aHR	adjusted hazard ratio
anti-TNF	Anti-tumour necrosis factor
aOR	adjusted odds ratio
AUC	area under the curve
AUROC	area under the receiver operating characteristic curve
B-mode	brightness mode
BUSS	Bowel Ultrasound Score
BWCE	bowel-wall contrast enhancement
BWF	bowel-wall flow
BWP	bowel-wall pattern
BWS	bowel-wall stratification
BWT	bowel-wall thickness
CD	Crohn’s disease
CDS	colour Doppler signal
CEUS	contrast-enhanced ultrasonography
CI	confidence interval
CRP	C-reactive protein
df	degrees of freedom
DOR	diagnostic odds ratio
FC	fecal calprotectin
FN	false negative
FP	false positive
FPR	false-positive rate
H-FEI	harmonic flash-echo imaging
HR	hazard ratio
IBUS-SAS	International Bowel Ultrasound Segmental Activity Score
ICA	ileocolonic anastomosis
i-fat	inflammatory mesenteric fat
IQR	interquartile range
IUS	intestinal ultrasonography
LR+	positive likelihood ratio
LR−	negative likelihood ratio
mo	months
MRI	magnetic resonance imaging
N/n	number
N/A	not applicable
NR	not reported
OCBS	oral-contrast bowel sonography
OCUS	oral-contrast ultrasonography
OR	odds ratio
POCER	Postoperative Crohn’s Endoscopic Recurrence trial
PRISMA-DTA	Preferred Reporting Items for Systematic Reviews and Meta-Analyses of Diagnostic Test Accuracy Studies
PROSPERO	International Prospective Register of Systematic Reviews
QUIPS	Quality In Prognosis Studies
QUADAS-2	Quality Assessment of Diagnostic Accuracy Studies 2
RE	random-effects
ROC	receiver operating characteristic
SD	standard deviation
Se	sensitivity
SICUS	small intestine contrast ultrasonography
Simple-US	Simple Ultrasound Score
Sp	specificity
SROC	summary receiver operating characteristic
SUS-CD	Simple Ultrasound Score for Crohn’s Disease
TA-IUS	transabdominal intestinal ultrasonography
TN	true negative
TP	true positive
y	years