eMedicine Specialties > Radiology > Pediatrics

Necrotizing Enterocolitis

Beverly P Wood, MD, MS, PhD, Professor, Departments of Radiology and Pediatrics, Division of Medical Education, Keck School of Medicine, University of Southern California

Updated: Nov 10, 2008

Introduction

Background

Image 1.


The radiograph demonstrates multiple dilated loops in the large bowel and small bowel. Note the pneumatosis intestinalis with bubbly and linear gas collections in the bowel wall.

Image 4.


Portal venous air is present in a patient with pneumatosis intestinalis.

Presentation

Demographics

The incidence of necrotizing enterocolitis (NEC) varies from isolated cases to nursery epidemics. The population group most often affected is ill, preterm neonates.⁵

The incidence rates of necrotizing enterocolitis are similar in all developed countries in which high-quality health care is available for premature infants.

The incidence in premature neonates is highest in those with very low birth weights.⁶ NEC is less commonly seen in premature neonates with higher birth weights and in full-term neonates.

Currently, the mortality rate of patients with necrotizing enterocolitis is less than 20% when infants are treated early in the course of the illness. Without treatment, the mortality rate is extremely high.

Morbidity associated with NEC includes bowel stricture, peritoneal adhesions, and bowel perforation. If perforation occurs, the necrotic bowel is surgically resected. Resection of large lengths of bowel may result in short-bowel syndrome.

Necrotizing enterocolitis exhibits no sexual predilection.
 

Presentation

The onset of necrotizing enterocolitis may occur from 2 weeks to several months after birth. The meconium is usually passed normally. The initial signs of NEC include abdominal distention and gastric retention of fluid. Manifestations of the disease develop after enteric feedings begin.

The onset of NEC may be insidious, and sepsis may occur before any intestinal abnormality is noted. The spectrum of presentations ranges from mild NEC with guaiac-positive stool to severe NEC with peritonitis, bowel perforation, shock, and possible death. The progression of NEC may be rapid; however, progression of the disease usually occurs after 72 hours.

Obviously bloody stool is observed in approximately 25% of patients.

The distal ileum and proximal colon are most commonly involved in necrotizing enterocolitis, although any region of the bowel may be involved. The stomach may be involved as well.

Pneumatosis is a late finding in NEC and usually indicates some necrosis of the bowel wall. The presence of irritability and bowel distention, especially when associated with bloody stool, is pathognomonic of NEC.^7,8


Natural History

Several factors contribute to the development of neonatal necrotizing enterocolitis. The underlying pathology is one of gas accumulation in the submucosal layers of the bowel wall that progresses to necrosis. Eventual necrosis of the bowel loops, perforation, systemic sepsis, and death may result from NEC. The bowel regions most often affected are the right side of the colon and the distal ileum, although any portion of the bowel is susceptible.

The major or most common contributor to NEC is sepsis; however, indwelling vascular catheters, the use of assisted ventilation, respiratory acidosis, and hypoxemia are contributing factors as well. NEC is primarily a complication of premature birth, which may be associated with hypoxemia, acidosis, hypotension, sepsis, and stress. NEC may occur in ill full-term neonates, particularly those with a history of sepsis, hypoxia, asphyxia, or difficult resuscitation.

Polycythemia, the use of hypertonic formulas or medicines, and too-rapid feeding may cause mucosal injury. Epidemics of NEC have been documented, and infectious agents such as Clostridium perfringens, Escherichia coli, Staphylococcus epidermidis, and rotavirus have been identified in association with NEC. Most often, no pathogen is identified.^{9,10,11,12,13}

The presence of free air indicates a bowel perforation; in such cases, surgical exploration and resection of necrotic bowel is needed. Intensive therapy is started immediately. Feeding is stopped, nasogastric decompression is performed, and intravenous fluids are administered. Once cultures of blood, stool, and cerebrospinal fluid are obtained, systemic antibiotics are started; these may include anti-Pseudomonas medications and an aminoglycoside.¹⁴

When present, umbilical catheters are removed; assisted ventilation should be initiated if distention contributes to hypoxia. If hypotension develops, resuscitation is initiated with the administration of blood, plasma, crystalloid, and/or dopamine, as indicated. The patient's course is monitored with frequent radiography, including cross-table lateral views, to evaluate perforation.

Treatment

Medical treatment fails in approximately 20% of patients who have associated pneumatosis intestinalis. Pneumatosis intestinalis is lethal in at least 25% of these patients.

Strictures develop at the site of the necrotizing lesion in approximately 10% of patients. Resection of the stricture is curative.

Complications that may occur after massive intestinal resection include short-bowel syndrome, cholestatic jaundice, and conditions related to total parenteral alimentation via central venous catheters.¹⁵  Complications may be prevented with judicious feeding and the use of breast milk.¹⁶

Differential Diagnoses

Other Problems to Be Considered

Obstruction resulting from tenacious intestinal content in infants who are fed high-energy formulas
Hirschsprung disease
Intestinal hypoperistalsis syndromes
Adynamic ileus

Radiography

Technique

Infants suspected of having necrotizing enterocolitis (NEC) should undergo periodic radiography of the abdomen. In some centers, infants in whom NEC is highly suspected undergo routine frontal abdominal radiography every 4-6 hours. Cross-table lateral examinations with a horizontal beam are useful for detecting subtle, early collections of free air, although some clinicians prefer to use lateral decubitus radiographs to detect free air. In the presence of peritoneal adhesions, keeping the patient in the decubitus position for a prolonged period ensures that the air moves to the highest point. (See Images 5-13 below.)

Image 5.


This radiograph shows free air secondary to bowel wall necrosis.

Image 6.


Left lateral decubitus radiograph shows free air.

Image 7.


Portal venous air is present in a patient with pneumatosis intestinalis.

Image 8.


The radiograph demonstrates multiple dilated loops in the large bowel and small bowel. Note the pneumatosis intestinalis with bubbly and linear gas collections in the bowel wall.

Image 9.


Increasing pneumatosis intestinalis is seen in this radiograph.

Image 10.


Anteroposterior image shows necrotizing enterocolitis with pneumatosis intestinalis.

Image 11.


Lateral abdominal image shows pneumatosis intestinalis.

Image 12.


Image obtained during examination with a water-soluble enema shows the pneumatosis well. This technique is not recommended.

Image 13.


In this radiograph, free air is observed over the liver that outlines the falciform ligament. This finding indicates perforation of the bowel, which necessitates surgical exploration and resection of necrotic bowel.

• A high index of suspicion is essential for the diagnosis of necrotizing enterocolitis.
• Small amounts of free air may not be easily visible on supine abdominal radiographs.
• Thickening of the bowel wall may not be easily observed in the presence of a dilated bowel.

Computed Tomography

Imaging pearls

• The use of CT is not advocated for the diagnosis of necrotizing enterocolitis or for identifying the presence of free air.
• CT scanning or an examination with a water-soluble enema may be used to demonstrate pneumatosis or a site of perforation.

Findings

Ultrasonography

Imaging findings

Ultrasonography of the abdomen characteristically shows thick-walled loops of bowel with hypomotility.

Intraperitoneal fluid is often present.

In the presence of pneumatosis intestinalis, gas is seen in the portal venous circulation within the liver.¹⁷

Multimedia

Media file 1: The radiograph demonstrates multiple dilated loops in the large bowel and small bowel. Note the pneumatosis intestinalis with bubbly and linear gas collections in the bowel wall.

Media file 2: Increasing pneumatosis intestinalis is seen in this radiograph.

Media file 3: Anteroposterior image shows necrotizing enterocolitis with pneumatosis intestinalis.

Media file 4: Lateral abdominal image shows pneumatosis intestinalis.

Media file 5: This radiograph shows free air secondary to bowel wall necrosis.

Media file 6: Left lateral decubitus radiograph shows free air.

Media file 7: Portal venous air is present in a patient with pneumatosis intestinalis.

Media file 8: Image obtained during examination with a water-soluble enema shows the pneumatosis well. This technique is not recommended.

Media file 9: In this radiograph, free air is observed over the liver that outlines the falciform ligament. This finding indicates perforation of the bowel, which necessitates surgical exploration and resection of necrotic bowel.

References

1. Chung DH, Ethridge RT, Kim S, Owens-Stovall S, Hernandez A, Kelly DR, et al. Molecular mechanisms contributing to necrotizing enterocolitis. Ann Surg. Jun 2001;233(6):835-42. [Medline].

2. Claud EC, Walker WA. Hypothesis: inappropriate colonization of the premature intestine can cause neonatal necrotizing enterocolitis. FASEB J. Jun 2001;15(8):1398-403. [Medline].

3. Di Lorenzo M, Krantis A. Altered nitric oxide production in the premature gut may increase susceptibility to intestinal damage in necrotizing enterocolitis. J Pediatr Surg. May 2001;36(5):700-5. [Medline].

4. Duro D, Kamin D, Duggan C. Overview of pediatric short bowel syndrome. J Pediatr Gastroenterol Nutr. Aug 2008;47 Suppl 1:S33-6. [Medline].

5. Hunter CJ, Upperman JS, Ford HR, Camerini V. Understanding the Susceptibility of the Premature Infant to Necrotizing Enterocolitis (NEC). Pediatr Res. Dec 10 2007;[Medline].

6. Manogura AC, Turan O, Kush ML, Berg C, Bhide A, Turan S. Predictors of necrotizing enterocolitis in preterm growth-restricted neonates. Am J Obstet Gynecol. Jan 11 2008;[Medline].

7. Buchheit JQ, Stewart DL. Clinical comparison of localized intestinal perforation and necrotizing enterocolitis in neonates. Pediatrics. Jan 1994;93(1):32-6. [Medline].

8. Casey L, Lee KH, Rosychuk R, Turner J, Huynh HQ. 10-year review of pediatric intestinal failure: clinical factors associated with outcome. Nutr Clin Pract. Aug-Sep 2008;23(4):436-42. [Medline].

9. Cakmak Celik F, Aygun C, Cetinoglu E. Does early enteral feeding of very low birth weight infants increase the risk of necrotizing enterocolitis?. Eur J Clin Nutr. Nov 28 2007;[Medline].

10. Premji S, Chessell L. Continuous nasogastric milk feeding versus intermittent bolus milk feeding for premature infants less than 1500 grams. Cochrane Database Syst Rev. 2001;(1):CD001819. [Medline].

11. Ververidis M, Kiely EM, Spitz L, Drake DP, Eaton S, Pierro A. The clinical significance of thrombocytopenia in neonates with necrotizing enterocolitis. J Pediatr Surg. May 2001;36(5):799-803. [Medline].

12. Hunter CJ, Petrosyan M, Ford HR, Prasadarao NV. Enterobacter sakazakii: An Emerging Pathogen in Infants and Neonates. Surg Infect (Larchmt). Aug 7 2008;[Medline].

13. Gagliardi L, Bellù R, Cardilli V, De Curtis M. Necrotising enterocolitis in very low birth weight infants in italy: incidence and non-nutritional risk factors. J Pediatr Gastroenterol Nutr. Aug 2008;47(2):206-10. [Medline].

14. Bury RG, Tudehope D. Enteral antibiotics for preventing necrotizing enterocolitis in low birthweight or preterm infants. Cochrane Database Syst Rev. 2001;(1):CD000405. [Medline].

15. Sigalet DL. Short bowel syndrome in infants and children: an overview. Semin Pediatr Surg. May 2001;10(2):49-55. [Medline].

16. Ng E, Shah VS. Erythromycin for the prevention and treatment of feeding intolerance in preterm infants. Cochrane Database Syst Rev. Jul 16 2008;CD001815. [Medline].

17. Saxena A, Galwa RP. Sonographic findings and outcome in necrotizing enterocolitis. Pediatr Radiol. Nov 2007;37(11):1180. [Medline].

Keywords

necrotizing enterocolitis, NEC, neonatal colitis, neonatal enteritis, necrotic appendicitis of the newborn, neonatal gastrointestinal disease, complication of prematurity

Contributor Information and Disclosures

Author

Beverly P Wood, MD, MS, PhD, Professor, Departments of Radiology and Pediatrics, Division of Medical Education, Keck School of Medicine, University of Southern California
Beverly P Wood, MD, MS, PhD is a member of the following medical societies: American Academy of Pediatrics, American Association for Women Radiologists, American College of Radiology, American Institute of Ultrasound in Medicine, American Medical Association, American Roentgen Ray Society, Association of University Radiologists, Radiological Society of North America, and Society for Pediatric Radiology
Disclosure: Nothing to disclose.

Medical Editor

Fredric A Hoffer, MD, FAAP, FSIR, Professor of Radiology, University of Washington; Section Chief of Interventional Radiology, Department of Radiology, Seattle Children's Hospital and Regional Medical Center
Fredric A Hoffer, MD, FAAP, FSIR is a member of the following medical societies: American Academy of Pediatrics, Children's Oncology Group, Radiological Society of North America, Society for Pediatric Radiology, and Society of Interventional Radiology
Disclosure: Nothing to disclose.

Pharmacy Editor

Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand
Disclosure: Nothing to disclose.

Managing Editor

David A Stringer, BSc, MBBS, FRCR, FRCPC, Professor, National University of Singapore; Head, Diagnostic Imaging, KK Women's and Children's Hospital, Singapore
David A Stringer, BSc, MBBS, FRCR, FRCPC is a member of the following medical societies: British Columbia Medical Association, Canadian Association of Radiologists, European Society of Paediatric Radiology, Ontario Medical Association, Radiological Society of North America, Royal College of Physicians and Surgeons of Canada, Royal College of Radiologists, and Society for Pediatric Radiology
Disclosure: None None None

CME Editor

Robert M Krasny, MD, Consulting Staff, Department of Radiology, The Angeles Clinic and Research Institute
Robert M Krasny, MD is a member of the following medical societies: American Roentgen Ray Society and Radiological Society of North America
Disclosure: Nothing to disclose.

Chief Editor

John Karani, MBBS, FRCR, Consulting Staff, Department of Radiology, King's College Hospital, London
Disclosure: Nothing to disclose.

Evidence-based care guideline for necrotizing enterocolitis (NEC) among very low birth weight infants.
Cincinnati Children's Hospital Medical Center.  2005 Jul 14 (revised 2007 Feb).  12 pages.  NGC:005522
 

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