Limited by large body habitus on ultrasound is a phrase used by radiologists in reports. This means the ultrasound study is not very good because of increased fat tissue or obesity. This alerts your doctor that the test is limited. That additional testing may be needed for the symptoms or conditions he has in mind.
Ultrasound uses high frequency sound waves to produce images of the body. In the case of obesity, the ultrasound waves have to travel a farther distance to reach the site of interest. Excessive fat also weakens the ultrasound waves that go the the site of interest and return to the probe.
Obesity may also limit how much the patient can move. The ultrasound technologist who performs the test has to find the best patient position to image the organ. This may require the patient to lay on their side. Some obese patients may have a difficult time holding their breath. This is sometimes needed to image structures in the body.
The Ultrasound images that we obtain in obese patients may not be as clear. Sometimes you can’t see the organ well or the detail is lacking. Sometimes the ultrasound waves can not penetrate the organ. The images may be grainy. We therefore don’t get enough information to provide an adequate evaluation.
This can be problematic especially in emergency settings when the information is needed for life threatening conditions. For example, imaging the aorta for aneurysm becomes difficult. Finding the appendix on ultrasound can be challenging as well. Fortunately, many conditions can be imaged with other tests like CT which are not as severely limited by obesity.
Limited by large body habitus on ultrasound is therefore a message to your doctor indicating that because of obesity, we can’t get a good test. The information from this ultrasound test is limited. Other tests such as CT should be considered. The diagnostic testing should not stop at this ultrasound test.