Central Auckland > Public Hospital Services > Starship Child Health >

Starship Paediatric Radiology

Public Service, Radiology, Paediatrics

Ultrasonography/Ultrasound (US)

Ultrasonography is the creation and interpretation of images that are formed by high frequency sound (ultrasound), in combination with sophisticated computerisation. A beam of sound that is higher in frequency than can be heard by humans, is sent into the body from a small crystal in a hand-held scanner head (transducer).  When the beam meets an interface between tissues of different density, echoes of the sound beam are sent back into the transducer and fed into a computer. The computer creates an image that is displayed on a television screen. 

The scans are usually done when the child is lying down on a padded table next to the ultrasound machine. The parent(s) or caregiver(s) can stay in the scanning room. The child is positioned for the specific examination by the ultrasonographer or doctor who is doing the study. The transducer is moved over the area of interest after water soluble gel is put on the child’s skin to prevent air getting between it and the transducer surface. Sound does not pass through air nearly as well as it does through soft tissues and fluid.
Ultrasonography is a very safe type of imaging; this is why it is so widely used during pregnancy. It does not hurt; the only feeling the child has is of the transducer being moved over the skin.

Ultrasonography is particularly useful in the neonatal nursery for the imaging of the neonatal brain through the anterior fontanelle (soft spot of the skull) for evaluating solid organs in the abdomen like the liver, kidneys, pancreas and spleen, for investigating certain problems of muscles and cartilage, and for identifying collections of fluid, diagnosing some tumours or masses, and providing a means of their localisation if a biopsy is needed.

  • Preparation for abdominal scans is 4 hours of no food or milk before the study so that there is less air and food throughout the gastrointestinal tract. The gallbladder will be full of bile if the child is fasting; it is easier to evaluate when it is distended. For those less than 3 years of age, 3 hours fasting is adequate.
    Clear fluids can be given, but no fizzy drinks.
  • Preparation for renal scans is lots of fluids given by mouth. If toilet trained, the child should have a full bladder for the beginning of the scans. After the scans of the bladder are obtained, the child is allowed to empty the bladder before the kidneys are imaged.
  • Preparation for a pelvic scan includes lots of fluid by mouth or intravenous route. The child should have a full bladder so that structures in the pelvis, like uterus and ovaries in a girl, are visible. When the bladder is empty, loops of bowel fill the pelvis and the genital tract cannot be seen.
  • Other scans with ultrasound require no preparation.

This page was last updated at 11:51AM on April 14, 2021.