Observation Status
A Medicare outpatient classification for short hospital stays where patients receive monitoring and treatment without being formally admitted as inpatients, billed under Medicare Part B rather than Part A.
Observation Status is a term from U.S. hospital cost and quality reporting — the field that produces the CMS Hospital Compare program, the Medicare Inpatient Payment files, and the patient-facing tools built on top of them. The definition below covers what the term means in CMS files, what it does not mean, and how it interacts with the other measures CMS publishes. On the LakeQuality value rubric, Observation Status is one of the inputs (directly or indirectly) to the combined cost-and-quality grade. Understanding how the term is computed at CMS — what counts and what does not — is part of reading hospital pages defensibly.
Each hospital page on LakeQuality surfaces the specific Observation Status value for that facility (when CMS reports one), so the general definition here translates into a concrete data point on the per-hospital pages you actually use.
How It Works
Observation status is an outpatient designation for hospital stays where the physician is evaluating whether the patient needs inpatient admission or can be safely discharged, typically for monitoring of chest pain, syncope, dehydration, or exacerbation of chronic conditions. Under the Two-Midnight Rule effective October 1, 2013, stays not expected to cross two midnights are generally billed as observation. Observation is paid under the Outpatient Prospective Payment System (OPPS) as APC 8011 (Comprehensive Observation Services) at approximately $2,300-$2,500 per stay for Medicare, or separately-billed observation hours (G0378) plus other billable services. The financial consequences for patients can be severe. Unlike inpatient stays with a single Part A deductible ($1,676 in 2025) covering all services for days 1-60, observation stays are billed under Part B with a $257 annual deductible plus 20% coinsurance on every outpatient service: observation hours, each medication, labs, imaging, physician services. A 48-hour observation stay can produce patient out-of-pocket costs of $1,500-$4,000+, often exceeding the equivalent inpatient deductible. Observation stays also do not satisfy the three-day qualifying inpatient stay required for Medicare SNF coverage, meaning patients who need post-discharge rehabilitation after an observation stay must pay out of pocket (typically $500-$800 per day for SNF care in 2024-2025). The "NOTICE Act" of 2015 requires hospitals to provide patients on observation more than 24 hours with a Medicare Outpatient Observation Notice (MOON) within 36 hours of the observation designation, so patients know their classification. Observation use has grown substantially: approximately 2.5 million Medicare observation stays annually by 2024, up from 800,000 in 2006. Hospitals and MA plans frequently dispute observation vs. inpatient determinations, and Medicare Advantage aggressive observation use was a major driver of the 2024 rule requiring MA plans to follow the Two-Midnight Rule.
Related Terms
- Two-Midnight Rule, A Medicare policy effective October 1, 2013 that presumptively classifies hospital stays spanning two midnights as inpatient and stays less than two midnights as outpatient observation, with significant payment and patient cost-sharing consequences.
- Medicare Advantage (Part C), A private health insurance alternative to traditional Medicare that covers Parts A and B and usually Part D, enrolling over half of all Medicare beneficiaries as of 2024.
- Centers for Medicare & Medicaid Services (CMS), The federal agency within the Department of Health and Human Services that administers Medicare, Medicaid, CHIP, and the ACA marketplace, setting hospital payment rates, quality standards, and the data that HospitalCostData uses.
- Inpatient Prospective Payment System (IPPS), Medicare's payment system for acute-care hospital inpatient stays, paying a fixed amount per MS-DRG rather than reimbursing each individual service.
- UB-04 Claim Form, The standardized hospital billing form (also called CMS-1450) used by hospitals and other institutional providers to bill Medicare, Medicaid, and commercial insurers for facility services.
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About This Definition
This definition is part of the HospitalCostData Hospital Pricing Glossary, 47 terms explaining hospital costs, quality ratings, and healthcare billing. Written for patients, journalists, researchers, and healthcare professionals.