H. pylori stool antigen test checks for H. pylori proteins in a stool sample.
It’s one of the main non-invasive ways to diagnose or confirm clearance of the infection.
Has a high — sensitivity and specificity both around 90-95% when done correctly.
Stop PPIs (omeprazole, esomeprazole, etc.) for 1-2 weeks** before testing
Stop antibiotics and bismuth for 4 weeks before testing
H2 blockers (like famotidine) are generally okay.
Use:
Initial diagnosis (alternative to urea breath test or endoscopy biopsy).
Test of cure— confirming eradication after treatment, usually done 4+ weeks after finishing antibiotics and still off PPIs.
May be used as a screening test for the
Urea breath test: similarly accurate, sometimes preferred, but needs special equipment/logistics
Blood antibody test: NOT recommended for confirming cure — antibodies can stay positive for months to years even after successful treatment, since it just shows past exposure
Endoscopy with biopsy: more invasive, used when endoscopy is already needed for other reasons (ulcers, bleeding, alarm symptoms)