Precautions for Dermal Filler Injections Near Labial Arteries
When injecting dermal fillers near the superior and inferior labial arteries, maintain injection depth above (superficial to) the orbicularis oris muscle using small gauge needles (27-30G) or cannula (25G), inject in a retrograde fashion, and avoid the submucosal plane—particularly at the midline and medial segments where arteries are most superficial and variable. 1, 2
Critical Anatomical Considerations
Vascular Anatomy and Risk Zones
The superior labial artery has its largest lumen diameter at the labial commissure (0.85 mm) and smallest at the midline (0.56 mm), with the most superficial depth occurring at the midpoint between the commissure and Cupid's bow (4.29 mm from skin surface). 3
The labial arteries demonstrate significant anatomical variability in their course, with 29% variability in the upper lip and 32% in the lower lip along their path. 4
The highest risk location is the medial and middle segments of the vermilion zone, where both superior and inferior labial arteries are located in the submucosal plane in the majority of specimens. 5, 4
Arterial Distribution Patterns
In 78.1% of cases, the labial arteries are positioned submucosally (between oral mucosa and orbicularis oris muscle), in 17.5% intramuscularly, and in only 2.1% subcutaneously. 4
The midline location in both upper and lower lips is the most variable anatomically, requiring heightened caution during injection. 4
The variable, superficial course of the superior labial artery and its large caliber place it at significant risk for intra-arterial injection at all points along its course. 3
Recommended Safe Injection Technique
Optimal Injection Depth and Approach
Inject above (superficial to) the orbicularis oris muscle to avoid vascular complications, as vessels can be encountered within 1mm of the injection site. 1, 2
Use either needle technique (27-30 gauge) in retrograde fashion into each quadrant, or cannula technique (25 gauge) with only two entry points for the entire procedure. 6, 1
Administer 0.2-0.5 mL per quadrant to avoid compression of neurovascular structures. 6, 2
Safer Anatomical Zones
The subcutaneous plane in the paramedian location of both upper and lower lips represents the safer location for volumizing material application. 4
Vermilion border and marginal injections are recommended for safe and effective lip augmentation, avoiding deep injection around the oral commissure. 5
Prohibited Injection Zones
High-Risk Areas to Avoid
Deep injection around the oral commissure is prohibited due to high risk of arterial injury. 5
Submucosal injection of the medial and middle segments of the vermilion zone is contraindicated because both superior and inferior labial arteries are located in the submucosa in these areas. 5
The cannula should not be inserted in the submucosa even when everting the vermilion, as labial arteries are consistently located in this plane. 5
Common Complications and Prevention
Expected Adverse Events
Warn all patients preoperatively about bruising (lasting 7-9 days), swelling, and tenderness, as these are the most frequent treatment-related effects that resolve spontaneously. 1, 2
Most adverse events are mild to moderate and self-limited, resolving within days to weeks. 1
Serious Vascular Complications
Vascular compromise and subsequent tissue necrosis is a rare but disfiguring complication that frequently occurs in regions of the lip and nasolabial fold supplied by the superior labial artery. 3
Serious complications including vascular occlusion leading to cutaneous necrosis and blindness can occur as a result of lip enhancement using dermal fillers. 7
Arterial injuries occur most commonly at the medial segment of the vermilion zone of both upper and lower lips, at the terminal part of the labial arteries or a distal branch. 5
Clinical Pitfalls to Avoid
Do not treat the perioral area too superficially without maintaining injection depth above the orbicularis oris muscle to prevent vascular injury. 1
Avoid injecting at the midline where arterial position is most variable and arteries are more frequently found in superficial positions. 4
The upper lip has a higher chance of arterial injury than the lower lip due to arterial anatomy, requiring extra caution. 5
Use small gauge needles (30G) and lower injection depths in delicate perioral areas to minimize vascular complications. 1