Sonography of the coccyx in newborns and infants.

The ultrasonic appearance of the coccyx was studied in 61 newborn infants and young children without known congenital abnormalities. The coccyx was easily seen in all children as a hypoechoic structure with a variable number of vertebral body ossification centers. Knowledge of the normal appearance of the coccyx can prevent confusion with pathologic conditions such as abscesses or tumors and can be helpful in the detection of congenital coccygeal abnormalitis