Redefining the surface anatomy of the parotid duct: an in vivo ultrasound study.

Background: The surface anatomy of the parotid duct is important when assessing facial lacerations and in facial rejuvenation surgery but is inconsistently described in reference texts. The aim of this study was to map the surface anatomy of the adult parotid duct using ultrasound.
Methods: Fifty healthy adults (31 women; mean age, 33 years) were scanned by an experienced sonographer using a 13-5 MHz linear probe and a Siemens Sonoline Antares ultrasound machine. The caliber, length, and course of the parotid duct were recorded bilaterally.
Results: The parotid duct was identified bilaterally in all participants. One subject had a double duct bilaterally. In the remaining 49 individuals (98 ducts), the duct had a mean maximum internal caliber of 0.6 ± 0.2 mm and length 42 ± 7.5 mm. Ninety-two (94 percent) ducts were below the most popular surface marking, which is reported as a line between the lower border of the tragus and mid philtrum. In 93 percent of individuals, the duct was within 1.5 cm of the middle half of a line between the lower border of the tragus and cheilion.
Conclusion: A more accurate description of the surface anatomy of the parotid duct should assist with early diagnosis of parotid duct injuries and avoidance of iatrogenic injury.
Clinical Question/level of Evidence: Diagnostic, IV.