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Handheld Metal Detector Confirmation of Radiopaque Foreign Bodies in the Esophagus
Ross M. Younger, MD;
David H. Darrow, MD, DDS
Arch Otolaryngol Head Neck Surg. 2001;127:1371-1374.
ABSTRACT
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Objective To examine the utility of handheld metal detectors in confirming the
position of radiopaque foreign bodies in the esophagus before delayed endoscopic
removal.
Design Prospective study of patients evaluated between June 1, 1997, and August
31, 1999.
Setting Tertiary pediatric referral center.
Patients Twenty-six of 139 children presenting consecutively for evaluation of
esophageal foreign bodies met eligibility criteria and completed the study
protocol. Inclusion in the study was contingent on a delay of at least 6 hours
from the time of diagnosis to the time of endoscopic removal. All patients
underwent both radiographic evaluation and handheld metal detector scanning
of the chest and abdomen on presentation and immediately before endoscopic
removal.
Results All patients evaluated during the study period had coins lodged within
the esophagus. Handheld metal detector scanning accurately confirmed this
position before endoscopic removal in all cases.
Conclusion Our data suggest that handheld metal detectors may obviate the need
for repeated radiographs in patients whose foreign bodies cannot be removed
at presentation.
INTRODUCTION
EARLY REMOVAL of ingested foreign bodies located in the esophagus is
paramount to avoiding potentially devastating complications. Nevertheless,
such objects rarely require emergency intervention, and there is usually ample
time for proper preoperative evaluation. Because most esophageal foreign bodies
are radiopaque, routine management usually entails initial anteroposterior
and lateral neck and chest radiographs. These studies confirm the ingestion
of a foreign body, establish the location of the foreign body in the esophagus,
characterize the shape and orientation of the foreign body, and rule out the
presence of multiple foreign bodies. Sometimes, several hours may elapse before
definitive treatment; in these cases, an anteroposterior radiograph is commonly
repeated to confirm that the foreign body has not migrated distally. These
studies add expense and additional radiation exposure to the preoperative
workup. The objective of this study was to examine the utility of handheld
metal detectors (HHMDs) in confirming the position of radiopaque foreign bodies
in the esophagus before delayed endoscopic removal. If accurate, HHMD scans
could preclude repeated radiographs and their concurrent cost and radiation
exposure without compromising necessary preoperative information.
PATIENTS, MATERIALS, AND METHODS
Candidates for inclusion in this study included all children evaluated
for esophageal foreign bodies at Children's Hospital of The King's Daughters,
Norfolk, Va, between June 1, 1997, and August 31, 1999. Patients enrolled
from this group had a radiographically confirmed esophageal foreign body and
no history of esophageal, pulmonary, cardiac, or other disease requiring thoracic
surgery with implementation of radiopaque hardware. Children with "high-risk"
foreign bodies (ie, disc batteries or objects with points, sharp edges, or
irregular or indeterminate shapes) or impending complications were excluded;
in these patients, removal was performed on an urgent basis. In each case,
endoscopic removal was electively delayed at least 6 hours as a result of
a full stomach or a nighttime hospital admission, necessitating repeated radiographs
at least 6 hours after the initial radiographs. A parent or guardian of each
patient signed a consent form approved by the institutional review board of
the Eastern Virginia Medical School, Norfolk.
After the initial history was taken and physical examination was performed,
patients underwent HHMD scanning and anteroposterior and lateral neck and
chest radiographs to include the gastric bubble or a review of studies already
completed by orders of the emergency department staff or personnel at an outside
facility. All metallic jewelry, eyeglasses, and clothing with metallic elements
were removed from them before scanning. With the child standing or held upright
away from metal interferences, an HHMD (Garrett Super Scanner; Garrett Security
Systems, Garland, Tex) was passed over the child's body in a "zigzag" fashion
from the cervical esophagus to the umbilicus anteriorly and posteriorly (Figure 1). The anatomic level of an audible
signal from the HHMD was recorded on the patient's skin and compared with
the original radiographic findings. The timing of endoscopic removal of an
esophageal foreign body was at the discretion of the attending otolaryngologist
and anesthesiologist. Another HHMD scan was performed within the hour before
endoscopic removal of the foreign body, followed by repeated anteroposterior
radiographic imaging. Data recorded included the age and sex of patients;
whether the event was witnessed vs unwitnessed; time from foreign body ingestion
to endoscopic removal; time between initial and repeated radiographs; original
location of the foreign body by radiographs and HHMD scans; and final location
of the foreign body by radiography, HHMD scanning, and endoscopy.
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Figure 1. The metal detector is passed in
a "zigzag" fashion over the cervical esophagus in front of (A) and behind
(B) the patient.
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RESULTS
A total of 139 patients presented for evaluation of suspected esophageal
foreign bodies during the 2-year study; 29 were eligible for study inclusion.
Three patients did not undergo the second radiographic evaluation, leaving
26 who completed the study. Patients' ages ranged from 9 to 92 months (median,
30 months); 13 patients were boys and 13 were girls. Ingestion of the foreign
body had been witnessed in 13 of the 26 patients. In cases in which the time
of the event could be established, median time to foreign body removal was
14 hours (range, 8 hours to 25 weeks). Mean time between radiographs was 8.8
hours (range, 5.0-15.0 hours).
In 24 of 26 patients, preoperative radiographs demonstrated a radiopaque
foreign body at the sternal notch. In 1 patient, the foreign body was identified
substernally, and in the remaining patient it was at the gastroesophageal
junction. In all patients, the HHMD scan confirmed the position of the foreign
body. In 2 patients, signal was also inexplicably detected over the lower
extremities.
Before undergoing endoscopic removal, all 26 foreign bodies were predicted
by HHMD scanning to be stable in location, and, in all cases, repeated anteroposterior
radiographs of the chest confirmed the position. On rigid esophageal endoscopy,
100% of the foreign bodies were found to be coins, and all were in the locations
predicted by preoperative studies. In 1 patient excluded from the study for
failure to undergo follow-up radiography, no foreign body was found on rigid
endoscopy. Metal detector scanning in the operating room suggested that the
foreign body had moved distally, and the object was found in the stomach on
subsequent flexible endoscopy. No postoperative complications were observed.
COMMENT
Esophageal foreign bodies are most common in children aged 6 months
to 6 years who are inclined to use the oral cavity to explore their environments.
Some esophageal foreign bodies pose potentially devastating risks to children,
including reflexive regurgitation with aspiration, esophageal perforation,
upper respiratory tract infections, mediastinitis with or without abscess,
tracheoesophageal fistula, aortoesophageal fistulas, extraluminal migration
of the foreign body, false or true esophageal diverticula, and esophageal
obstruction.
Despite the changing nature of esophageal foreign bodies during the
past 25 years, coins remain by far the most common foreign body ingested by
children.1 Symptomatic esophageal coins or
those resulting from witnessed ingestions are rarely associated with significant
morbidity because they are removed promptly. However, because coin impactions
of long duration may cause complications and nearly half are asymptomatic,2 it has been suggested that all children with suspected
coin ingestions undergo anteroposterior and lateral neck and chest radiographs
to include the gastric bubble to assess for an esophageal impaction and any
associated complications.2-5
The initial radiographic studies yield valuable information: presence or absence
of a radiopaque foreign body; presence of multiple radiopaque foreign bodies;
size, shape, and orientation of the foreign body; and mediastinal or thoracic
complications from resultant esophageal perforations. These studies may also
suggest the presence of nonradiopaque foreign bodies when periesophageal inflammation
is seen.
On the other hand, many esophageal foreign bodies pass uneventfully
through the gastrointestinal tract. Hodge et al2
reported that 10 (40%) of 25 confirmed esophageal foreign bodies passed spontaneously
into the stomach after 1 to 5 hours.2 Schunk
et al4 reported that 6 of 9 asymptomatic and
2 of 21 symptomatic patients passed coins spontaneously into the stomach within
4 hours. These authors suggest waiting as long as 12 to 24 hours to allow
coins to pass spontaneously, thus avoiding an invasive procedure without an
increased risk of severe complications. Furthermore, in many cases, there
may be a delay in management of an esophageal foreign body from the time of
initial diagnosis. Reasons for such delays may include transfer of the patient
to an appropriate facility for treatment; a full stomach, which could cause
complications for patients during induction of anesthesia; availability of
the endoscopist or the endoscopy suite; or late-night admission to the hospital.
When the delay exceeds the 4- to 5-hour wait described by Schunk4
and Hodge2 and their colleagues, many practitioners
repeat the anteroposterior radiograph to confirm the persistence of a foreign
body within the esophagus before endoscopic removal.
Use of an HHMD for following the progression of coins through the gastrointestinal
tract was first described in a letter by Lewis6
in 1980. Kessler et al7 subsequently reported
a case in which an HHMD accurately localized an esophageal razor blade that
went undetected both on plain films and fluoroscopic swallow with contrast.
Arena and Baker8 reported that HHMD scans correctly
diagnosed 15 positive cases and 13 negative cases of gastrointestinal tract
metallic foreign bodies when plain radiographs were used as the gold standard.
They recorded no false-positive or false-negative results. Ros and Cetta9 studied the use of HHMDs in localizing ingested coins
in children using simulated scans of metallic foreign bodies through soft
tissues. Distances between the scanner and the foreign body were taken from
measurements from the anterior chest to the gastroesophageal junction on computed
tomographic images of healthy children aged 3 months to 6 years. The authors
reported an accuracy of 100% in 40 positive cases and 10 negative cases at
distances of 6.1 to 7.9 cm.9 They subsequently
reported10 sensitivity of 91% and specificity
of 100% in localizing swallowed coins in a clinical trial of 14 children.
The sole failure of the Garrett Super Scanner was in a child with a rectal
coin in whom management was not likely to be affected.10
Biehler et al11 reported sensitivity and specificity
of 100% in detecting 27 coins in 30 cases of suspected coin ingestion. They
correctly identified 13 cervical esophageal, 4 middle-to-lower esophageal,
and 10 subdiaphragmatic coins. In addition, they argued that $5642 could have
been saved (mean ± SD, $188.96 ± $87.29) had only the HHMD scans
been performed.
The accuracy of the HHMD for detecting noncoin foreign bodies is not
firmly established. Ros and Cetta12 reported
failure to detect several objects, including a safety pin, paper clip, tack,
watch battery, AA battery, and iron pill, in simulated scans through an examiner's
forearm. Subsequently, however, Sacchetti et al13
reported 94% sensitivity and 100% specificity in detecting 15 of 16 radiopaque
foreign bodies (11 coins, a button battery, a medallion, a token, and a leaded
glass marble). The undetected foreign body was a sewing needle that was barely
perceptible on plain films.13 The HHMD used
was the same as that used by Ros and Cetta12
at one of the 2 emergency department settings in the study. Tidey et al14 recently reported the correct positive and negative
detection of 13 radiopaque foreign bodies in 20 children, including 8 coins,
1 ball bearing, 1 screw, 1 gold ring, 1 staple, and 1 washer. None of the
foreign bodies were localized to the esophagus, however.14
A recent study15 using HHMDs to localize
ingested foreign bodies, performed in part at Eastern Virginia Medical School,
compared the technique of experienced investigators with that of inexperienced
investigators. Using chest radiographs as a gold standard, metal detection
by experienced investigators had a positive predictive value of 90.9% and
a negative predictive value of 100%. In less experienced hands, HHMDs achieved
a positive predictive value of 77.0% and a negative predictive value of 96.6%,
reflecting a higher false-positive rate. The difference between experienced
and inexperienced investigators was not statistically significant; however,
this difference may explain the false-positive signals detected in our study,
in which the resident on call performed the HHMD scan.
Our review of the literature found no studies comparing the accuracy
or sensitivity of different HHMDs. While several investigators9-10,13, 15
used the same Garrett Super Scanner used in the present study, other devices
used included the EBEX 610 (Ebiner, Köln, Germany),8
model 2000 (White's Electronics, Inc, Sweet Home, Ore),8
Backpacker-2 TR (AH Electronics, Inc, Arlington Heights, Ill),11
Enforcer G2 (Garrett Security Systems),13 and
AD 15 (Adams Electronics, Inc, East Sussex, England, and Enid, Okla).14 It is our impression that smaller, more sensitive
scanners may more accurately predict the position of the foreign body and
may be useful in reducing the frequency of false-positive scans. Such devices
are being developed, and a comparative study would be a consideration for
future investigation.
Our protocol for evaluation of esophageal foreign bodies still calls
for initial radiographic imaging of the chest. High-risk foreign bodies must
be identified immediately because these objects require earlier intervention.
In addition, we have observed cases in which the radiographic findings significantly
altered our instrumentation and approach to the foreign body (Figure 2). On the other hand, Seikel et al15
reported a case in which 2 HHMD scans identified an ingested aluminum can
pull tab that was not seen on initial radiographs of the chest. In some cases,
therefore, both modalities may be useful.
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Figure 2. Anteroposterior radiograph of
the chest (A) demonstrating a round foreign body (arrow) consistent with a
coin; however, the object is also round on the lateral radiograph (B). The
foreign body removed at endoscopy was a marble.
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All of the radiopaque foreign bodies in this study were metallic and
were, in fact, coins. The results must therefore be interpreted with caution
when the type of foreign body remains uncertain. Other study limitations include
a small sample size and the absence of multiple or migrated foreign bodies.
Although complications did not occur in the study group and are extremely
unlikely in the selected population, such events could potentially occur during
the "delay" interval in a larger population and would be missed radiographically
using the study protocol. Nevertheless, our data suggest that HHMDs are a
useful adjunct in the evaluation and treatment of esophageal foreign bodies
when removal is performed on a delayed basis. Although the HHMD used in this
study retails for $199 and can be purchased at a significant discount, cost
savings as a result of eliminating a repeated radiograph were estimated to
be $87.30 per patient. In addition, radiation exposure was reduced by 50 to
100 mRad (0.5-1 mGy) per patient. We conclude that HHMDs have a place in the
preoperative evaluation of esophageal foreign bodies.
AUTHOR INFORMATION
Accepted for publication June 11, 2001.
Presented in part at the 79th Annual Meeting of the American Bronchoesophagological
Association, Palm Beach, Fla, May 12, 1998.
Corresponding author: David H. Darrow, MD, DDS, Department of Otolaryngology–Head
and Neck Surgery, Eastern Virginia Medical School, 825 Fairfax Ave, Norfolk,
VA 23507.
From the Departments of Otolaryngology–Head and Neck Surgery
(Drs Younger and Darrow) and Pediatrics (Dr Darrow), Eastern Virginia Medical
School, Norfolk.
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