Definition of the lateral bulge deformity after primary cleft lip repair using real-time high-resolution ultrasound.

: The lateral bulge is a common secondary deformity after primary cleft lip repair; however, its underlying anatomy remains undefined. The purpose of this study was to use real-time high-resolution ultrasound to better understand the anatomy underlying the lateral bulge deformity. Twenty-three patients with a lateral bulge were included in addition to 12 patients without clefts to validate ultrasound measurements. Muscle and connective tissue dimensions were recorded at standardized landmarks using ultrasound, both at rest and with movement. The cleft and noncleft sides (right and left in noncleft patients) were compared within groups, and ratios between sides were compared across groups using parametric and nonparametric tests. Repeat measurements were recorded to calculate intrarater reliability. Orbicularis oris thickness was greater on the cleft side in the lateral bulge group at rest, both at the philtral column and alar crease (P < 0.001), and with facial movement at the corresponding landmarks (alar crease: smile P < 0.001 and pucker P = 0.003; philtral column: smile P < 0.001 and pucker P = 0.001). The ratio for levator width was also greater in the lateral bulge group (P < 0.001). No differences were identified between sides at the corresponding landmarks in the noncleft group. Ultrasound enabled real-time high-resolution evaluation of anatomic differences underlying the lateral bulge deformity. It was associated with greater orbicularis oris thickness and levator width on the cleft side. Findings from this study may guide future surgical correction of the lateral lip bulge.