Background <p>Acute nonvariceal upper gastrointestinal bleeding (ANVUGIB) is a common clinical emergency disease with high morbidity and mortality. <i>H. pylori</i> (HP) testing during hospitalization increases the eradication rate of HP and improves the prognosis of patients. The use of stool samples to detect HP has potential clinical application value in ANVUGIB patients, but its accuracy has yet to be verified.</p> Aim <p>To evaluate the accuracy of the monoclonal antibody-based stool antigen test (SAT) and PCR fluorescent probe assay for detecting fecal HP in patients with ANVUGIB.</p> Methods <p>We evaluated the accuracy of monoclonal antibody-based SAT and PCR fluorescent probe assays for fecal HP detection in ANVUGIB patients hospitalized at Beijing Luhe Hospital Affiliated with Capital Medical University between April 2022 and December 2023. Fecal HP nucleic acid detection by nested PCR combined with Sanger sequencing was used as the gold standard.</p> Results <p>In total, 82 patients with ANVUGIB were included. All patients received PPI medication, and 35.4% received antibiotic therapy. Compared with serum HP antibody and fluorescent probe PCR, monoclonal antibody-based SAT has relatively good performance in detecting fecal HP (AUC = 0.841, 0.785 and 0.795, respectively). The combination of these two methods for the detection of HP can improve diagnostic sensitivity but does not improve diagnostic accuracy. The fecal hemoglobin content, use of antibiotics, and duration of PPI use had no significant effect on the accuracy of monoclonal antibody-based SAT or fluorescent probe PCR detection of fecal HP.</p> Conclusion <p>Monoclonal antibody-based SAT has good performance for detecting fecal HP in ANVUGIB patients and is not affected by the fecal hemoglobin content, antibiotic use, or PPI use.</p>