ULTRASOUND: ALL YOU NEED TO KNOW

What is an ultrasound?

Ultrasound, also called sonography or ultrasonography, is a non-invasive imaging method that uses high-intensity sound waves to produce images of structures within the body. The ultrasound examinations can be carried out either using an ultrasound device outside the body or by placing a small device inside the body, depending upon the part of the body to be diagnosed. An ultrasound picture obtained from the procedure is called a sonogram which provides valuable diagnostic information and can assist in selecting suitable treatments for various diseases and health conditions. 

How does an ultrasound work?

The ultrasound image is produced based on the reflection of the waves from the body structures. The sound waves are emitted and received from a small, hand-held probe or transducer. The transducer directs high-frequency sound waves into the body that are reflected back by the tissues along the path of the beam. The strength (amplitude) of the sound signal and the time it takes for the wave to travel through the body provide the information necessary to produce an image. The reflected sounds, or echoes, are recorded to create an image visible on a monitor. 

What are the different kinds of ultrasounds?

There are three main categories of ultrasound imaging:

• Pregnancy ultrasound (prenatal ultrasound)

• Diagnostic ultrasound (clinical conditions)

• Ultrasound guidance for procedures.

Pregnancy ultrasound - Healthcare providers often use ultrasound (often called prenatal or obstetric ultrasound) to confirm pregnancy, estimate gestational age, monitor fetal growth, and check the developmental parameters of the baby during pregnancy.

Diagnostic ultrasound - Doctors use diagnostic ultrasounds to view internal organs for their physiology and proper functioning. Diagnostic ultrasound can be carried out for the abdominal cavity, breasts, kidneys, pelvis, rectum, and more.

Ultrasound guidance for procedures - Ultrasound techniques can also be used to perform certain medical procedures precisely. The most common use of ultrasound is to guide needle placement to sample fluid or tissue from tendons, joints, muscles, cysts or fluid collections, soft-tissue masses, Organs (liver, kidney, or prostate), and transplant organs (liver, kidney, or pancreas).

Examples of other procedures that may require ultrasound guidance include embryo transfer for in vitro fertilization, nerve blocks, confirming the placement of an IUD (intrauterine device) after insertion, and lesion localization procedures.

How to prepare for an ultrasound scan?

Before an ultrasound scan, a few instructions must be followed to help improve the clarity and quality of the sonogram. You may be advised to:

• Drink water and not go to the toilet until after the scan – it is generally recommended before a scan of your unborn baby or your pelvic area.

• Avoid eating or drinking for several hours before the scan – This is directed before scanning the digestive system, including the liver and gallbladder.

• Change into suitable clothing - Depending on the area of your body to be examined, the hospital may ask you to remove some clothing and wear a hospital gown.

• Medication before the scan - A sedative may be needed to help you relax which is generally administered through a small tube into the back of the hand or the arm. In some cases, an injection of a harmless substance called a contrast agent may also be given before the scan to enhance the clarity of the images.

What happens during an ultrasound scan?

Most ultrasound scans last between 15 and 45 minutes and can be done in a hospital radiology department; either by a doctor, radiographer, or sonographer. There are different kinds of ultrasound scans, depending on the body part to be scanned and the purpose of diagnosis; three main types of ultrasound scanning are:

• External ultrasound scan – the probe is moved over the skin.

• Internal ultrasound scan – the probe is inserted into the body.

• Endoscopic ultrasound scan – the probe is attached to a long, thin, flexible tube (an endoscope) and passed further into the body.

What are the Risks and Concerns associated with the Ultrasound scan?

Ultrasound procedures are a safe and reliable technique with no evidenced risk factors as they use low-power sound waves, unlike other scans, such as CT scans, and do not involve radiation exposure. Though the external and internal ultrasound scans do not exhibit any side effects and are generally painless, one may experience slight discomfort as the probe is pressed over the skin or inserted into the body. Furthermore, internal ultrasound may impose a small risk of complications, such as internal bleeding. However, in the case of endoscopic ultrasounds, one can be a bit more uncomfortable and may suffer from temporary side effects, such as a sore throat or bloating. 

Though ultrasound is a valuable tool, it has limitations. The sound waves produced by the ultrasound machine do not travel well through air or bone, hence are not effective at imaging body parts that have gas in them or are covered by bony structures, such as the lungs or brain. In addition, an ultrasound cannot perform diagnostic analysis for the organs located very deep in the human body. For such a diagnosis, your healthcare provider may order other imaging tests, such as CT or MRI scans or X-rays.