We’ve done multiple columns on hazards related to MRI. And we’ve emphasized the dangers of metallic or ferromagnetic items overheating during MRI and causing injury. But we’ve just come across one we have not encountered before: harm due to MRI in patients who have ingested magnets. A recent paper (Bailey 2012) describes a case of a 5 y.o. boy who had ingested magnets and had an MRI that led to bowel perforation. The authors review the literature and come up with a recommended tool to screen for magnets before MRI is performed.
The authors note that most cases of ingested magnets occur in young children and most often boys and are often, in fact typically, not witnessed. Most are passed in the stool without incident and less than 10% require intervention (only 1% requiring surgery). However, swallowing multiple magnets may be more troublesome since the magnets adhere to each other, increasing the likelihood they might obstruct the bowel.
In their index case, the authors note the patient actually presented to an ED with complaints of neck pain. Initial workup focused on the cervical spine and included a normal CT scan of the neck and normal lumbar puncture. A decision to do an MRI of the brain and cervical spine was then done under moderate sedation and was also negative. The following day his neck pain was better but he now had severe abdominal pain and would not eat. Abdominal X-rays showed air in the peritoneal cavity and 11 small round metallic objects in the left upper quadrant. At surgery, four full-thickness small intestinal perforations were found and 11 small spherical magnets were removed from the peritoneal cavity. The magnets were most likely from a magnetic game the child had been playing near. He had an uneventful recovery.
The hospital changed their MRI screening protocol. While they still do a written and verbal questionnaire of the children and parents for presence of metallic objects, they now also have all children change into a hospital gown and undergo screening using a hand-held ferromagnetic detection scanner.
Very interesting case. Children do frequently ingest non-food items and may not be able to verbally tell you they did so. So maybe use of ferromagnetic scanners will become routine in children. Conceivably it might also find a role in screening older patients whose medical condition precludes providing a history of metallic objects ingested or implanted.
Interestingly, the day after we had prepared this column the US Consumer Product Safety Commission filed an administrative complaint against a manufacturer of toy magnets (CPSC 2012) based on more than 2 dozen reports of young children and teenagers swallowing the magnets. Many of those had visceral perforations or intestinal obstructions and required surgery. That report does not specifically mention the MRI risk noted in the Bailey paper. But it certainly points out that such ingestion of magnets is not rare.
Some of our prior columns on patient safety issues in the radiology or MRI suite:
· October 16, 2007 “ ”
· September 16, 2008 “More on Radiology as a High Risk Area”
· October 7, 2008 “Lessons from Falls....from Rehab Medicine”
· January 2010 “Falls in the Radiology Suite”
· August 2010 “Sedation Costs for Pediatric MRI”
· January 25, 2011 “Procedural Sedation in Children”
· February 19, 2008 “
Bailey JR, Eisner EA, Edmonds EW. Unwitnessed magnet ingestion in a 5 year-old boy leading to bowel perforation after magnetic resonance imaging: case report of a rare but potentially detrimental complication. Patient Safety in Surgery 2012; 6: 16 (19 July 2012)
CPSC (U.S. Consumer Product Safety Commission). CPSC Sues Maxfield & Oberton Over Hazardous Buckyballs® and Buckycube™ Desk Toys. Action prompted by ongoing harm to children from ingested magnets. News Release July 25, 2012