A type 1 excludes note is a pure excludes. It means "not coded here". A type 1 excludes note indicates that the code excluded should never be used at the same time as O00-O08. A type 1 excludes note is for used for when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
continuing pregnancy in multiple gestation after abortion of one fetus or more (
ICD-10-CM Diagnosis Code O31.1
Continuing pregnancy after spontaneous abortion of one fetus or more