1. A 40 year old man underwent total gastrectomy and an esophago jejunostomy procedure for cancer of the stomach. Postoperatively he was maintained on total parenteral nutrition and a continuous naso - enteral drainage. On the 4^th post operative day he developed desaturation in the pulse oximeter which showed a SpO2 of 80%. At the same time he became hypotensive and developed a fever of 104 F. the best investigation to be ordered at this point would be:

1. A urine culture
2. An Ultrasound abdomen
3. A CT scan of the abdomen
4. An X Ray of the chest.

Answer: X Ray chest is the investigation of choice in this patient at this point. The most probable diagnosis is aspiration pneumonia. Given the risk of recent abdominal surgery, a continuous naso enteral drainage tube in situ and the clinical picture of desaturation, fever and hypotension, the most likely diagnosis is aspiration pneumonia.