Pilot Randomized Control Trial of Necrotizing Enterocolitis Screening Abdominal Radiograph Versus Bowel Ultrasound Plus Abdominal Radiograph in Premature Neonates

Necrotizing enterocolitis (NEC) is the most common bowel disease in premature and low birth weight neonates. NEC is defined by the loss of mucosal integrity of the bowel wall enabling bacteria and other toxins to permeate into the bowel causing ischemia and necrosis which can lead to bowel perforation and sepsis. NEC can result in substantial morbidity and mortality and prolonged hospital stay.

In the past, abdominal radiography has been scored on a standard scale that correlated with outcomes. Duke University Medical Center developed a standardized ten-point radiographic scale, the Duke Abdominal Assessment Scale (DAAS) (Appendix B) and was proven to be directly proportional to the severity of NEC on patients that underwent surgery. Abdominal radiographs are assessed for gas pattern, bowel distention, location and features, pneumatosis (gas in bowel wall), portal venous gas, and pneumoperitoneum (free air in peritoneal cavity) to indicate the level of suspicion of NEC. The use of abdominal radiographs is the most common assessment for suspected NEC in infants, however, there have been recent studies done on the utility of bowel ultrasound to aid in early diagnosis of NEC due to the ability to evaluate peristalsis, echogenicity and thickness of bowel wall, pneumatosis and the capability of doing color Doppler to evaluate blood perfusion. A University of Toronto study used ultrasound to assess bowel perfusion with color Doppler in neonates and found a correlation between absence of bowel wall perfusion and the increased severity of NEC on surgical pathology. Although there are similar signs found between abdominal radiography and bowel ultrasound, some of the more severe features such as, pneumoperitoneum, were found to be more sensitive on bowel ultrasound, thus potentially leading to more definitive treatment. Currently, there is no good study evaluating whether the use of bowel ultrasound affects clinical outcomes in VLBW patients over the use of abdominal radiography alone.

The use bowel ultrasound has yet to be adopted in the setting of suspicion for NEC at our institution. This is primarily due to the lack of expertise of the ultrasound technologists, radiologists and clinicians. With literature dating back to 2005 supporting the use of bowel ultrasound in diagnosis of severity of NEC, we would like to see if a regimen involving combined ultrasound and radiograph screening for NEC would make a difference in clinical outcomes (morbidity, mortality, and length of stay (LOS)) compared with radiograph screening alone.

Calprotectin is a protein found in the stool that, at elevated levels, indicates gastrointestinal inflammation. The addition of fecal biomarkers to the diagnostic work up for NEC also has promising impact. It has been suggested that fecal calprotectin levels obtained at the time of suspicion of NEC may be a useful noninvasive indicator to determine the severity of inflammation in the intestine and whether it is related to NEC or other forms of inflammation. Correlation of the fecal biomarkers with findings on BUS may be helpful to more definitively diagnose NEC.