A prospective comparison of intestinal sonography and abdominal radiographs in a neonatal intensive care unit

No study reported in the literature comprehensively compares findings on neonatal abdominal radiographs with sonography.

To compare the findings on abdominal radiographs and sonograms in infants in intensive care, to better understand how the various intestinal gas patterns on radiographs relate to the spectrum of appearances on sonography and, second, to evaluate the ability of sonography to differentiate necrotizing enterocolitis from other intestinal pathology.

We prospectively evaluated sonograms and radiographs, blinded to the other modality and to clinical information. Patients' charts were reviewed by a third blinded reader and used as a reference standard for diagnosis. We made associations between sonographic findings, radiographic intestinal gas patterns and clinical diagnoses.

We included 75 infants with gestational ages between 23 weeks and 41 weeks. Sonographic abnormalities were present in infants with all radiographic intestinal gas patterns, including normal patterns. We only saw absent intestinal perfusion and fluid collections on sonography (suggesting intestinal necrosis and sealed perforation) in infants with intestinal dilatation with elongation on radiographs. Separation of intestinal loops on radiographs was most commonly caused by reasons other than intestinal wall thickening. Increased intestinal echogenicity or free fluid with echoes on sonography correlated with a diagnosis of necrotizing enterocolitis, whereas anechoic free fluid correlated with absence of necrotizing enterocolitis.

Sonography is complementary to radiographs in infants with suspected intestinal pathology, with a spectrum of appearances seen on each modality. Some sonographic findings either strongly suggest necrotizing enterocolitis or supply evidence against this diagnosis.