Foreign body removal in the emergency department

Foreign body removal is a bread-and-butter emergency department skill that hides three examiner traps. The first is the compartment: soft tissue, ocular, aural, and nasal FBs share a technique spine — anaesthesia, a good light, a sterile field, the right instrument, and a systematic exploration — but each has its own equipment, its own escalation trigger, and its own pitfall. The second is the material: metal and glass are radio-opaque and announce themselves on a plain film, but wood and plastic are radiolucent and will be missed on an X-ray, declared instead as a late necrotising infection. The third is the one true emergency: the button battery, whose electrolysis at the negative pole generates hydroxide and liquefies tissue within hours, is the foreign body the Fellowship candidate must never observe, never delay on, and never mistake for a coin. The bar is that a candidate who has read only this topic could remove the common FBs in an OSCE station, defend the imaging and the post-removal care in a viva, and name the four scenarios that mandate an immediate referral rather than an ED attempt.[1][5]

Definition and indications

A foreign body is any object of exogenous origin that lodges in a tissue or body cavity and is not meant to be there. The indications for removal are the pain, the functional disturbance (a foreign sensation in the eye, an obstructed ear or nose), the infection risk (the contaminated splinter, the plantar puncture), the toxicity (the button battery, the alkaline disk), the chemical injury (the iron rust ring that stains the cornea), and the retained-object-inoculation risk of any contaminated wound. The indication is strengthened when the object is sharp, organic, or a battery, and weakened — but rarely dropped — when the object is inert, small, deep, and asymptomatic, where a conservative leave-and-review strategy is occasionally defensible. [1]

The Fellowship decision point is not whether to remove but where to remove and with whom. The ED scope is the FB that is superficial, visible, accessible, and in a cooperative or sedatable patient. The four compartments and their ED-removable FBs are the soft tissue (the splinter, the superficial glass shard, the metal shaving), the ocular surface (the conjunctival FB, the superficial corneal FB and its rust ring), the external ear canal (the bead, the cotton-bud tip, the dried insect — never a button battery), and the nasal cavity (the bead, the foam, the food — with the button battery as the cannot-miss emergency). Anything deeper — an intraocular FB, a button battery in the oesophagus or the stomach, an FB embedded in a tendon or a joint, a deeply impacted aural FB, or an FB in an uncooperative child who cannot be safely sedated — is referred.[1]

Contraindications — the foreign body that is NOT removed in the ED

The contraindications are the situations in which an ED removal attempt will harm the patient — by pushing the object deeper, by damaging a critical structure, by delaying definitive treatment, or by anaesthetising an uncooperative child unsafely. The Fellowship candidate must name these out loud before reaching for the forceps. [1]

Relevant anatomy and landmarks

The four compartments have distinct anatomy that governs both the technique and the complications. In the soft tissue, a superficial FB lies in the dermis or the subcutaneous fat, and the relevant anatomy is the local neurovascular bundle and the tendon — a glass shard at the wrist, a needle near the digital nerve, a splinter in the palm all sit adjacent to structures a forceps or a hook can damage. The ocular surface comprises the conjunctiva (with the fornices where a FB hides, especially under the upper lid) and the cornea (the epithelium, Bowman's layer, and the stroma — a superficial FB sits in the epithelium and a rust ring forms where iron oxidises into the Bowman layer). The external ear canal is an S-shape: to straighten the adult canal, pull the pinna posterosuperiorly; to straighten the paediatric canal, pull the pinna posteroinferiorly. The tympanic membrane is at the medial end, and a forceps advanced blindly risks a perforation. The nasal cavity has the septum medially, the inferior turbinate laterally, and the floor below; a button battery lodged against the septum erodes through it within hours.[5][7]

The single anatomical pitfall that costs marks is the upper lid eversion. A patient with a foreign-body sensation and a fluorescein-staining linear vertical corneal abrasion (the "rail track") has a retained subtarsal FB under the upper lid until proven otherwise — the lid must be everted (with a cotton bud or a wire swab as a fulcrum) and the fornix swept before the patient is discharged, or the abrasion will recur with every blink. [1]

Equipment

The FB tray varies by compartment, but the shared kit is a bright focused light (a headlamp or a slit lamp), magnification (loupes or the slit lamp), sterile gloves and a sterile field, local anaesthetic, and sharp container disposal. The compartment-specific instruments are listed below. [1]

Patient preparation and consent

Preparation is the same four steps for every FB. Position and immobilise — the adult is seated comfortably with the head stabilised against a headrest; the child is held upright on a parent's lap with the parent's hand across the forehead and the other across the arms (the "bear hug"), or in a papoose board if available. Consent — the procedure, the instruments, the possible need for more than one attempt, the fallback of referral, and the rare complications (canal laceration, perforation, infection, a retained fragment). Anaesthesia — never attempt a painful removal on an unsedated patient; the movement causes the iatrogenic injury. Light and exposure — the headlamp or slit lamp aimed directly, the speculum placed, the assistant holding the patient still. [1]

For the child, procedural sedation is often the better part of valour — ketamine 1 to 2 mg/kg intravenously or 4 to 5 mg/kg intramuscularly provides a dissociated, still, breathing patient in whom an aural or nasal FB can be removed safely on the first attempt, sparing the child the trauma of a repeated forceps attempt and the canal trauma that results. Refer to the procedural-sedation topic for the full monitoring standard. [1]

Local anaesthetic and topical doses

The anaesthesia is tailored to the compartment. For the soft tissue, infiltrate lidocaine 1 per cent at a maximum of 3 mg/kg plain (about 20 mL in the 70 kg adult) or 7 mg/kg with adrenaline (about 50 mL), buffered 9:1 with sodium bicarbonate to halve injection pain, through a 25G needle at the field around the FB — never into the FB itself, which distorts the anatomy and pushes it deeper. Adrenaline-containing solution is never injected into an end-artery territory (the finger, the toe, the nose tip, the pinna, the penis). For the ocular surface, instil amethocaine (tetracaine) 0.5 to 1 per cent drops — one drop into the lower fornix, repeated once after a minute; the cornea is anaesthetised within 30 seconds. For the aural canal and the nasal mucosa, soak a cotton pledget in lidocaine 4 per cent with adrenaline 1:1000 and leave it in the canal or the nostril for 5 to 10 minutes for topical anaesthesia and vasoconstriction — this shrinks the mucosa and reduces the bleeding that otherwise obscures the field. LET gel (lidocaine-epinephrine-tetracaine) provides needle-free anaesthesia for the paediatric soft-tissue FB. [1]

Stepwise technique — soft tissue foreign body

The soft tissue FB is approached as a mini-surgical exploration. After anaesthesia and a sterile field, the technique runs to a fixed sequence. [1]

The structural errors are to explore blind (the iatrogenic nerve injury), to fail to image a radiolucent FB (the missed wood that returns as necrotising fasciitis), and to close a contaminated wound over a missed fragment (the trapped inoculum).[2][8]

Stepwise technique — ocular foreign body and the rust ring

The ocular FB is the one compartment where the slit lamp is the operator's hands — it magnifies the FB, it allows a steady approach with a needle, and it confirms the post-removal fluorescein stain. [1]

The post-removal antibiotic for the simple corneal abrasion is debated — the Cochrane review found no clear evidence that topical antibiotics improve healing over placebo for uncomplicated abrasions, but chloramphenicol remains standard practice to prevent bacterial superinfection of the epithelial defect, and is mandatory after a rust-ring removal and for any contact-lens-related abrasion (which needs an anti-pseudomonal cover such as a fluoroquinolone).[3][4] A patient who wears contact lenses is told to discard the lens and not to reinsert it until the defect has healed and been reviewed.

Stepwise technique — aural foreign body

The aural FB is the paediatric favourite, and the technique depends entirely on the shape and the nature of the object. The single rule that governs the whole compartment is the smooth-spherical rule: a bead, a bean, a marble, or a cotton-bud tip cannot be grasped with forceps — forceps push it deeper against the tympanic membrane, and the attempt converts a removable FB into an impacted one needing a general anaesthetic. [1]

The discriminators the examiner rewards: kill the insect before you pull; never forceps a smooth FB (use a hook, suction, or glue); never irrigate a swollen seed or a perforated TM; and the button battery is removed within the hour, not observed.[5][6]

Stepwise technique — nasal foreign body

The nasal FB is almost always a paediatric presentation, and the button battery is the cannot-miss emergency. The technique splits into the positive-pressure technique for the cooperative child and the instrumental technique for the uncooperative or the impacted FB. [1]

The button battery in the nose is the single most dangerous nasal FB. The mechanism is the electrolysis of tissue fluid at the negative pole, which generates hydroxide ions and produces an alkaline (not acidic) liquefactive necrosis of the nasal septum and the turbinates within hours of insertion. A battery left in the nose for over 24 hours causes a septal perforation in a high proportion of cases; the long-term outcomes include saddle-nose deformity, chronic sinonasal disease, and growth disturbances.[7] The candidate must name the mechanism — electrolysis, alkaline necrosis — and the urgency — removal within hours, never observed.

Imaging — radio-opaque versus radiolucent

The imaging decision rests on the material. Metal is radio-opaque and is seen on a plain X-ray in two projections; glass is variably radio-opaque (most soda-lime and leaded glass is visible, but some is not); wood and plastic are radiolucent and are missed on a plain film. The Carneiro Radiographics review established the multimodality approach: a plain film for the metal and the glass, a high-frequency linear ultrasound (10 to 15 MHz) for the wood and the plastic (which appear as an echogenic linear object with a posterior acoustic shadow and an anechoic halo if chronic), and a CT for the orbital, the intraocular, or the deeply embedded FB.[1][9] A CT is also the modality of choice for the suspected wooden orbital FB — the wood is hypodense on CT and can be mistaken for air (a classic pitfall); an MRI is contraindicated if any metal is suspected, and wood on MRI is hypointense on T2.

The discriminating question on every retained FB is: is this object radio-opaque or radiolucent? If radio-opaque, image with an X-ray; if radiolucent, image with an ultrasound (or a CT for the deep or the orbital).[1][9] The candidate who orders a plain X-ray for a suspected wooden splinter and discharges a negative result has made the textbook error — the wood is invisible, the splinter remains, and the patient returns with a necrotising soft-tissue infection.[2]

Differential diagnosis — retained foreign body versus resolved

The differential on every FB presentation is whether the object is still there. The history is the first clue — a patient who felt something enter and can still feel it usually has it; a patient who felt something enter and now feels nothing may have expelled it (the coughed-out or sneezed-out FB) or may have a residual fragment. The signs that argue for a retained FB are the persistent pain, the localised infection (a cellulitis, an abscess, a draining sinus), the recurrent or a non-healing wound, and the functional disturbance (a foreign-body sensation in the eye, an obstructed nose, a blocked ear). The signs that argue for resolution are the recovered object (the parent brings the bead in a tissue), the resolved symptoms, and the normal examination. [1]

The discriminating question on every presentation is: has this FB resolved, or is a fragment retained? The default is to assume retention until imaging excludes it — a missed retained FB is the most common source of the late return and the litigation.[2][8]

Post-removal care — tetanus, wound toilet, antibiotics

After the FB is removed, the post-care is the same four steps. Tetanus prophylaxis is assessed at every FB removal — the wound type (a clean minor wound versus a contaminated, a puncture, or a tetanus-prone wound) and the vaccination history (the number of documented doses and the time since the last dose). A patient with fewer than three documented doses, or a contaminated wound with over five years since the last dose, receives a tetanus-diphtheria-acellular-pertussis (dTPa) booster; a patient with an unknown or incomplete primary course and a tetanus-prone wound also receives tetanus immunoglobulin 250 IU intramuscularly. Wound toilet — copious saline irrigation, debridement of devitalised tissue, and a non-adherent dressing. Antibiotics are NOT routine for the clean removed FB; they are reserved for the contaminated wound (the bite, the plantar puncture, the heavily soiled splinter), the immunocompromised host, the prosthetic-valve or joint patient, and the established infection. The plantar puncture through a shoe sole is treated with ciprofloxacin 500 mg orally twice daily for 7 days to cover Pseudomonas; the mammalian bite is treated with amoxicillin-clavulanate 875/125 mg orally twice daily.[8]

Discharge and safety-net — the patient is discharged with advice to return for the spreading redness, the increasing pain, the fever, the numbness or weakness (a nerve injury), and the reduced vision (after an ocular FB). The ophthalmology review is at 24 to 48 hours for the corneal FB and the rust ring; the wound review is at 48 hours for the contaminated wound left open; the button-battery patient is reviewed by ENT at 1 week for the delayed perforation.[7]

Complications — procedure-related and disease-related

The complications split into those caused by the procedure and those caused by the missed or the retained FB. The procedure-related complications are the canal laceration (the bleeder that obscures the field after a forceps slip), the tympanic membrane perforation (the forceps advanced blindly, or the irrigation under pressure through a perforated TM), the nasal septal injury (the forceps tearing the mucosa), the corneal abrasion from the needle or the burr (the iatrogenic defect larger than the original FB), and the retained rust ring or fragment (the incomplete removal). The disease-related complications are the infection (the cellulitis, the abscess, the necrotising fasciitis of the missed wood), the alkaline necrosis of the button battery (the septal perforation, the facial nerve palsy, the canal stenosis), the intraocular injury (the endophthalmitis, the retinal detachment, the siderosis from a retained iron FB), and the delayed presentation of a retained FB as a chronic draining sinus or a non-healing wound.[2][7]

Pitfalls and practical tips

The pitfalls are the inverse of the structure. Failing to image the radiolucent FB — the missed wood that returns as necrotising fasciitis. Ordering an X-ray for a wooden splinter and discharging the negative — the textbook error. Reading a hypodense orbital lesion on CT as surgical emphysema — the missed orbital wood. Forceps on a smooth spherical aural FB — the impacted bead that needs a general anaesthetic. Pulling a live insect from the ear — the abraded canal and the perforated TM. Missing a subtarsal FB — the vertical corneal rail-track abrasion that recurs with every blink. Closing a contaminated wound over a missed fragment — the trapped inoculum. Failing to recognise the button-battery halo sign on the X-ray — the delayed necrosis. Attempting an intraocular FB removal in the ED — the globe that is destroyed. The repeated failed attempt in an uncooperative child — the canal that bleeds, the FB that impacts, the general anaesthetic that was avoidable. [1]

The practical tips are the opposite: image before you explore (the two-view X-ray or the high-frequency ultrasound); kill the insect before you pull (oil or lidocaine drops); hook behind a smooth FB, never forceps; evert the upper lid on every ocular FB; recognise the button-battery halo sign and remove within the hour; never remove an intraocular FB in the ED (shield and refer); never irrigate a perforated TM or a swelling seed; refer the deep, the impacted, the uncooperative-child, and the neurovascular-adjacent FB; and apply the two-attempt rule — stop and refer after two failed attempts, before the canal or the mucosa is traumatised.[1][5][6]

Special populations

The child is the commonest FB patient and the one most at risk of an iatrogenic injury from a repeated attempt. The principle is the single best attempt under optimal conditions — a good light, an assistant, topical anaesthesia, and procedural sedation (ketamine 1 to 2 mg/kg intravenously) for the uncooperative child with an aural or nasal FB. The positive-pressure (parent's kiss) technique succeeds for many anterior nasal FBs without any instrumentation.[6] The diabetic and immunocompromised patient has a lower threshold for antibiotic prophylaxis and a 48-hour review after a contaminated FB. The anticoagulated patient bleeds more from a canal laceration or a mucosal tear — meticulous haemostasis and pressure replace dose modification. The contact-lens wearer with a corneal abrasion after FB removal needs an anti-pseudomonal topical (a fluoroquinolone), is told to discard the lens, and is reviewed at 24 to 48 hours to exclude a bacterial keratitis. The occupational or high-velocity injury (the hammering-metal worker with a suspected intraocular FB) is imaged with a CT before any manipulation; the threshold to refer to ophthalmology is low.

Evidence and the regional guidelines

The contemporary framework rests on five evidence streams. The imaging evidence — the Carneiro Radiographics review — established the multimodality approach: a plain X-ray for the metal and the glass, a high-frequency ultrasound for the wood and the plastic, and a CT for the orbital and the deep.[1] The point-of-care-ultrasound evidence — the Osborne study of wooden-FB detection by medics — confirmed the high-frequency linear probe as the bedside tool for the radiolucent soft-tissue FB.[9] The corneal-FB evidence — Xu's review of corneal-FB management and the Cochrane review of antibiotic prophylaxis for the corneal abrasion — established the slit-lamp-and-needle technique and the chloramphenicol post-care, with the caveat that the simple abrasion may not strictly need a topical antibiotic.[3][4] The aural and nasal-FB evidence — the Ponnuvelu management algorithm and the Morris epidemiology study of nasal and aural FB removal — codified the technique-by-shape approach and the positive-pressure method.[5][6] The button-battery evidence — the Heilig study of long-term outcomes after nasal button-battery injuries — established the alkaline-liquefactive-necrosis mechanism, the urgency of removal within hours, and the high rate of delayed complications including septal perforation and saddle-nose deformity.[7] The plantar-puncture evidence — the Chachad review — established the Pseudomonas cover for the through-shoe-sole puncture and the high rate of retained FB in this injury.[8] The missed-FB evidence — the Chaulagain case report of a missed wooden FB causing necrotising fasciitis — is the cautionary example of the radiolucent-FB trap.[2]

Exam pearls

• The button battery is the emergency — electrolysis at the negative pole generates hydroxide and liquefies the tissue within hours; the halo (double-ring) sign on X-ray distinguishes it from a coin; remove within the hour, never observe.
• Radiolucent FB = ultrasound, not X-ray — wood and plastic are missed on a plain film; a high-frequency linear probe finds the echogenic object with a posterior acoustic shadow; a missed wooden FB returns as necrotising fasciitis.
• Never forceps a smooth spherical aural FB — use a right-angle hook behind it, a wide-bore suction, or cyanoacrylate on an applicator stick; forceps push it deeper and impact it.
• Kill the insect before you pull — instil oil or lidocaine drops to drown a live insect in the ear, then remove the dead insect; a struggling insect abrades the canal and the tympanic membrane.
• Evert the upper lid on every ocular FB — a vertical linear corneal abrasion is the rail-track sign of a retained subtarsal FB; the fluorescein stain is the diagnostic test.
• The two-attempt rule — stop and refer after two failed attempts in an uncooperative child; the third attempt traumatises the canal and impacts the FB.
• Shield the intraocular FB — never remove, never apply pressure; keep nil by mouth, give ceftriaxone 1 g intravenously, and refer to ophthalmology for theatre. [1]

Red flags