Ultrasound also called sonography or ultrasonography is a diagnostic imaging method that uses high-frequency sound waves to produce images of various structures in your body. The images provide important information for diagnostic and therapeutic purposes.
Typically, ultrasonography procedures use a machine outside your body. High-frequency sound waves are transmitted via a transducer probe. These waves pass into your body and are reflected by the different organs present in your body. The machine uses the ‘time taken for the waves to reflect to produce images.
Ultrasound does have certain limitations. Sound waves do not travel well through air or bone making ultrasound ineffective in assessing tissues and organs that have gas in them or are covered under bones (brain). To determine any abnormality in such organs, your doctor might recommend other diagnostic tests like CT scans or MRI scans.
In this article, we will go through some details about diagnostic ultrasound and its common uses.
Ultrasound is used for a lot of reasons, including:
- During pregnancy – ultrasonography is used extensively during pregnancy to monitor your uterus, ovaries, and the development of your baby. It can be used to determine the age of your pregnancy, the sex (gender) of your baby, and/or different anomalies of your pregnancy.
- Suspicion of gallbladder disease – gallbladder is a pouch-like organ next to your liver. People who have gallstones can be diagnosed easily using ultrasound.
- Evaluation of cardiovascular diseases – your doctor may recommend you to get an ultrasound to check your vascular blood flow and to diagnose other cardiovascular problems
- Guided ultrasound – ultrasound is commonly used to guide needles or instruments for different procedures like amniocentesis and biopsies (taking tissue samples).
- Breast lump – lump(s) in the breast can be assessed by the use of ultrasound. It can indicate the presence of abnormal tissue in your breast.
- Suspicion of thyroid diseases
- Genitourinary disease – examination of kidney, bladder, testes, and prostate gland
- Assess inflammation or damage to your joint (synovitis)
- If you have metabolic bone disease
- General well-being test
Diagnostic ultrasound is preferred in a lot of situations as it is a very safe procedure. It uses low-power sound waves that have no known risk.
Generally, ultrasonography procedures require no special preparation. In a few conditions your doctor would advise you to do the following:
- Avoid eating or drinking a few hours before your scan – this is advised in scans like gallbladder scans.
- Keeping a full bladder before your scan – in pelvic ultrasound scans your doctor would ask to have a full bladder. You should not urinate until the end of your exam or when told by your doctor.
- Special advice for children – depending on the type of scan and the age of your child, your doctor will advise you on certain preparations or precautions.
You will also need to change into a hospital gown before your scan or be asked to wear loose clothing. You would be required to remove clothing from the specific area that is going to be scanned. You should also leave valuable jewellery at home as you may be asked to take them off before your exam.
the procedure starts with you lying flat on a table. Your doctor will then apply gel to the skin over the area that will be examined. The Gel acts as a conductor for sound waves by preventing the formation of air pockets and decreasing the insulator effect of the skin. The gel is water-based and is very easy to remove.
Your doctor or sonographer (trained technician) will then place the transducer against the skin where the gel was applied and move gently around the area. The transducer works by sending and then receiving sound waves, thus producing an image on the screen.
In some cases, an ultrasound will be performed inside your body. The transducer is attached to a probe which is inserted into your body through natural openings. These ultrasounds are:
- Transoesophageal echocardiogram – the probe is inserted through the mouth and into the oesophagus to take images of the heart.
- Transrectal ultrasound – the probe is placed in your rectum to obtain images of the surrounding organs.
- Transvaginal ultrasound – a special transducer is inserted through the vaginal opening in order to get images of the uterus and ovaries.
Ultrasound is a pain-free procedure; however, you might feel a cold sensation during gel application or the moving of the transducer. Having a full bladder might make you a little uncomfortable.
Generally, an ultrasound will take around 30 to 60 minutes to complete.
After your ultrasound, the gel will be cleaned with a cloth. You can then put your clothes back and go home. You should urinate only when your exam is done. You can carry out your normal activities after your exam.
During an ultrasound, images are being taken. These images are ready in about 30 minutes. A radiologist (specialised doctor to interpret radiological scans). The radiologist will then send the reports to your doctor who will then discuss these results with you. You may also get the images to take along.
As discussed above, an ultrasound can confirm the diagnosis of several conditions. Your doctor will inform you if everything is working appropriately or if you would need some form of treatment.
Adam A, et al., eds. Grainger & Allison’s Diagnostic Radiology: A Textbook of Medical Imaging. 6th ed. Philadelphia, Pa.: Churchill Livingstone Elsevier; 2015. https://www.clinicalkey.com. Accessed Jan. 8, 2018
Ultrasound: What is general ultrasound imaging? RadiologyInfo.org. http://www.radiologyinfo.org/en/info.cfm?pg=genus. Accessed Jan. 8, 2018.
AskMayoExpert. Imaging for musculoskeletal arthritides and metabolic bone disease. Mayo Foundation for Medical Education and Research; 2017.Atwell TD (expert opinion). Mayo Clinic, Rochester, Minn. Feb. 6, 2018.
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