Jen Jen Chen MSIII
Radiology, December 2006
Oregon Health and Science University
What is IS?
• 1 portion of the small bowel invaginating into the distal portion of small
bowel, pulled in by peristalasis
• Type of intussusception depends on segment of bowel that is involved
– Starting at the ileocolic junction  ileocolic intussusception
Intussusceptum
=proximal portion
Intussuscipen
=distal portion
Epidemiology
Second most common cause of acute abdominal pain in children
following appendicitis
Found between 3 months to 2 years of age, peaking at 5-7 months
Variable incidence by geographical location ~ 0.9 - 4/1000 live births
worldwide
US: 0.5-2.3/1000 live births
Declining rates recently, possibly from shift from inpt  outpt
2:1 male to female
Causes estimated 2.3 deaths/million and 18-56 hospitalizations
/100,000
 Theorized to have a seasonal pattern but only confirmed by two
studies
3 types of IS:
1. Intraluminal
= Mass pulled forward by peristalsis and brings
continued bowel wall with it.
2.
Intramural
=Bowel wall abnormality prevents normal
contraction, a.k.a. lead point
3.
Extraluminal
=Extraluminal abnormality prevents normal
contraction, a.k.a. lead point
Why does IS happen?
Idiopathic 60%
Most are ileocolic
 Lead point <10%
•Most common is Meckel’s diverticulum
•Other possibilities include : polyps, hemangiomas, lymphomas, cysts
•American and European studies showing <10% of cases having a lead
point
More common post-abdominal surgery and in CF patients
Hypotheses of etiologies:
-Lymphoid tissue swelling
-Dietary factors
-Rotavirus and polio vaccine
-Mesenteric LN swelling
Just as a refresher…
The Rotavirus Connection
•Rhesus rotavirus tetravalent (RRV-TV) was introduced in 1998 as a 3 part
vaccination (2, 4, 6 months)
•Resulted in 15 cases of intussusception which occurred 3-14 days after the first
injection
•Withdrawn from market 9 months later
•Total estimate of approximately 1 million doses to 0.5 million infants
•Studies done after withdrawal showed risk of 1/10,000 – 1/32,000
•Possible causes
-bolus of virus causing high viral titer
-replication of wild-type rotaviruses
•Pentavalent, bovine-human reassortant rotavirus vaccine and RIX4414 vaccine
are on the horizon
-safety trials underway
Pathophysiology
invagination of the bowel
Obstruction resulting in compression of the vessels
and venous congestion and bowel wall edema
Infarction,
perforation
If left untreated, FATAL
Classic Triad
Colicky
abdominal pain
“Currant Jelly” bloody stools
Abdominal Mass
-sausage shaped
-pulling knees up to abdomen
•Multiple studies have shown that classic triad is only present in 20-50%
•70% found to have 2 sx
•9% found to have 1 sx
Other common signs of presentation
•Colicky pain – found to be best indicator
85% incidence
4-5 min of pain + pulling up knees to abdomen  10-20 min of rest
•Lethargy
•Dance’s sign = RUQ mass above RLQ space
•Irritability
•Vomiting
•Diarrhea/Constipation
•Up to 20% pain free on presentation
Diagnosis
The longer you take to diagnose, the
higher the probability of surgery and
mortality
Diagnosis made by clinical presentation
and imaging
However, clinical suspicion can guide
the modality of imaging…
Abdominal X-Ray
Conventionally, first-line modality for suspected intussusception
Low sensitivity, high false negative rate
Can be negative in early IS
Uses:
-Diagnosis of IS
-Evaluating for risk of perforation before enema treatment
-Diagnosis of other diseases (SBO, LBO, volvulus)
•Findings:
1) Intracolonic mass
2) Target sign
3) Crescent sign
4) SBO
5) Presence/absence of gas in RLQ
Where is
the target
sign?
Created by gas
trapped
between two
layers of
intestinal wall
Where is
the
crescent
sign?
Created by gas
surrounding
invagination
Gas in RLQ?
There is dilation of
LUQ, but no
presence of gas
anywhere else in
the bowel.
Literature review
•(Ratcliffe, et al) Four observers evaluated 1120 plain films for 4 IS signs (mass,
target, crescent, SBO)
Crescent sign most accurate, but least common (30%)
Abdominal mass most unreliable, but most common (78%)
Target sign in middle
SBO not specific for IS
•(Sargent, MA) Three observers evaluated 182 AXR (60 with IS, 122 without IS) to
determine interobserver variability and validity of IS signs
Agreement among all observers in only 7pts with IS
Equivocal reading in >50% overall
PPV of 32-42%, depending on position of AXR
Abdominal mass and absence of RLQ gas has best PPV
•(Hernandez, et al) Retrospective review of 80 AXR of known IS by 2 pediatric
radiologists
-Triad of mass, SBO, and absence of gas found in only 1%
24% found to be normal
29% diagnosed as IS
-diagnostic findings are crescent and target sign
Ultrasound
•Used to diagnose IS and prevent unnecessary enemas
High sensitivity and specificity
No radiation exposure
•Findings:
-target sign (transverse)
-pseudokidney or sandwich sign (longitudinal)
Target Sign
Central hyperechoic region (C) surrounded by hypoechoic and
homogeneous edge (bowel wall)
Sandwich sign
Cylindrical hyperechoic
center (C) that
continues from
intestinal lumen and is
surrounded on both
sides by hypoechoic
mesentary (M)
Literature
•(Pracros, et al) Found 100% accuracy in diagnosing 145 cases of IS
out of 426 pts with clinical suspicion
-IS diagnosis must have 3 findings: target sign, sandwich sign
(found longitudinally) and continuity between intestinal lumen
and intussusceptum
-Needs to be scanned in transverse and saggital section
•(Verschelden, et al) US used to detect 34 cases IS out 83 pts with
clinical suspicion
-100% NPV
-100% sensitivity, 88% specificity
-False positives from 4 feces in colon and 1 perforated
Meckel’s diverticulum
•Both studies showed that target sign by itself is nonspecific – also
occurs in Crohn’s, hematomas, and volvulus
The Enema
Conventionally considered the gold standard
in diagnosis
All 3 types are used, depending on institution
BUT more invasive (and scary for kids!)
-catheter placed into rectum
-buttocks taped together
-barium shot into bowels
-fluoroscopy to confirm IS and reduce if
possible
And gives small dose of radiation
Consider using smaller tube to introduce air
to test for obstruction first, because would
you really want this in your child???
3 types of enemas:
Pneumatic
Pros – Clean, quick
Cons – Less experience, more difficult to detect Is in pts with gas
in SB proximal to IS
Hydrostatic
Pros - No staining of peritoneum
Cons – Could cause rapid fluid shifts if not using isoosmolar
concentrations
Barium
Pros – Familiar technique
Cons – Perforation, higher chance of peritoneal contamination
There are not yet any large, prospective studies comparing the success
of pneumatic vs hydrostatic…stay tuned
Pneumatic Enema: Before and After
Barium Enema:
From dusk till
dawn
Treatment
17% of IS spontaneously reduce
1st – NPO, IV fluids, NG tube
2nd – surgery consult
Otherwise, tx by reduction enemas or surgery
Reduction Enema
•Successful when flow moves
into ileum
•Pt is under sedation
•Disadvantages – missed lead
points, higher recurrence rate,
perforation, and radiation
exposure
•But benefits outweigh risks –
less invasive than surgery, faster
recovery
Surgery
•Indications – irreducible by
enema, necrotic IS, age, long
duration of sx, SBO, or clinical
signs/sx of peritonitis or bowel
infarction
In a nutshell…
Base your next move on CLINICAL SUSPICION…
If low suspicion  AXR
-if negative, unlikely to be IS
If medium suspicion  AXR  US
-if US negative, unlikely to be IS
If high suspicion, you can skip AXR and proceed directly to US
Got skills?
You are now the
radiologist on call—
Pt is 8 yo girl in ED
with low-grade
fever and colicky R
abdominal pain.
ED physician wants
a barium enema.
You think…
WWADFBVD??
(What would a doctor from Burlington, Vermont do???)
Answer:
DON’T DO THE ENEMA!!
It may be 2/3 of the classical triad, but THINK! Pt is too old
to have an IS. Cases may happen, but it is not necessary to
proceed directly to an enema. What if it was your kid?
Choose an AXR to evaluate…
What do
you see?
Look
closer!
Appendicolith!!
The next night…
ED calls for a 5 month old male with colicky abdominal pain and a
RUQ longitudinal mass…
See
anything?
Crescent
sign!
THE
END!!!
References
Agostino JD. “Common abdominal emergencies in children” Emer Med Clinics of N Amer (2002) 20(1): 139-151.
Bruce J, Soo YH, Cooney DR, et al. “Intussusception: evolution of current management” Journ Pediatr Gastroen and Nutr
(1987) 6:663-674.
Byrne AT, Goeghegan T, Govender P, Lyburn ID, Colhoun E, Torreggiani WC. “The imaging of intussusception” Clin Rad (2005)
60: 39-46.
Daneman A, Alton DJ. “Intussusception: issues and controversies related to diagnosis and reduction” Pediatr Gastrointes
Radiol (1996) 34(4): 743-756.
Daneman A, Navarro O. “Intussusception, Part 1: A review of diagnostic approaches” Pediatr Radiol (2003) 33: 79-85.
Daneman A, Navarro O. “Intussusception, Part 2: An update on the evolution of management” Pediatr Radiol (2004) 34: 97108.
Daneman A, Navarro O. “Intussusception, Part 3: Diagnosis and management of those with an identifiable or predisposing
cause and those that reduce spontaneously” Pediatr Radiol (2004) 34: 305-312.
Fischer TK, Bihrmann K, et al. “Intussusception in early childhood: a cohort study of 1.7 million children” Pediatr (2004)
114(3): 782-785.
Hernandez JA, Swischuk LE, Angel CA. “Validity of plain films in intussusception” Emer Rad (2004) 10: 323-326.
Huppertz HI, Soriano-Gabarro M, et al. “Intussusception among young children in Europe” Pediatr Inf Dis Journal (2006)
25(1): S22-S29.
Meyer JS. “The current radiologic management of intussusception: a survey and review” Pediatr Radiol (1992) 22:323-325.
References cont.
Pracros JP, Tran-Minh VA, Morin De Finfe CH, Deffrenne-Pracros P, Louis D, Basset T. “Acute intestinal intussusception in
children: contribution of ultrasonography (145 cases)” Ann Radiol (1987) 30(7): 525-530.
Ratcliffe JF, Fong S, Cheong L, Connell PO. “The plain abdominal film in intussusception: the accuracy and incidence of
radiographic signs” Pediatr Radiol (1992) 22: 110-111.
Sargent MA, Babyn P, Alton DJ. “Plain abdominal radiography in suspected intussusception: a reassesment” Pediatr Radiol
(1994) 24:17-20.
Verschelden P, Filiatrault D, et al. “Intussusception in children: reliability of US in diagnosis – prospective study” Radiol
(1992) 184: 741-744.