Gastric foreign material is commonly encountered on abdominal imaging, especially radiographs. The type and significance of the foreign material in determining whether there is obstruction of the gastrointestinal tract is frequently a primary or secondary clinical question.
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Terminology
Gastric foreign material and foreign bodies are terms used to describe objects in the lumen of the stomach. If it is not clear whether food or foreign material is present, the more general term is often used.
Epidemiology
Gastric foreign material is a common presentation to the emergency service. Dogs are most commonly affected, however cats and other pets such as ferrets and rabbits may be seen.
Risk factors
Risk factors include appetite (food items such as bones, corn cobs), inappropriate ingestion (clothing items, rope, toys), and natural material ingestion (hair, grass).
Associations
Behavioral issues may result in repeat ingestion of one or more items over time.
Clinical presentation
Animals may present with vomiting or anorexia over a few hours or days. The owner may be aware or unaware of any ingestion of foreign material, or may suspect it has occurred.
Location
Foreign material in the stomach may be solitary, or have multiple sites of continuous or discontinuous distribution. Material in the stomach lumen may not cause acute obstruction depending on the volume and ability to move. If the material becomes lodged in the pylorus, acute obstruction becomes evident. Portions of the material may also be present in the small intestine, either attached to the gastric portion or distant from it. Linear (textile) foreign bodies may be anchored in the stomach and continue through the small intestine.
Macroscopic appearance
The material retrieved from the stomach may be composed of plastic, bone, grass/food material, rubber, or other substances.
Radiographic features
Foreign material often appears structured on imaging, and may be soft tissue opacity or have a higher or lower density. Foreign material may not be directly visualized in all cases, and imaging features of obstruction are used to diagnose the presence of foreign material.
Radiography
Foreign material in the stomach may be mixed with food, and the identification of it relies on identifying abnormal structured shapes and any difference in opacity. Pet food has a characteristic texture that is a mixture of soft tissue and gas. Any linear, square, or striated material can be indicative of foreign material, especially if it is more opaque than food. Foreign material can also trap gas, causing outlines to be seen.
Gas often acts as a natural contrast medium in the stomach, and it can be used to advantage by positioning the animal in left lateral, right lateral, ventrodorsal, +/- dorsoventral positions.
Ultrasound
Ultrasound can be used to detect foreign material in the stomach, and is most often used when the question is whether there is foreign material in the pylorus causing obstruction. The presence of gas in the fundus and body of the stomach make this less diagnostic as a test, however if the stomach is filled with fluid or food it may be more successful.
Small foreign bodies and linear/textile foreign bodies can lodge in the pylorus causing obstruction, yet not be visible on radiographs. Positioning the dog with fluid filling the pylorus aids in visualizing the area.
Foreign material can be identified by its structure, and often causes a "clean" or "hard" shadow (anechoic) distal to the object's surface.
CT
CT can be used for identifying gastic foreign material, however is not often used as a primary diagnostic modality. Foreign material is often seen incidentally on CT imaging for other disorders. CT has high sensitivity for non-soft tissue opacity materials and may detect metal, plastic, or bone in the stomach.
Radiology report
When describing gastric foreign material, an underlying question is often whether it is significant or obstructive. A degree of uncertainty may be present and should be clearly communicated.
Morphology
location in the gastric lumen
size and number of objects
opacity of objects
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size of stomach and primarily gas or fluid contents
Relationship to/involvement of
-
pylorus, as this is often associated with obstruction
Treatment and prognosis
The history and clinical signs combined with imaging features often determine whether this is an incidental finding or an indication of obstruction.
Gastric obstruction with foreign material includes an animal with vomiting or anorexia, enlargement of the stomach (fluid is most significant), and visible foreign material on one or more imaging modalities.
Incidental foreign material may be found on imaging for other disorders. The stomach is usually normal in size, contains food, and there is no suspicion of obstruction in the clinical history.
Indeterminate cases can be re-imaged after a period of time to track progress of the material through the gastrointestinal tract. Fasting the animal during the recheck interval aids in removing food material that obstructs the foreign material.
Treatment may include medical management, gastroscopy and retrieval, or gastrotomy.
Complications
Complications may include aspiration pneumonia from vomiting, or perforation of the foreign body.
Differential diagnosis
The differential diagnosis is usually food vs foreign material. Time and repeat imaging or addition of another modality can help to resolve these questions.
Practical points
use multiple views (3-4) when evaluating a suspected foreign body in the stomach on radiographs
position the animal right side down to image the pylorus with ultrasound if not visible in dorsal recumbency
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