Developmental physiology of the gastrointestinal tract and feed intolerance in preterm neonates

Manifestations of gastrointestinal hypomotility such as large/bile stained gastric residuals, abdominal distension, and vomiting, are very common in the first few weeks of life in preterm neonates, especially those with gestation under 28 weeks at birth, and are often interpreted as feed intolerance. Necrotising enterocolitis (NEC) is a potentially disastrous illness with significant mortality, and morbidity including long term neurodevelopmental impairment, in this population. The scientific basis for the diagnosis and interpretation of signs of feed intolerance is not clear. Inability to differentiate manifestations of ileus of prematurity from those of early (Stage I) NEC is the single most important reason for frequently withholding enteral nutrition in preterm neonates. The decision to start, continue, upgrade or stop enteral feeds in extremely preterm neonates continues to be based on poorly understood clinical parameters such as volume and colour of gastric residuals, and abdominal distension. This chapter reviews the developmental physiology of the gastrointestinal tract and the clinical studies on the significance and/or management of the various manifestations of feed intolerance in extremely preterm neonates. The need for further research on this important clinical issue is emphasised considering the fact that suboptimal nutrition due to the frequent withholding of enteral feeds increases the risk of postnatal growth restriction in extremely preterm neonates.