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Reported by Debasis Das, SpR Radiology Checked by Gabby May, Clinical Fellow, Manchester Royal Infirmary Guy’s & St Thomas’ Hospitals, London
Three part question
In [patients who are suspected to have fish or chicken bones impacted in the oesophagus] is [computerised tomography better than plain radiography] at [identifying and localising a foreign body]?
Clinical scenario
A 60-year-old man attends the emergency department complaining that a fish bone has got stuck in his throat. Clinical examination rules out impaction within the pharynx so you are concerned that the bone has become impacted within the oesophagus. Prior experience tells you that oesophageal abrasions secondary to ingested bones can often mimic impaction, that rigid oesophgoscopy (the definitive investigation) carries a significant mortality and morbidity rate, and that the most readily available non-invasive investigations, lateral neck and chest x rays, are often unreliable. You wonder whether a computed tomography (CT) scan of the neck would be a more accurate non-invasive tool?
Search strategy
Medline 1966—week 3, February 2006. Limit to human and English. ({exp. Tomography, Spiral Computed/or exp. Tomography, X-ray computed/or CT. mp.} AND [{fish bone. mp.} OR {foreign body. mp. OR exp. Foreign bodies}] AND {exp. Esophagus/or oesophageal. mp.})
Search outcome
Altogether 66 papers found, of which 62 were irrelevant or of insufficient quality. The remaining four papers have been systematically reviewed.
Comment(s)
The studies reviewed above clearly show that CT of the neck is an extremely accurate, non-invasive diagnostic tool with a high PPV. However, of the 58 patients in the four series with positive x ray findings, there were only 3 false-positives. Thus, disregarding study 4 (which is appears to be a small-scale pilot study for study 2 with skewed results), it is unsurprising that studies 1–3 all still recommend plain x ray as the initial radiographic screening tool. Positive results, which include soft tissue changes, warrant oesophagoscopy, while negative results should lead to a CT scan of the neck. Bearing in mind that there was 100% sensitivity amongst the 144 patients undergoing CT, and that there was just one false positive amongst the 80 patients with positive results, only visualisation of an actual fish or chicken bone should result in an oesophagoscopy at this point. Similarly, a negative CT scan should confidently exclude fish and chicken bones.
CLINICAL BOTTOM LINE
CT is more effective than plain radiography at identifying and excluding impacted oesophageal fish and chicken bones. However, plain radiography is also specific enough for positive results to warrant oesophagoscopy without any further imaging, and should thus continue being utilised as the first line radiological investigation.
Reported by Debasis Das, SpR Radiology Checked by Gabby May, Clinical Fellow, Manchester Royal Infirmary Guy’s & St Thomas’ Hospitals, London