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, Ps- 76/min., BP- 130/80 mm Hg. Abdomen was soft, slightly painful in the right iliac region on deep palpation, the symptoms of the peritoneum irritation were 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/hour. Specify the doctor's further tactics: