Ultrasound is a non-invasive procedure that uses sound waves, not radiation, to assess body structures. A technologist applies gel over the area of interest and presses an ultrasound transducer onto the skin. The transducer generates sound waves and detects the echo produced in the body. A computer interprets the echo and provides detailed images for the radiologist.
Ultrasound imaging is also called diagnostic sonography, and your ultrasound technician may be called a diagnostic sonographer. The difference between the terms is simple: ultrasound is the process of using equipment to take sonograms (images), while sonography is the use of these images for diagnostic purposes.
For you as a patient, the human touch of your sonographer can dramatically impact your ultrasound experience. That’s why Insight Medical Imaging travels across the country, from British Columbia to Nova Scotia, to recruit the best diagnostic medical sonographers to perform our exams.
Common Ultrasound Procedures
The most familiar form of ultrasound imaging is an obstetric procedure for pregnant women. While many other evaluations use ultrasound, obstetric imaging is so well-known, it is top of mind in almost every patient.
Ultrasound is also commonly used to examine the:
- Musculoskeletal tendons and ligaments (joints)
- Renal system (kidneys, ureters, bladder)
- Soft tissue
- Testicles (scrotum)
- Vascular structures
What to Expect During an Ultrasound
- When examining certain body parts, we may ask you to change into a gown to allow easier access. Sometimes our technologists can rearrange your clothing to expose a body part so you do not have to change.
- The technologist will apply a warm, hypoallergenic ultrasound gel and move the transducer (probe) around the area of interest with moderate pressure to obtain images.
- This pressure should not cause any pain. Please inform your technologist of any discomfort.
- The technologist may ask you to change positions – on your side, sitting, or standing – so they can obtain the best possible images.
- After we capture all necessary images, one of our radiologists will review the results and send a detailed report to your doctor. We try our best to send the report as soon as possible, usually within one business day.
What Substance Is Put on Your Body During an Ultrasound?
Before your sonographer begins the scan, they will apply a warm lubricating substance to the area of interest. This substance is known as ultrasound transmission gel.
During your exam, the ultrasound probe is pushed against this gel to help capture images. The gel is hypoallergenic, non-irritating, and non-sensitizing, so you are unlikely to have a reaction.
The gel reduces acoustic impedance and conducts the sound waves between the probe and your body. Ultimately, it creates a bridge between the probe and your tissue, allowing for clear transmission.
Sound Waves vs. Radiation
Most forms of medical imaging lead to some level of radiation exposure, either through injection or external contact. Ultrasound scans differ because they use high-frequency sound waves to generate images that are then used for diagnosis.
If you are planning on having children you must be completely transparent with your doctor before scheduling an imaging exam, as unnecessary radiation exposure during pregnancy or while breastfeeding can have a lifelong impact.
If your physician can avoid exposing you to unnecessary radiation and still reach a conclusive diagnosis, they will likely refer you for an alternative form of imaging, such as ultrasound or magnetic resonance (MRI).
Ultrasound Limitations from Tissue Composition
The three factors that significantly impact ultrasound effectiveness and visibility are:
- Density – Sound waves cannot pass through hard, dense objects, such as bone or calcifications.
- Gas – Gas in the gastrointestinal (GI) system and bowel is a strong sound-wave reflector that negatively impacts transmission and can create reverberation artifacts in diagnostic imaging.
- Depth – The deeper something is inside your body, the less likely ultrasound waves will penetrate the tissue with the same efficiency.
Why is Drinking Water Vital for Certain Ultrasound Exams?
Some ultrasound exams require special preparation, such as drinking water before the appointment. While this may seem like an odd request, it is very important.
We instruct patients to drink four (8oz) glasses of water, finishing all four glasses 60 minutes before their appointment, and not to urinate. Drinking this amount of water forces your urinary bladder to expand, pressing the uterus up and moving other organs, such as the bowel, out of the way.
If you do not drink the correct amount of water or you urinate before the scan, your bladder will shrink and contract, making it difficult to examine the walls.
The water inside your expanded bladder also allows the high-frequency sound waves to penetrate deeper into your abdomen, beyond the rigid, bony pelvic structure. Essentially, the water moves your internal organs into a better position and provides a clear window for higher-quality imaging.
Other ultrasound exams require that you fast (do not eat) for a certain period before your scan. Fasting ensures there is no digesting matter inside your stomach at the time of your scan. Digesting food in your stomach is dense, so sound waves have a harder time penetrating and creating a clear image.
Discomfort from Ultrasound Exam Prep
We understand it can be difficult and uncomfortable to fast or to drink a large volume of water without relief. That’s why we do our best to get you in on time for your exam and, if possible, perform parts of the exam that require a full bladder first.
If you are in an uncomfortable amount of pain from drinking water, tell our receptionists or sonographers. Sometimes you can release a little urine before your exam after consulting with our staff.
Other times, your sonographer will try to capture specific photos at the beginning of the appointment and then allow you to go to the washroom for a little relief before finishing the rest of the exam.
If you have experienced discomfort or pain from a full bladder in the past, there is a high likelihood it was from drinking water too early or continuing to drink right up until your exam.
We suggest that you drink all four (8oz) glasses of water in a 30-minute window. This window should start 90 minutes before your appointment (so you finish drinking 60 minutes before your exam). This has proven to be the best compromise for patient comfort while still allowing us to capture high-quality images.
Certain ultrasound exams for women may require additional imaging in the form of an internal exam. These scans are performed transvaginally and give our radiologists more detailed images for diagnosis.
Typically, we conduct internal ultrasounds on women who have a pelvic, renal, obstetric, or combined abdomen/pelvic appointment.
To make this portion of the exam more comfortable, patients can request female sonographers at the time of booking. It is important to understand that because of the volume of exams and staffing limitations, we cannot always meet this request.
However, if a male sonographer must perform your internal ultrasound, we ensure that a female colleague is in the room with you during the scan to chaperon.
Biopsy Needle Guidance with Ultrasound
Ultrasound imaging is highly useful for visualizing musculoskeletal anatomy and guiding interventional radiology procedures, such as biopsy, in real time.
Conventional guidance with fluoroscopy or CT imaging relies on short exposure to ionizing radiation. Ultrasound guidance uses sound waves instead of ionizing radiation.
Benefits of Ultrasound Guidance over Traditional Guidance
Ultrasound guidance offers the following benefits:
- Zero exposure to ionizing radiation
- Longer insertion window
- Improved needle placement accuracy
- Reduced risk of injury to neighbouring anatomy
- Real-time confirmation of procedural success
Insight Medical Imaging uses ultrasound guidance for many intervention procedures, such as core and aspiration biopsy and wire localization, as well as pain management injections. Learn more about ultrasound guided biopsy, including preparation, how the exam is commonly performed, what you can expect after the injection, and more.
Planning your next appointment? Learn more about ultrasound exam preparation and find the clinic most convenient for you.