1) What is an Ultrasound?
Ultrasound scan, also called sonogram, diagnostic sonography, and ultrasonography, is a machine that utilizes high frequency sound waves to generate an image of the inside of the body. It is often used to detect problems in the liver, kidney, abdomen, or the heart and is helpful to surgeons carrying out biopsies. Ultrasound is noninvasive—not penetrating the skin or body openings—and diagnostic—determines what disease is present. The sound waves used in an ultrasound cannot be heard by human ear and are safe. Additionally, as ultrasound images are captured in real-time, they can display the internal organ’s structure and movement in the body, as well as the blood flowing through blood vessels.
There are many types of ultrasound imaging: the conventional ultrasound, the three-dimensional ultrasound, the four-dimensional ultrasound, and the Doppler ultrasound. While a conventional ultrasound shows images in thin, flat sections of the body, 3-D ultrasound formats the sound wave data into 3-D images, and 4-D ultrasound formats the 3-D ultrasound in motion. Furthermore, a Doppler ultrasound, part of an ultrasound examination, evaluates blood flow through a blood vessel. These Doppler measurements are then converted into an array of colors (Color Doppler), provide greater detail of blood flow (Power Doppler), or visualized graphically in terms of distance traveled per unit of time (Spectral Doppler).
Today, ultrasound is commonly used in medicine as health care professionals utilize sonography for diagnosis or treatment. It is beneficial for a variety of conditions, such as:
1) Obstetric (pregnancy related) uses (viewing the uterus and fetus during pregnancy, detecting congenital heart disease, demonstrating if fetus is of expected size, noting the date of conception, revealing multiple pregnancy, identifying fetal abnormalities, and using amniocentesis)
2) Non-obstetric uses (scanning kidneys, pancreas, liver, thyroid gland, breasts, etc., examining internal organs, and reviewing outcome of procedures)
Ultrasonography uses ultrasounds that travel through soft tissues and fluids and bounces back off dense surfaces. During the ultrasound examination, a transducer—that views the target organ and generate images—is used. This machine emits sound and detects the returning echoes when it is placed on or over the studied body part. The ultrasound waves easily pass through fluids and soft tissues, while they are unable to penetrate bone or gas. Likewise, the denser the object the ultrasound hits, the more of it bounces/echoes back. This bouncing back—echo—creates the ultrasound image features with varying shades of gray corresponding with different levels of density. This is similar to the principles of sonar developed for ships at sea. The echoes produced as sound passes through an object can identify distance, size, and the shape of the objects inside. Then the computers in the ultrasound machine analyze these echoes, transforming them into moving images of the organ or tissue being examined.
Additionally, there are three basic procedures of specialized ultrasound, including:
- Echocardiography, a specialized diagnostic technique of an ultrasound, examines the heart’s actions and functions. This type of ultrasound detects structural and some functional abnormalities of the heart wall, valves, and large blood vessels. Because abnormal opening and closing of valves differ from normal heart movement patterns, an echocardiography is especially valuable for studying disorders of the heart valves. It can also measure the blood flow across the valves.
- Other diagnostic uses of echocardiography include:
i. detecting swellings caused by weakening of the heart wall or the blood vessel walls (aneurysms)
ii. detecting congenital heart disease
iii. finding problems with the large blood vessels
iv. finding the presence of a blood clot in one of the chambers of the heart
v. identifying any enlargement or damage of the heart muscle—cardiomyopathy
vi. recognizing Pericarditis—a condition in which the pericardium, the membrane that covers the heart, becomes inflamed
2) Doppler Echocardiography: A recently developed ultrasound technique, the Doppler echocardiography indirectly measures the blood’s flow velocity as it passes through the heart. It examines malfunctioning valves in aortic stenosis (narrowing of the aortic valve opening) or mitral insufficiency (failure of the mitral heart valve to close properly) and assess congenital heart disease patients.
3) Ultrasound for Biopsy: Ultrasound with fine-needle biopsy (inserting a very thin and hollow needle into an organ to remove tissue or fluid for examination) is a common type of ultrasound use. The ultrasound’s real-time, moving image is valuable in guiding the needle accurately to a specific spot.
A sonographer is the medical professional performing ultrasound scans. Usually, the sonographer holds a transducer placed on the surface of the patient’s body. At other times, transducers (endovaginal trasducer, endorectal transducer, and transesophageal trasducer) are placed internally for more detailed images. Radiologists, cardiologists, or other medical specialists then interpret the scans/images.
2) What happens during an Ultrasound?
For most ultrasound exams, you will lay face-up on an examination table that tilts or moves. A clear water-based gel will be applied to the target area of the body to eliminate air pockets between the transducer and the surface of the area. This will help the transducer make secure contact with the body so the sound waves will smoothly pass into your body. Then, the sonographer presses the transducer firmly against the skin in various locations, scanning the area of interest or angling the sound beam from a farther location to better see an area of concern.
Note: The same transducer will be used to perform a Doppler sonography.
Generally, an ultrasound examination is complete within 30 minutes to an hour. Then, after the examination, you may be asked to dress and wait while the radiologists review your ultrasound images.
In some ultrasound scans, the transducer is inserted into a natural opening in the body with a probe attached to it. For example, in a transvaginal ultrasound, the transducer will be inserted into a woman’s vagina to examine the uterus and ovaries. In a transrectal ultrasound, it will be inserted into a man’s rectum to examine the prostate. In a transesophageal echocardiogram, it will be inserted into the esophagus to take images of the heart.
3) What should I do to prepare for an Ultrasound?
To prepare for an Ultrasound scan, wear comfortable and loose-fitting clothing if the center does not provide gowns to wear during the procedure. Usually, you will be asked to remove all jewelry and clothing in the area to be scanned.
Specific type of examination will have different preparations. For some examinations, doctors may inform you not to eat or drink for a maximum of 12 hours before your appointment. For other examinations, doctors may instruct you to drink six or more glasses of water two hours prior to your scan. At such conditions, avoid urinating so that your bladder is full when the examination begins.
4) What are the risks?
Generally, for a standard ultrasound scan, there are no harmful effects on humans.
Since most ultrasound scanning is noninvasive (no injections or needles), it is usually painless. Unlike other imaging methods, ultrasound is easy-to-use, less expensive, and does not use any ionizing radiation. As a result, it is the preferred imaging modality for diagnosing and monitoring pregnant women with their unborn babies.
5) Are there any after effects?
Generally, ultrasound scanning is quick, easy, and painless. If scanning over a tender area of your body, you may feel pressure or minor pain from the transducer. If the transducer is inserted into an opening of the body, you may also feel minimal discomfort. If a Doppler ultrasound is performed, you may hear pulse-like sounds changing in pitch as the blood flow is monitored and measured. Nevertheless, after the gel is wiped off after the completion of the imaging, you may immediately resume your normal activities without difficulty.
6) What happens with the Ultrasound scan results?
A radiologist who is specifically trained to interpret radiology examinations will analyze the images. Then your primary care physicians or the physician that referred the exam to you will receive a signed report of the images. They will be the ones to share the results with you. In some other cases, the radiologist may review the results with you at the end of your examination.
Often, follow-up examinations will be necessary. In such cases, your doctor will explain the exact reason for requesting another exam. Some reasons include: to clarify questionable findings, to detect any change in a known abnormality over time, or to assess the effectiveness of the treatment.