Neurosurgery Coding Alert

Question: I'm confused by the Medicare instructions recommending that a diagnosis from the 800.0-959.9 range be used when billing critical care to show that care was unrelated to the surgery. If the patient underwent surgery because he had a skull fracture, for instance, why use one of these diagnoses if the reason for critical care is probably shock or some other condition? Codes 800.0-959.9 are for injuries, burns, etc. which probably brought the patient in for surgery initially. Rhode Island Subscriber Answer: Section 4822 of the Medicare Carriers Manual, which deals with critical care (99291-99292), states, "critical care services provided during a global surgical period for a seriously injured or burned patient are not considered related to a surgical procedure" and dictates, "Documentation that the critical area was unrelated to the specific anatomic injury or general surgical procedure performed must be submitted. An ICD-9-CM code in the range 800.0-959.9 (except 930-939) which clearly indicates that the critical care was unrelated to the surgery is acceptable documentation." But section 4822 also clarifies that the primary diagnoses should say why you are treating the patient and that codes 800.0-959.9 should be used as a secondary diagnosis. For instance, a trauma victim has a craniotomy with evacuation of hematoma. After surgery, the neurosurgeon provides close monitoring, including a return trip to the hospital for elevated intracranial pressure. The cumulative critical care time, if more than 30 minutes, should be reported with 99291 (Critical care, evaluation and management of the critically ill or critically injured patient; first 30-74 minutes).

Each additional 30 minutes beyond 74 minutes may be claimed with add-on code +99292 ( each additional 30 minutes). Append modifier -24 (Unrelated evaluation and management service by the same physician during a postoperative period) to the critical care code to further demonstrate that the critical care was not related to the craniotomy. Use a primary diagnosis of 852.xx (Subarachnoid, subdural, and extradural hemorrhage, following injury) to indicate the specific aspect of the patient's trauma being treated with the craniotomy (adding fourth and fifth digits to indicate the specific nature of the hemorrhage).

The critical care would be coded to indicate the underlying nature of the injury (for instance, concussion, 850.x; or cerebral contusion, 851.xx) as well as the elevated intracranial pressure (348.2). Quite often there are significant comorbidities, such as shock (958.4) or coma (780.0x), that may also be listed as secondary diagnoses. As long as the different conditions and circumstances are documented for the surgery and the critical care, all carriers should honor the claim.