A 75-year-old male patient complains of slight pain in the right iliac region. The abdominal pain arose 6 days ago and was accompanied by nausea. Surgical examination revealed moist tongue, heart rate - 76 bpm. BP -130/80 mm Hg. Abdomen is soft, slightly painful in the right iliac region on deep palpation, the symptoms of the peritoneum irritation are doubtful. In blood: RBCs - 4,0 × 1012/l, Hb-135 g/l, WBCs - 9,5 × 109/l, stab neutrophils - 5%, segmentonuclear - 52%, lymphocytes -38%, monocytes - 5%, ESR - 20 mm/h. Specify the doctors further tactics: