 [ Symptoms ] i had 2 endometrial biopsy both came negative do i need another biopsy [ Disease ] i know you believe the problem is sinus drainage but has anyone evaluated you for acid reflux i mention this because people especially those with sinus problems often believe they are constantly coughing up nasal drainage when actually they are coughing up stomach acid you can test this theory yourself by taking an over the counter antacid for a few days to see if it helps the problem a lot of people are not aware stomach acid can move all the way up the esophagus into the posterior portion of the mouth especially when sleeping sometimes acid reflux is actually diagnosed by a dentist who notices substantial erosion of the molars caused by stomach acid if the antacid helps or if you can correlate a pattern of phlegm with food intake you might take up the acid reflux idea with your health care provider during your next visit wishing you well