Constriction rings syndrome is a congenital limb malformation disorder with an extremely variable clinical presentation characterized by the presence of partial to complete, congenital, fibrous, circumferential, constriction bands/rings on any part of the body, although a particular predilection for the upper or lower extremities is seen. Phenotypes range from only a mild skin indentation to complete amputation of parts of the fetus (e.g. digits, distal limb). Compression from the rings may lead to edema, skeletal anomalies (e.g. fractures, foot deformities) and, infrequently, neural compromise.

The middle finger is more than 2 SD above the mean for newborns 27 to 41 weeks EGA or above the 97th centile for children from birth to 16 years of age AND the five digits retain their normal length proportions relative to each other (i.e., it is not the case that the middle finger is the only lengthened digit), or, Fingers that appear disproportionately long compared to the palm of the hand.