1. Date: 2005/09/22 Speaker: Intern 吳忠泰
Faingold et al. Radiology May 2005;
Pediatric Imaging
Necrotizing Enterocolitis: Assessment of Bowel Viability with Color Doppler US
Date: 2005/09/22
Speaker: Intern 吳忠泰

2. Necrotizing Enterocolitis (NEC)
An acute or chronic inflammatory GI disease
Primarily affects the pre-term neonate
50% in BW < 1500 gm
10% in full-term neonate
The most common site
Distal ileum and proximal colon
Unclear etiology
Ischemia, infection, feeding, inflammatory mediator
Acute: Within 5 days after birth; Chronic: Later than 4 months after birth
Site: Ileum, A-colon, cecum, T-colon, less in sigmoid colon, jejunum and stomach
Ischemia: Reperfusion injury, free radical
Infection: Corona virus, Coxsackie virus, KP, Salmonella, E. coli, Clostridium
Feeding: Feeding within 48hrs after birth

3. Necrotizing Enterocolitis (NEC)
S/S:
Feeding intolerance, abdominal distension, rectal bleeding, shock-like appearance
Dx: Abdominal X-ray
Pneumatosis intestinalis, hepatic venous gas, pneumoperitoneum
Tx:
NG decompression, broad-spectrum ABx
Operation when perforation
Prognosis: Mortality rate 30~40%
S/S: Diarrhea, peritonotis (20~30%), perforation, weakness, acidemia, bacteremia (60%), DIC, shock
Abdominal X-ray q6~8 hr in acute phase
Complication: Bowel obstruction, stenosis

4. Purpose Absence of bowel wall perfusion at color Doppler US
Bowel necrosis Operation
Indicate?

5. Materials Group A: 30 control neonates
17 boys and 13 girls
GA 24~41 wks (mean 36.8 wks)
No GI or CV abnormality
Group B: 32 proved or suspected NEC
19 boys and 13 girls
GA 24~40 wks (mean 32.7 wks)
Disease stage:
Modified Bell’s staging criteria
P > 0.99

6. Modified Bell’s Staging Criteria

7. Materials Excluding criteria Abdominal wall defects
Large amount of bowel gas
Hemodynamic instability
Low MAP
HR < 100 or > 200
Metabolic acidosis with pH < 7.2
Plt < 50’000 / mm3
SaO2 < 90%

8. Methods Abdominal US Abdominal X-ray
SMA, SMV, SMA flow, portal venous gas, free fluid, free air
Bowel wall echotexture, bowel wall thickness, bowel loop, intramural air, peristalsis
Intestinal mural blood flow (count the color Doppler signals as dots and lines per cm3)
Abdominal X-ray

9. Results In group A SMA flow (+) Intramural gas (-)
Portal venous gas (-)
Free air (-), ascites (-)
Bowel wall 1.1 to 2.6 mm
Normal gut appearance
10 contractions/ min

10. Results In group A Bowel wall perfusion Dots: 1~9 (mean 3.8 per cm3)
Line: 0~2

11. Results

12. Results In group B Not specific for necrosis
Bowel wall thickening
Pneumatosis intestinalis
Absence of peristalsis
Highly suggestive for ischemia
Bowel wall thinning (< 1mm)

13. Results In NEC stages I and II (12 pts) Pneumoperitoneum (-)
10 of 12: Normal to increased bowel perfusion
2 of 12: Isolated segment of bowel with
absent blood flow; operation proved
bowel necrosis

14. Results
Y appearance
Rim pattern
Arterial wave
Pallisading

15. Results In NEC stage III (10 pts) 4 of 10: Pneumoperitoneum (+)
10 of 10: Absent perfusion in isolated or
multiple segments
6 of 10: Pathologic proved (4 laparotomy, 2
autopsy)
3 of 10: Pneumoperitoneum in X-ray
1 of 10: Unknown
6 of 10: Died

16. Results

17. Results In risk for NEC (non-NEC) (8 pts)
4 congenital heart disease, 3 sepsis, 1 pulmonary hypoplasia and malrotation
0 of 8: Absence of bowel perfusion
3 of 8: Upper limit
1 of 8: Lower limit
No necrosis was found
2 by laparotomy and 3 by autopsy

18. Results Sensitivity: 100% Specificity: 90%
Positive predictive value: 83%
Negative predictive value: 100%

19. Discussion US findings Pathologic findings match Normal gut pattern
Hyperemic pattern
Absence of perfusion
Normal bowel
Inflammed bowel
Necrotic bowel

20. Discussion Detection of bowel wall necrosis
Color Doppler more sensitive than abdominal X-ray
Sensitivity
X-ray 40%
Color Doppler 100%

21. Discussion Reclassification of severity grade 2 pts from II to IIIB
6 pts from IIIA to IIIB

22. Advantages
Color Doppler US are more accurate than clinical examination and abdominal X-ray in detection bowel wall necrosis
Reclassify the severity
Assist surgical indication
Non-invasive, no radiation
Can be performed at the bedside

23. Limitations Large amounts of bowel gas Unstable vital signs
Interoperator variability
Small population samples
Apparent clinical status while performing the examination
Patient beyond the excluding criteria?

24. Thanks for Your Attention…