Imaging modality		Positive likelihood ratio	Negative likelihood ratio	Negative appendectomy prevalence (%)*	Length of emergency department stay (minutes)	Positive findings	Representative fair price†
Ultrasonography						Increased pelvic fluid, noncompressible tubular structure > 6 mm	$150
	Point-of-care	10.4	0.4	8.1‡	154
	Experienced sonographer	36.8	0.2		141
	Novice sonographer	6.9	0.5		170
	Formal	93.8	0.4		288
Computed tomography				4.5	487§	Appendix diameter > 6 mm with surrounding inflammation	$325 to $525
	Noncontrast	6.4	0.12
	Dual contrast	8.3	0
	Rectal contrast	18.6	0.07
Magnetic resonance imaging		19.8	0.05	—	—	Increased pelvic fluid, lymphadenopathy, terminal ileum swelling	$650