmentation could be a possible cause of blindness following filler injections. This study evaluated the risk by simulating clinical scenarios of marginal injections to the upper and lower lips and then evaluated the risk of vascular injuries.
  
  
  METHODS
  A 22G cannula was inserted bilaterally along the wet-dry junction of the upper and lower lip margins in fifteen cadavers, and then both lips were dissected to verify possible injuries to the superior and inferior labial arteries. The position of the labial arteries in the vermilion zone was documented to determine the appropriate injection technique.
  
  
  RESULTS
  In the marginal injections to the lips, arterial injuries occurred at the medial segment of the vermilion zone of both the upper and lower lips, at the terminal part of the labial arteries or a distal branch. Considering arterial anatomy, the upper lip has a higher chance of arterial injury than the lower lip. The cannula should not be inserted in the submucosa as it is recommended to evert the vermilion because both the superior and inferior labial arteries are located in the submucosa of the medial and middle segments of the vermilion in all specimens.
  
  
  CONCLUSIONS
  Awareness of the possibility of vascular injury is necessary during injections of the medial segments of the vermilion of the lips. Vermilion border and marginal injections are recommended for safe and effective lip augmentation. Deep injection around the oral commissure and submucosal injection of the medial and middle segments of the vermilion zone are prohibited because of the high risk of arterial injury.
  
  
  METHODS
  This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.
authors.affiliation: The Chula Soft Cadaver Surgical Training Center and Department of Anatomy, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, 1873 Rama 4 Road, Pathumwan, Bangkok, 10330, Thailand. tansatitapinuntrum@gmail.com.
authors.forename: Tanvaa
authors.initials: T
authors.lastname: Tansatit
authors.affiliation: The Chula Soft Cadaver Surgical Training Center and Department of Anatomy, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, 1873 Rama 4 Road, Pathumwan, Bangkok, 10330, Thailand.
authors.forename: Prawit
authors.initials: P
authors.lastname: Apinuntrum
authors.affiliation: The Chula Soft Cadaver Surgical Training Center and Department of Anatomy, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, 1873 Rama 4 Road, Pathumwan, Bangkok, 10330, Thailand.
authors.forename: Thavorn
authors.initials: T
authors.lastname: Phetudom
mesh_terms: D001766:Blindness / Q000209:etiology / Q000517:prevention & control*; D002102:Cadaver; D003357:Cosmetic Techniques / Q000009:adverse effects*; D004210:Dissection; D006801:Humans; D007267:Injections / Q000009:adverse effects* / Q000379:methods; D008046:Lip / Q000098:blood supply* / Q000601:surgery; D057772:Vascular System Injuries / Q000209:etiology / Q000517:prevention & control*
keywords: Cadaver; Cannula; Emboli; Filler injections; Lip augmentation