Three organizations certify diagnostic medical sonographers in the United States: ARDMS, ARRT, and CCI. All three are nationally recognized. A sonographer earns a credential from one (or more) of them, and which one comes up depends on the specialty and the path someone took to get there. Here’s how they line up.
| ARDMS | ARRT | CCI | |
|---|---|---|---|
| Full name | American Registry for Diagnostic Medical Sonography | American Registry of Radiologic Technologists | Cardiovascular Credentialing International |
| Main sonography credentials | RDMS, RDCS, RVT, RMSKS | Sonography (S), plus Vascular Sonography and Breast Sonography | RCS (cardiac), RVS (vascular), and others |
| Exam structure | SPI exam + a specialty exam | Sonography credential within the Registered Technologist (R.T.) system | Registry-level exams by specialty |
| Specialty focus | General, cardiac, vascular, musculoskeletal | General sonography, plus vascular and breast | Cardiac and vascular |
| Renewal | MOC: 25 CMEs per 3-year cycle (+ annual steps) | Continuing education within the R.T. system | 36 CEUs per 3-year cycle (registry-level credentials) |
All three are nationally recognized credentialing bodies. None of them is “the real one” and the others fakes — they’re recognized organizations that certify sonographers, and many employers and licensing states accept credentials from more than one. Below is what separates them.
ARDMS: the most common starting point
ARDMS is the body most people mean when they say a sonographer is “registered.” It issues four primary credentials: RDMS (general), RDCS (cardiac), RVT (vascular), and RMSKS (musculoskeletal). There’s also a Midwife Sonography Certificate.
Its exam structure is two-part. You pass the Sonography Principles & Instrumentation (SPI) exam, plus a specialty exam in your area. The vascular credential, for example, is SPI plus the Vascular Technology exam. ARDMS credentials are earned by examination only — there’s no other route.
ARDMS credentials are maintained through a Maintenance of Certification program. Holders complete 25 continuing medical education credits over each three-year period, plus an annual attestation, a renewal fee, and an annual knowledge check.
ARRT: the radiologic technology pathway
ARRT is the American Registry of Radiologic Technologists. It’s best known for certifying X-ray, CT, and MRI technologists — but it also certifies sonographers.
ARRT offers a Sonography (S) credential within its broader Registered Technologist system. It also offers Vascular Sonography and Breast Sonography credentials. People who come to sonography from a radiologic technology background often credential through ARRT because they’re already inside that system.
That’s the practical difference. ARRT is the natural fit for someone whose training is rooted in radiologic technology, where the Sonography credential sits alongside other imaging certifications.
CCI: the cardiovascular specialist
CCI stands for Cardiovascular Credentialing International. As the name suggests, its focus is the heart and blood vessels.
CCI issues the RCS (Registered Cardiac Sonographer) and the RVS (Registered Vascular Specialist), among others. These are registry-level credentials earned by passing CCI’s specialty exams. Sonographers who work in echocardiography labs and vascular labs often hold CCI credentials.
CCI’s registry-level credentials, including RCS and RVS, require 36 continuing education units per three-year renewal cycle. (The first renewal is a fee only, with no CEU requirement that cycle.)
Where the bodies overlap — vascular is the clearest case
The lines aren’t perfectly clean. Vascular sonography is the best example. A vascular sonographer might hold the ARDMS RVT or the CCI RVS. These are distinct credentials from different organizations, but they cover similar ground. Some sonographers hold both.
Cardiac is similar: ARDMS issues the RDCS, and CCI issues the RCS. Both are cardiac credentials. State licensing rules and individual employers often recognize more than one, which is why you’ll see sonographers in the same lab holding credentials from different bodies.
How to think about which body comes up
The body you credential through usually follows from your program and your specialty, not from a free choice made in a vacuum.
- General sonography students most often end up with ARDMS.
- People coming from radiologic technology often credential through ARRT.
- Cardiac and vascular specialists frequently hold CCI credentials — sometimes alongside an ARDMS one.
Where it matters concretely is licensure and hiring. The four states that license sonographers recognize credentials from all three bodies. Many job listings will accept a credential from any of the three for a given role. So the question is less “which is best” and more “which one fits the specialty and program in front of me.”
Key takeaways
- ARDMS, ARRT, and CCI are the three nationally recognized organizations that certify sonographers in the U.S.
- ARDMS is the most common general path: SPI exam plus a specialty exam, with credentials like RDMS, RDCS, RVT, and RMSKS.
- ARRT certifies sonographers through a Sonography (S) credential inside its radiologic technology system — a natural fit for people from that background.
- CCI focuses on cardiac and vascular work, issuing credentials like RCS and RVS.
- The bodies overlap most in vascular and cardiac, where credentials from different organizations cover similar work. Many employers and all four licensing states recognize more than one.