• upper gastrointestinal symptoms (dysphagia, heartburn, nausea, vomiting) ^c
• lower gastrointestinal symptoms (altered bowel habit, rectal bleeding, pain relieved by defecation) ^c  

Why?

Absence of upper or lower GI symptoms does not rule out disease, but makes it more likely if present

Patient	Target Disorder and Reference Standard	Diagnostic Test	LR+ (95% CI)	Post-test Probability	LR- (95% CI)	Post-test Probability
iron deficiency anaemia c (pre-test probability: 60%)	upper GI disease (gastroscopy)	upper GI symptoms	4.1 (1.8 to 9.6)	86%	0.49 (0.35 to 0.69)	43%
iron deficiency anaemia c (pre-test probability: 30%)	lower GI disease (colonoscopy)	lower GI symptoms	2.1 (1.1 to 4.2)	48%	0.73 (0.52 to 1.0)	24%