A 33-year-old man presented to the emergency department with diarrhea and fever for 1 d. The patient developed diarrhea without hematochezia more than 10 times. In addition, he vomited his stomach contents twice without hematemesis, which was accompanied by fever (38.2 °C). The patient had had repeated belching, bloating and diarrhea for 7 years, but the examinations that were performed, including blood tests, abdominal ultrasonography, and computed tomography (CT) examinations, showed no abnormalities. Therefore, it was recommended that the patient undergo gastrointestinal endoscopy after he presented to the outpatient department of gastroenterology in our hospital. According to our center's bowel preparation requirement, the patient was given 2 boxes of regular PEG dissolved in 4 Liters of water for bowel preparation. After adequate bowel preparation, the patient underwent gastrointestinal endoscopy, including both gastroscopy and, on December 30, 2021. We performed the gastroscopy first, followed by the colonoscopy. The results of the gastroscopy showed hiatal hernia, chronic nonatrophic gastritis with erosions, and multiple polyps in the fundus (removed by biopsy forceps). There were 2 gastric polyps (0.2-0.3 cm) in total, all of which were Yamada type II. We used biopsy forceps for cold biopsy, and the pathological diagnosis was fundic gland polyps. The colonoscopy showed no abnormal findings (no congestion, injury, diverticulum, or mass in the colonic mucosa). After the examination, the patient had no complaints of discomfort and left the hospital after receiving the examination results. The patient denied any family history of digestive tract disease. On physical examination, the vital signs were as follows: Body temperature, 39 °C; blood pressure, 114/65 mmHg; heart rate, 115 beats per min; and respiratory rate, 18 breaths per min. No positive signs were observed in the abdomen. The laboratory tests returned the following results: Plasma D-dimer, 21800.00 μg/L; brain natriuretic peptide (BNP), 7330.00 pg/mL; white blood cells, 35.07 × 109/L; C-reactive protein, 142.55 mg/dL; procalcitonin, 78.43 ng/mL; lactic acid, 3.3 mmol/L; creatinine, 391 μmol/L; alanine aminotransferase, 255 U/L; aspartate aminotransferase, 204 U/L; total bile, 72.3 μmol/L; direct bile, 41.1 μmol/L; and γ-glutamyltransferase, 219 U/L. The changes in laboratory examination results are shown in Figure. The abdominal CT examination showed no abnormalities, and lung CT showed a small amount of inflammation in the lower lobe of the left lung.