Necrotizing enterocolitis: review of state-of-the-art imaging findings with pathologic correlation.

Plain abdominal radiography is the current standard imaging modality for evaluation of necrotizing enterocolitis (NEC). Sonography is still not routinely used for diagnosis and follow-up, as it is not widely recognized that it can provide information that is not provided by plain abdominal radiography and that may affect the management of NEC. Like plain abdominal radiography, sonography can depict intramural gas, portal venous gas, and free intraperitoneal gas. However, the major advantages of abdominal sonography over plain abdominal radiography are that it can depict intraabdominal fluid, bowel wall thickness, and bowel wall perfusion. Sonography may depict changes consistent with NEC when the plain abdominal radiographic findings are nonspecific and inconclusive. Thinning of the bowel wall and lack of perfusion at sonography are highly suggestive of nonviable bowel and may be seen before visualization of pneumoperitoneum at plain abdominal radiography. The mortality rate is higher after perforation; thus, earlier detection of severely ischemic or necrotic bowel loops, before perforation occurs, could potentially improve the morbidity and mortality in NEC. The information provided by sonography allows a more complete understanding of the state of the bowel in patients with NEC and may thus make management decisions easier and potentially change outcome.