Hospitals hear "authorization" and "review" used interchangeably, but they're different checks at different points in a patient's stay. Mixing them up is how a denial gets blamed on the wrong step — and fixed in the wrong place.
Three Reviews, Three Moments
Prior Authorization — Before or at Admission
The payor decides up front whether it will approve the admission or service, based on the clinical information the ordering physician's office or clinic submits. If this step fails, the problem shows up as a denied or delayed admission.
Concurrent Review — During the Stay
While the patient is in the hospital, their clinical status is re-checked against the payor's criteria — in a well-run program, every day. This is what keeps the authorization on file matching the care actually being delivered. If it fails, the problem shows up as denied days in the middle of a stay. See What Is Concurrent Review? for the full definition.
Retrospective Review — After Discharge
The payor reviews the record after the patient has gone home, and can deny or reduce payment if the record doesn't support the stay. By then the documentation can't be improved — it can only be submitted as it stands.
Where Denials Slip Through
Each review fails in a different way, which is why the fix for one doesn't fix the others. A strong prior authorization process does nothing for day four of a stay if nobody re-certifies that the patient still needs to be there. And a clean concurrent record is what a retrospective reviewer will be reading later, so gaps left during the stay become denials after it.
That's why the in-stay step is often the most practical place to catch a problem: while the patient is still in the hospital, a gap in the record can be fixed and sent to the payor before it turns into a denial.
What Medicare's Hospital Rules Already Expect
Continued-stay review isn't an optional extra. Under Medicare's hospital Conditions of Participation, a hospital's utilization review plan must provide for review of the medical necessity of "admissions to the institution," "the duration of stays," and "professional services furnished" for Medicare and Medicaid patients — and review of admissions "may be performed before, at, or after hospital admission"[1].
The same rule requires the hospital's utilization review committee to consult the practitioner responsible for the patient's care, and give them the chance to present their views, before determining that an admission or continued stay is not medically necessary[1]. This is the hospital's own internal review, separate from what a payor does, but it shows the duration of a stay is a standing regulatory expectation, not just a payor preference. The rule doesn't prescribe daily review — how often to check is a program design choice.
Where bServed Fits
bServed's work centers on the middle step: daily concurrent review of every active inpatient and observation case, securing and maintaining authorization during the stay, and building clean appeals when a denial does occur. See Concurrent Reviews and Securing Authorizations for how that's structured.
At Hospital 4, daily medical necessity review using evidence-based clinical criteria cut concurrent denials by 40%.
For the broader denial-prevention workflow, see How Hospitals Reduce Denial Rates.