Abstract: Objective: To investigate the value of high-frequency ultrasound in the diagnosis and treatment of mini-microform cleft lip. Methods: Based on the inclusion and exclusion criteria, data from 12 patients with mini-microform cleft lip were collected, in which 10 were males and 2 were females, with a mean age of 2.6 years. All patients took frontal photographs and underwent high-frequency ultrasonography prior to surgery. Indicators, such as the thickness of subcutaneous connective tissue and the superficial layer of the orbicularis oris muscle, the deep layer of the orbicularis oris muscle, and the thickness and angle of the cross fiber bundles of the orbicularis oris muscle, were measured and evaluated. Results: High-frequency ultrasound revealed the depression of red lip and midface ridge. Irregular low echoes were seen in the superficial orbicularis oris muscle and subcutaneous connective tissue layer of upper lip on the affected side. The thickness of superficial orbicularis oris muscle layer was significantly thinner than that of the healthy side (P=0.002). No significant abnormal echoes were seen in the deep orbicularis oris muscle and connective tissue. The angle between the crossed fiber bundles of the orbicularis oris muscle and the horizontal reference line was greater on the affected side than on the healthy side (P<0.001). Conclusion: High-frequency ultrasonography can visualize the abnormalities of subcutaneous connective tissue of the upper lip and the orbicularis oris muscle in patients with very mini-microform cleft lip, and the findings can aid in the development of personalized treatment plan.

Key words: high-frequency ultrasound, mini-microform cleft lip, orbicularis oris muscle, crossed fiber bundle