Date: 2005/09/22 Speaker: Intern 吳忠泰 Faingold et al. Radiology May 2005; 587-594 Pediatric Imaging Necrotizing Enterocolitis: Assessment of Bowel Viability with Color Doppler US Date: 2005/09/22 Speaker: Intern 吳忠泰

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

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

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

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

Modified Bell’s Staging Criteria

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%

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

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

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

Results

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

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

Results Y appearance Rim pattern Arterial wave Pallisading

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

Results

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

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

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

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

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

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

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?

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