DOI:10.2214/AJR.06.1257
AJR 2007; 189:81-88
© American Roentgen Ray Society
Imaging Manifestations of Meckel's Diverticulum
Khaled M. Elsayes1,
Christine O. Menias2,
Howard J. Harvin2 and
Isaac R. Francis1
1 Department of Radiology, University of Michigan Health Center at Ann Arbor,
Ann Arbor, MI 48100-0030.
2 Mallinckrodt Institute of Radiology, Washington University, St. Louis,
MO.
Received September 22, 2006;
accepted after revision January 15, 2007.
Address correspondence to K. M. Elsayes
(kelsayes{at}med.umich.edu).
CME
This article is available for CME credit. See
www.arrs.org
for more information.
Abstract
OBJECTIVE. Meckel's diverticulum is the most common congenital
anomaly of the gastrointestinal tract, found in 2% of the population in
autopsy studies. Most patients remain asymptomatic during their lifetime.
Complications of Meckel's diverticulum are reported to occur in approximately
4–40% of patients and include inflammation (diverticulitis), hemorrhage,
intussusception, small-bowel obstruction, stone formation, and neoplasm. The
purpose of this article is to familiarize the radiologist with the current
imaging of Meckel's diverticulum and its presenting complications. The
spectrum of diagnostic findings on various imaging techniques will be
reviewed.
CONCLUSION. Meckel's diverticulum and its complications are a
serious health problem. Familiarity of the radiologist with the appearance of
this pathologic entity enables an accurate diagnosis in emergent settings.
Keywords: abdominal imaging • congenital malformation • diverticulum • Meckel's diverticulum
Introduction
Meckel's diverticulum is the most common congenital anomaly of the
gastrointestinal tract. It is seen in 2% of the population, and it is caused
by failure of the omphalomesenteric duct to regress. The point of attachment
of a Meckel's diverticulum to the bowel varies. Most (75%) Meckel's
diverticula are found within 100 cm of the ileocecal valve
[1]. Meckel's diverticulum
occurs with equal frequency in both sexes, but symptoms from complications are
more common in male patients. Meckel's diverticula are typically asymptomatic
and usually are found incidentally, with a lifetime risk of complications
reported to be 4–40% [2].
Heterotopic gastric and pancreatic mucosa are frequently found histologically
in the diverticula of symptomatic patients
[2]. The most common
complications are hemorrhage from peptic ulceration, small-intestinal
obstruction, and diverticulitis
[3].
The purpose of this article is to familiarize the radiologist with the
current imaging of Meckel's diverticulum and its presenting complications. The
spectrum of diagnostic findings on various imaging techniques will be
reviewed.
Embryology and Anatomy
Meckel's diverticulum was named after Johann Friedrich Meckel, who
described its anatomy and embryology in 1809
[4]. Meckel's diverticulum is a
remnant of the omphalomesenteric or vitelline duct, which connects the yolk
sac to the midgut through the umbilical cord. This duct is typically
obliterated by the 5th–8th week of gestation. Failure of duct closure
results in diverticulum (90% of cases), omphalomesenteric fistula, enterocyst,
or a fibrous band.
Meckel's diverticulum arises from the antimesenteric border of the distal
small bowel, typically 40–100 cm from the ileocecal valve, with a
typical length of up to 5 cm and diameter of up to 2 cm. Blood supply to this
diverticulum typically comes from the omphalomesenteric artery (a remnant of
the primitive vitelline artery arising from an ileal branch of the superior
mesenteric artery).
Meckel's diverticula are lined with heterotopic mucosa in up to 60% of
cases in the following manner: gastric mucosa, 62%; pancreatic, 6%; both
gastric and pancreatic, 5%, jejunal, 2%; Brunner's glands, 2%; and gastric and
duodenal, 2% [5].
Imaging Findings and Usefulness of Various Imaging Techniques
Various imaging techniques have been used for diagnosing Meckel's
diverticulum. Conventional radiographic examination is of limited value and is
usually unrevealing. However, it may show enteroliths, findings of bowel
obstruction, and the presence of gas or a gas–fluid level in the
diverticulum.
Conventional barium studies (small-bowel follow-through study,
enteroclysis, or retrograde ileal opacification by means of barium enema) have
been largely replaced by other imaging techniques for evaluation of patients
with acute symptoms.
Meckel's diverticulum is not often seen on routine barium studies because
of its small ostium, filling with intestinal contents, and peristalsis with
rapid emptying. Meticulous examination with enteroclysis has been reported to
be more sensitive [6].
On barium studies, Meckel's diverticulum appears as a blind-ending pouch
arising from the antimesenteric side of the distal ileum
(Fig. 1). Filling defects in
the diverticulum may suggest gastric mucosa or tumor
[3].
Meckel's diverticulum may be inverted, serving as lead point for
intussusception, and appears as a soft polypoid filling defect
[7].
Sonography
Although of limited value, sonography has been used for the investigation
of Meckel's diverticulum [8].
High-resolution sonography usually shows a fluid-filled structure in the right
lower quadrant having the appearance of a blind-ending, thick-walled loop of
bowel, with the typical gut signature and a clear connection to a peristaltic,
normal small-bowel loop (Fig.
2). The echo-free contents should not be compressed or expressed
into the connecting bowel loop
[8]. Hyperechoic mucosa
("gut signature") is always detected, and enteroliths are
visualized as shadowing echogenic foci
[8].
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Fig. 2 —Sonogram in 30-year-old woman shows blind-ending thickened
loop with gut signature correlating with inflamed Meckel's diverticulum
(short arrow) in right lower quadrant. Note cecum (long
arrow) and iliac vessels (arrowhead).
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CT
On CT, Meckel's diverticulum is difficult to distinguish from normal small
bowel in uncomplicated cases. However, a blind-ending fluid- or gas-filled
structure in continuity with small bowel may be seen. CT may also show
enteroliths, intussusception, diverticulitis, and small-bowel obstruction. A
recent innovation of CT enterography has resulted in better visualization of
small bowel and consequent higher sensitivity in the diagnosis of Meckel's
diverticulum [9]
(Fig. 3). CT enterography
combines the improved spatial and temporal resolution of MDCT with large
volumes of ingested neutral enteric contrast material to permit visualization
of the small-bowel wall
[9].
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Fig. 3 —37-year-old man with occult gastrointestinal bleeding. Axial
image from CT enterography examination shows increased enhancement in Meckel's
diverticulum (arrow). Surgical pathology confirmed ectopic gastric
mucosa.
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Angiography can show the persistent omphalomesenteric artery in most
individuals with a Meckel's diverticulum who present with chronic
gastrointestinal bleeding (Figs.
4A and
4B). However, the recognition
of a persistent vitellointestinal artery may be difficult because of overlying
vessels, and superselective catheterization of distal ileal arteries may be
necessary. The omphalomesenteric artery typically arises from mid or distal
branches of the superior mesenteric artery. Ectopic gastric mucosa may show a
dense blush (Figs. 4A and
4B). Extravasation of contrast
material in cases of active bleeding typically requires bleeding > 0.5
mL/min in order to be visualized
[10].
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Fig. 4A —17-year-old girl with abdominal pain and rectal bleeding.
Selective angiograms of superior mesenteric artery show focal region of
pooling surrounding Meckel's diverticulum with contrast blush
(arrow).
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Fig. 4B —17-year-old girl with abdominal pain and rectal bleeding.
Selective angiograms of superior mesenteric artery show focal region of
pooling surrounding Meckel's diverticulum with contrast blush
(arrow).
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Scintigraphy
Scintigraphy with 99mTc-Na-pertechnetate has only minor
diagnostic value and a limited sensitivity of 60% in diagnosing Meckel's
diverticulum [11]. However, it
aids in the diagnosis of diverticula with ectopic gastric mucosa.
Pertechnetate is taken up by mucin-secreting cells of the gastric mucosa and
ectopic gastric tissue. Higher sensitivity in pediatric (85–90%) than in
adult (60%) patients is noticed
[11]. This could be due to
earlier symptoms (such as hemorrhage) in patients with ectopic gastric mucosa
(Figs. 5A,
5B,
5C, and
5D).
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Fig. 5A —26-year-old woman with Meckel's diverticulum.
Technetium-99m-labeled heat-damaged RBC scans show focus of intense activity
(arrows, B–D) in right lower quadrant on initial flow
study. Operative findings confirmed hemorrhagic Meckel's diverticulum.
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Fig. 5B —26-year-old woman with Meckel's diverticulum.
Technetium-99m-labeled heat-damaged RBC scans show focus of intense activity
(arrows, B–D) in right lower quadrant on initial flow
study. Operative findings confirmed hemorrhagic Meckel's diverticulum.
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Fig. 5C —26-year-old woman with Meckel's diverticulum.
Technetium-99m-labeled heat-damaged RBC scans show focus of intense activity
(arrows, B–D) in right lower quadrant on initial flow
study. Operative findings confirmed hemorrhagic Meckel's diverticulum.
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Fig. 5D —26-year-old woman with Meckel's diverticulum.
Technetium-99m-labeled heat-damaged RBC scans show focus of intense activity
(arrows, B–D) in right lower quadrant on initial flow
study. Operative findings confirmed hemorrhagic Meckel's diverticulum.
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Imaging of Complications of Meckel's Diverticulum
Reported complication rates range from 4% to 40%, with complications
including bleeding, bowel obstruction, enterolith formation, retention of
foreign bodies, inflammation (diverticulitis or ulceration), and neoplasm
[2,
5,
12]. Detection of heterotopic
gastric mucosa is of paramount significance because it can result in serious
complications such as bleeding. CT and scintigraphy play an important role in
the diagnosis of heterotopic mucosa (Figs.
5A,
5B,
5C,
5D, and
6).
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Fig. 6 —26-year-old woman. Axial contrast-enhanced CT scan shows
blind-ending Meckel's diverticulum with thickened mucosal folds
(arrow). Pathology confirmed ectopic gastric mucosa in Meckel's
diverticulum.
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Hemorrhage
Hemorrhage accounts for up to 30% of symptomatic Meckel cases
[12]. Hemorrhage usually
occurs secondary to ectopic gastric mucosa. Hemorrhage has been reported to be
more common and more severe during childhood. Angiography is usually used to
diagnose hemorrhage secondary to the bleeding Meckel's diverticulum (Figs.
4A and
4B).
Bowel Obstruction
Bowel obstruction accounts for up to 40% of symptomatic Meckel's
diverticula [12] (Figs.
7A and
7B). Obstruction can be caused
by trapping of a bowel loop by a mesodiverticular band, a volvulus of the
diverticulum around a mesodiverticular band (Figs.
8A and
8B), and intussusception, as
well as by an extension into a hernia sac (Littre's hernia). Obstruction has
been found to occur more frequently with a giant Meckel's diverticulum. MDCT
is a sensitive technique for diagnosing small-bowel obstruction
[13]. Ileocolonic
intussusception can rarely occur secondary to an invaginated Meckel's
diverticulum. In these cases, CT reveals dilated loops of proximal small bowel
with an intraluminal mass seen in the ascending colon. This intracolonic mass
is an intus-suscepted ileum
[14] (Figs.
9A and
9B).
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Fig. 7A —23-year-old man. Axial contrast-enhanced CT images show
blind-ending fluid-filled structure (arrow, A) resulting in
small-bowel obstruction. Operative findings confirmed Meckel's
diverticulum.
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Fig. 7B —23-year-old man. Axial contrast-enhanced CT images show
blind-ending fluid-filled structure (arrow, A) resulting in
small-bowel obstruction. Operative findings confirmed Meckel's
diverticulum.
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Fig. 8A —21-year-old woman with right lower quadrant pain and
neutrophilia. Axial CT scans show U-shaped loop of bowel in pelvis, suggesting
volvulus of diverticulum around mesodiverticular band (arrow).
Operative findings confirmed torsion of Meckel's diverticulum.
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Fig. 8B —21-year-old woman with right lower quadrant pain and
neutrophilia. Axial CT scans show U-shaped loop of bowel in pelvis, suggesting
volvulus of diverticulum around mesodiverticular band (arrow).
Operative findings confirmed torsion of Meckel's diverticulum.
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Enterolith Formation
Enterolith formation is an uncommon complication of Meckel's diverticulum
despite diverticula being the most likely sites of a small-bowel enterolith.
Enteroliths can be seen in 3–10% of Meckel's diverticula
[12]. Enteroliths are thought
to form as a result of stasis. Approximately 50% of enteroliths can be seen on
radiography. However, unenhanced CT should be more valuable in detecting an
enterolith (Figs. 10A,
10B,
11A, and
11B).
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Fig. 10A —31-year-old woman. Axial CT scans show enterolith
(arrow, A) in dilated infected Meckel's diverticulum. Note
adjacent infiltration of ileocolic mesentery, suggesting superimposed
diverticulitis (arrows, B).
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Fig. 10B —31-year-old woman. Axial CT scans show enterolith
(arrow, A) in dilated infected Meckel's diverticulum. Note
adjacent infiltration of ileocolic mesentery, suggesting superimposed
diverticulitis (arrows, B).
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Fig. 11B —28-year-old woman with vomiting and abdominal pain. CT scan
shows enteroliths (arrow) in neck of diverticulum. Operative findings
confirmed obstructed Meckel's diverticulum containing enterolith.
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Inflammation
Diverticulitis accounts for up to 30% of symptomatic cases
[12]. Diverticulitis commonly
occurs secondary to acid secretion from ectopic gastric mucosa. It also can
occur due to obstruction by enteroliths, foreign bodies, or neoplasm.
Scintigraphy has been used for diagnosing Meckel's diverticulitis secondary to
heterotopic gastric mucosa and usually shows a focal high uptake indicative of
heterotopic gastric mucosa with an adjacent region of low-grade tracer
localization attributable to the inflammatory mass
[15]. CT is a sensitive
technique for diagnosing Meckel's diverticulitis, which usually appears as a
blind-ending pouch of variable size with mural thickness and containing fluid,
air, or particulate material with surrounding mesenteric inflammation
[16] (Figs.
10A,
10B,
12A,
12B, and
12C).
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Fig. 12A —28-year-old man with 1 week of epigastric pain that
subsequently localized to right lower quadrant. CT scans show inflammatory
process in right lower quadrant (arrows, A) with small abscess
(arrow, B and C). Operative exploration confirmed
perforated Meckel's diverticulitis.
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Fig. 12B —28-year-old man with 1 week of epigastric pain that
subsequently localized to right lower quadrant. CT scans show inflammatory
process in right lower quadrant (arrows, A) with small abscess
(arrow, B and C). Operative exploration confirmed
perforated Meckel's diverticulitis.
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Fig. 12C —28-year-old man with 1 week of epigastric pain that
subsequently localized to right lower quadrant. CT scans show inflammatory
process in right lower quadrant (arrows, A) with small abscess
(arrow, B and C). Operative exploration confirmed
perforated Meckel's diverticulitis.
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Neoplasm
Neoplasms arising in Meckel's diverticula are rare, accounting for up to 3%
of complicated cases [14]. The
most frequently reported neoplasm complicating a Meckel's diverticulum is
carcinoid tumor. Other reported tumors include leiomyoma
(Fig. 13), leiomyosarcoma
[17], angioma, neuroma,
lipoma, carcinosarcoma, and adenocarcinoma
[18,
19]. These tumors have
nonspecific imaging features, including a sessile or lobulated filling defect.
Malignant neoplasms may infiltrate the adjacent mesenteric fat
[19].
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Fig. 13 —37-year-old woman with melena. Technetium-99m-labeled RBC
study shows bleeding in right lower quadrant (arrow). Operative
findings confirmed Meckel's diverticulum with ulcerated leiomyoma (thought to
be cause of bleeding).
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Perforation
Meckel's diverticulum can rarely be complicated by perforation, which is a
serious health event. Perforation is usually secondary to inflammatory
diverticulitis, gangrene, and peptic ulceration
[20–22].
Perforation can be suggested by the presence of free intraperitoneal air in
the setting of Meckel's diverticulum. This can be further detected on CT
(Figs. 14A,
14B, and
14C).
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Fig. 14A —34-year-old man. Serial CT slices through lower abdomen show
perforated Meckel's diverticulum (black arrow, B).
Extraluminal gas (arrow, A), and inflammatory changes
(white arrow, B) are seen adjacent to diverticulum. Operative
findings confirmed imaging findings.
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Fig. 14B —34-year-old man. Serial CT slices through lower abdomen show
perforated Meckel's diverticulum (black arrow, B).
Extraluminal gas (arrow, A), and inflammatory changes
(white arrow, B) are seen adjacent to diverticulum. Operative
findings confirmed imaging findings.
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Fig. 14C —34-year-old man. Serial CT slices through lower abdomen show
perforated Meckel's diverticulum (black arrow, B).
Extraluminal gas (arrow, A), and inflammatory changes
(white arrow, B) are seen adjacent to diverticulum. Operative
findings confirmed imaging findings.
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Conclusion
Meckel's diverticulum and its complications are a serious health problem.
Familiarity of the radiologist with the appearance of this pathologic entity
enables an accurate diagnosis in emergent settings.
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Abstract
Introduction
