Ultrasound is a non-invasive medical imaging technique that uses high-frequency sound waves to create images of internal body structures. This method allows healthcare professionals to visualize organs, tissues, and blood flow without radiation. It provides real-time information, making it a versatile tool in many medical fields.
How Ultrasound Technology Works
Ultrasound imaging uses sound waves to map out an area. A transducer, or probe, emits high-frequency sound waves and listens for the echoes that bounce back. These sound waves travel through the body, reflecting off boundaries between different tissues. The transducer receives these echoes, and their return time and intensity provide information about the structures’ size, shape, and consistency. A computer then interprets this data in real-time to generate a two-dimensional image, where fluid-filled cysts appear dark and solid structures appear lighter.
Common Diagnostic Ultrasounds
Diagnostic ultrasounds are used across various medical specialties to visualize internal body parts and identify conditions. Each type targets specific areas or functions, offering unique insights.
Obstetric Ultrasounds
Obstetric ultrasounds are routinely performed during pregnancy to monitor the health and development of the unborn baby. These scans confirm the due date, detect multiple pregnancies, and assess fetal growth and anatomy. They do not expose the mother or child to radiation. Ultrasounds are commonly performed between 8 and 13 weeks and again between 18 and 20 weeks of gestation.
Abdominal and Pelvic Ultrasounds
Abdominal ultrasounds examine organs within the abdomen, including the liver, gallbladder, pancreas, spleen, and kidneys. This scan helps locate the source of abdominal pain, assess abnormal enlargement, or detect issues like kidney stones or tumors. Pelvic ultrasounds focus on organs in the pelvic area, such as the uterus, ovaries, and bladder in women, and the bladder and prostate in men. These can identify conditions like ovarian cysts, uterine fibroids, or prostate issues.
Vascular Ultrasounds
Vascular ultrasounds, often called Doppler ultrasounds, assess blood flow through major arteries and veins. They detect blockages, narrowing of blood vessels, or blood clots, such as deep vein thrombosis (DVT).
Cardiac Ultrasounds
Cardiac ultrasounds, also known as echocardiograms, produce images of the heart’s structure and function. They visualize the heart’s chambers, valves, walls, and blood vessels, assisting in the detection of valve issues, fluid buildup, or heart muscle problems.
Musculoskeletal Ultrasounds
Musculoskeletal ultrasounds examine muscles, tendons, ligaments, and joints. They help diagnose injuries like tendon tears, inflammation, sprains, or strains, and can guide injections into joints.
Breast Ultrasounds
Breast ultrasounds investigate lumps or changes in breast tissue, often as a follow-up to a mammogram, especially in women with dense breast tissue. They help distinguish between fluid-filled cysts and solid masses.
Thyroid Ultrasounds
Thyroid ultrasounds check for nodules, swelling, or irregularities in the thyroid gland, located in the neck. This scan evaluates the gland’s size, shape, and condition.
Specialized and Therapeutic Ultrasound Applications
Beyond standard diagnostic imaging, ultrasound technology offers specialized diagnostic techniques and therapeutic uses. These applications provide enhanced visualization or direct treatment capabilities.
3D and 4D Ultrasounds
Three-dimensional (3D) and four-dimensional (4D) ultrasounds provide enhanced views. A 3D ultrasound creates a static, multi-dimensional picture of internal structures. A 4D ultrasound displays these 3D images in real-time motion, often used in obstetrics to observe fetal movements.
Elastography
Elastography is a specialized diagnostic technique that uses ultrasound to assess tissue stiffness. This method is useful in evaluating conditions like liver fibrosis or characterizing breast lesions, as changes in tissue stiffness can indicate disease.
Therapeutic Ultrasounds (HIFU)
Therapeutic ultrasounds use focused sound waves for treatment, not imaging. High-Intensity Focused Ultrasound (HIFU) is a non-invasive modality that uses highly focused waves to heat and destroy targeted tissues, such as tumors or uterine fibroids, without surgical incisions. It concentrates energy precisely at the intended target to cause cellular destruction.
Preparing for an Ultrasound
Preparation for an ultrasound varies by scan type; always follow facility instructions.
For certain abdominal ultrasounds, such as those of the gallbladder, patients may fast for several hours to improve image clarity by reducing gas and intestinal activity. For pelvic ultrasounds, patients often drink several glasses of water for a full bladder, which helps visualize pelvic structures.
Patients should wear loose, comfortable clothing and may change into a hospital gown. Remove all jewelry or metal objects from the scanned area, as these can interfere with imaging. While most ultrasounds are painless, some, like those requiring a full bladder, might cause mild discomfort.