NEONATAL NECROTIZING ENTEROCOLITIS
Neonatal necrotising enterocolitis (NEC) is a serious GIT complication in preterm and critically sick or septic newborns, characterized by progressive abdominal distension, hematochezia and vomiting or retention of nasogastric feeds.
Incidence: NEC may develop in ~3-5% of NICU cases, most common in: (a) extreme preterms (lt;32 weeks), and
(b) critically sick newborns, e.g. birth asphyxia, sepsis, shock and acidosis. Early enteral feeding in these cases is an additional risk factor.
Pathogenesis is still evolving, but two factors are most important and inter-related:
a. Ischemic gut mucosal injury due to shock or hypoxia, leading to stasis and infection, and
b. Local enteral Infection due to early feeding or septicemia, aggravating the mucosal injury.
Irrespective of primary event, the net result is intestinal stasis and infection, further complicated by necrotizing mucosal injury, perforation and peritonitis. Clinically, NEC usually presents on 3-4th day, with a triad of:
• Gross, tender, tympanic abdominal distension suggestive of paralytic ileus.
• Retention of nasogastric feeds (gt;25% of previous feed) or vomiting,
• Hematochezia, i.e. per-rectal bleeding, with/without upper GIT bleeding
In addition, systemic signs of sepsis, shock or other perinatal complications are often present.
Diagnosis is largely clinical, supported by radiological findings (Fig. 12.19). Pneumatosis intestinalis, i.e. presence of intramural gas bubbles in intestinal wall is pathognomic radiological feature of NEC, though frequently missed. Other X-ray features include fixed-loop pattern, bowel-wall edema, air in portal/hepatic vein or pneumoperitoneum, suggestive of intestinal perforation.
Supportive investigations include stool examination for hematochezia, blood/stool cultures and other relevant investigations, e.g.
serum electrolytes.Severity of NEC may be staged (Bell's criteria) as:
• StageI(SuspectedNEC) with mild distension, retention of feeds/vomiting, minimal X-ray abnormality.
• Stage II (Definite NEC), with marked distension, hematochezia, absent bowel sounds and/or pneumatosis intestinalis on X-ray.
• Stage III (Advanced NEC) with DIC, shock, peritonitis and radiological signs of pneumoperitoneum or extraintestinal (portal vein) gas.
Fig. 12.19: Neonatal necrotizing enterocolitis: (A) Pneumatosis intestinalis; (B) Gas under diaphragm.
Management of these cases include:
• Management of primary causative factor, i.e. perinatal complications.
• Nil orally with continuous nasogastric drainage to rest the bowel and drain gastric secretion/bleeds.
• IV fluid therapy, to provide nutrition and maintain fluid and electrolyte balance.
• Systemic antibiotics to control infection. Local gut sterilization is not routinely indicated.
• Blood/packed cell transfusions, in cases with severe GIT bleeding.
• Constant monitoring of abdominal girth and other vital/laboratory parameters
• Surgical intervention in perforation or peritonitis.
Enteral feeding may be restarted gradually after 48-72 hours of the control of GIT bleeding, absence of abdominal distension and appearance of bowel sounds; though recurrences are not uncommon.
Outcome: With best possible treatment, mortality is nil in stage I, 5-10% in stage II and gt;50% in stage III disease.
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