Table 4.

Signs looked for on US

Signs looked for with ultrasound, n = 118	Evaluated by a n [%]	Reported association with adverse outcome b
Focal fluid collections	111 [94%]	A[16, 37, 57]
Turbid/echoic fluid	109 [92%]	A[19, 37, 54, 57], B[16]
Portal venous gas	109 [92%]	B[16]
Bowel wall thickening	107 [91%]	A[37, 57], B[16]
Pneumatosis intestinalis/intramural gas	101 [86%]	B[16]
Clear/anechoic fluid	101 [86%]
Pneumoperitoneum/free gas	93 [79%]	A[16]
Intestinal motility	92 [78%]	A[37], B[33]
Bowel wall perfusion (with Doppler)	76 [64%]	B[16, 33, 35]
Mesenteric circulation (with Doppler)	68 [58%]
Bowel wall thinning	67 [57%]	B[35]

^a)Percentages refer to respondents from hospitals where ultrasound is done for NEC, n = 118 respondents: 41 neonatologists, 41 paediatric surgeons, and 42 radiologists. Six held double specialties in neonatology and paediatric surgery. No significant differences between specialties were observed. ^b) Adverse outcome such as need for surgical intervention or death, associations as reported in the literature. References within square brackets

A. Independently associated with adverse outcome

B. Associated with adverse outcome if present together with other signs

As for intestinal motility and bowel wall perfusion, reported associations refer to reduced motility and absent perfusion

Signs stated in free text were echogenicity of the intestinal wall, bowel motility, amount and location of fluid collections, and “zebra sign”, all of which are thought to be covered by the response alternatives above