Foreign Bodies: Introduction
by Tim B. Hunter, MD and Mihra S. Taljanovic, MD, PhD
Foreign bodies are uncommon, but they are important and interesting. Sometimes, they may provide a great deal of lowbrow amusement. Foreign bodies may be ingested, inserted into a body cavity, or deposited into the body by a traumatic or iatrogenic injury. They may go unrecognized or mistaken for a normal structure or a normally functioning medical device. Because of this, they can cause harm to the patient.
Most ingested foreign bodies pass through the gastrointestinal tract without a problem. Most foreign bodies inserted into a body cavity cause only minor mucosal injury. However, ingested or inserted foreign bodies may cause bowel obstruction or perforation; lead to severe hemorrhage, abscess formation, or septicemia; or undergo distant embolization.
Motor vehicle accidents and bullet wounds are common causes of traumatic foreign bodies. Metallic objects, except aluminum, are opaque, and most animal bones and all glass foreign bodies are opaque on radiographs. Most plastic and wooden foreign bodies (cactus thorns, splinters) and most ﬁsh bones are not opaque on radiographs.
All patients should be thoroughly screened for foreign bodies before undergoing a magnetic resonance imaging study. This screening may consist of a detailed questionnaire filled out by the patient, a detailed medical history obtained by the MRI technologist, or possibly radiographs to look for a suspected foreign body, such as a tiny piece of metal in the eye.
The interpretation of ultrasonographic (US), computed tomographic (CT), and magnetic resonance (MR) imaging studies is particularly fraught with error if one does not appreciate the presence of a medical device or a foreign body. It is crucial that all US, CT, nuclear medicine, and MR images be interpreted in light of any current radiographic studies of the same body region. The scout image obtained for CT and MR imaging studies should be examined carefully for unexpected foreign bodies and medical apparatus and for unexpected bone, bowel, and soft-tissue lesions not easily visualized on cross-sectional images.
Appearance of Foreign Bodies on Radiographs
||Glass of all types; most metallic objects except aluminum; most animal bones and some fish bones; some foods; some soil fragments; some medications and poisons (CHIPES: chloral hydrate, condoms, cocaine; heavy metals; iodides, iron; psychotrophics-phenothiazines; enteric-coated pills, barium; and solvents)
|Non opaque Materials
||Most foods and medicines; most fish bones; most wood, splinters, thorns of all types; most plastics; most aluminum objects
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