A 52 year old man presents with a 2 day history of left sided lower abdominal pain, diarrhoea, nausea and urinary frequency. He has a past medical history of Type 2 Diabetes Mellitus, Diverticulosis and Gastro-Oesophageal Reflux Disease. On examination, his temperature is 38.1oC and he is haemodynamically stable. His urine dipstick is clear. He has palpable distention and tenderness in the left iliac fossa and rectal examination reveals peri-rectal fullness.
Based on the likely diagnosis, what is the most appropriate initial management option?