Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
The Radiologic Manifestations of
Necrotizing Enterocolitis
Lynn Ramirez-Avila
Harvard Medical School Year IV
Gillian Lieberman, MD
September 2003
2
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
Baby R
• Former 28.5 weeker with episodes of
respiratory distress in the first days of life
• On day of life 8 Baby R started full feeds
• On day of life 8 Baby R developed marked
abdominal distension & guaiac positive
stools
3
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
Objectives
• Overview of necrotizing enterocolitis
• Overview of common radiologic findings in
nectrotizing enterocolitis
• Review the future role of imaging modalities
in diagnosing necrotizing enterocolitis
4
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
Necrotizing Enterocolitis (NEC)
• Is the necrosis of the mucosa or submucosa of any
portion of the GI tract
• Affects predominantly preterm & low birth weight
infants
• Other risk factors include:
– Compromise of mucosal integrity & bowel integrity
– Compromised mesenteric blood supply
– Changes in bowel lumen
5
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
Pathophysiology
• Multifactorial process that usually affects terminal ileum
and right colon
• Exact pathophysiologic mechanism is not known, but it
is thought that:
• Bacterial colonization
• Intestinal hypoxia
• Formula feeding
Activation of
proinflammatory
mediators &
subsequently bowel
necrosis
6
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
Arterial Supply of the Colon
Superior Mesenteric Artery
Ileocolic, Right colic, Superior
Mesenteric Arteries
Norman W, http://mywebpages.comcast.net/wnor/smlintestinebloodsupply.jpg
Terminal Ileum, Cecum,
Right Colon
Venous Tributaries
Superior Mesenteric Vein
Hepatic Portal Vein
7
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
Clinical Presentation
• Usually occurs in days 3-10 of life
• Systemic symptoms include:
– Apnea, bradycardia, temperature instability, lethargy,
poor feeding
• Gastrointestinal symptoms include:
– Diarrhea, abdominal distention, gastric retention,
gasterointestinal bleeding
8
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
BELL Criteria
Stage Clinical Signs
I (Suspected) Abdominal distension, poor
feeding, vomiting
II (Definite) Abdominal distension, poor
feeding, vomiting, GI bleeding
III (Advanced) Abdominal distension, poor
feeding, vomiting, GI bleeding &
septic shock
Summarized from Rencken et al, 1997
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Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
Imaging Modalities
• Radiologic imaging is key to diagnosis and
monitoring
• If NEC is suspected, abdominal films are
obtained every 12-24 hours
• Supine abdominal, cross table lateral view, or
left-side-down decubitus are standard
10
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
Plain films and Bell Criteria
Stage Clinical
Signs
Radiologic Findings
I (Suspected) Abdominal
distension, poor
feeding, vomiting
Ileus
II (Definite) Abdominal
distension, poor
feeding, vomiting,
GI bleeding
Intestinal pneumatosis & portal
venous air
III (Advanced) Abdominal
distension, poor
feeding, vomiting,
GI bleeding &
septic shock
Ileus, intestinal pneumatosis,
portal venous air,
pneumoperitoneum
Summarized from Rencken et al, 1997
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Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
Normal Neonatal Abdominal
Radiograph
• Liver is prominent in pediatric
abdominal films
• Difficult to discern the small
from large intestine
• Bowel gas pattern bordering the
liver is likely to be the transverse
colon
• Bowel gas pattern in the lower
pelvic region likely to be the
rectum
Courtesy Dr. W. Durgin, BIDMC
12
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
Radiography & Stage I NEC
• Nonspecific radiographic findings:
– Diffuse gaseous distension of intestine
– Loss of normal bowel gas pattern symmetry
13
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
Bowel Distension
From Buonomo, C. 1999. Imaging of neonatal gastrointestinal
obstruction. Rad Clin North America, 37(6): 1187-98.
• Occurs in the small intestine,
colon, or both
• Distension of the small intestine
often occurs 4-48 hours before the
onset of clinical signs
• Distension of large colon occurs in
30% of NEC patients
• This is a relatively non-specific
sign
14
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
Bowel Distension Radiographic
Differential
– Meconium Ileus
– Total Colonic Anganlionosis
– Mid-gut volvulus
– Gastroenteritis, peritonitis, sepsis
15
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
Abnormal Gas Distribution
From Buonomo, C. 1999. Imaging of neonatal
gastrointestinal obstruction. Rad Clin North America,
37(6): 1187-98.
16
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
Radiology & Stage II NEC
• Pneumatosis intestinalis is essentially
pathognomonic for NEC
• Portal venous gas is correlated with worse
prognosis
17
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
Pneumatosis Intestinalis
Courtesy of Dr. Makris, Children’s Hospital Boston
• Intramural Air
• Focal versus diffuse
• Air can be located in the
- Submucosa
Bubbly/cystic
- Subserosa
Linear/curvilinear
18
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
Pneumatosis Intestinalis (continued)
Courtesy of Dr. Makris, Children’s Hospital Boston
Radiographic Differential
•In combination with dilated bowel
indicative of NEC
•Feces
•Milk impaction secondary to onset of
feeding
•Benign pneumatosis from extension from
air in the mediastinum
•Congenital obstruction (atresias,
imperforate anus, meconium plug, etc.
•Hirschsprung’s
19
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
Portal Venous Gas (PVG)
• Associated with severe
NEC and babies with
PVG have worst outcomes
• Visualized better on cross
table lateral view
• On ultrasound PVG is
seen as moving
echogenicity in portal vein
Courtesy Dr. W. Durgin, BIDMC
20
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
PVG (continued)
http://www.hawaii.edu/medicine/pediatrics/neoxray/neoxray.html
Radiographic Differential
•Iatrogenic via umbilical vein
catheters
•Air in biliary tree secondary
to duodenal atresia with
incompetent Sphincter of
Oddi
21
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
Radiology & Stage III NEC
• Persistent (sentinel) loop sign
• Asymmetric bowel dilatation
• Ascites
• Pneumoperitoneum
22
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
Persistent Loop Sign (Sentinel Loop)
• Is the persistence of a dilated loop of bowel on
subsequent radiographs for 24 to 36 hours
From Buonomo, C. 1999. Imaging of neonatal gastrointestinal
obstruction. Rad Clin North America, 37(6): 1187-98
Radiographic Differential
•Appendicitis
•Paralytic Ileus
•Pancreatitis
•Drug-induced
23
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
Pneumoperitoneum
http://bms.brown.edu/pedisurg/Brown/Image%20bank%20pages/NEC.html
Radiographic Differential
•Idiopathic perforation
•Focal intestinal perforation
•Intestinal obstruction
•Iatrogenic (puncture with
nasogastric tube)
24
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
Baby R
• Baby gram radiographic findings:
- Distended bowel loops
-Pneumatosis intestinalis
- Free Air under the left diaphragm
Courtesy of Dr. Makris, Children’s Hospital Boston
25
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
Treatment of NEC
• Clinical Management
– Discontinue feeds
– IV fluids
– Gastric decompression via NG tube
– Total parenteral nutrition
– Broad-spectrum antibiotics
• Surgical Management
– Indications include pneumoperitoneum, sentinel loops,
ascites, or worsening clinical picture
– Resection of the necrotic bowel, proximal enterostomy,
with subsequent reanastomosis at a later time
26
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
Outcome of Baby R
•Underwent exploratory
laparotomy
•Subsequently had right
hemicolectomy with ileocecal
valve resection
• Follow-up radiograph is
shown
Courtesy of Dr. Makris, Children’s Hospital Boston
27
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
Chronic Complications of NEC
• Usually occurs a few weeks after acute disease
• Radiographic follow-up conducted for 2 years
• Course can be complicated by NEC strictures,
bowel obstruction, enterenterofistulae,
enterocysts
28
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
Post-NEC Stricture
•Single or multiple strictures occur
•Commonly occur in the left colon
• Spontaneous resolution of NEC strictures occurs
• Routine barium enemas are performed in children who
undergo surgery, but not in children who have had medical
management of NEC
29
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
NEC Strictures
From Buonomo, C. 1999. Imaging of neonatal gastrointestinal
obstruction. Rad Clin North America, 37(6): 1187-98
From Rabinowitz, JG. “Radiographic Manifestations” in
Neonatal Necrotizing Enterocolitis, Brown EG, Sweet AY eds.
1980
30
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
NEC & other Imaging Modalities
• Abdominal plain radiographs are
nonspecific in the early and late stages of
NEC
• The use of computed tomography in NEC
diagnosis has been explored
• Use of MRI in NEC diagnosis is under study
31
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
NEC & CT
• The permeation of contrast administered
into ischemic bowel has been reported in
animal models of NEC
• The contrast is resorbed from the
peritoneum & is excreted into the urinary
system
32
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
NEC & CT (continued)
• Study included babies with NEC and controls (n=22) who were orally
given non-ionic contrast
• After contrast administration, they collected the urine of babies with NEC
and controls and CT the urine
• They found that after contrast, the urine of babies with suspected and
definite NEC have higher Hounsfield Units than controls
Control
Urine
Urine of babies who
underwent other GI
study
Urine of babies with
suspected NEC
Urine of babies with
definite NEC
5.6 HU +/- 3.9 6.7 HU +/- 3.2 26.0 HU +/- 3.4 71.0 HU +/- 18.8
summarized from Rencken et al, 1997
33
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
NEC & MRI
• Maalouf et al report MRI findings of NEC amongst a
group of low birth weight and preterm infants and their
controls
• They conclude that the following characteristics were
associated with severe forms of NEC:
– Fluid levels within lumen
– Intramural gas
– Bubble-like appearance in bowel wall
• Bowel areas with a bubble-like appearance corresponded
to areas of bowel that were surgically resected
34
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
NEC & MRI
From Maalouf: Pediatrics, Volume 105(3).March 2000.510-514
Bubble-like Appearance Air-fluid levels
Intramural Air
35
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
NEC & Ultrasound
From Kodroff et al, 1984
Pseudo-kidney sign
• Non-specific sign seen in any process
where blood, pus, fluid, tumor invades
bowel wall
• Necrotic bowel cannot be
distinguished from inflammatory bowel
disease
•Given, demographics of preterm
population, this sign is most consistent
with NEC
36
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
Portal Venous Gas & Ultrasound
Right Upper Quadrant
U/S
Liver Ultrasound of Neonate with NEC
From Merrit et al, 1984
Echogenicities in
liver parenchyma
Microbubble in
portal veinNormal Ultrasound
37
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
Conclusion
• The incidence of NEC is increasing secondary to
increased survival of low-birth weight and pre-
term infants
• Diagnostic imaging, specifically plain films are
important in the diagnosis, progression, and
follow-up of NEC
• But, secondary to the sensitivity of current
abdominal plain films, the use of CT, MRI, and
U/S could provide a more sensitive and specific
imaging alternative
38
Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
References
• Brown University Department of Pediatric Surgery http://bms.brown.edu/pedisurg/Brown/Image%20bank%20pages/NEC.html
• Buonomo C (1999). The Radiology of Necrotizing Enterocolitis in Neonatal Imaging Rad Clin North America 37: 1999.
• Caplan MS, Jilling T (2001). New Concepts in necrotizing enterocolitis. Curr Opin Ped 13: 111.
• Kodroff MB, Hartenberg, MA, Goldschmidt RA (1984). Ultrasonographic diagnosis of gangrenous bowel in neonatal necrotizing enterocolitis. Ped Rad 14: 168.
• Fotter R, Sorantin (1994). Diagnostic imaging in necrotizing enterocolitis. Acta Paed Supp 398: 41.
• Kodroff MB, Hartenberg, MA, Goldschmidt RA (1984). Ultrasonographic diagnosis of gangrenous bowel in neonatal necrotizing enterocolitis. Pediatr Radiol
14: 168.
• Merritt CRB, Goldsmith JP, Sharp MJ. (1984) Sonographic Detection of Portal Venous Gas in Infants with Necrotizing Enterocolitis. AJR 143: 1059.
• Maalouf EF, Fagbemi A, Duggan PJ, Jayanthi S, Counsell SJ, Lewis HJ, Fletcher AM, Lakhoo K, Edwards AD. (2000) Magnetic Resonance Imaging of
Intestinal Necrosis in Preterm Infants. Pediatrics 105: 510.
• Norman, W. Superior Mesenteric Artery Ilustration available [Online] http://mywebpages.comcast.net/wnor/smlintestinebloodsupply.jpg. September 10, 2003.
• Rabinowitz, JG. (1980). Radiographic Manifestations in Monographs in Neonatology: Neonatal Necrotizing Enterocolitis Brown EG, Sweet AY (eds). New
York: Grune and Stratton.
• Reeder MM, WG Bradley (2001). Reeder and Felson’s Gamuts in Radiology: Comprehensive List of Roentgen Differential Diagnosis. New York: Springer
Verlag Publishing.
• Renken IO, Sola A, Al-Ali F, Solano JP, Goldbergt HI, Cohen PA, Gooding CA. (1997). Necrotizing Enterocolitis: Diagnosis with CT Examination of Urine
after Enteral Administration of Iodinated Water-soluble Contrast Material. Ped Radiology 205: 87.
• Schanler RJ. (2003). Up to Date: Clinical features and treatment of necrotizing enterocolitis in newborns available [Online] www.uptodate.com September 10,
2003.
• Wood BP. (2002). E medicine: Necrotizing Enterocolitis available [Online]: http://www.emedicine.com/radio/topic469.htm.
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Lynn Ramirez-Avila, HMS IV
Gillian Lieberman, MD
Acknowledgements
• Dr. J. Makris, Children’s Hospital Boston
• Dr. W. Durgin, BIDMC
• Dr. G. Lieberman, BIDMC
• Pamela Lepkowski
• Larry Barbaras, BIDMC Webmaster
The Radiologic Manifestations of Necrotizing Enterocolitis
Baby R
Objectives
Necrotizing Enterocolitis (NEC)
Pathophysiology
Arterial Supply of the Colon
Clinical Presentation
BELL Criteria
Imaging Modalities
Plain films and Bell Criteria
Normal Neonatal Abdominal Radiograph
Radiography & Stage I NEC
Bowel Distension
Bowel Distension Radiographic Differential
Abnormal Gas Distribution
Radiology & Stage II NEC
Pneumatosis Intestinalis
Pneumatosis Intestinalis (continued)
Portal Venous Gas (PVG)
PVG (continued)
Radiology & Stage III NEC
Persistent Loop Sign (Sentinel Loop)
Pneumoperitoneum
Baby R�
Treatment of NEC
Outcome of Baby R
Chronic Complications of NEC
Post-NEC Stricture
NEC Strictures
NEC & other Imaging Modalities
NEC & CT
NEC & CT (continued)
NEC & MRI
NEC & MRI
NEC & Ultrasound
Portal Venous Gas & Ultrasound
Conclusion
References
Acknowledgements