When you should use the 79 modifier for post-operative issues. Although many providers are tempted to use the 78 modifier for post-operative complications, they may be wrong--and could face a denial. You should use modifier 79 to report an unrelated procedure or service by the same physician during the postoperative period, says Complications such as infection, hemorrhage or dehiscence are all complications of the original surgery. They "may require additional services, but are still related to the original surgery," says Lewis. So you should be very careful about using the 79 modifier for complications in the postoperative period. It may be "stretching the definition too far." Medicare won't pay for postoperative complications unless they require a return to the operating room, notes In that case, say experts, you should use the 78 modifier. But because the 78 modifier specifies a return to the OR, you shouldn't use it for bedside or office services. "Treatment for post-op complications that do not require a return to the OR may be billed to commercial payers when contractually allowed," Center adds. So if you're billing a non-Medicare payor for postoperative complications that Classic scenario: For example: