Clinical features

Look for ^c

• macroscopically bloody stool
• severe abdominal pain
• vomiting 

Why?

Severe abdominal pain or vomiting makes inflammatory bowel disease less likely

Patient	Target Disorder and Reference Standard	Diagnostic Test	LR+ (95% CI)	Post-test Probability	LR- (95% CI)	Post-test Probability
colitis undergoing sigmoidoscopy c (pre-test probability: 50%)	inflammatory bowel disease ( stool culture, histology, follow-up )	macroscopically bloody stool	1.8 (1.2 to 2.5)	64%	0.23 (0.10 to 0.53)	18%
		severe abdominal pain	0.26 (0.073 to 0.95)	20%	1.2 (0.99 to 1.5)	54%
		vomiting	0.34 (0.14 to 0.82)	25%	1.5 (1.0 to 1.8)	60%