Inclusion Criteria:

Patients must meet at least one criterion from each of the following three categories:

Historical Factors:

• Feeding intolerance defined as vomiting of 2 or more feedings within 24 hours or any vomitus containing bile, or the presence of gastric residuals of volume greater than 6cc/kg or any aspirate containing bile
• Apneic/bradycardic episodes
• Oxygen desaturation episode not otherwise explained
• Guaiac positive or grossly bloody stools

Physical Examination Findings:

• Abdominal distention recorded by practitioner
• Capillary refill time greater than 2 seconds
• Abdominal wall discoloration
• Abdominal tenderness

Radiographic Findings:

• Pneumatosis intestinalis
• Portal venous gas
• Ileus
• Dilated bowel
• Pneumoperitoneum
• Air/fluid levels
• Thickened bowel walls
• Ascites or peritoneal fluid
• Free intraperitoneal air

Exclusion Criteria:

Patients will be excluded for any of the following:

• Major gastrointestinal anomaly
• Prior abdominal operation
• Family does not consent to participate (A list of patients for whom consent was refused will be maintained in order to avoid contacting these families repeatedly. All families who refuse consent will be queried as to the reason for refusal).