A 60-years old male has been operated for carcinoma of caecum and right hemicolectomy has been done. On the fourth post - oprative day, the patient develops fever and pain in the legs.The most important clinical entity one should look for is -: (A) Urinary tract infection, (B) Intravenous line infection, (C) Chest infection, (D) Deep vein thrombosis
Answer is D. Old age and post operative period are risk factor for deep vein thrombosis.