It's all about the relational structure (or lack thereof) of your database. I hope the books you read gave some good instruction on relational design, because without it a database is more like a spreadsheet (but slower).
The basic rule of reports is to do the report in the table which actually has all the data (if possible), or "child to parent" access to it. But in this case that may not be possible. It seems that the base table here would be Procedures, which would have access to its "parent" Operations, which would have access to its parent(s) Surgeon (multiple surgeons per op?).
Complications would be children of a Procedure (always?). But any given Procedure may or may not have Complications (hopefully not).
So, the question arises, how many fields do you need from Complications. If only a few, you could possibly gather them, via the List() function, or via a Custom Function (requires FileMaker Pro Advanced to implement).
This is all doable, providing you have a decent relational structure. Many people do not think that is important at first. You can get away with inadequate design when just putting data fields on layouts. But then, when you get to reports (or any kind of real automation), you run into roadblocks. Heck, you may run into a few anyway, but only the "necessary" ones :-]
The main database structure is:
Patient (_kp patient)
Tumour (_kp tumour, _kf patient)
Treatment (_kp treatment, _kf tumour)
Follow up (_kp follow up, _kf patient)
This was set-up so that a particular patient could have more than 1 tumour with more than 1 treatment for that tumour and multiple follow ups.
For each of the look ups variables, they are in a look up table; the lookup table has 2 fields - description and code, when I am running my report, I can pull the description if I want to use it locally or use the code field instead if it is for uploading to government. These have a relationship set and are in the look up values list.
SURGEON_GMC_CODE field is linked to the _lookup surgeon gmc code table for the lookup etc
There are about 20 surgeons and 20 procedures that we record for the purposes of this.