Foreign body

Foreign bodies are objects lying partially or wholly within the body that originated in the external environment. Foreign body placement is voluntary or involuntary.



There are many ways in which a foreign body can be introduced into various parts of the human body. 


Aspirated foreign bodies will have a clear clinical correspondence: choking, coughing, neck pain or struggling to breathe. Risk factors for foreign body aspiration include intubation, neurological deficit, facial trauma, and dental instrumentation. The right main bronchus is the most common site of obstruction due to the anatomy of the bronchial tree favoring the right side (larger diameter, more vertical orientation). Often two orthogonal plain radiographs are the primary investigation of choice 12.


Many surgical procedures deliberately introduce foreign bodies either deliberately in the form of hemostatic clips (most common), stents, valve replacements, pacing boxes, catheters etc. or accidentally when a surgical instrument or surgical pack are inadvertently left in situ. 


Ingested foreign bodies range from pediatric patients placing objects in their mouths, to mental-health related self-harm, to bones stuck in the pharynx or gastrointestinal tract. Coins account for 70% of pediatric ingested foreign bodies and will typically become ‘stuck’ at the level of the cricopharyngeus muscle 8,14.

Sharp ingested foreign bodies can be potentially problematic when lodged in the esophagus, patients will often require emergency endoscopy, more often than not if the sharp object is within reach of endoscopy it will be removed before it progresses further 12.

Plastic bread clips are diagnostically challenging, the limited literature on this foreign body suggests they are invisible on both plain radiography and CT, and the rigid shape can cause bowel perforations or gastrointestinal hemorrhage 15,16.

Drug packing

Drug packing is a well-documented form of foreign body. Often drugs are placed within condoms, or wrapped in foil, latex or cellophane, then swallowed or inserted anally or vaginally. These should be considered hazardous to the patient until evacuated due to the possibility of the containment method rupturing.


Most rectal foreign bodies are inserted via the anus, although occasionally the foreign body has been ingested and has passed through to lie in the rectum. Commonly, rectal foreign bodies are used for sexual purposes 1-3. Rectal foreign will vary case to case. The main problem with this is the often delayed presentation due to the reluctance of patients to present to emergency departments. Patients may suffer from extraperitoneal mucosal injuries or suffer from a more severe complication such as perforation 1-5.

Two plain radiographs are recommended to accurately demonstrate the size, shape and location of the rectal foreign body. This should be performed before a digital examination to prevent staff-related injuries from sharper foreign bodies.

Soft tissue

Most soft tissue foreign bodies are involuntary, resulting from an accident. The most commonly reported soft tissue foreign bodies are glass, metal and splinters from wood 5. It is imperative to locate foreign bodies before they become infected or worse damage close-by organs. Patients may have a delayed presentation with a foreign body granuloma

Radiographic features

The investigation of foreign bodies relies heavily on radiology and every foreign body will have an optimal modality for investigation 17. Metal, glass and stone can be visualized very well using conventional plain film radiography, whereas more organic structures, such as wood, may require further imaging such as ultrasonography 5-7

Plain radiographs

The radiological appearance in plain radiography of foreign bodies is dependent on three factors: the x-ray attenuation of the foreign body, the surrounding structures and any overlying structures that may veil the object. 

The anatomical location will not only affect the radiopacity of the suspected foreign body, but the rate of magnification as the object is placed further or closer to the detector, lateral cervical radiographs can have a magnification rate of up to 21.6% 9-11.


Most foreign bodies are hyperechoic.


The density of the foreign material in the body can range markedly, so the use of multiple window settings is crucial in identifying the presence of the objects. Routinely soft tissue, lung, and bone windows should be assessed. Certain plastics may be occult on CT.


The signal intensity of the foreign material in the body can range markedly, but most objects cause artefact of some sort. Certain objects may be occult on MRI, such as those made of wood or plastic.

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Cases and figures

  • Case 1: stiletto shoe
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  • Case 2: bullet
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  • Case 3: prosthetic eye
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  • Case 4 : tarsal plate weight for facial palsy
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  • Case 5: crayon in nose
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  • Case 6: tongue stud
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  • Case 7: hook with prawn in pinna
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  • Case 8: swallowed T-bone
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  • Air rifle pellet
    Case 9: gunshot wound to the neck
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  • Case 10: slow K tablet in trachea
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  • Case 11: aspirated foreign body - dental crown
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  • Case 12: chicken bone in bronchus
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  • Case 13: needle in breast
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  • Case 14: guide wire
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  • Case 15: metallic foreign bodies
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  • Case 16: coin in esophagus
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  • Case 17: intra-cardiac nail
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  • Case 18: esophageal knife
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    Case 19: lost CVC wire in IVC
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  • Case 20: razor blades
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  • Case 21: fishbone in liver
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  • Case 22: body packer
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  • Case 23: penile implant
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  • Case 24: pelvic sickle cell complications
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  • Case 25: staple gun injury
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  • Case 26: screw through thong
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  • Case 27: ingested button batteries
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  • Case 28: menstrual cup device
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  • Case 29: glass rectal foreign body
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  • Case 30: retained surgical swab following thyroidectomy
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  • Case 31: pelvic gossypiboma
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  • Case 32: TASER in neck
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