What is ultrasound?

Ultrasound uses high frequency sound waves which are produced by a probe called a transducer to detect changes in density within the body or blood flow. They work like bat echo location and have been used in pregnancy for looking at the baby's health for over 30 years. No medical research has shown any side effects. No link to increased cancer risk has been established.

For some ultrasound scans patients do not need to do anything to get ready (prepare) for the scan. But some scans need the patient to have a full bladder or to not eat for a few hours before the scan. You will be told how to prepare for your exam when you receive your appointment.

You will be asked to lie on a couch and a water based gel will be placed between your body and the transducer. The transducer will then be pressed against you to get the best image. Sometimes this can feel a little uncomfortable.

Most scans are done with the transducer on the skin. Sometimes a special transducer is used which goes in the vagina or rectum, depending on the scan. If this is needed, the person doing the scan will talk with you about it first.

The sonographer or operator undertaking the exam may not be able to provide you with the results of the exam at the appointment and they may be sent to your doctor following the exam.

The British Medical Ultrasound Society has some very useful information targeted at patients here.


  • Ultrasound is not thought have any significant side effects.

  • However, it is not right for all conditions.

  • It is not recommended that ultrasound is used without a medical reason.

  • People carrying out ultrasound imaging will be trained to keep risks such as thermal heating as low as possible.

  • Ultrasound should not be used by an untrained individual.

  • If you have any more questions please ask a healthcare professional.