Hi thanks for your question.
is diagnosed during EGD that is esphago gastro duodenoscopy and it is confirmed by biopsy
. Yes this very common situation in which squamoous mucosa of esophagus is replaced by gastric mucosa
, commonly occur due GERD
that is gastro intestinal disorder. Yes this is possible that after two negative biopsies the third biopsy turns out to be positive. This purely depends upon the site, from where biopsy is taken and it is possible that during previous 2 procedures biopsy might have not been taken from correct site.
Hope this answers your question