As pilot work examining the relationship between post-operative oxygen consumption and complications in patients having contemporary major abdominal surgery , the investigators need to define and grade the severity of complications. The Post-Operative Morbidity Survey (POMS) is a simple outcome scale designed to record the incidence of clinically important complications - specifically complications likely to keep a patient in hospital. A POMS score performed on Day 5 is likely to be discriminative between patients who are recovering well, and those who are developing complications. POMS is easily performed, has good internal validity and is predictive of a prolonged length of stay. POMS is not a simple additive scale; however patients with POMS score of 1 or greater are highly likely to remain in hospital, whereas those with a score of 0 are likely to be able to go home.