The Use of Probiotics in the Prevention of Necrotizing Enterocolitis in Preterm Infants

Abstract

Necrotizing enterocolitis (NEC) is defined as inflammation and necrosis of the bowel. It is the final manifestation of vascular, mucosal, and metabolic insults to the immature intestine (1, 2). NEC is a common gastrointestinal emergency in newborns and one of the leading causes of morbidity and mortality in neonatal intensive care units (NICU), with a mortality rate of 15% to 30% (3, 4). No single unifying theory exists for the pathogenesis of NEC that explains all the clinical observations associated with the disorder. Proposed mechanisms for the development of NEC include immature intestinal motility, digestion, circulatory regulation, barrier function, innate immunity, and abnormal bacterial colonization (2, 3). The most frequent risk factors associated with NEC include prematurity and low birth weight. Over 90% of neonates who develop NEC are born preterm. Extremely low birth weight (<1000 g) infants <28 weeks' gestational age (GA) are the most susceptible. Other risk factors for the development of NEC include asphyxia, acute cardiopulmonary disease, polycythemia, hyperviscosity syndromes, exchange transfusions, aggressive enteral feeding, and abnormal colonization of the intestine with enteric pathogens (1–5). Many nonspecific signs may trigger the suspicion of NEC, such as abdominal tenderness or distention, feeding intolerance, bloody stools, and apnea. The definite signs of NEC include pneumatosis intestinalis and portal venous gas, which are revealed by x-rays. Abdominal x-rays are performed to diagnose and determine progression of NEC. Laboratory values, such as complete blood count with differential, arterial blood gas measurements, and electrolytes, are measured as well as obtaining blood and stool cultures to look for other signs of NEC and rule out other conditions (2). To better classify and diagnose NEC using nonspecific and definite signs and symptoms of NEC, Bell's staging criteria were developed: suspected NEC is classified as stage 1, proven NEC as stage 2, and severe cases as stage 3 (1, 5) (Table ​(Table11). Table 1 Bell's staging criteria for necrotizing enterocolitis∗