The Blood Supply of the Lips: A Systematic Review and Meta-Analysis

The arterial anatomy of the lips is highly variable, influencing both reconstructive and aesthetic procedures. Despite extensive anatomical studies, potential perfusion relationships within the perioral region remain underexplored. This review introduces a new anatomical hypothesis, the "steal phenomenon", which describes a possible redistribution of perfusion (or filler material) from the upper lip toward the nasal and ophthalmic territories through pre-existing anastomoses.

Electronic databases, including Medline (PubMed), Embase, Scopus, and Web of Science, were systematically searched to gather studies examining the blood supply to the lips.

Twenty-three studies were included. The superior labial artery (SLA) was absent in 3.55% of cases; when present, it most commonly originated above the oral commissure (OC) (80.71%) at a mean distance of 11.95 mm. The inferior labial artery (ILA) was absent in 13.45% of cases and most frequently located below the OC (72.44%) at an average distance of 21.99 mm. Both arteries most commonly coursed through the submucosal plane, with the SLA and ILA, reported in this layer in up to 84.8 and 81.25% of cases, respectively. Mean arterial depths were approximately 5.2 mm for both vessels.

This review highlights the considerable variability of the labial vasculature and its implications for procedural safety. No lip plane can be regarded as entirely free of vascular structures, emphasizing the need for individualized, anatomically guided injection technique. The proposed steal phenomenon offers a theoretical explanation for the upper lip's greater susceptibility and underscores the importance of cautious, patient-specific practice supported by ultrasound when available.

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