Ultrasound of the gastrointestinal tract: possibilities of the method

Ultrasound examination of the gastrointestinal tract is a method for visualizing the esophagus, stomach, small intestine, and colon using the reflection of ultrasound waves from tissue. This method allows for the assessment of the wall structure, thickness, and layering, as well as major pathological changes. [1]

It's important to distinguish between gastrointestinal ultrasound and standard abdominal ultrasound. Abdominal ultrasound typically focuses on the liver, gallbladder, pancreas, and spleen. Gastrointestinal ultrasound focuses on the intestinal and stomach walls and their function. [2]

The method is particularly useful as a first, safe, and accessible diagnostic step. It quickly reveals whether there are gross changes that require more precise methods, such as endoscopy or CT scanning. [3]

Ultrasound examination is well suited for dynamic monitoring. It can be repeated as often as necessary to monitor treatment, because ultrasound does not involve radiation exposure. [4]

However, the method has limitations. Gas in the intestines and body type can impair visibility, while small mucosal erosions, early tumors, and many functional disorders are better detected endoscopically. Therefore, ultrasound more often answers the question of "is there a structural problem" and "where is it located" rather than replacing all other examinations. [5]

Table 1. Advantages and limitations of ultrasound examination of the gastrointestinal tract

What does the method provide?	What are the limitations?
Safe and can be repeated frequently	Gas and bowel contents interfere with visualization
Quickly reveals gross pathology	Minor lesions of the mucous membrane are less visible
Assesses the intestinal walls and motility	Does not always detect early tumors
Suitable for children and pregnant women	Sometimes requires additional methods

When the study is prescribed: indications and goals

Gastrointestinal ultrasound is most often prescribed for abdominal pain, bloating, a feeling of heaviness after eating, unstable stool, and other signs of digestive problems. In this situation, the doctor looks for inflammation, thickening of the intestinal walls, dilated intestinal loops, or large masses. [6]

This method is useful for initially determining the causes of dyspepsia, which is a combination of complaints of nausea, heartburn, early satiety, and upper abdominal discomfort. Ultrasound can reveal signs of gastroduodenitis, large ulcers, or impaired gastric emptying. [7]

This test is often used when inflammatory bowel disease is suspected. It helps identify diffuse or focal thickening of the wall, loss of normal layering, and increased blood flow within the wall. These signs do not provide a definitive diagnosis, but they do suggest where to look next. [8]

Ultrasound is also prescribed to monitor existing conditions. For example, in cases of chronic colitis, Crohn's disease, diverticulitis, after bowel surgery, or during long-term use of medications that can affect digestion. [9]

A separate goal is preventative assessment in at-risk individuals. This applies to patients with chronic liver and biliary tract diseases, metabolic disorders, and a family history of digestive system pathology, as these are the patients most likely to have associated problems. [10]

Table 2. Indications for ultrasound examination of the gastrointestinal tract

Situation	Why is it prescribed?
Abdominal pain, bloating, unstable stool	Search for inflammation, dilation, thickening of the walls
Dyspepsia, nausea, heaviness after eating	Evaluation of the stomach and duodenum
Suspected inflammatory bowel disease	Identification of affected areas and activity
Monitoring of treatment or after surgery	Dynamics of changes, complications
Risk group for digestive diseases	Early detection of structural problems

What does ultrasound show in the stomach and intestines?

In the stomach, ultrasound allows one to assess the wall thickness, its layering, and the presence of large polyps or tumors. It can also indirectly assess impaired motility and evacuation if contents are retained longer than usual. [11]

In the small and large intestines, the method visualizes the wall along its entire accessible length: it measures thickness, evaluates homogeneity and layering, and identifies significant inflammation, edema, or fibrosis. A normal wall appears uniform and multilayered. [12]

Ultrasound can detect large tumors, diverticula, abscesses, obstructed intestinal loops, and free fluid in the abdominal cavity. This is especially important in acute pain, when it is necessary to quickly determine the risk of complications. [13]

Doppler ultrasound, which assesses blood flow in the intestinal wall, helps distinguish active inflammation from more subdued, cicatricial processes. Inflammation typically increases blood flow. [14]

It's important to remember that ultrasound is poor at detecting small erosions and early ulcers, so if such conditions are suspected, the doctor will refer the patient for an endoscopy. In this case, ultrasound acts as a "map," showing the overall situation and the most suspicious areas. [15]

Table 3. What changes can be seen

Department	What is being assessed?	What can be found
Stomach	Wall thickness and layering, peristalsis	Large polyps, tumors, signs of inflammation, delayed evacuation
Small intestine	Thickness, layering, loop expansion	Inflammation, swelling, partial obstruction
Colon	Thickness, local changes	Colitis, diverticula, large tumor masses
Vascular regime	Blood flow in the wall	Signs of active inflammation

Preparing for the study

The quality of the ultrasound depends heavily on the amount of gas and intestinal contents. Therefore, it is usually recommended to limit gas-producing foods for 3-4 days, including legumes, cabbage, fresh baked goods, sugary carbonated drinks, and large amounts of raw vegetables and fruits. [16]

Before the examination, an absorbent or anti-bloating agent is often prescribed, and if constipation is a concern, a mild laxative or bowel cleanse is prescribed. The specific regimen depends on the specific area being examined and the person's symptoms. [17]

If the goal is to evaluate the stomach and upper gastrointestinal tract, the examination is usually performed on an empty stomach. The last meal should be 6-8 hours beforehand. Water is usually allowed, but in moderation. [18]

For some protocols, especially for children or mild complaints, preparation may be minimal. However, if in doubt, it's best to refer to the clinic's instructions to avoid receiving a test that's "empty" in terms of information. [19]

Regular medications should only be discontinued with the consent of the attending physician. Some medications should be temporarily postponed until after the procedure to prevent interference with motility and gas production. [20]

Table 4. Preparation step by step

Term	What to do	For what
In 3-4 days	Eliminate foods that cause gas	Reduce the amount of gas
In 1 day	Sorbent or anti-bloating agent, if necessary, bowel cleansing	Improve the visibility of the walls
On the day of the study	Do not eat for 6-8 hours, drink according to the instructions	Empty stomach and less contents
Medicines	Take as usual unless otherwise directed.	Do not disrupt treatment

How does the procedure work and how safe is it?

The examination is performed in the supine and lateral positions. A gel is applied to the skin, the doctor moves the transducer over the abdomen, and sometimes asks you to hold your breath or change position to better examine the area. [21]

If a stomach ultrasound is performed, you may be asked to drink some water before the examination. This helps to straighten the walls and better visualize the contours. For the intestines, a standard external approach without filling is most often used. [22]

The procedure is painless. Only light pressure from the sensor may be applied, especially in the painful area, but this is brief and controlled. [23]

There are virtually no contraindications. Temporary restrictions may apply in the case of fresh burns, severe skin inflammation in the sensor area, or immediately after certain contrast-based examinations that may reduce ultrasound accuracy. [24]

Ultrasound does not use ionizing radiation, so it is considered safe for children, pregnant women, and people with chronic conditions that require frequent monitoring. [25]

Table 5. Safety and limitations

Paragraph	What you need to know
Pain	Usually no, only pressure sensor
Duration	On average 10-30 minutes
Radiation exposure	Absent
Contraindications	Almost none, except for temporary skin
Can be repeated	Yes, to monitor treatment

How to read the results and when additional methods are needed

The conclusion typically describes the wall thickness, echogenicity, layering, presence of dilated loops, free fluid, and focal lesions. The physician compares this with the symptoms and test results, as ultrasound alone rarely provides a definitive diagnosis. [26]

If a localized thickening of the wall or a suspicious mass is detected, the next step is often endoscopy with biopsy. This is necessary to directly view the mucosa and obtain tissue for analysis, something ultrasound cannot do. [27]

If obstruction, complicated diverticulitis, or widespread inflammation is suspected, computed tomography (CT) or magnetic resonance imaging (MRI) may be necessary. Ultrasound is a rapid initial investigation in these cases. [28]

A normal ultrasound result does not always indicate the absence of disease. For example, functional disorders, irritable bowel syndrome, or early erosive processes may not show ultrasound signs. In such cases, a decision is made based on clinical findings and other tests. [29]

It's important for patients to retain the report and share it with their physician, rather than attempting to interpret the terms themselves. The same description may have different meanings depending on the patient's symptoms and laboratory findings. [30]

Table 6. When ultrasound is supplemented with other studies

Find or situation	What is it supplemented with?	For what
Suspected ulcer, erosion, early tumor	Endoscopy with biopsy	Direct assessment of the mucosa
Signs of obstruction or complications	Computed tomography	Detailing the extent and causes
Suspected active inflammation	Doppler, tests, sometimes endoscopy	Activity assessment and accurate diagnosis
Normal ultrasound for severe complaints	Functional tests, endoscopy	Searching for causes without structural changes