DOI:10.2214/AJR.07.3741
AJR 2008; 191:736-742
© American Roentgen Ray Society
MDCT and 3D Imaging in Transient Enteroenteric Intussusception: Clinical Observations and Review of the Literature
Karen M. Horton1 and
Elliot K. Fishman
1 Both authors: Department of Radiology, Johns Hopkins Medical Institutions, 601
N Caroline St., Rm. 3253, Baltimore, MD 21287.
Received January 28, 2008;
accepted after revision March 22, 2008.
Address correspondence to K. M. Horton.
Abstract
OBJECTIVE. This article will review the current role of MDCT and 3D
imaging in the diagnosis and management of adults with enteroenteric
intussusception.
CONCLUSION. Because of significant advancements in CT along with its
increasing use, detection of enteroenteric intussusceptions by CT has
increased. These findings are sometimes in asymptomatic patients, often
transient, and without an identifiable lead point. This has complicated the
management of adult patients with intussusception because not every patient
with intussusception may need surgery.
Keywords: 3D imaging • CT • intussusception
Introduction
Adult intussusception is thought to be rare, accounting for an estimated 5%
of all intussusceptions and only 1% of small-bowel obstructions
[1]. Unlike intussusceptions in
children, which are idiopathic in 90% of cases, adult intussusceptions were
traditionally thought to have an identifiable cause in the majority of cases.
For example, in a series of 25 adult intussusceptions reported by Agha
[2] in 1986, a causative factor
was identified in 23 patients (92%), and the other two cases were considered
to be idiopathic. Similarly, in a series of 13 adult intussusceptions reported
by Erkan et al. [3] in 2005, a
pathologic cause for the intussusception was identified in 92.3%, and only one
case was considered to be idiopathic.
Given these statistics, the surgical literature supported surgical
exploration in all adults presenting with intussusception. However, because of
significant advancements in CT scanners along with increasing use of CT, the
detection of enteroenteric intussusceptions by CT has increased. These
findings are sometimes in asymptomatic patients, often transient, and without
an identifiable lead point. This has complicated the management of adult
patients with intussusception because not every patient with CT evidence of
enteroenteric intussusception may need surgery. This article will review the
current role of MDCT and 3D imaging in the diagnosis and management of
patients with intussusception, with a particular emphasis on adult
enteroenteric intussusception.
Anatomy and Pathophysiology of Intussusception
Intussusception occurs when a segment (intussusceptum) of the
gastrointestinal tract invaginates (or telescopes) with its mesenteric fold
into the adjacent segment (intussuscipiens). This telescoping results from
altered peristalsis, which pulls the intussusceptum into the intussuscipiens.
A variety of factors can act as a lead point and result in intussusception,
including tumors, ingested foreign bodies, enteric tubes or suture material,
and Meckel's diverticulum. The exact cause of the intussusception in patients
in whom no lead point is identified is not definitely known, but is thought to
be due to dysrhythmic bowel contractions
[4], likely precipitated by
edema, inflammation, or infection. In theory, any process that alters normal
peristalsis is capable of triggering an intussusception.
Intussusception can occur anywhere along the gastrointestinal tract.
Gastric intussusception is very rare. Enteroenteric intussusceptions are much
more common than gastric intussusception and result when one loop of small
bowel invaginates into the adjacent small bowel. They can be categorized as
duodenojejunal, jejunojejunal, or jejunoileal. Large-bowel intussusception can
be classified as ileocolic or colocolic and has a high reported association
with underlying tumors [5].
Adult Enteroenteric Intussusceptions
Presentation
Patients can present with a variety of symptoms depending on the underlying
cause. Intussusceptions with a lead point may result in abdominal pain,
nausea, vomiting, and obstructive symptoms
[4,
6]. If the intussusception is a
result of an underlying malignancy, patients may also report weight loss or
bleeding [4].
Intussusception in patients without an identifiable lead point may produce
symptoms such as abdominal pain with cramping. However, an intussusception
without a lead point does not typically produce obstructive symptoms
[7]. In fact, patients may be
asymptomatic, and the intussusception may be transient. Intussusceptions are
now being detected incidentally on CT in patients being scanned for unrelated
reasons [4]. Physical
examination may show diffuse or localized abdominal tenderness but is often
unremarkable unless obstruction or ischemia is present.
Location
Adult enteroenteric intussusceptions are thought to be relatively rare.
They can be classified as duodenojejunal, jejunojejunal, or jejunoileal.
Ileocecal intussusceptions, which are typically classified as a colonic
intussusception, are reported to be the most common of all the
gastrointestinal intussusceptions, although enteroenteric intussusceptions can
account for up to 40% of cases
[8]. Reports of proximal
small-bowel intussusceptions, such as duodenojejunal and jejunojejunal, are
particularly uncommon in the literature
[8].
Cause
Enteroenteric intussusceptions can result from a variety of causes
including tumors and inflammatory disease. In some cases, a cause is not
identified, and these are classified as idiopathic. In a review of 668
reported cases of adult small-bowel intussusception from multiple series,
Felix et al. [5] reported in
1976 that 17% were caused by malignant tumors and 40% were caused by benign
tumors. Malignant lesions include carcinoid, metastases, leiomyosarcoma, and
adenocarcinoma. Benign tumors that have been reported to result in
intussusception include lipoma, neurofibroma, hemangioma, and inflammatory
polyps [3]. Meckel's
diverticulum is also a well-documented cause of small-bowel intussusception,
often ileocecal [3]. In these
cases, CT reveals dilated loops of small bowel with an intraluminal mass
involving the ascending colon
[9].
Inflammatory small-bowel conditions such as Crohn's disease (Fig.
1A,
1B) and celiac disease can
result in enteroenteric intussusceptions that are typically transient
[2,
10]. Nonobstructive
small-bowel intussusception has also been reported in patients with giardiasis
[11]. In malabsorption
syndromes, it is thought that the dilated loops somehow disturb peristalsis
and therefore can result in the intussusception
[8,
12]. In the tropics, most
cases of adult small-bowel intussusception are caused by gastrointestinal
infections [13]. In many
patients, the underlying cause may not be discovered (Figs.
2A,
2B,
2C,
3A,
3B,
3C,
3D,
4A,
4B,
4C,
5A,
5B,
6A,
6B,
6C).
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Fig. 1A —73-year-old man with long-standing history of Crohn's disease
who presented with abdominal pain. Patient had history of right hemicolectomy
and two previous small-bowel obstructions as well as squamous cell cancer of
tongue. MDCT with oral and IV contrast material administration was performed.
Small-bowel series was performed next day (not shown), which showed only
edematous jejunal loops but no intussusception, no mass, and no obstruction.
Patient was treated conservatively, and his pain resolved. Axial image shows
classic CT appearance of enteroenteric (jejunojejunal) intussusception
(arrow). There was no evidence of obstruction, although small bowel
was minimally dilated.
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Fig. 1B —73-year-old man with long-standing history of Crohn's disease
who presented with abdominal pain. Patient had history of right hemicolectomy
and two previous small-bowel obstructions as well as squamous cell cancer of
tongue. MDCT with oral and IV contrast material administration was performed.
Small-bowel series was performed next day (not shown), which showed only
edematous jejunal loops but no intussusception, no mass, and no obstruction.
Patient was treated conservatively, and his pain resolved. Coronal
volume-rendered 3D image nicely shows invagination (arrows) of bowel
as well as mesenteric fat and vessels.
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Fig. 2A —34-year-old man with polycythemia vera, factor II deficiency,
and spherocytosis. Patient presented with abdominal pain. MDCT with only oral
contrast administration was performed. Small-bowel series was also performed
(not shown), which showed no evidence of intussusception. Patient was treated
conservatively, and his symptoms resolved. Axial MDCT image shows
intussusception (arrow) in left abdomen involving jejunum. This is
likely jejunojejunal intussusception.
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Fig. 2B —34-year-old man with polycythemia vera, factor II deficiency,
and spherocytosis. Patient presented with abdominal pain. MDCT with only oral
contrast administration was performed. Small-bowel series was also performed
(not shown), which showed no evidence of intussusception. Patient was treated
conservatively, and his symptoms resolved. Coronal multiplanar reformation
image shows short-segment intussusception (arrow) but no
obstruction.
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Fig. 2C —34-year-old man with polycythemia vera, factor II deficiency,
and spherocytosis. Patient presented with abdominal pain. MDCT with only oral
contrast administration was performed. Small-bowel series was also performed
(not shown), which showed no evidence of intussusception. Patient was treated
conservatively, and his symptoms resolved. Axial image from repeat CT 2 days
after A and B shows resolution of intussusception.
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Fig. 3A —31-year-old woman with remote history of Burkitt's lymphoma
who presented for routine follow-up. Patient was asymptomatic. MDCT with
administration of IV and oral contrast material was performed. Repeat CT 4
days later (not shown) did not show any intussusceptions. Given history of
lymphoma, patient is being closely followed but has shown no evidence of
recurrent intussusception or recurrence of her lymphoma over the past 12
months. Axial MDCT image shows short-segment intussusception (arrow)
in left abdomen.
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Fig. 3B —31-year-old woman with remote history of Burkitt's lymphoma
who presented for routine follow-up. Patient was asymptomatic. MDCT with
administration of IV and oral contrast material was performed. Repeat CT 4
days later (not shown) did not show any intussusceptions. Given history of
lymphoma, patient is being closely followed but has shown no evidence of
recurrent intussusception or recurrence of her lymphoma over the past 12
months. Axial MDCT image shows short-segment intussusception (arrow)
in right abdomen.
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Fig. 3C —31-year-old woman with remote history of Burkitt's lymphoma
who presented for routine follow-up. Patient was asymptomatic. MDCT with
administration of IV and oral contrast material was performed. Repeat CT 4
days later (not shown) did not show any intussusceptions. Given history of
lymphoma, patient is being closely followed but has shown no evidence of
recurrent intussusception or recurrence of her lymphoma over the past 12
months. Coronal multiplanar reformation (MPR) image shows same short-segment
(arrow) in left abdomen as in A.
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Fig. 3D —31-year-old woman with remote history of Burkitt's lymphoma
who presented for routine follow-up. Patient was asymptomatic. MDCT with
administration of IV and oral contrast material was performed. Repeat CT 4
days later (not shown) did not show any intussusceptions. Given history of
lymphoma, patient is being closely followed but has shown no evidence of
recurrent intussusception or recurrence of her lymphoma over the past 12
months. Coronal MPR image shows same short-segment (arrow) in right
abdomen as in B.
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Fig. 4A —23-year-old woman with 2-week history of intermittent
abdominal pain. Patient has had no nausea or vomiting but has had minimal
diarrhea. MDCT with administration of IV and oral contrast material was
preformed. Axial MDCT image shows jejunojejunal intussusception
(arrow).
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Fig. 4B —23-year-old woman with 2-week history of intermittent
abdominal pain. Patient has had no nausea or vomiting but has had minimal
diarrhea. MDCT with administration of IV and oral contrast material was
preformed. Coronal volume-rendered 3D image shows jejunojejunal
intussusception, which measured 9 cm in length (arrows). There was no
obstruction. Small-bowel series was performed same day (not shown), which was
normal, without intussusception.
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Fig. 4C —23-year-old woman with 2-week history of intermittent
abdominal pain. Patient has had no nausea or vomiting but has had minimal
diarrhea. MDCT with administration of IV and oral contrast material was
preformed. MDCT was repeated next day after small-bowel series. Coronal
multiplanar reformation image shows no evidence of obstruction or
intussusception. The patient's symptoms resolved over 24 hours, and she was
discharged. She will undergo follow-up with gastrointestinal series for
small-bowel capsule endoscopy.
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Fig. 5A —46-year-old woman with 1-month history of intermittent
abdominal pain. MDCT with administration of IV and oral contrast material was
performed. Subsequent enteroclysis (not shown) showed rapid peristalsis but no
intussusception. Small-bowel enteroscopy was performed and showed
intussusception but no mass. Patient's symptoms continued, and she underwent
exploratory laparotomy. No intussusception or mass was found. Axial MDCT
images show intussusception (arrow, A) in left abdomen. No
obstruction was noted.
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Fig. 5B —46-year-old woman with 1-month history of intermittent
abdominal pain. MDCT with administration of IV and oral contrast material was
performed. Subsequent enteroclysis (not shown) showed rapid peristalsis but no
intussusception. Small-bowel enteroscopy was performed and showed
intussusception but no mass. Patient's symptoms continued, and she underwent
exploratory laparotomy. No intussusception or mass was found. Axial MDCT
images show intussusception (arrow, A) in left abdomen. No
obstruction was noted.
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Fig. 6A —33-year-old man with history of alcohol and drug abuse and
untreated hepatitis C who presented to emergency department with abdominal
pain. MDCT with administration of IV and oral contrast material was performed.
Axial (A), coronal multiplanar reformation (MPR) (B), and
sagittal MPR (C) MDCT images show short-segment jejunojejunal
intussusception (arrows). Small-bowel series was performed
immediately after CT (not shown) and was normal. Patient's symptoms resolved
with conservative treatment.
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Fig. 6B —33-year-old man with history of alcohol and drug abuse and
untreated hepatitis C who presented to emergency department with abdominal
pain. MDCT with administration of IV and oral contrast material was performed.
Axial (A), coronal multiplanar reformation (MPR) (B), and
sagittal MPR (C) MDCT images show short-segment jejunojejunal
intussusception (arrows). Small-bowel series was performed
immediately after CT (not shown) and was normal. Patient's symptoms resolved
with conservative treatment.
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Fig. 6C —33-year-old man with history of alcohol and drug abuse and
untreated hepatitis C who presented to emergency department with abdominal
pain. MDCT with administration of IV and oral contrast material was performed.
Axial (A), coronal multiplanar reformation (MPR) (B), and
sagittal MPR (C) MDCT images show short-segment jejunojejunal
intussusception (arrows). Small-bowel series was performed
immediately after CT (not shown) and was normal. Patient's symptoms resolved
with conservative treatment.
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Patients infected with HIV are at risk for intussusception, both from
underlying tumors, such as Kaposi's sarcoma, as well as from a variety of
infections and inflammatory conditions that effect the gastrointestinal tract
[13] (Fig.
7A,
7B). Meyerson et al.
[14] reported an ileocolic
intussusception in a patient with AIDS in whom lymphoid hyperplasia was noted
in the terminal ileum as a potential cause but without evidence of associated
infection. Wood et al. [15]
reviewed eight cases of adult intussusception over a 10-year period. Three of
the eight patients had AIDS. In the AIDS patients, all of the intussusceptions
were diagnosed on CT. The authors noted that AIDS-associated intussusception
is becoming a clinical problem, and CT is an effective method of diagnosing
it. Intussusception should be a diagnostic consideration in HIV-positive
patients presenting with abdominal pain
[15]. In patients with an
underlying mass, the lead-point mass can sometimes be detected on CT (Fig.
8A,
8B,
8C,
8D,
8E).
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Fig. 7A —55-year-old man with history of groin hernia repair who
presented with abdominal pain. MDCT with administration of IV and oral
contrast material was performed. Small-bowel series was performed (not shown),
which was normal. Pain resolved without treatment. Axial MDCT images show
jejunojejunal intussusception (arrows) in left abdomen. There was no
evidence of obstruction.
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Fig. 7B —55-year-old man with history of groin hernia repair who
presented with abdominal pain. MDCT with administration of IV and oral
contrast material was performed. Small-bowel series was performed (not shown),
which was normal. Pain resolved without treatment. Axial MDCT images show
jejunojejunal intussusception (arrows) in left abdomen. There was no
evidence of obstruction.
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Fig. 8A —35-year-old woman with history of breast cancer and acute
abdominal pain. MDCT with administration of IV and oral contrast material was
performed. Patient was moderately tender on physical examination. Exploratory
laparotomy was performed and revealed long-segment jejunojejunal
intussusception with 3-cm lead-point mass. This was resected. Many additional
polyps were found in remainder of small bowel, and two other lesions were
resected. Pathology revealed hamartomatous polyps in patient with previously
unsuspected Peutz-Jeghers syndrome. Large arrows point to intussusception.
Axial MDCT images show long-segment (at least 15 cm) enteroenteric
(jejunojejunal) intussusception in left abdomen.
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Fig. 8B —35-year-old woman with history of breast cancer and acute
abdominal pain. MDCT with administration of IV and oral contrast material was
performed. Patient was moderately tender on physical examination. Exploratory
laparotomy was performed and revealed long-segment jejunojejunal
intussusception with 3-cm lead-point mass. This was resected. Many additional
polyps were found in remainder of small bowel, and two other lesions were
resected. Pathology revealed hamartomatous polyps in patient with previously
unsuspected Peutz-Jeghers syndrome. Large arrows point to intussusception.
Axial MDCT images show long-segment (at least 15 cm) enteroenteric
(jejunojejunal) intussusception in left abdomen.
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Fig. 8C —35-year-old woman with history of breast cancer and acute
abdominal pain. MDCT with administration of IV and oral contrast material was
performed. Patient was moderately tender on physical examination. Exploratory
laparotomy was performed and revealed long-segment jejunojejunal
intussusception with 3-cm lead-point mass. This was resected. Many additional
polyps were found in remainder of small bowel, and two other lesions were
resected. Pathology revealed hamartomatous polyps in patient with previously
unsuspected Peutz-Jeghers syndrome. Large arrows point to intussusception.
Axial MDCT images show long-segment (at least 15 cm) enteroenteric
(jejunojejunal) intussusception in left abdomen.
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Fig. 8D —35-year-old woman with history of breast cancer and acute
abdominal pain. MDCT with administration of IV and oral contrast material was
performed. Patient was moderately tender on physical examination. Exploratory
laparotomy was performed and revealed long-segment jejunojejunal
intussusception with 3-cm lead-point mass. This was resected. Many additional
polyps were found in remainder of small bowel, and two other lesions were
resected. Pathology revealed hamartomatous polyps in patient with previously
unsuspected Peutz-Jeghers syndrome. Large arrows point to intussusception.
Coronal multiplanar reformation images nicely show length of involvement. Lead
point (small arrows, E) is seen.
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Fig. 8E —35-year-old woman with history of breast cancer and acute
abdominal pain. MDCT with administration of IV and oral contrast material was
performed. Patient was moderately tender on physical examination. Exploratory
laparotomy was performed and revealed long-segment jejunojejunal
intussusception with 3-cm lead-point mass. This was resected. Many additional
polyps were found in remainder of small bowel, and two other lesions were
resected. Pathology revealed hamartomatous polyps in patient with previously
unsuspected Peutz-Jeghers syndrome. Large arrows point to intussusception.
Coronal multiplanar reformation images nicely show length of involvement. Lead
point (small arrows, E) is seen.
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Enteroenteric intussusception may be more common than previously realized
now that CT is being used so commonly, and this may explain why more cases of
transient or self-limiting intussusception are being reported. In the series
by Lvoff et al. [16], the
authors conducted a computerized search of 69,040 abdominal and pelvic CT
reports and identified 37 cases of intussusception, of which 84% were
self-limiting. In a similar study by Warshauer and Lee
[17], only six of 29 (21%)
patients with small-bowel intussusception were found to have a lead point at
surgery. In a recent large series by Rea et al.
[18], the authors reviewed
380,999 CT reports that yielded 170 adults with intussusception. Of those, 149
were enteroenteric. Only 30 of 170 patients underwent surgery. Fifteen of the
30 surgical patients had pathologic findings that correlated with the CT
findings. Seven patients had enteroenteric intussusceptions, which included
two benign neoplasms, one adhesion, one local inflammation, one previous
anastomosis, one Crohn's disease, and one idiopathic.
CT Appearance
Three CT patterns of intussusception have been described and are thought to
correspond to different stages of the process. They were initially described
by Merine et al. [19] in 1987.
The target appearance occurs when an intraluminal soft-tissue mass and
eccentric fat density are seen as a result of the intussusceptum and the
intussuscepting mesentery
[19]. This pattern usually
corresponds to an early intussusception with only minimal obstruction, if any.
These patients typically do not have signs of ischemia at pathology
[19]. The reniform pattern is
described as a bilobed density with peripheral high attenuation and lower
attenuation centrally [19].
This appearance is thought to result from a thickening bowel wall surrounding
the intussusceptum, probably resulting from underlying ischemia. The
sausage-shaped pattern results from alternating areas of low and high
attenuation related to the bowel wall, mesenteric fat and fluid, intraluminal
fluid, contrast material, or air
[19]. This is thought to be
similar to the coiled-spring appearance of an intussusception on conventional
contrast-enhanced examinations. Patients with this appearance had no clinical
or pathologic evidence of ischemia in a series by Merine et al.
[19].
It can be difficult to identify the lead point on CT. Often, even when a
leading mass is seen, it is not possible to reliably distinguish a malignant
from benign neoplasm, unless the mass is of fat density, indicating a
lipoma.
In 2004, Dawes et al. [20]
described the use of CT with multiplanar reconstruction (MPR) in the
evaluation of adult intussusception. The authors noted that the MPRs can be
used to confirm the diagnosis and can help visualize and characterize an
underlying mass [20]. In a
case report by Siddiqi et al.
[21] in 2007, the authors
successfully used coronal CT reformations in a patient with an ileocolic
intussusception to diagnose the lead point (appendiceal mucocele)
preoperatively.
In our experience, MPRs and 3D imaging can be useful in both the
identification of intussusception as well as in characterization. The MPRs
also can help better measure the length of the intussusception by helping to
fully appreciate the course. The axial imaging plane may not be optimal to
fully characterize an intussusception, identify an underlying lead point, and
detect evidence of obstruction or ischemia. The best CT protocol for the
identification of intussusception has not been studied.
In our practice, if an intussusception was suspected clinically, we use
water as an oral contrast agent. The low-density luminal water may help in
identification of an underlying lead point and allow excellent visualization
of the enhancing bowel wall, which is important to identify ischemia. Also,
water as an oral contrast agent will not interfere with 3D volume rendering as
a traditional positive oral contrast agent would.
Three-dimensional volume rendering will also allow visualization of the
mesenteric vessels in cases of complicated intussusception. This will also aid
in surgical planning. IV contrast material is essential to opacify the
mesenteric vessels as well as to enhance the wall of the gastrointestinal
tract. An injection rate of 4–5 mL/s is needed to adequately enhance the
mesenteric vessels. Dual-phase imaging is performed to ensure visualization of
both the mesenteric arteries and veins if intussusception is suspected
clinically.
Most cases of intussusception found on CT are not suspected clinically. The
patient typically presents with nonspecific or abdominal pain and cramping.
Therefore, positive oral contrast agents are usually used in this setting, and
typically one venous phase acquisition is obtained. Even if positive oral
contrast material is used, MPRs and 3D imaging can be helpful. For optimal
visualization of the intussusception and potential underlying mass, thin
collimation is especially helpful. Submillimeter collimation will result in
isotropic data sets, which maintain high resolution in any plane. For example,
with 64-MDCT, we would choose the 0.65-collimator setting and create 0.75-mm
slices reconstructed every 0.5 mm for 3D review.
Management
Traditionally, adult intussusceptions were treated with surgical
exploration and resection because of the high reported incidence of underlying
tumors, whether malignant or benign
[3,
5,
22]. Most of the surgical
literature was based on patients with obstruction or other severe complaints
that warranted surgical exploration. The diagnosis of intussusception was
usually not made preoperatively. Therefore these statistics regarding the high
incidence of lead points in patients with adult small-bowel intussusception
may not be applicable to a situation in which a small-bowel intussusception is
identified on CT in an asymptomatic patient. Given the increased detection of
intussusception by MDCT, even in asymptomatic patients, and given the
recognition that intussusceptions may be transient, there is ongoing
controversy regarding the optimal management.
In cases of colonic intussusception, treatment usually consists of surgical
resection in an en-bloc manner
[3]. Reduction is usually not
attempted because of the chance of perforation and potential spillage of
microorganisms and malignant cells, given the high incidence of malignant
tumors as the lead point in colon intussusceptions
[3]. In patients with
small-bowel intussusception and obstruction or severe symptoms requiring
surgery, the surgeon will attempt to reduce the intussusception before
resection unless there are signs of ischemia or strangulation
[3].
There continues to be controversy regarding the management of incidentally
detected enteroenteric intussusceptions, transient intussusceptions, or
intussusceptions in patients will only minimal symptoms. Lvoff et al.
[16] 37 cases of adult
small-bowel intussusception in an attempt to determine if CT findings can be
used to distinguish between self-limiting cases and those requiring surgical
exploration and potential resection. In that series, six patients underwent
surgery, and all six were found to have tumors as a lead point. Thirty-one
patients were followed conservatively, and none required surgery over a mean
follow-up of 5.2 months [16].
The authors performed an extensive multivariate logistic regression analysis,
which showed that the length of the intussusception was the only variable that
was an independent predictor of outcome. All 20 patients with an
intussusception 3.5 cm or less in length had causes that were self-limiting,
and six of 17 patients in which the intussusception measured greater than 3.5
cm in length required surgery and had a lead point. The authors concluded that
an intussusception less than 3.5 cm in length is likely to be self-limiting
[16].
Catalano [8] reported five
cases of transient jejunojejunal intussusception diagnosed on CT. The patients
were asymptomatic. This study is interesting because, in the surgical
literature, proximal small-bowel intussusception is considered rare, although
peristaltic activity is normally greater in the proximal small bowel compared
with the distal small-bowel. None of the five patients in Catalano's report
had a defined cause such as lead point, infection, or malabsorption
[8]. The incidentally detected
intussusceptions were thought to be functional. When Catalano combined the
five cases of transient jejunal intussusception with three cases of transient
ileal intussusception reported in the literature, a few similarities were
noted [10,
19]. The bowel loops proximal
to the intussusception were of normal caliber
[11]. The involved bowel loop
was of normal caliber or was only slightly dilated
[3]. There is almost always a
triangular or crescent-shaped fat density caused by eccentrically placed
mesentery [4]. There was a
short, or sometimes long, soft-tissue density extending into the bowel lumen
in a central or eccentric position, similar to the described target sign
[8].
Catalano [8] concluded that
when a proximal (jejunal) intussusception with a target appearance without an
identifiable cause or obstruction is detected on CT in an asymptomatic
patient, it is likely a self-limiting transient intussusception rather than a
classical obstructing intussusception that requires surgery for a presumed
lead point.
Therefore proximal small-bowel intussusceptions measuring less than 3.5 cm
in length and without obstruction or an obvious lead point are likely to be
self-limiting and of no clinical significance. According to Jain and Heap
[23], intussusceptions greater
than 3.5 cm without obstruction or an obvious lead point should probably be
followed by a small-bowel series, enteroclysis, or CT enteroclysis. If there
is an associated obstruction, signs of ischemia, or a lead point identified,
surgical exploration is warranted.
In the series by Rea et al.
[18], 170 patients were
identified with intussusception on CT, including enteroenteric (87.6%),
ileocecal (4.7%), colocolonic (5.9%), and gastroenteric (1.8%). Only 30 of 170
patients underwent surgery, 15 of whom had pathologic features that correlated
with the CT findings. The other 15 surgical patients had no intussusception at
surgery. The surgical patients all were symptomatic versus 53.3% of the
observation group. The surgical patients also had longer intussusception (9.6
cm) versus the observation group (3.8 cm)
[18]. Of the patients who did
not undergo surgery, no patient required subsequent operative exploration for
intussusception at a mean 14.1-month follow-up
[18]. This study further
supports conservative follow-up of short-segment enteroenteric
intussusceptions in patients without obstructive symptoms.
Conclusion
Because of significant advancements in CT scanners along with increasing
use of CT, the detection of enteroenteric intussusceptions by CT has
increased. These findings are sometimes in asymptomatic patients, often
transient, and without an identifiable lead point. Radiologists must be
familiar with this phenomenon. Some findings on CT may be helpful in guiding
management. For example, the identification of a mass as the lead point and
the presence of associated obstruction or ischemia are indications for
surgical exploration. In asymptomatic patients, the CT identification of a
proximal (jejunal), short (< 3.5 cm) intussusception with a characteristic
target sign and without obstruction may indicate a self-limiting process that
can be managed conservatively. More investigation is necessary.
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Abstract
Introduction
