AJR: Radiographic scale helps predict NEC severity in infants

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The use of  (the Duke abdominal assessment scale (DAAS), a radiographic scale, can help physicians predict disease severity in infants with necrotizing enterocolitis (NEC), according to a study published in the November issue of the American Journal of Roentgenology.

Caroline L. Hollingsworth, MD, from the department of radiology at Duke University Medical Center in Durham, N.C., and colleagues wrote that the DAAS “provides a standardized 10-point radiographic scale that increases with disease severity. For every one point increase in the DAAS score, patients are more likely to have severe disease and more likely to need a surgical intervention."

According to the authors, NEC is one of the most common causes of surgical intervention in the premature infant and radiography is an important component in the assessment of infants suspected of having NEC. Earlier studies have reported that mortality rates for infants with advanced NEC can more than double when pneumoperitoneum is present, the authors said, so the use of a standardized abdominal radiography scale could be of value in the early detection of patients at risk for developing severe NEC.

The authors performed a controlled study of 43 patients who underwent at least two, two-view abdominal radiographic series within 48 hours of surgical intervention for NEC. The control group included 86 patients with suspected NEC who did not undergo surgery for NEC.

DAAS scores were assessed by one radiologist with 20 years of experience and another radiologist with six years of experience in pediatric radiology. Both radiologists had two years of experience using the DAAS.

In the evaluation of the first study group's radiographic series, the researchers reported that 26 of the 43 patients had DAAS scores of seven or greater, while three of the 86 patients in the control group had DAAS scores of seven or greater. In the study group, seven patients were scored as nine (portal venous gas), nine were scored as eight (highly probable or definite pneumatosis) and 10 were scored as seven (fixed, dilated loops).

The evaluation of the second follow up radiographic series in the study group showed that 40 of the 43 patients had DAAS scores of seven or greater—20 progressing to pneumoperitoneum, while the other 20 had scores of seven, eight and nine.

The investigators used logistic regression to assess the association between severe NEC and DAAS score. The 129 patients in the study and control groups were included in the model and, according to the authors, for every one point increase in the score “patients were statistically significantly more likely to have severe NEC, as indicated by the need for surgical intervention.”

Of those patients in the study group, 23 underwent resection of gangrenous bowel, while 12 underwent peritoneal drain placement. NEC totalis was found during abdominal exploration in five patients, which made those cases inoperable, the authors wrote.

The authors concluded that the DAAS scale “can be a useful tool in the setting of NEC because the scale increases with disease severity when using surgical intervention for complications of NEC as a surrogate for severe disease.”  And since the logistic regression analysis showed that every one point increase in DAAS score is significantly associated with an increased risk of severe NEC, radiographic findings corresponding to higher DAAS scores indicate an infant is more likely to have severe NEC.