A summary of statistical analysis of key BUS and AXR findings derived from previous meta-analyses, obtaining a range of data without further statistical analysis
| Statistical significance of key bowel ultrasound findings* | ||||||
| BUS finding | For the diagnosis of NEC | Eventual need for surgery or death | ||||
| Sens (%)28 | Spec (%)28 | AXR correlate | AXR Sens (%)10 | AXR Spec (%)10 | OR15 16 | |
| Early findings | ||||||
| Increased bowel perfusion | – | – | None. | – | – | NSS |
| Simple (anechoic) ascites | 45 | 92 | Bowel loops displaced centrally if large volume. | – | – | NSS |
| Dilated bowel | – | – | Dilated bowel. | – | – | 3.50–3.59 |
| Intermediate findings | ||||||
| Portal venous gas | 27 | 94 | PVG. | 13 | 100 | NSS |
| Pneumatosis intestinalis | 48 | 91 | Pneumatosis. | 44 | 100 | 2.01–2.23 |
| Bowel wall thickening | 31 | 67 | Enlarged mucosal folds. | – | – | 3.7–4.74 |
| Increased bowel echogenicity | – | – | None. | – | – | 8.58 |
| Late findings | ||||||
| Bowel wall thinning | 22 | 96 | None. | – | – | 7.11–7.97 |
| Absent peristalsis | 3 | 95 | Stationary patulous bowel loops on serial exams. | – | – | 8.19–10.68 |
| Absent bowel perfusion | – | – | None. | – | – | 6.08–6.99 |
| Focal fluid collections | 19 | 98 | None. | – | – | 15.37–17.92 |
| Complex (echogenic) ascites | – | – | None. | – | – | 11.28 |
| Pneumoperitoneum | 27 | 94 | Pneumoperitoneum. | 52 | 92 | 8.25–9.63 |
*Data reported are a compilation of the currently known sensitivity and specificity as reported in the referenced meta-analyses. It should be noted that not all studies included reported data on all categories. Further research is needed in this area to elucidate the most accurate data.
AXR, abdominal radiograph; BUS, bowel ultrasound; NEC, necrotising enterocolitis; NSS, not statistically significant; PVG, portal venous gas.