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American Association of Oral and Maxillofacial Surgeons

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Differences between ICD-9 and ICD-10 Complication of Care Coding

March 19th, 2013

Postoperative complications are defined as unexpected problems that arise from a prior surgery. The most frequent complications are bleeding, infection and protracted pain. Although, not all complications are considered postoperative complications. ICD-10 guidelines state there must be a cause-and-effect relationship between the care provided and the condition and an indication within the documentation that the condition is a complication. Many complications are expected when certain surgeries are performed. These expected complications are also known as postoperative conditions rather than postoperative complications. The surgeon's documentation must clearly indicate that the pain, bleeding, etc. is not normal or routine for the procedure and must clearly associate these symptoms with a post-operative complication. If ever there is any doubt, the coder must query the surgeon.

Like ICD-9-CM, there are three incidence types for a postoperative complication within ICD-10:

  1. Immediate postoperative: 0-2 days following surgery (e.g. bleeding, hemorrhage)
  2. Early postoperative: 2-5 days following surgery (e.g. fever, pneumonia, vomit)
  3. Late postoperative: after 5 days (e.g. wound infection, fistula)

Within the ICD-9 coding system, the majority of complication codes used to classify complications that involve multiple anatomical sites, body systems, or prosthetic devices, implants, and grafts are located within the section titled "Complications of Surgical and Medical Care, NEC" (996-999). Codes describing a particular anatomical site or body system (Specified complications classified elsewhere) can be found located throughout categories 001-799. Examples of OMS related ICD-9 complication codes would be:

  • 525.71- Osseointegration failure of a dental implant
  • 998.6- Persistent postoperative fistula

Unlike ICD-9-CM, the ICD-10-CM code system will include the postoperative complication codes within diagnosis-specific body system chapters. The ICD-10-CM classification system provides significant improvements through greater detailed information and the ability to continue to add new codes in order to stay current with any future advancements in medicine.

Also different from ICD-9-CM, ICD-10-CM provides the ability to identify the patient's encounter. In order to select the appropriate ICD-10-CM code, the provider's documentation will need to specify the encounter for the postoperative complication. A seventh character will be used to identify the patient's encounter of care such as:

  • A Initial encounter
  • D Subsequent encounter
  • S Sequela




Persistent postoperative fistula


Persistent postoperative fistula, initial encounter


Persistent postoperative fistula, subsequent encounter


Persistent postoperative fistula, sequela

For more information on ICD-10-CM and all of its changes, watch the ICD-10-CM and Coding and Billing Workshops pages of the AAOMS web site for information on educational offerings.