DOI:10.2214/AJR.04.1297
AJR 2005; 185:1048-1050
© American Roentgen Ray Society
Endoscopic Video Capsules: Radiologic Findings of Spontaneous Entrapment in Small Intestinal Diverticula
Ron C. Gaba1,
Paul K. Schlesinger2 and
Andrew C. Wilbur1
1 Department of Radiology (M/C 931), University of Illinois Medical Center at
Chicago, 1740 W. Taylor St., Chicago, IL 60612.
2 Department of Medicine, Section of Digestive Diseases and Nutrition (M/C 716),
University of Illinois Medical Center at Chicago, Chicago, IL 60612.
Received August 18, 2004;
accepted after revision October 15, 2004.
Address correspondence to R. C. Gaba.
Introduction
Wireless capsule endoscopy is a relatively new diagnostic technique for the
detection of small intestinal disease. This minimally invasive procedure
generally poses few risks to the patient, and reported complications typically
are related to capsule retention
[1-4].
To our knowledge, only one case of video capsule entrapment within a
small-bowel diverticulum has been reported
[1]. In that instance, capsule
retention was due in part to a nearby stricture, and the diagnosis was made
surgically. We report the first known case of prolonged spontaneous video
capsule entrapment in small intestinal diverticula in which the diagnosis was
made radiologically.
Case Report
A 60-year-old woman was evaluated for chronic iron deficiency anemia of
uncertain cause. She had no gastrointestinal symptoms to suggest a source of
blood loss and no history of gastrointestinal surgery.
Esophagogastroduodenoscopy and colonoscopy were unrevealing, and treatment
with oral iron produced a limited response. Small-intestine evaluation was
thus pursued.
A barium small bowel follow-through was reported initially as significant
only for a 2-cm diverticulum in the second portion of the duodenum. Later
review showed a 5-cm diverticulum in the distal ileum
(Fig. 1A). Wireless capsule
endoscopy (M2A capsule, Given Imaging) was performed
(Fig. 1B). Unfortunately, as
the endoscopic images revealed, the capsule became lodged in a small
intestinal segment containing stagnant contents and eventually lost battery
power. A second endoscopic capsule examination 3 weeks later yielded a similar
result.
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Fig. 1A —60-year-old woman undergoing wireless capsule endoscopy.
Magnified view from barium small bowel follow-through shows large distal ileal
diverticulum (long arrow) and smaller duodenal diverticulum
(short arrow).
|
|
One week after the second attempt, the patient still had not passed either
of the capsule devices. Oral laxatives were not helpful. Although the patient
was asymptomatic, radiologic evaluation was initiated. An abdominal radiograph
showed two video capsules in the right lower quadrant
(Fig. 1C). CT of the abdomen
revealed that these video capsules were caught within two separate diverticula
arising from a loop of distal small bowel, each of which was also filled with
mottled-appearing material suggestive of stagnation (Figs.
1D and
1E). The patient elected
expectant management, but 2 months later, neither capsule had been
expelled.
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Fig. 1D —60-year-old woman undergoing wireless capsule endoscopy.
Axial (D) and reconstructed coronal (E) unenhanced CT images
show one of the two endoscopic capsules (arrow) lodged within rounded
small-bowel diverticulum.
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Fig. 1E —60-year-old woman undergoing wireless capsule endoscopy.
Axial (D) and reconstructed coronal (E) unenhanced CT images
show one of the two endoscopic capsules (arrow) lodged within rounded
small-bowel diverticulum.
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|
Discussion
Wireless capsule endoscopy was approved for clinical use in the United
States in 2001 and currently represents an increasingly used method for
diagnostic evaluation of the small intestine, predominantly in cases of occult
gastrointestinal bleeding. It is therefore important for radiologists to be
familiar with the procedure, the imaging appearance of the video capsule, and
the radiologic diagnosis of complications that may arise.
A preliminary small bowel follow-through is commonly performed before
wireless capsule endoscopy. The primary objective of this procedure is to
exclude significant luminal narrowing of the small intestine before capsule
ingestion. The endoscopic capsule examination then begins when the patient
swallows the 1.1 x 2.6 cm, 4-g capsule, which contains a camera, light
source, batteries, and transmitter. As the capsule traverses the small
intestine, it relays images to a recorder worn on a belt around the patient's
waist. The capsule battery has a lifespan of approximately 8 hr, typically
enough time for it to image the entire small bowel as it passes through.
Prokinetic agents are often given to ensure complete transit. Recorded images
are downloaded and analyzed later.
Most capsules are naturally expelled within 72 hr (range, 24-222 hr) of
ingestion [5]. Endoscopic
capsules are disposable and used only once. Approximately 1-2% of ingested
capsules may be retained within the small intestine for longer than 72 hr
[6]. Of these, most will still
pass spontaneously. A small percentage of retained capsules will resist
passage, and in almost all reported cases, this is due to the presence of a
small intestinal pathology such as stricture, ulcer, or tumor. These
obstructed capsules may require operative removal. A recent study of 937
patients undergoing wireless capsule endoscopy revealed that seven (0.75%)
required surgical intervention for capsule removal
[3].
Typically, passage across the ileocecal valve into the cecum is documented
during the capsule endoscopy study itself. Radiologic evaluation is
recommended when this does not occur. Radiographically, the endoscopic video
capsule appears as a small, corrugated rectangular metallic object that
resembles a lantern (Fig. 1F).
Serial abdominal radiographs after capsule ingestion should show passage of
the capsule through the gastrointestinal tract, whereas retained capsules
maintain a persistent position. In addition, capsule retention should prompt
further investigation for an underlying pathologic cause not identified on the
preliminary diagnostic evaluation. Some recommend that exploratory laparotomy
and intraoperative enteroscopy be performed on all patients in whom the
capsule remains within the small bowel for 5 days or longer
[7]. As seen in this case,
however, CT is a useful adjunct in identifying the location of the capsule,
depicting an obstructive cause, and revealing associated complications. CT
evaluation should be considered before surgical therapy in cases of capsular
retention.
Congenital and acquired diverticula of the small intestine are uncommon,
occurring with an estimated incidence of 1-2% in the general population
[8]. Although the presence of
large or numerous small-bowel diverticula is a relative contraindication to
video capsule endoscopy [2],
this does not generally preclude examination. The likelihood of capsule
entrapment within a small-bowel diverticulum is considered to be small. One
report of 75 patients examined with wireless capsule endoscopy showed only a
single case of a capsule entering a diverticulum, and it exited spontaneously
after 5 hr [4]. At our
institution, this case is the only one encountered in the more than 250
capsule endoscopy examinations performed between April 2002 and July 2004.
Interestingly, retention of endoscopic capsules in large intestinal
diverticula has not been encountered, to our knowledge, despite their greater
incidence compared with diverticula of the small bowel. Screening for
large-bowel diverticulosis before wireless capsule endoscopy examination is
considered unnecessary, although colonoscopy is nevertheless often performed
in patients with gastrointestinal bleeding.
Because no strict criteria define the exact size or number of small
intestinal diverticula that constitute an absolute contraindication to
wireless capsule endoscopy, the decision to proceed with this examination in a
patient with isolated small intestinal diverticulosis is best made on a
case-by-case basis. The small risk of possible capsule entrapment and the
clinical impact of the prospective diagnostic result must be considered
carefully. Potential complications of diverticular capsule entrapment include
incitement of bacterial overgrowth, bowel wall erosion, perforation, and
fistula formation. It is more likely, however, that the capsule will remain
silently within a diverticulum or eventually become extruded and pass
spontaneously. Thus, initial conservative management of asymptomatic patients
is justified. As a final precaution, a retained endoscopic video capsule
constitutes an absolute contraindication to MRI (M2A capsule user manual,
Given Imaging). Exposure to strong magnetic fields may result in capsule
motion and a missile effect that can cause injury to internal structures.
References
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Introduction
Case Report
