Case Report

The 23-years-old G1P0 patient was examined in the 34th week of gestation because anxiety caused by hyperactivity of the fetus. The pregnancy was uneventful and first and second trimester screenings were unremarkable. Cardiotocography, Amniotic Fluid Index, Doppler measurements, and fetal biometry were within normal limits. We observed the following isolated finding:

Images 1, 2, 3: The images show tangential scanning plane of the fetal lips. The upper lip has a hyperechoic round prominence in the midline (arrow) representing "sucking callus" of the lip. The image 3 is supplemented with a drawing elucidating the observed structures.

Images 4, 5, 6: 3D images of the fetal face showing a round prominence in the midline of the upper lip representing "sucking callus" of the lip. 

Image 7: Postnatal image of the newborn showing the "sucking callus" of the upper lip. 

Sucking calluses (or sucking pads) appear on the mucosa caudal to the closure line of the lips and are hyperkeratotic pads which later desquamate over 3–6 months. When these lesions are congenital, they are indicative of vigorous sucking in utero; they are sometimes seen together with sucking blisters on hands and wrists. The presence of sucking pads at birth represents an effective sucking reflex and as such it was recommended as a screening tool that indicates an intact motor neuron function in neonates. Histologically, there is epithelial hyperplasia and intracellular edema secondary to friction. No therapy is required.

References

1. D. S. Levy et al. Repeatability of the sonographic assessment of fetal sucking and swallowing movements. Ultrasound Obstet Gynecol 2005; 26: 745–749
2. Lawrence F. Eichenfield, Ilona J. Frieden, Neonatal and Infant Dermatology, third Edition 2014, Elsevier Saunders.