Emergency department utilization review is the check that decides, while a patient is still in the ED, whether care is medically necessary and which status fits: observation, inpatient, or discharge. It is the first review of the stay, and it shapes every review that follows. This guide covers how it works, how it connects to the rest of the stay, and when hospitals outsource it.
Why Review Starts in the Emergency Department
Medicare's hospital rules require a utilization review plan that covers the medical necessity of admissions, the duration of stays, and professional services, and they state that review of admissions "may be performed before, at, or after hospital admission"[1]. Reviewing before or at admission has a practical advantage: the patient is still there, so a gap in the record can still be corrected. After discharge, the record can only be submitted as it stands.
Real-Time Utilization Management in the ED
Real-time utilization management means the criteria are applied as the decision is made, not afterward. bServed's ED program runs 24/7 from first patient contact: validating medical necessity against InterQual and MCG criteria, assigning the correct admission status, and communicating directly with ED providers. Specialized software integrates with any EMR to surface utilization signals and track authorization status, so reviewers work from the hospital's existing record. See Emergency Department Utilization Review for the full service.
Observation vs. Inpatient Status Review at the Front Door
The status call is the most consequential decision made in the ED. Under the two-midnight rule, inpatient admission is generally supported when the admitting physician expects the patient to need hospital care that crosses two midnights, and observation is the outpatient status used while that decision is still being made. People often search for "23-hour observation." The label is shorthand for a short observation stay. The test is the physician's documented expectation and the patient's clinical picture, not the clock.
For Medicare Advantage, plans have had to follow the two-midnight rule since January 1, 2024, though they can still deny inpatient status for lack of medical necessity[2]. See Observation vs. Inpatient Status Review for the service, and Observation vs. Inpatient Status, Explained for how the rule works.
From the ED Into Medical Necessity Review and Concurrent Review
The first review sets the baseline. From admission, medical necessity review services continue against the payor's criteria, and inpatient concurrent review services re-check the case every day. Authorization is tracked alongside through hospital authorization management, so coverage doesn't lapse mid-stay. If the patient was stabilized and needs further care, see Post Stabilization Review, Explained.
Outsourced Emergency Department Utilization Review
ED admissions don't follow business hours, and many hospitals struggle to staff nights, weekends and holidays with experienced reviewers. Some hospitals outsource ED utilization review for that reason, in whole or in part. Federal rules still put the utilization review plan on the hospital, so involve your compliance team and ask any vendor how its reviewers fit your plan. For the full decision framework, see Outsourced Utilization Management: When It Makes Sense for a Hospital, and for what to ask a vendor, How to Choose a Utilization Management Company.
What It Looks Like in Results
Hospital 3, a rural hospital, started an Emergency Department utilization program from a standing start: admission rate up 30% and payor denials down 40%. Hospital 1 ran ED utilization management alongside behavioral health, recovering $3M+ in cash with a 10X verified ROI. At Hospital 4, the observation rate fell to 30% from 70%. See Hospital Denial Prevention for how a strong first review connects to fewer denials later.