Different Types of Ultrasonography Tests: Uses, Benefits, Safety and More

Ultrasonography, commonly called ultrasound, sonography or USG, is one of the most widely used medical imaging tests. It uses high-frequency sound waves to create real-time images of organs, tissues, blood vessels and other structures inside the body. Unlike X-rays and CT scans, ultrasound does not use ionising radiation, which is one reason it is widely used during pregnancy and for repeated examinations when medically necessary.

One of the biggest advantages of ultrasound is its versatility. A doctor may recommend an abdominal ultrasound to examine the liver or gallbladder, a pelvic ultrasound to assess the uterus and ovaries, a Doppler ultrasound to study blood flow, or a musculoskeletal ultrasound to evaluate tendons, muscles and ligaments.

There is no single “best” ultrasound for everyone. The appropriate type depends on which part of the body needs to be examined and what your doctor is looking for.

What Is Ultrasonography?

Ultrasonography is an imaging technique that uses sound waves above the range of normal human hearing. During the examination, a device called a transducer or probe sends sound waves into the body. These waves bounce back differently from different tissues. The ultrasound machine processes the returning echoes and produces images on a screen.

Most external ultrasound examinations involve applying a water-based gel to the skin and moving the probe over the area being examined. Depending on the examination, the probe may also be designed for internal examinations, such as transvaginal or transrectal ultrasound.

Ultrasound can be used to:

• Examine internal organs
• Detect cysts, stones and some masses
• Assess pregnancy and fetal development
• Examine the thyroid, breast and prostate
• Evaluate muscles, tendons and ligaments
• Assess blood vessels and blood flow
• Help detect blood clots
• Guide certain biopsies and other procedures
• Monitor some medical conditions over time

Stanford Health Care lists a wide range of ultrasound examinations, including abdominal, breast, obstetric, pelvic, musculoskeletal, thyroid, vascular, scrotal and Doppler studies.

What Are the Different Types of Ultrasonography Tests?

There are many types of sonography, and they can be classified either by the body part being examined or by the ultrasound technology being used.

1. Abdominal Ultrasound

An abdominal ultrasound examines organs and structures within the abdomen.

It may be used to assess the:

• Liver
• Gallbladder
• Pancreas
• Spleen
• Kidneys
• Urinary bladder
• Abdominal blood vessels

Doctors commonly recommend abdominal ultrasound when investigating abdominal pain, gallstones, certain liver abnormalities, kidney problems, unexplained organ enlargement and other conditions.

For example, ultrasound is often an appropriate first imaging test when gallbladder disease is suspected because it can detect gallstones and evaluate the gallbladder without radiation.

2. Pelvic Ultrasound

A pelvic ultrasound examines structures in the lower abdomen and pelvis.

It may assess the:

• Uterus
• Ovaries
• Cervix
• Urinary bladder
• Prostate in men
• Other pelvic structures

Pelvic ultrasound can help investigate pelvic pain, abnormal bleeding, ovarian cysts, fibroids and other reproductive-system concerns.

It can be performed transabdominally, with the probe placed on the lower abdomen, or transvaginally, using a specially designed probe inserted into the vagina.

3. Obstetric or Pregnancy Ultrasound

Obstetric ultrasound is used to monitor pregnancy and assess the developing fetus.

Depending on the stage of pregnancy and clinical requirement, ultrasound can help assess:

• Gestational age
• Fetal growth
• Fetal position
• Placental position
• Number of fetuses
• Certain structural abnormalities
• Fetal wellbeing

Ultrasound plays an important role in pregnancy because it provides real-time imaging without ionising radiation.

4. Breast Ultrasound

Breast ultrasound uses sound waves to examine breast tissue.

It may be used to:

• Evaluate a breast lump
• Distinguish fluid-filled cysts from solid lesions
• Further investigate an abnormality found during another examination
• Assess certain breast symptoms

Ultrasound may complement mammography rather than automatically replace it. The appropriate test depends on factors such as age, symptoms and the clinical question.

5. Thyroid Ultrasound

A thyroid ultrasound provides detailed images of the thyroid gland in the neck.

It can help evaluate:

• Thyroid nodules
• Cysts
• Changes in thyroid size
• Certain structural abnormalities
• Lymph nodes in the neck

It is also frequently used to help guide a needle biopsy when tissue sampling is required.

6. Vascular Ultrasound and Doppler

Vascular ultrasound examines blood vessels, while Doppler technology provides information about blood movement.

It may be used to evaluate:

• Arteries
• Veins
• Blood flow
• Narrowing of vessels
• Blockages
• Blood clots
• Some aneurysms

Doppler ultrasound is particularly useful because conventional ultrasound primarily shows anatomy, whereas Doppler can assess the movement and flow of blood.

7. Musculoskeletal Ultrasound

Musculoskeletal ultrasound examines soft tissues such as:

• Muscles
• Tendons
• Ligaments
• Joints
• Some superficial nerves
• Certain soft-tissue abnormalities

It can be useful for evaluating tendon injuries, muscle tears, inflammation and some superficial lumps. Ultrasound also has the advantage of allowing certain structures to be assessed dynamically while the patient moves.

8. Echocardiography

An echocardiogram is a specialised ultrasound examination of the heart.

It can provide information about:

• Heart chambers
• Heart valves
• Heart muscle
• Heart function
• Blood flow through the heart

Fetal echocardiography examines the developing baby’s heart, while paediatric echocardiography evaluates the hearts of children.

9. 3D and 4D Ultrasound

Traditional ultrasound generally produces two-dimensional images. 3D ultrasound processes ultrasound information to create three-dimensional images, while 4D ultrasound adds movement or real-time imaging to the 3D information.

These technologies may have specific clinical applications, although not every patient requires 3D or 4D imaging.

10. Transvaginal and Transrectal Ultrasound

Some organs are difficult to evaluate adequately from outside the body. In such situations, a specially designed ultrasound probe may be used internally.

A transvaginal ultrasound provides detailed imaging of the uterus, ovaries, cervix and other pelvic structures. A transrectal ultrasound may be used to examine the prostate and surrounding structures.

What Are the Three Types of Sonography?

There isn’t one universally accepted classification that says there are only three types of sonography. However, if you are referring to the three broad imaging formats, they are commonly described as:

1. 2D or conventional ultrasound – produces standard two-dimensional images.
2. Doppler ultrasound – evaluates movement, particularly blood flow.
3. 3D/4D ultrasound – produces three-dimensional images, with 4D adding real-time movement.

There are also numerous ultrasound examinations classified according to the body part being studied, such as abdominal, breast, thyroid, obstetric and musculoskeletal ultrasound.

What Is a Type 2 Ultrasound?

The term “Type 2 ultrasound” is not a universally standard medical classification for ultrasound examinations.

In pregnancy, however, people sometimes use “Type 2 ultrasound” when they actually mean a Level II ultrasound, also called a targeted ultrasound, detailed anatomy scan or anomaly scan.

A Level II scan provides a more detailed assessment of fetal anatomy than a routine pregnancy ultrasound and may be recommended when there is a specific clinical indication or when a detailed anatomical assessment is needed.

If your prescription says “Type 2 ultrasound,” it is best to confirm the exact examination with your doctor or diagnostic centre because terminology can vary between providers.

What Is the Difference Between USG and Sonography?

There is essentially no difference between USG and sonography.

USG is an abbreviation commonly used for ultrasonography or ultrasound scan, while sonography is another term for the same imaging technology.

For example:

• USG abdomen = abdominal ultrasound
• USG pelvis = pelvic ultrasound
• Sonography abdomen = abdominal ultrasound
• Ultrasound thyroid = thyroid sonography

The exact terminology on a prescription may vary, but the underlying imaging technique is generally the same.

What Is the Difference Between USG and Doppler?

A conventional ultrasound primarily creates images of anatomical structures. Doppler is a specialised ultrasound technique that evaluates movement, particularly blood flow.

For example, a routine ultrasound may show the structure of a blood vessel, while Doppler can provide information about blood moving through that vessel.

Doppler techniques include colour Doppler, power Doppler and spectral Doppler, among others. Colour Doppler can display information about the speed and direction of blood flow using colour mapping.

Therefore, Doppler is not a completely separate imaging technology from ultrasound. Rather, Doppler is an advanced application of ultrasound.

Which Is Better, USG or MRI?

Neither is universally better. Ultrasound and MRI answer different medical questions.

Ultrasound is often preferred when:

• Real-time imaging is useful
• Pregnancy needs to be assessed
• Gallstones or certain abdominal conditions are suspected
• Blood flow needs to be evaluated
• Superficial soft tissues need examination
• A quick, accessible examination is appropriate

MRI may be preferred when detailed images of deeper soft tissues are required or when ultrasound cannot provide sufficient information.

For example, if an initial ultrasound does not provide a clear answer about a particular soft-tissue problem, MRI may be recommended for more detailed evaluation.

So the question should not be “Which is better?” but rather “Which test is more appropriate for this particular medical problem?”

Which Type of Sonography Is Best?

There is no single best type of sonography.

The best examination is the one that answers the specific clinical question.

For example:

Your doctor may sometimes recommend more than one imaging modality depending on your symptoms and initial findings.

Which Is Better: CT Scan or Sonography?

Again, neither is automatically better.

Ultrasound has important advantages because it does not use ionising radiation and can provide real-time imaging. CT, on the other hand, uses X-rays and can produce detailed cross-sectional images of the body.

Ultrasound may be preferred for conditions such as gallstones, pregnancy, superficial soft-tissue problems and certain vascular conditions.

CT may be more appropriate when doctors need rapid, detailed cross-sectional imaging, particularly for certain emergencies, trauma or conditions involving areas that ultrasound cannot adequately visualise.

In some situations, ultrasound is the first test and CT or MRI is used if the ultrasound findings are inconclusive or if more detailed imaging is required.

What Are the Disadvantages of Sonography?

Although ultrasound is highly useful, it has limitations.

Some disadvantages include:

• Limited penetration: Sound waves do not pass easily through bone or air, making some organs difficult to examine.
• Operator dependence: The quality of the examination depends partly on the skill and experience of the person performing it.
• Body habitus: Excess body tissue can sometimes reduce image quality.
• Limited field of view: Ultrasound may not provide the same broad anatomical overview as CT or MRI.
• Some abnormalities may be difficult to detect: Very small, deep or complex abnormalities may require another imaging method.
• Patient discomfort in some examinations: Internal examinations may feel uncomfortable.
• Gas can interfere with imaging: Gas in the bowel can make certain abdominal structures difficult to visualise.

These limitations do not make ultrasound inferior. They simply mean that the correct imaging test depends on the clinical situation.

Is Sonography Risky?

Diagnostic sonography is generally considered very safe when appropriately performed.

Unlike X-rays and CT scans, ultrasound does not use ionising radiation. Healthdirect describes ultrasound as safe and suitable for use during pregnancy, while Cleveland Clinic notes that research has largely shown ultrasound technology to be safe when appropriately used.

The American Institute of Ultrasound in Medicine recommends prudent use of diagnostic ultrasound and following the ALARA principle — as low as reasonably achievable — meaning exposure should be kept to the minimum necessary to obtain the required diagnostic information.

How Many Times Is an Ultrasound Safe?

There is no fixed lifetime limit such as “you can have only 10 or 20 ultrasounds.”

When an ultrasound is medically indicated, it can be repeated when necessary. This is particularly important when doctors need to monitor a condition or follow pregnancy.

However, “safe” does not mean that unnecessary scans should be performed repeatedly without a reason. AIUM recommends minimising exposure time and using ultrasound at appropriate settings to obtain the required diagnostic information.

For pregnancy especially, medically indicated ultrasound examinations should be performed according to the advice of the treating obstetrician or healthcare professional.

Can an Ultrasound Give Wrong Results?

An ultrasound can sometimes produce inconclusive, limited or inaccurate findings, but this does not necessarily mean the machine has “given a wrong result.”

Several factors can affect ultrasound accuracy, including:

• The location and size of an abnormality
• Patient body habitus
• Bowel gas
• The position of an organ or fetus
• The type of ultrasound used
• The quality of the equipment
• Operator experience
• Whether the abnormality is visible on ultrasound at all

Ultrasound findings also need to be interpreted in the context of symptoms, physical examination and laboratory results.

If an ultrasound is unclear or doesn’t explain a patient’s symptoms, the doctor may recommend another test such as CT, MRI, X-ray, blood tests or a repeat ultrasound.

This is why a normal ultrasound does not always mean that every possible disease has been ruled out.

How to Prepare for an Ultrasound

Preparation depends on the type of ultrasound.

You may be asked to:

• Fast for several hours before certain abdominal examinations.
• Drink water and maintain a full bladder for some pelvic scans.
• Empty your bladder before a transvaginal examination.
• Wear comfortable clothing that allows access to the area being examined.
• Follow specific instructions provided by your doctor or diagnostic centre.

Preparation requirements vary considerably between examinations, so it is important to follow the instructions given for your particular scan.

What Happens During a Sonography Test?

For a typical external ultrasound, you will lie on an examination table. The sonographer applies a small amount of gel to your skin and moves the transducer over the area being examined.

You may be asked to change position, hold your breath briefly or remain still so that clearer images can be obtained. The examination is generally painless, although some pressure may be necessary.

Most ultrasound examinations are relatively quick, although the duration varies according to the type of scan and the complexity of the examination.

Frequently Asked Questions About Different Types of Ultrasonography

1. What are the three types of sonography?

Broadly, ultrasound imaging can be described as 2D conventional ultrasound, Doppler ultrasound and 3D/4D ultrasound. However, there are many other types based on the body part being examined, including abdominal, pelvic, obstetric, breast, thyroid, vascular and musculoskeletal ultrasound.

2. What is a Type 2 ultrasound?

“Type 2 ultrasound” is not a universal medical classification. In pregnancy, the term may sometimes be used informally to refer to a Level II or detailed ultrasound, such as a targeted anatomy or anomaly scan. Always confirm the exact terminology with your doctor.

3. Is Doppler better than normal ultrasound?

Not necessarily. Doppler provides additional information about blood flow, while conventional ultrasound is primarily used to examine anatomy. The appropriate test depends on what your doctor needs to evaluate.

4. Is USG the same as sonography?

Yes. USG, ultrasound and sonography are commonly used terms for the same basic imaging technology.

5. Which is better, USG or MRI?

Neither is universally better. Ultrasound is excellent for many abdominal, pelvic, pregnancy, vascular and superficial soft-tissue examinations, while MRI provides highly detailed images of many soft tissues and deeper structures.

6. Which type of sonography is best?

There is no single best type. The appropriate examination depends on the body part, symptoms and suspected condition.

7. Which is better, CT scan or sonography?

It depends on the medical problem. Ultrasound does not use ionising radiation, whereas CT uses X-rays. CT may provide more comprehensive cross-sectional imaging in situations where ultrasound has limitations.

8. What are the disadvantages of sonography?

Ultrasound can have difficulty imaging through bone and gas, and image quality may be affected by body habitus and operator experience. Some deeper or complex conditions may require CT or MRI.

9. Is sonography risky?

Diagnostic sonography is generally considered safe when appropriately performed. It uses sound waves rather than ionising radiation.

10. How many times is an ultrasound safe?

There is no fixed maximum number of medically indicated ultrasound examinations. Ultrasound can be repeated when clinically necessary, although unnecessary exposure should be avoided.

11. Can an ultrasound give wrong results?

Ultrasound can occasionally miss abnormalities or produce inconclusive findings. Factors such as bowel gas, body habitus, lesion size, location and operator experience can affect the examination. If the findings don’t match the clinical picture, additional testing may be recommended.

Final Thoughts

Ultrasonography has become an essential part of modern medical diagnosis because it is versatile, widely available, relatively quick and does not use ionising radiation. From abdominal and pelvic scans to pregnancy ultrasound, echocardiography, Doppler studies and musculoskeletal imaging, different forms of sonography serve different purposes.

The most important point is that there is no universally “best” ultrasound test. The right examination depends on what needs to be investigated. In some cases, ultrasound may be all that is required; in others, doctors may recommend CT or MRI for additional information.

If your doctor has prescribed an ultrasound, follow the preparation instructions carefully and choose a diagnostic centre with appropriately trained professionals and suitable equipment. The quality of both image acquisition and interpretation matters when making an accurate diagnosis.

For patients in Kolkata, Sparsh Diagnostic Centre offers a range of ultrasonography and related imaging services, including abdominal, breast, obstetric and gynaecological ultrasound, fetal echocardiography, paediatric and adult echocardiography, vascular studies and musculoskeletal sonography.