There are several synonyms for the term "due to operation" that can be used interchangeably. One common term is "as a result of surgery," which is often used to describe the reason for a medical outcome or change in condition. Another synonym is "because of a procedure," which emphasizes the action taken to remedy a problem or address a health concern. "Following surgery" is also a suitable replacement, as it emphasizes the temporal relationship between the operation and any subsequent effects. Other similar terms include "post-operation" and "after undergoing a surgical procedure," both of which convey the same basic meaning as "due to operation".