Umbilical hernia. Coloured 3-D ultrasound scan of a foetus with an umbilical hernia (lower right). This is a protrusion of part of the abdominal contents through a hole in the abdominal wall near the umbilicus (belly button). It is a fairly common defect in newborn babies, but will usually close naturally during early childhood. Surgery may be necessary if the hernia persists or is very large. Ultrasound scanning is a diagnostic technique that sends high-frequency sound waves into the body via a transducer. The returning echoes are recorded and used to build an image of an internal structure.