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March 07, 2017

Metal Detector Instead of X-rays for Swallowed Coins and Other Metallic Objects

Handheld Metal Detector
Due to a recent rash of consults of patients swallowing coins and other foreign bodies mainly in kids but adults too, it occurred to me that a handheld metal detector similar to one that is used in airport security screening can quickly and easily determine whether a metal object is present within the body as well as where.

This quick screening can serve three purposes...

1) X-rays can be avoided along with its radiation exposure. Typically, a neck, chest, and abdominal x-ray may be taken.
2) It is a heck of a lot cheaper than an x-ray as well as trip to the emergency room.
3) X-rays can miss certain small metal foreign bodies like those made from aluminum, but a metal detector won't.

Question is does a metal detector, which uses a magnetic field to detect metal objects, actually work for this purpose?

Apparently yes according to several medical research papers (see references below). The information was convincing enough that my office has purchased one for just these reasons.

According to one study, when it comes to coins and button batteries, metal detectors have a sensitivity of 100% and a specificity of 91.7%. When ALL metal objects are included, the sensitivity drops to 89.1% and specificity down to 91.7%. Sensitivity is even lower at 71% if coins and button batteries are excluded.

The metal detector accurately localized where the object was 73% of the time.

A few case reports described a situation where an x-ray could not see the metal object (razor blade and aluminum tab ring), but the metal detector was easily able to detect it.

A word of advice when purchasing for medical uses... make sure you get the metal detector meant for lumber which typically can detect metal objects at greater depths (up to 6 inches) rather than one meant for security screening which is limited to less than 2 inches.


References:
Diagnostic uses of metal detectors: a review. Int J Clin Pract. 2005 Aug;59(8):946-9.

Identification and topographic localization of metallic foreign bodies by metal detector. J Pediatr Surg. 2004 Aug;39(8):1245-8.

The use of a hand-held metal detector for localisation of ingested metallic foreign bodies - a critical investigation. Eur J Pediatr. 2004 Apr;163(4-5):257-9. Epub 2004 Feb 5.

Use of a metal detector in the location of a swallowed razor blade in the oesophagus. J Laryngol Otol. 1990 May;104(5):435-6.

Metal detector and swallowed metal foreign bodies in children. J Accid Emerg Med. 1999 Mar;16(2):123-5.

Using a metal detector to locate a swallowed ring pull. J Accid Emerg Med. 1995 Mar;12(1):64-5.


Fauquier blog
Fauquier ENT

Dr. Christopher Chang is a private practice otolaryngology, head & neck surgeon specializing in the treatment of problems related to the ear, nose, and throat. Located in Warrenton, VA about 45 minutes west of Washington DC, he also provides inhalant allergy testing/treatment, hearing tests, and dispenses hearing aids. Google+ Christopher Chang, MD Bio

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