Pardon my ignorance but........
Hello,
I cannot give you exact measurements but the way I have always remembered distal from proximal is Distal=Distant (they bypass more intestine) And proximal=Close proximity(they bypass less). Just a silly way I lept the two straight in my head. Sorry I could not be more help. Type in Distal vs Proximal into a web searcher like Webcrawler and I am certain you can get your question answered. Tracy