"e-say" of the dermal matrix - LadyWriter

Mastectomies, now is completing final phase of breast reconstruction after having had tissue expanders in place.  He says s/l "e-say" of the dermal matrix was incised or the "e-say" of the dermal matrix was up against the expander.  He is very good dictator, so is frustrating to me not to figure this out.  Perhaps an acronym?  Thanks!