21

Swallowed foreign bodies

The most common foreign bodies1

Children: coins

Radiography…

Occasionally, a coin will lodge in the oesophagus. Some of these patients will be asymptomatic. An unrecognised coin can cause clinical problems including erosion of the mucosa which may result in an abscess or mediastinitis4. It is important to confirm that any swallowed coin has passed beyond the oesophagus. If the CXR is clear then the parents can be reassured that the coin will be passed within a few days.

Does the stool need to be checked? Sometimes a coin will be overlooked in the stool; the parents would be better advised to return to the Emergency Department (ED) only if the child becomes symptomatic.

Coin composition: coins in the UK and in the European Union are made of steel or alloys of various metals and sometimes coated with copper. In effect, these coins are inert. This does not apply worldwide. For example, in 1982 because of the cost of copper the one cent coin in the USA (commonly referred to as the penny) was minted with a mainly zinc core and a thin copper coating. Interaction between gastric acid and zinc can cause ulceration in the stomach. This possibility led to various scares and the consequent overuse of routine AXR. The penny constituents were not changed, but eventually a practical recommendation was made and widely adopted: if a USA penny has been swallowed and the CXR is clear then an AXR need only be obtained in a child who subsequently developes intestinal symptoms. The latter is an exceptionally rare occurrence.

Hand held metal detector (HHMD) scanning5–7

Consider this as an alternative to radiography. Advantages of a HHMD include:

Pitfall. If using a HHMD, a definite history in relation to the swallowed foreign body being a coin is most important. If the history is uncertain and the foreign body could be a magnet or a cluster of magnets (see p. 359) then a false reassurance might be provided by the HHMD. A safety net: concern regarding a cluster of magnets masquerading as a swallowed coin can be eliminated by passing a compass over the abdomen8. The lack of compass movement will exclude a magnet.

Pitfall (2). The majority of retained coins are situated in the upper oesophagus9–11 at the level of the cricopharyngeus muscle. An impacted coin can be missed if the whole neck below the level of the angle of the mandible is not included on the CXR.

Adults: fish bones

Fish bones comprise more than 70% of all foreign body events that cause an attendance to some EDs12,13. Complications resulting from an impacted fish bone are rare but can be serious. These include: neck abscess, mediastinitis and lung abscess.

Fish bone impaction is very different to that of other impacted foreign bodies14,15.

▪ Infrahyoid impaction is much less frequent. In one series15 approximately 90% of fish bones were situated in the oro-pharynx, whereas approximately 90% of other foreign bodies (poultry bones, dentures, wood splinters, coins, pork bones and lamb bones) were impacted more distally in the laryngeal pharynx or upper oesophagus.

Radiography.

What to look for.

Infrequent but important FBs

Sharp objects other than fish bones

Many sharp objects pass through the intestines without causing a problem. Nevertheless a sharp or pointed object may penetrate the oesophagus or the bowel. The presence of the swallowed object needs to be confirmed (or excluded).

Radiography:

▪ For metallic foreign bodies such as nails, needles, screws or razor blades a CXR and an AXR are indicated.

▪ For chicken, pork chop18, or lamb bones a lateral view of the neck is indicated. Approximately 90% of these foreign bodies, when impacted, will be found to be lodged in the hypopharynx or upper oesophagus15. This is a very different position of impaction as compared with impacted fish bones (see pp. 352–353).

▪ Wood and plastic foreign bodies are radiolucent and will not be identified on a radiograph. If clinical suspicion is high (eg a swallowed and impacted pencil or toothpick) then CT, or a contrast medium swallow, or endoscopy, will be indicated.

▪ Aluminium (eg as in a drink can ring pull) is of very low radiodensity19 and is rarely detectable on a radiograph. An aluminium ring pull (aka aluminium tab) will be detected by a HHMD5–7. Many countries have largely overcome the swallowed ring pull problem by producing ring pulls that remain attached to the can after the can is opened. Nevertheless, it is still possible to detach the ring pull from the can by wiggling it. Therefore the swallowing of ring pulls has not been eliminated entirely20.

Why is a bowel perforation relatively infrequent?10,21

90% of swallowed foreign bodies pass through the intestine without any problem, and this includes many nails and razor blades.

Sharp metallic foreign bodies rarely perforate the bowel wall. The intestine resists perforation and laceration partly because it is lined with mucus, is very pliable, and when a sharp FB reaches the colon it becomes encased with faeces.

Travelling head first: a pin or needle will often pass through the intestine with the blunt end leading21,22. It has been suggested that ingested needles and pins tumble and turn until the blunt end faces forwards!

When perforations do occur they may be silent. A needle lying in the soft tissues outside of the bowel may be discovered years later on an AXR obtained for other reasons21.

Button batteries23–27

An impacted button battery (BB) is a diagnostic and endoscopic emergency. If ingested, a CXR is crucial. Obtain it as soon as the patient arrives in the ED.

Most small size BB ingestions do not cause damage, provided the BB does not lodge in the oesophagus. The frequency of lodgement is increasing with widespread usage of the 20–25 mm diameter lithium batteries. A BB stuck in the oesophagus can cause serious mucosal injury. The damage is primarily caused by an electrical current that hydrolyzes soft tissue and results in liquefactive necrosis, not leakage of battery contents. Damage can occur very quickly, sometimes within one or two hours of lodgement23,24. Mucosal damage can result in oesophageal perforation, tracheoesophageal fistula, stricture formation, and death24. Rapid diagnosis and emergency removal of a lodged battery is essential.

Note: BBs can also cause a similarly serious injury if placed in the ear or nose23,24,27.

Magnets6,10–12,28

Powerful rare earth magnets can be found in toys, jewellery items, beads, nose and tongue piercings, studs, desk toys, stress relievers, homeopathic and naturalistic aids, and other items such as bracelets used in folk medicine.

Swallowing magnets appears to be relatively common amongst autistic children with access to magnetic pieces8.

The ED aim is to determine whether more than one magnet has been swallowed. If a child swallows more than one magnet and they pass through the pylorus then the separate pieces can attract each other across different bowel loops. Gut wall necrosis, perforation, fistulae, haemorrhage, and volvulus are potential and serious consequences. Alternatively, a child might swallow one magnet and another piece of metal to which it is attracted. This is also dangerous.

Pitfalls.

1. On the AXR a cluster of magnets clumped tightly together across different bowel loops can be misread as a harmless necklace or other single object. Avoid this risk by putting a compass against the patient's abdomen8. If the compass indicates the object is a cluster of magnets, then it represents a surgical emergency.

2. Detection using a metal detector (p. 350) poses a similar risk. If there is uncertainty as to what has been swallowed, then a magnet detected by a HHMD might be assumed, erroneously, to be a coin. Placing a compass against the abdomen will assist. Lack of compass movement will exclude a magnet.