JDMS 19:231–238 July/August 2003 231

ARTICLE
10.1177/8756479303251144

JOURNAL OF DIAGNOSTIC MEDICAL SONOGRAPHY July/August 2003 VOL. 19, NO. 4

INTUSSUSCEPTION / Pendergast, Wilson

JDMS 19:231–238 July/August 2003

JDMS 19:231–238 July/August 2003

Intussusception:
A Sonographer’s
Perspective Intussusception, the invagination of one portion
of the intestine into another, is considered a true
emergency, which most commonly affects pedi-
LEE ANN PENDERGAST, RDMS atric patients. It occurs when bowel (small or
large) telescopes within itself, creating an ob-
MICHELLE WILSON, BS, APS, RDMS, RDCS structive mass. Peristalsis exacerbates the more
proximal bowel into the lesion, causing the
intussusception to have a “sleeve”-like shape.
The lesion propagates distally, with obstructive
ischemia and possible necrosis occurring over
time. With the improvement of technology in di-
agnostic imaging, sonography has become the
initial imaging modality of choice. The authors
present a case study and current review of the lit-
erature regarding intussusception from a sonog-
rapher’s viewpoint.

Key words: intussusception, intussusceptum, intus-

suscipiens, ultrasound, pediatric emergency

Intussusception has been a well-known and de-

scribed pathology since the 19th century.1,2 The
pathogenesis includes the invagination of one por-
tion of the intestine into another. It is one of the
most common surgical emergencies in infancy and
early childhood.3–5 This disorder must promptly be
recognized and treated because a misdiagnosis or
delay in diagnosis may increase morbidity.
When intussusception occurs, compression and
angulation of the mesenteric vessels of the
invaginated bowel can lead to a strangulating ob-
struction. Necrosis of the outer layer of the intesti-
nal wall begins and extends more proximally into
the lesion. As necrosis occurs, the incidence of per-
foration or prolapse of the intestine into the
peritoneal cavity increases.
From Kaiser Vallejo Medical Center, Vallejo, California.
Typically, infants with intussusception are pre-
Correspondence: Lee Ann Pendergast, Kaiser Vallejo Medical viously healthy, then present with intermittent, se-
Center, 975 Sereno Drive, Vallejo, CA 94589. E-mail: seathrew@ vere cramping and abdominal pain. Vomiting is
aol.com.
commonly noted, and bloody mucoid stool is en-
DOI: 10.1177/8756479303251144 countered in about half the cases.1,3–8 In the mid-
232 JOURNAL OF DIAGNOSTIC MEDICAL SONOGRAPHY July/August 2003 VOL. 19, NO. 4

FIG. 1. Transverse image of the right upper quadrant. The arrow depicts a mass, medial to the gallbladder.

1980s, the advances in ultrasound technology in- pany, Mountain View, CA) was performed with a
creased sonography’s capability to include intus- 4-8 MHz curved transducer, and a 5-7 MHz linear
susception with an almost 100% positive predictive transducer. Examination of the right upper quad-
value.1,4,9,10 We present a case study of intus- rant, just medial to the gallbladder, revealed a well-
susception in a three-year-old child, in which delineated mass (see Fig. 1). In transverse views,
sonography depicted the lesion and a manual re- this mass exhibited a “doughnut” sign, which in-
duction was necessary for correction. A review of cluded a radiolucent rim surrounded by layers of al-
the literature, types and locations of intussuscep- ternating echogenicity and sonolucency. In a
tion, clinical presentations, and current diagnostic longitudinal view, the classic “pseudokidney” sign
imaging modalities and treatments will be pre- was displayed (see Fig. 2). Color Doppler imaging
sented. revealed vascularity in the peripheral and internal
aspect of this lesion (see Fig. 3). The contents of the
Case Study right lower quadrant did not reveal any evidence of
acute appendicitis. Sonographic impression was
A pediatric patient presented to the emergency significant for probable intussusception. The pa-
department with intermittent generalized abdomi- tient was referred for a hydrostatic enema for re-
nal pain, which started 12 hours prior. Clinically, duction.
she was conscious, afebrile, alert, and had no recent An 18-French Red Robin tube was inserted into
history of diarrhea or vomiting. Prior to this epi- the rectum. Under direct fluoroscopic observation,
sode, the patient had been healthy. Her physical 4:1 diluted Gastrografin was instilled. There was
findings included abdominal tenderness, a right up- free flow of contrast from the rectum to cecum,
per quadrant mass, and occult blood in her stool. with reflux into the appendix. A persistent 4.5-cm
Laboratory studies revealed an unremarkable com- filling defect at the ileocecal valve was present, be-
plete blood count, Chem 7, and urinary analysis. yond which contrast did not reflux. This was felt to
An abdominal x-ray was ordered, which re- be consistent with an ileocolic intussusception.
vealed a paucity of bowel gas in the right lower Three attempts were made at reducing the lesion,
quadrant. There was no evidence of a small bowel all of which were unsuccessful. No reflux was ob-
obstruction or free intraperitoneal air. Intussus- served into the terminal ileum. There was no evi-
ception could not be excluded by this study. dence of bowel perforation.
An abdominal sonogram was then ordered. The patient then underwent exploratory lapar-
Sonography (Sequoia; Acuson, a Siemens Com- otomy to manually reduce the ileocolic intus-
 INTUSSUSCEPTION / Pendergast, Wilson 233

FIG. 2. Transverse image of the intussusception with vascular flow in the median and periphery.

FIG. 3. Intussusception in a longitudinal plane. The classic sonographic “pseudokidney” or “sandwich” sign is displayed.

susception. The peritoneal cavity was entered elected to be performed. The patient tolerated the
without incident. The intussusception was identi- procedure well and was returned to the recovery
fied and manually reduced in a retrograde fashion room in satisfactory condition.
without difficulty. No serosal tears or ischemic ap- The patient has had a satisfactory postoperative
pearance was noted. No pathological lead point course after reduction of her ileocolic intussuscep-
was identified. An incidental appendectomy was tion and incidental appendectomy.
234 JOURNAL OF DIAGNOSTIC MEDICAL SONOGRAPHY July/August 2003 VOL. 19, NO. 4

Discussion good vascular flow in the intussuscipiens and intus-

susceptum.
More than 50% of intussusception cases occur in A diagnostic barium enema displays intus-
children younger than one year of age, with less susception as a “coiled spring” of bowel with sur-
than 10% of cases occurring in children older than rounding air-filled levels. Until the 1980s, this was
five years of age or adults.3 There is an overwhelm- considered the gold standard to diagnose intus-
ing peak incidence of intussusception in children susception. More emphasis has now been placed on
between the ages of five and nine months. A strong sonography as the primary imaging modality, as
male preponderance of 2:1 is well recognized in the 50% of clinically suspected cases have a negative
literature.11–13 Ninety percent of cases of intus- result, and exposure of radiation to the patient is
susception are idiopathic.3,14 In the 10% of cases avoided (see Table 1).
secondary to an underlying abnormality or distinct
pathological lead point, Meckel’s diverticulum ap- CLINICAL OVERVIEW
pears to be the most common culprit.3,12 Besides
Clinical presentation includes specific and non-
Meckel’s diverticulum, duplication cysts, intesti-
specific signs; however, no one presenting symp-
nal polyps, appendicitis, foreign bodies, and lym-
tom is definitive for intussusception (see Fig. 4).
phomas affect older children. Patients with cystic
Classically, infants are healthy and thriving and
fibrosis also seem to have a higher incidence of
suddenly present with intermittent, colicky, severe
intussusception.12 Occurrence of intussusception in
cramping and abdominal pain. In between the pain-
more than one patient of the same family has rarely
ful attacks, infants typically are calm and seem to
been reported.14 Adult intussusception most com-
be unaffected, sometimes even lethargic.3–5,12,13,15,16
monly affects the small bowel and is associated
The reason for lethargy in children with intus-
with a malignant lesion in 50% of cases.1
susception is not well understood. Some have hy-
Plain radiography has a low positive predictive
pothesized a release of endogenous opioids
value of only 28% to 50%.3,7,12,15 However, this
secondary to bowel ischemia, thus leading to the al-
study is helpful in excluding intestinal perforation,
tered level of consciousness.3,17 The infant is often
bowel obstruction, or intestinal masses. Sonog-
restless and refuses feedings. Vomiting is almost as
raphy has proven to be effective but operator de-
common a finding as abdominal pain, yet painless
pendent. Classic signs of intussusception with
intussusception is not uncommon. Another pre-
sonography include the “doughnut” or “target”
senting sign might include a dark red and mucoid
sign when viewed in the transverse plane, which
stool, referred to as “currant jelly” stool. However,
was present in our patient. This is sonographically
currant jelly stool is present in cases of intus-
noted as a circular mass with a hypoechoic outer
susception in only 10% to 20% of the time.1,6 A
rim and a central hyperechoic core. Another find-
clinical diagnosis may be difficult and masking,
ing suggestive of intussusception with sonography
and a delay may be life threatening owing to the de-
is the “sandwich” or “pseudokidney” sign, which
velopment of bowel necrosis and its sequelae.
was also present in our case study. Sono-
We encountered two separate “classic” clinical
graphically, this is characterized as a tubular or
triads for intussusception in the literature. The first
oval structure with a hyperechoic center sur-
triad includes abdominal pain, red currant jelly
rounded by hypoechoic borders. The hyperechoic
stool, and a palpable abdominal mass, but these are
areas represent mesenteric fat, which is pulled with
present in less than 50% of cases.3,9,10,12,18 Our pa-
vessels and lymph nodes into the intussuscipiens.
tient presented with this clinical triad. The second
The sonolucent periphery is apparently the edema-
classic clinical triad includes abdominal pain, the
tous wall of the intussuscepted intestinal head. It
passage of stool mixed with blood and mucous, and
has been suggested in the literature that the absence
vomiting.11,12,19,20 As with the first clinical triad, this
of blood flow by Doppler exam could be indicative
second clinical triad is found to be present less than
of necrotic or ischemic bowel.9 Our patient had
50% of cases of intussusception.
 INTUSSUSCEPTION / Pendergast, Wilson 235

TABLE 1.
Summary of Current Diagnostic Imaging Modalities Used for Intussusception
Findings Success Rate Disadvantages Comments
1,3,7
Plain Soft tissue mass with two concentric 50% Plain radiography may Helpful to exclude
radiography circles of fat density “target sign”1 not give any specific intestinal perforation
Paucity of air in the right iliac fossa4 information about the Some authors recommend
Absence of cecal gas and stool presence or absence of a three-way view
Loss of visualization of the tip of other surgical or medical radiographic series9
the liver15 conditions
Low positive predictive
value
Sonography Longitudinal plane: mass has a 100%1,4,9,10 Relies on a competent Experienced sonographer
tubular appearance sonographer can readily depict
Transverse plane: “doughnut sign” Lacks potential intussusception of the
peripheral rim is hypoechoic with therapeutic benefit small bowel
a homogeneous thickness and No radiation exposure
contour; central echogenic area Can sometimes identify
represents the lumen other pathologies
Color Doppler studies have been
shown to be useful in the
evaluation of necrotic bowel wall
Diagnostic “Coiled spring” of bowel with 100%; Risk of perforation with Can be more cost-
enema surrounding air-filled levels traditionally a barium enema is effective with a positive
the gold approximately 3% case as the diagnosis and
standard Small doses of radiation the treatment can be
are delivered accomplished with one
Invasive procedure, if procedure
the test is negative 50% of the clinically
suspected cases have a
negative enema result

LOCATIONS/TYPES masses in the right upper quadrant, which is de-

The most proximal segment of the intestine is scribed as being “sausage” shaped. When present,
classified as the “intussusceptum,” and the more this mass may be found to enlarge noticeable dur-
distal portion that houses the intussusceptum is ing episodes of pain.5,7,11 Our patient was able to
known as the “intussuscipiens.” The condition is point directly at the palpable mass, an area of intus-
named according to the portion of bowel creating susception, which narrowed our sonographic in-
the intussusceptum and the distal extent of the vestigation.
intussuscipiens. Less than 1% of intussusception cases occur
The most common type of intussusception is during the neonatal period.18 In neonates younger
ileocolic (80%), often due to a pathological lead than 1 month of age, the ileocolic form is again the
point near the ileocecal valve5 (see Fig. 5). Children most common; however, 30% of these patients
less frequently have involvement of the ileoileal, have an identifiable lead point.3
colocolic, and jejunojejunal variations.1,4 Children older than the age of five years most
Ileocolic intussusception usually begins proxi- commonly have ileocolic intussusception; how-
mal to the ileocecal valve as a short ileoileal ever, with an increase in age, the likelihood of an
invagination, which then advances with peristalsis ileoileal, jejunojejunal, and colocolic intussuscep-
into the colon.4 The vast majority of ileocolic intus- tion increases.
susception cases contain their apex in the ascend- Adult intussusception occurs in the small bowel
ing or transverse colon.6 Cases of ileocolic more than 75% of the time, and it is associated with
intussusception commonly present with abdominal malignant lesions more than 50% of the time.1,21,22
236 JOURNAL OF DIAGNOSTIC MEDICAL SONOGRAPHY July/August 2003 VOL. 19, NO. 4

100
93

90

80

70
64

60

50 46
42
40
40

30
FIG. 5. Anatomical relationship of the ascending colon, ileum,
20
ileocecal valve, and appendix veriform.
14
10
10
nal organs being disturbed during surgery. The sec-
0 ond most common etiology for adult intus-
Specific Non-Specific
Abd. Pain Abd. Mass Rectal Bleeding susception is found in postsurgical patients.5
Vomiting Diarrhea Fever Adults with postoperative intussusception will of-
Abd. Bowel Sounds
ten have a delay in the occurrence of this lesion af-
ter surgery, with approximately 90% occurring two
FIG. 4. Summary of the most common clinical presentations
and symptoms.
weeks after surgery.
SOURCE: See references 1, 2, 6, and 11. The overall recurrence rate of intussusception is
7% to 8%.7,12 It most commonly occurs after a pri-
mary nonoperative reduction, and typically a recur-
rence will occur within a short amount of time if it
More than 90% of adult cases of intussusception is going to recur. There is no association between
have an identifiable lead point.5,6 gender, age, or anatomical location and recurrence
rates; however, patients with underlying medical
PATHOGENESIS conditions often have recurrences of ileocolic
In children younger than the age of two years, intussusception.5
lead points occur in less than 4% of all cases.1,16 Af-
TREATMENT
ter the age of two years, a distinct pathological lead
point is found in about 30% of all cases.1 Lymphoid In 1865, reports of using bellows to reduce
hyperplasia is commonly thought to be responsible intussusception were made.7 In 1927, the first bar-
for idiopathic intussusception. This occurs because ium enema reductions were reported.1 In the 1980s,
the wall of the terminal ileum of infants is rich in pneumatic reduction was first reported out of China
lymphoid tissue. It has been found that an upper re- with a high success rate.4,15 North American and
spiratory tract infection, viral illness, or enteritis European studies were still using water and barium
may proceed the development of idiopathic enemas for treatment, which yielded a reported
intussusception.12 success rate of 50% to 80%. Pneumatic reduction
Postoperative intussusception accounts for only enemas appear to be quicker and easier to perform;
1% to 2% of all cases.4,12 It affects both genders therefore, less radiation is delivered. Air reduction
equally and may occur with or without the abdomi- rates have been proven to range between 81% and
 INTUSSUSCEPTION / Pendergast, Wilson 237

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