*Necrotizing Enterocolitis DOI: http://dx.doi.org/10.5772/intechopen.85784*

*Pediatric Surgery, Flowcharts and Clinical Algorithms*

except in term babies [21].

isolated in 3% of cases.

**4. Pathology**

abstinence; fetal growth restriction; and perinatal hypoxia [20]. Despite the fact that no predilection for sex, race, or ethnicity has been conclusively established, a higher incidence is observed in male African American infants than in any other single demographic. This could be related to the higher incidence of prematurity in this ethnic group than in the general US population. Hypoxic ischemic injury is no longer considered a major predisposing factor in the development of NEC

NEC primarily affects the ileum and colon, the commonest location being ileocecal area [22]. The entire gastrointestinal tract may be involved in severe cases. On gross examination, the bowel loops are distended with areas of hemorrhage, congestion, necrosis, and pneumatosis (**Figure 1**). On microscopic examination, signs of inflammation, mucosal edema, bacterial invasion, submucosal and intramural gas bubbles, and ischemic transmural necrosis are seen. Intestinal perforation may happen when the entire thickness of bowel is involved leading to pneumoperitoneum, peritonitis, and portal venous gas (**Figure 2**). Microscopically, the predominant feature is coagulation necrosis, suggesting an ischemic origin of NEC. The aggregated inflammatory cells are both acute and chronic, such as neutrophils, lymphocytes, and macrophages representing an appropriate response to pathogenic bacterial invasion and tissue necrosis. Epithelial regeneration, granulation tissue formation and fibrosis may be seen suggesting reparative histological process [23]. Common pathogens isolated in NEC are Enterobacteriaceae including *Escherichia*, *Salmonella*, *Enterobacter*, and *Klebsiella* (68%); staphylococcal species (26%); clostridium species (4%); viruses including rota, echo, corona, and toro (11%); and candida (1%). No organism is

*Macroscopic appearance of necrotizing enterocolitis showing necrotic bowel loops. [Courtesy of Renu Sharma,* 

*MD, Professor of Pediatrics, University of Florida at Jacksonville, USA].*

**28**

**Figure 1.**

**Figure 2.** *Schematic presentation of pathogenesis of NEC.*
