There is a spectrum of this finding from total absence of the philtral ridges to a some prominence of the ridges. The central groove varies from absent to shallow. Normal values for the frequency of smooth philtrum are available. Grading of the smoothness of the philtrum, used in the assessment of Fetal Alcohol Syndrome, has been developed. This finding is greatly influenced by the facial expression, and care should be taken to evaluate the philtrum when the face is in a neutral position. A smooth philtrum can be associated with a Long philtrum. However, the two findings should be coded separately.