Which abdominal sign is present in this patient with intestinal infectious disease? Male, 18 years old. Abdominal pain and diarrhea for 2 days, with 7-8 bowel movements daily, scant stool containing mucus, accompanied by tenesmus. Laboratory tests: Stool microscopy shows WBC 20-30/HPF, RBC 5-10/HPF, macrophages 0-2/HPF.