This is probably the single most challenging step in the management of patients with ODS and it takes a lot of experience to do it well.

It is also fair to say that it takes quite a long time and experience in dealing with patients with ODS before a surgeon can develop the skill & knack to determine what is the dominant problem. This involves eliciting physical findings, deciding on the relevance of proctographic findings in a particular patient and decide whether patient's symptoms can be helped and by which line of management.

The situation is complicated by the fact that full extent of contrbuting pathology needs multiple tests to get as near clear picture as possible.