The difference between a certification and a state license, the bodies that issue credentials, how the exams are structured, and what it takes to keep a credential active.
Most sonographer jobs in the United States require a professional certification — but most states do not require a license. Those are two different things, and confusing them is the most common mistake prospective students make about this part of the field. A certification is a voluntary credential earned by passing national exams. A license is government permission to work in a particular state. This chapter separates the two, names the bodies involved, and walks through how a person actually becomes credentialed.
Certification vs. licensure
The distinction is simple once stated plainly.
Certification is issued by a national, non-governmental organization. It is technically voluntary, but in practice most employers require it, so it functions as the entry ticket to the field. A certified sonographer carries letters after their name (for example, RDMS) that signal they passed that body’s exams.
Licensure is issued by a state government and is legally required to work in the states that mandate it. Only a few states do. In every other state, there is no license to hold — certification is what employers look for.
For most people, the practical path is the same regardless of state: graduate from an accredited program, pass the national certification exams, and apply for a state license only if the state requires one.
The credentialing bodies
Three organizations issue most of the credentials sonographers hold. They overlap in some areas and specialize in others.
| Body | Focus | Common credentials |
|---|---|---|
| ARDMS (American Registry for Diagnostic Medical Sonography) | General, OB/GYN, abdominal, cardiac, vascular, musculoskeletal | RDMS, RDCS, RVT, RMSKS |
| CCI (Cardiovascular Credentialing International) | Cardiac and vascular | RCS, RVS, RCCS, RPhS |
| ARRT (American Registry of Radiologic Technologists) | Sonography for those entering from radiologic technology | Sonography (S), Vascular Sonography (VS), Breast Sonography (BS) |
The ARDMS is the largest and most widely recognized for general diagnostic sonography. CCI is the established body on the cardiovascular side, and many echocardiographers and vascular technologists hold a CCI credential, an ARDMS credential, or both. ARRT credentials are common among people who started as radiologic technologists and added sonography. Which body a person tests with usually follows their specialty and their school’s preparation, not a quality difference between the credentials.
How the ARDMS exams work
ARDMS certification is built from two parts, and understanding the structure removes a lot of confusion.
- The SPI exam — Sonography Principles and Instrumentation. This is the physics-and-instrumentation exam that underlies every ARDMS credential. It tests how ultrasound works, how the machine produces an image, and how to use it safely.
- A specialty exam — for example, the abdomen or OB/GYN exam for the RDMS, an adult echocardiography exam for the RDCS, or the vascular exam for the RVT.
A candidate must pass both the SPI and at least one specialty exam, and the two must be passed within a set time window of each other. Passing the SPI plus an abdomen or OB/GYN specialty exam, for instance, earns the RDMS (Registered Diagnostic Medical Sonographer). The same SPI exam paired with an adult echocardiography exam earns the RDCS (Registered Diagnostic Cardiac Sonographer); paired with the vascular exam, the RVT (Registered Vascular Technologist). Many sonographers hold more than one credential over time, but they take the SPI only once.
Becoming certified, step by step
The route to a first credential is consistent:
- Graduate from an accredited program. For the most direct eligibility, this means a CAAHEP-accredited program — see your educational path for the routes in and the coursework behind the exams for what the program covers. Candidates without an accredited program can sometimes qualify through a longer route that combines other education with documented clinical experience.
- Apply to the credentialing body and have eligibility verified.
- Pass the required exams — the SPI plus a specialty exam, for an ARDMS credential.
- Apply for a state license only if the state requires one (see below).
For how degree level connects to all of this, what degree you need for sonography covers the education side that feeds the credential.
State licensure
Most states do not license sonographers at all. A small number do. As of current SDMS tracking, mandatory state licensure applies in New Hampshire, New Mexico, North Dakota, and Oregon, and the specific requirements differ by state — typically a national certification (ARDMS or CCI) plus a state application. A few other states regulate the cardiac or vascular side specifically.
Because this list changes as states pass or amend legislation, the requirement should be confirmed directly with the state’s medical-imaging or radiologic-technology board before relying on it. Sonographers who move between states, or who travel for work, need to check licensure in each state they practice in — a credential is national, but a license is not.
Keeping a credential active
A certification is not permanent. Keeping it requires ongoing upkeep, which is part of advancing your credentials over a career.
For ARDMS credentials, maintenance currently includes continuing medical education (CME) — 30 ARDMS-accepted CME credits over a three-year cycle — along with an annual attestation and an annual renewal fee. Letting a credential lapse means going through a reinstatement process to get it back. The exact CME totals and rules vary by credential and change over time, so the current requirements should be confirmed with the issuing body. CCI and ARRT have their own continuing-education and renewal requirements on similar principles.
This upkeep is the routine background cost of holding a credential. It is modest compared with earning it, but it is ongoing, and it is the reason continuing education is a permanent feature of the job rather than a one-time hurdle.
The bottom line
Certification and licensure are not the same. Certification — from ARDMS credentials or the CCI or ARRT equivalents — is what nearly every employer expects, and it comes from passing national exams after an accredited program. Licensure is a state requirement that applies in only a few states. A sonographer’s practical task is to earn the certification their specialty calls for, keep it active with continuing education, and check whether the state they work in adds a license on top. The credential is the constant; the license is the local variable.
Go deeper on credentials
- The core registries: RDMS, RDCS, and RVT.
- Cardiac and vascular: CCI Credentials.
- The entry exam: The SPI Physics Exam.
- Going further: Multi-Credentialing and ARDMS vs CCI.