Yellow mucous down back of throat 4 weeks after sinus surgery (including sphenoid) and septoplasty. Is this normal?

Sounds like you are doing all the correct things after your operation. By 4 weeks most people's discharge settles down so this is a little unusual. Someone should have a look inside the nose with a scope and see what the problem is as one or some of the sinuses may have not settled down. It sounds like a course of antibiotics would be a good idea.

Hi funkymunkey123, Yellow discharge and pain are actually signs of persistent infection of the nose and sinus, which will require antibiotic treatment. The saline rinse is fine, but you should consult with your surgeon as perhaps you should be taking antibiotics as well, especially because you are using steroid nasal spray.