Ultrasonography is an imaging technique used for the diagnosis of certain conditions or as a routine scan during pregnancy. An image of the internal organs and structures can be created using ultrasound.

Sonography is performed to determine the source of a disease. In pregnant women, obstetric ultrasound is performed to observe the status of the foetus.

Unlike other imaging techniques, ultrasonography does not employ harmful radiation and hence is safe for pregnant women.

An X-ray uses radiation to capture an image of the internal anatomy, whereas sonography makes use of sound waves. X-rays are more commonly used to assess the bone structure, whereas ultrasound is used mainly to detect fluid build-up and visualise the tissue.

Preparation for sonography depends on the type of procedure. Some procedures require the patient to drink 1-2 litres of water. In some cases, patients are advised not to eat or drink anything 10-12 hours prior to the procedure.