The superficial anal reflex tests the integrity of a reflex arc involving S4 and S5 spinal segments.
Ensure all ethical considerations are met regarding informed consent to examination. Lie the patient on their side with the knees flexed, and gently stroke the anal margin with a suitable implement such as an orange stick. Watch for motion of the anal sphincter.
A normal response would involve visible contraction of the anal sphincter, whereas a positive finding would be if this were absent. This may indicate a local lesion such as cauda equine syndrome, or a pyramidal tract lesion.
Ensure that the patient is reasonably comfortable and relaxed; a reflex cannot be elicited if the anal sphincter is contracted.