Diagnostic ultrasound is generally considered safe when it is needed for medical care and performed by a trained professional. It uses sound waves, not the ionizing radiation used in X-rays or CT scans. No harmful effects have been confirmed with standard diagnostic use in people, but ultrasound energy can slightly heat tissue. That is why scans should be medically justified and kept as brief as needed to obtain useful images.
How does diagnostic ultrasound work?
Diagnostic ultrasound, also called sonography, uses high-frequency sound waves to create pictures of structures inside the body. A handheld device called a transducer sends sound waves into the body and receives the echoes that return. A computer converts these echoes into images that a healthcare professional can examine.
Ultrasound is used to assess organs, muscles, tendons, blood vessels and other soft tissues. It can help investigate symptoms, monitor certain conditions, assess blood flow and guide procedures such as needle biopsies. During pregnancy, it is commonly used to examine fetal development and the surrounding structures.
Why is ultrasound generally considered safe?
The main safety advantage of diagnostic ultrasound is that it does not use ionizing radiation. X-rays and CT scans use this type of radiation, whereas ultrasound creates images using sound waves. This makes ultrasound a useful imaging option when a healthcare professional needs to examine internal structures without exposing the patient to ionizing radiation.
According to RadiologyInfo, standard diagnostic ultrasound has no known harmful effects on humans. Its established clinical use and lack of ionizing radiation support its role in routine medical imaging. However, being generally safe does not mean that ultrasound energy has no biological effects under any circumstances.
What are the possible risks of diagnostic ultrasound?
Ultrasound energy can interact with body tissues in ways that produce biological effects. The US Food and Drug Administration (FDA) explains that ultrasound waves can cause slight tissue heating and, in some circumstances, cavitation. Cavitation refers to the formation of small gas bubbles in fluids or tissues. The long-term consequences of these effects are not fully known.
These potential effects are a reason to use ultrasound carefully, not a reason to avoid a medically recommended examination. The FDA considers ultrasound generally safe when appropriately trained healthcare providers use it prudently. The practical goal is to obtain the information needed for diagnosis while avoiding unnecessary exposure.
Does ultrasound cause tissue damage or cancer?
There is no established evidence that standard diagnostic ultrasound, when appropriately used, causes harmful effects in human patients. However, the available evidence does not prove that every possible biological effect has been ruled out. Ultrasound differs from imaging that uses ionizing radiation, but it should not be described as entirely risk-free under all conditions.
According to the American Institute of Ultrasound in Medicine (AIUM), no independently confirmed adverse effects caused by current diagnostic ultrasound instruments have been reported in human patients in the absence of contrast agents. The organization also emphasizes prudent use because biological effects have been observed in some laboratory and animal settings.
Is diagnostic ultrasound safe during pregnancy?
Ultrasound is widely used during pregnancy because it allows healthcare professionals to examine the fetus without using ionizing radiation. Medically indicated scans can provide important information about fetal development, pregnancy progress and findings that may need further assessment.
The AIUM's guidance on ultrasound safety during pregnancy supports a cautious approach that obtains the necessary diagnostic information with the lowest reasonable exposure. Research has not established a causal relationship between diagnostic ultrasound and recognized adverse effects in humans, although the absence of conclusive evidence does not prove that every possible risk is impossible.
For this reason, ultrasound during pregnancy should be performed by qualified healthcare professionals when there is a medical reason. The examination should use appropriate settings and last only as long as needed to obtain the required information.
Are keepsake pregnancy scans and home fetal Dopplers safe?
Commercial scans performed solely to create souvenir images or videos are different from examinations arranged for medical reasons. Unnecessary or prolonged exposure should be avoided, even when the purpose is simply to see the baby. The FDA discourages using ultrasound solely for non-medical keepsake purposes when this involves additional exposure.
Home fetal heartbeat monitors also deserve caution. The FDA advises that fetal heartbeat monitoring devices should be used by trained healthcare professionals when medically necessary. Untrained users may use them for longer than appropriate or misunderstand what they hear. Hearing a heartbeat at home cannot confirm that a pregnancy is healthy, and difficulty finding one cannot establish that something is wrong.
Are repeated ultrasound scans safe?
There is no single maximum number of diagnostic ultrasound examinations that applies to every patient. Repeat scans may be appropriate when a healthcare professional needs to monitor a condition, compare changes over time or obtain additional information that was not clear on an earlier examination.
The focus should be on whether each examination has a clear medical purpose, rather than on counting scans alone. Healthcare professionals are encouraged to follow the principle known as as low as reasonably achievable (ALARA): use the lowest reasonable ultrasound exposure that still produces images of sufficient quality for the clinical question.
The same principle applies to adults, children and newborns. If several scans are recommended, ask the referring clinician what each examination is intended to clarify and how the results may affect care. Do not postpone a medically necessary scan simply because you have already had one.
Does an ultrasound scan hurt or cause side effects?
Most external ultrasound examinations are painless. A healthcare professional applies gel to the skin and moves a probe across the area being examined. You may feel pressure as the probe moves, especially if the area is already tender or painful. The gel may feel cool, but the scan itself does not usually cause pain.
Some examinations use an internal probe inserted into the vagina or rectum. These scans may cause temporary discomfort during insertion or movement. The UK National Health Service (NHS) explains that internal ultrasound probes can be uncomfortable and advises patients to tell the person performing the scan if they experience pain.
Speak up if you feel uncomfortable. The healthcare professional may be able to adjust the probe position or pressure, explain the next step or pause the examination. You can ask questions about the procedure and discuss any concerns before it begins.
Are all types of ultrasound equally safe?
Different ultrasound examinations use different settings and techniques. A routine scan of an abdominal organ, a Doppler examination that assesses blood flow and a scan performed during pregnancy do not necessarily involve identical exposure conditions. Ultrasound energy, the equipment settings and the time spent scanning can affect the potential for biological effects.
Ultrasound can also be used to guide an invasive procedure, such as a biopsy or fluid aspiration. In these cases, the safety considerations include both the imaging and the procedure itself. Any risks associated with a needle, an injected substance or another part of the procedure should be discussed separately from the risks of ultrasound imaging.
For standard diagnostic examinations, qualified healthcare professionals select the appropriate technique and settings for the clinical purpose. The aim is to obtain useful images without unnecessary scanning or exposure.
How can you make an ultrasound examination safer?
You usually do not need to take special steps to protect yourself from the sound waves during a medically indicated ultrasound. The most useful precautions involve making sure the examination is appropriate and that you understand what it involves.
- Follow a medical recommendation. Have the scan when your healthcare professional considers it necessary to investigate symptoms, monitor a condition or guide care.
- Choose a qualified provider. Diagnostic ultrasound should be performed by appropriately trained healthcare professionals using suitable equipment.
- Avoid unnecessary scanning. Do not seek repeated examinations solely for reassurance or keepsake images without discussing their medical value with a clinician.
- Ask about specialized procedures. If the examination involves contrast agents, a needle or another intervention, ask about the risks specific to that procedure.
- Discuss any concerns beforehand. Tell the healthcare professional if you are anxious about an internal examination, experience pain or have questions about why the scan is needed.
When is ultrasound not the best imaging test?
Safety is only one consideration when choosing an imaging test. Ultrasound has practical limits: sound waves do not pass well through bone or air, and some deeper structures may be difficult to see clearly. The usefulness of a scan also depends on the body area being examined and the clinical question.
If ultrasound cannot provide the information needed, a healthcare professional may recommend another test, such as an MRI, X-ray or CT scan. The best option depends on the expected diagnostic benefit, the limitations of each technique and the patient's circumstances. A test that uses a different imaging method is not automatically less safe or more appropriate simply because ultrasound is available.
What should you remember about ultrasound safety?
For most patients, diagnostic ultrasound is a well-established and generally safe way to obtain medical images. It does not use ionizing radiation, and standard diagnostic use has no known harmful effects in humans. Nevertheless, ultrasound energy can produce biological effects, and its long-term consequences are not fully understood in every setting.
Medically indicated scans performed by trained professionals offer important diagnostic benefits. The sensible approach is to use ultrasound when it can answer a medical question, avoid unnecessary or prolonged exposure and discuss any concerns with the healthcare professional arranging the examination.