Association of new sonographic features with outcome in neonates with necrotizing enterocolitis

We have recently noted some sonographic features in necrotizing enterocolitis that have received little or no attention in the current literature. These include thickening of the mesentery, hyperechogenicity of intraluminal intestinal contents, abnormalities of the abdominal wall, and poor definition of the intestinal wall. It has been our impression that the above four sonographic findings are generally seen in neonates with more severe necrotizing enterocolitis and may be useful in predicting outcome.

The aim of this study is, firstly, to review a large series of neonates, known to have clinical NEC, to document how frequently the above four sonographic features occur in neonates with necrotizing enterocolitis and, secondly, to determine whether they are predictive of outcome.

We retrospectively analyzed the clinical, radiographic, sonographic, and surgical findings in neonates with necrotizing enterocolitis between 2018 and 2021. The neonates were categorized into two groups based on outcome. Group A included neonates with a favorable outcome defined as successful medical treatment with no surgical intervention. Group B included neonates with an unfavorable outcome defined as failed medical treatment requiring surgery (for acute complications or late strictures) or death because of necrotizing enterocolitis. The sonographic examinations were reviewed with attention to the features of mesenteric thickening, hyperechogenicity of intraluminal intestinal contents, abnormalities of the abdominal wall, and poor definition of the intestinal wall. We then determined the association of these four findings with the two groups.

We included 102 neonates with clinical necrotizing enterocolitis: 45 in group A and 57 in group B. Neonates in group B were born at a significantly earlier gestational age (median 25 weeks, range 22-38 weeks) and had a significantly lower birth weight (median 715.5 g, range 404-3120 g) than those in group A (median age 32 weeks, range 22-39 weeks, p = 0.003; median weight 1190 g, range 480-4500 g, p = 0.002). The four sonographic features were present in both study groups but with different frequency. More importantly, all four were statistically significantly more frequently present in neonates in group B compared to group A: (i) mesenteric thickening, A = 31 (69%), B = 52 (91%), p = 0.007; (ii) hyperechogenicity of intestinal contents, A = 16 (36%), B = 41 (72%), p = 0.0005; (iii) abnormalities of the abdominal wall, A = 11 (24%), B = 35 (61%), p = 0.0004; and (iv) poor definition of the intestinal wall, A = 7 (16%), B = 25 (44%), p = 0.005. Furthermore, the proportion of neonates with more than two signs was greater in group B compared to group A (Z test, p < 0.0001, 95% CI = 0.22-0.61).

The four new sonographic features described were found to occur statistically significantly more frequently in those neonates with an unfavorable outcome (group B) than in those with a favorable outcome (group A). The presence or absence of these signs should be included in the sonographic report to convey the radiologists concern regarding the severity of the disease in every neonate, suspected or known to have necrotizing enterocolitis, as the findings may impact further medical or surgical management.