The ARDMS Obstetrics & Gynecology examination is approximately 170 questions in three hours — multiple-choice, hotspot, and PACSim items — scored on a 300-to-700 point scale where 555 passes, at a published fee of $275 including the $100 non-refundable processing fee. It is one of two examinations behind the RDMS credential with the OB/GYN specialty: the SPI must also be passed within five years, in either order, and ARDMS re-evaluates the examination through periodic practice analyses to keep it matched to the specialty. PassProfessor’s companion practice program is in the works.
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The OB/GYN specialty is really two specialties sharing a probe: the gynecologic examination, organized by the cycle and the lifespan, and the obstetric examination, organized by the trimester and the survey. The registry examination tests both, plus the protocols and physics underneath them, and it tests them partly through item types — hotspots and simulated cases — that punish purely verbal knowledge. This guide does the planning work in the open: the two-examination credential structure, the prerequisite pathways and application mechanics, the format and its advanced item types, a content-area walk with a preparation method for each, the scoring scale, fees and retakes, and a study plan that sequences gynecology, the trimesters, and the supporting content the way the examination weights a candidate’s day. Everything factual comes from ARDMS’s published materials recorded in this guide’s internal sources section.
Which examination is this?
This guide covers the Obstetrics & Gynecology (OB/GYN) specialty examination administered by the American Registry for Diagnostic Medical Sonography (ARDMS) for the Registered Diagnostic Medical Sonographer (RDMS) credential — the sonographer-level examination. Physicians reach the same ARDMS examinations through ARDMS’s companion council arrangements, with their own application destination; this guide is written for the RDMS candidate. It does not cover the SPI examination except as the OB/GYN’s required partner, nor ARDMS’s other specialty examinations, nor the separate Fetal Echocardiography credential.
The real exam at a glance
| Fact of record | Detail |
|---|---|
| Credential | RDMS with the OB/GYN specialty — ARDMS |
| Partner examination | SPI (Sonography Principles and Instrumentation); both passed within five years of each other, either order |
| Format | Approximately 170 questions, 3 hours including a five-minute survey; multiple-choice, hotspot, and PACSim questions |
| Scoring | Point scale 300 to 700; 555 or better passes; not a percentage |
| Content | Female reproductive system; fetus in the first, second, and third trimesters; protocols and procedures; physics and instrumentation |
| Eligibility | One of ARDMS’s published prerequisite pathways (education + clinical experience); a Clinical Verification form may form part of the application, as ARDMS describes |
| Examination fee | $275 including the $100 non-refundable processing fee; +$50 at test centers outside the U.S., Canada, and Mexico |
| Retakes | Reapply after 3 days; 60-day wait before retaking |
| Currency | ARDMS maintains the examination through periodic practice analyses (job task analyses) of the specialty |
The two-examination structure
The RDMS with the OB/GYN specialty is earned by passing two examinations — this specialty examination and the SPI — within five years of each other, in either order. The structure mirrors the Abdomen specialty’s, and it drives the same calendar discipline: the first pass starts a five-year clock for the second; the 60-day retake wait runs inside that clock; and sequencing is a strategic choice. Candidates deep in OB/GYN clinical work often bank the specialty first while their survey skills are at working sharpness, then take the SPI; candidates from a physics-strong background reverse the order. Either is defensible — what is not defensible is letting an early pass drift toward its five-year horizon while the partner examination waits for a convenient season.
Who can take this exam — prerequisites and application
ARDMS admits candidates through published prerequisite pathways combining sonography education with clinical sonography experience. The most direct is graduation from a CAAHEP-accredited sonography program; other pathways combine degrees, related credentials, and documented clinical experience in proportions ARDMS’s prerequisite document defines. For this specialty, ARDMS’s application process also works with a Clinical Verification (CV) form: if a current OB/GYN CV form is already on file, the application and examination fee are what you submit; if not, the application, the fee, and a current CV form go together, as ARDMS’s application materials describe. Read the current prerequisite and application documents before paying anything: the $100 processing portion of the $275 fee is non-refundable, and eligibility or documentation errors are paid for by the candidate, not by ARDMS.
Format in detail — multiple choice, hotspot, and PACSim
Approximately 170 questions in three hours, including a five-minute survey. Three item families share the sitting. Multiple-choice items carry the knowledge base. Hotspot questions present an individual image and ask you to answer by marking directly on it — the practical sonography skill of locating a structure or finding, assessed literally. PACSim questions are ARDMS’s simulated clinical scenarios: case material worked through items that behave like a clinical encounter rather than a quiz. ARDMS publishes familiarization material for its advanced item types; use it before test day, because both hotspot and PACSim mechanics are simple but specific, and the time to learn an interface is not inside a scored sitting.
The study implication is the same one the Abdomen examination teaches, sharpened: this specialty’s knowledge is unusually visual. Trimester content is image content — a candidate preparing from text alone is preparing for a different examination from the one ARDMS delivers.
The content areas, one by one
ARDMS summarizes the examination as assessing the knowledge, skills, and abilities in the areas of the female reproductive system and the fetus in the first, second, and third trimesters, with all questions falling under the domains and subdomains of the published OB content outline — the document ARDMS directs candidates to review, and the one this walk-through follows in structure.
Gynecology — pelvic anatomy and physiology
The uterus in its layers and positions; the endometrium across the menstrual cycle and after menopause; the ovaries and their cyclical structures; the adnexa; the cervix; and the supporting pelvic anatomy — in transabdominal and transvaginal approaches. Layered over the normal: the specialty’s gynecologic pathology, from leiomyomas and endometrial conditions to ovarian cysts and masses, pelvic infection, and the sonographic evaluation of abnormal bleeding, pain, and palpable findings. Preparation method: anchor everything to the cycle and the life stage. The same measurement is normal, expected, or alarming depending on both, and the examination’s gynecology items are built on that dependence. Learn the normal pelvis at each phase first; pathology then reads as deviation, not as a second subject.
Obstetrics — the first trimester
Early pregnancy assessment: the gestational sac and its contents in sequence; embryonic development and early anatomy; dating by first-trimester measurement; cardiac activity and viability; the failing pregnancy and its appearances; ectopic pregnancy — its risk factors, its sonographic signs, and the indirect evidence when the ectopic itself is not seen; multiple gestation and the early determination of chorionicity and amnionicity; and trophoblastic disease. Preparation method: learn the developmental sequence as a timeline with measurements attached — what should be visible, at what size and age — because first-trimester items are timeline items: the finding is normal or diagnostic depending on where on the timeline it sits.
Obstetrics — the second and third trimesters
The specialty’s largest territory. The standard fetal anatomy survey, system by system — head and brain, face, spine, thorax and heart, abdomen and abdominal wall, urinary tract, skeleton — with the required views and their normal appearances. Biometry and growth: the standard measurements, their combinations, growth patterns, and the recognition of growth restriction and macrosomia. Amniotic fluid assessment. The placenta: location, previa, accreta-spectrum risk signs, abruption, and grading. The cervix and preterm risk. Fetal wellbeing: movement, tone, breathing, and the biophysical profile. Anomalies across systems and their characteristic findings. Multiple gestation and its complications, including twin-to-twin transfusion. Maternal conditions intersecting the pregnancy. Preparation method: survey-first, as with the Abdomen’s normal-first rule, but doubled — the survey must be reflexive in both its views and its measurements, because the anomaly, growth, and wellbeing items all measure the candidate against the normal survey’s standard. Study anomalies attached to the system and view where they appear, not as a separate catalogue.
Protocols and procedures
How the specialty’s examinations are performed: the components of complete gynecologic and obstetric examinations; measurement protocols and technique; Doppler in OB/GYN practice — where it is used, what it shows, and its safety discipline; the indications and limitations of the specialty’s examinations; and the documentation and communication the practice requires. Preparation method: rehearse the complete protocols as checklists until the components are automatic, and study Doppler as applied judgment — indication, waveform, interpretation — rather than as physics alone.
Physics and instrumentation
The applied physics of this specialty’s imaging: transducer selection, including the transvaginal approach and its technique; image optimization in pelvic and obstetric scanning; artifacts specific to these examinations; and the safety framework for obstetric scanning, including output display and the discipline of keeping exposure as low as reasonably achievable in examinations of a fetus. Preparation method: attach every principle to the OB/GYN situation that tests it — the artifact in the pelvis, the output question in the pregnancy — rather than reviewing SPI content generically.
How scoring works
Performance converts to a point score from 300 to 700, and 555 or better passes. The scale is not a percentage and is not a curve: the standard is fixed against the examination’s content, and ARDMS holds it constant across administrations through its examination development process, which periodically re-analyzes the specialty’s practice — the OB/GYN examination’s content outline rests on those practice analyses, and ARDMS directs candidates to the current outline as the authority on what is covered. Results mechanics follow the ARDMS pattern: a score report at the test center and posting to the candidate’s portal. For planning, treat the number as a gap measurement: a near miss identifies a preparation problem measured in content areas, and the 60-day retake wait plus the five-year SPI window define the time available to fix it.
Fees and retakes in full
The examination fee is $275, which includes a $100 non-refundable processing fee; candidates testing at centers outside the United States, Canada, and Mexico pay an additional $50. The fee purchases one attempt. If you do not pass, you may reapply after three days, but you must wait 60 days before retaking the examination. Those two rules together set the retake rhythm: the application machinery restarts almost immediately, the sitting itself waits two months, and the SPI window runs throughout. Candidates who hold a current Clinical Verification form on file resubmit the application and fee only, on the terms ARDMS publishes. After the credential is earned, it is maintained under ARDMS’s renewal and continuing education requirements, which apply to the RDMS as a whole rather than to this specialty separately.
A study plan that follows the examination
Phase 1 — Fix the frame (week 1). Confirm your prerequisite pathway, your CV-form status, and your SPI position and five-year deadline. Read the current OB content outline end to end once, slowly.
Phase 2 — Gynecology on its calendar (weeks 2–4). The normal pelvis by cycle phase and life stage, both approaches; then the gynecologic pathology as deviation from that normal. Checklists for the complete pelvic examination until automatic.
Phase 3 — First trimester as a timeline (weeks 4–6). The developmental sequence with its measurements; viability, ectopic, and multiplicity as timeline judgements. Image drills throughout — identification on real images, not diagrams.
Phase 4 — The survey and the late pregnancy (weeks 6–10). The largest block, matching the content’s weight: the normal anatomy survey to reflex standard, system by system; biometry and growth; fluid, placenta, cervix; wellbeing assessment; then anomalies attached to their systems and views, and multiple gestation’s complications.
Phase 5 — The frame: protocols and physics (weeks 9–11, overlapping). Protocols as checklists, Doppler as applied judgement, and obstetric scanning safety as doctrine. Practise hotspot-style location on images and work scenario sets in PACSim’s spirit: case first, questions after.
Phase 6 — Full sittings (final two weeks). Timed practice at the real shape — approximately 170 questions, three hours, image-heavy — reviewed by content area, with the final days reserved for logistics and ARDMS’s advanced-item familiarization material.
What makes this test demanding
The OB/GYN examination demands simultaneity: two patients, two specialties’ worth of content, and three item formats in one sitting. Its anomaly content is parasitic on normal knowledge in a way that punishes catalogue-style study, its first-trimester content is timeline-exact, and its safety content carries an ethical weight the items do not let you treat as trivia — output discipline in obstetric scanning is examined because it matters. The candidates who do well are the ones whose normal survey is a reflex, whose image knowledge is genuinely image knowledge, and whose calendar — prerequisites, CV form, SPI window — was managed before it could manage them.
How the content areas connect
This examination’s areas are often studied as five separate shelves — gynecology, the early pregnancy, the later pregnancy, protocols, physics — and the sitting does not respect the shelves. A later-pregnancy item about growth quietly assumes the first-trimester timeline, because dating established early is the reference every later measurement is judged against; misjudge the foundation and the growth judgement built on it fails with it. A gynecology item about abnormal bleeding assumes the cycle-anchored normal described above, and then assumes protocol knowledge as well: which approach, which views, which measurements make the examination complete rather than merely performed. A wellbeing item assumes the survey, the fluid assessment, and the Doppler judgement together, in the proportions a real case would demand them.
The practical consequence is that revision should end integrated even though learning begins separated. In the final phase of preparation, work in mixed sets that move between the pelvis and the pregnancy, between a measurement question and a protocol question, without warning — because that is the sitting’s actual texture. When you miss an item in a mixed set, classify the miss by the connection that failed, not only by the area it came from. Was the normal reference itself shaky? Was the timeline misplaced, so that a correct finding was judged against the wrong stage? Was the image read correctly but the protocol consequence missed? Those are three different repairs, aimed at three different habits, and a candidate who lumps them together as a single weak area will re-study a great deal of material that was never the problem.
There is also a deliberate, constructive way to exploit the connections while you are still learning. Study each anomaly twice: once where it belongs, attached to its system and its survey view, and once from the measurement or finding that first betrays it, working backwards to the system it lives in. Study each gynecologic condition twice as well: once against the cycle phase in which it presents most characteristically, and once against the life stage that changes its significance. That double pass is slower per topic and faster per examination, because the items approach conditions from both directions and your knowledge will already be organized both ways.
A note on sequencing the two halves deserves emphasis before the mistakes, because it governs the plan’s shape. Gynecology and obstetrics share anatomy, approaches, and scanning habits, but they organize time differently — one by the cycle and the life stage, the other by the developmental timeline — and candidates who interleave them too early often find the two calendars blurring into each other. The plan therefore builds each half on its own organizing principle first, and only then mixes them, in the integrated revision described above. Learn each clock separately; then practise telling both times at once, which is what the sitting, and indeed the specialty’s working week, actually requires.
Common preparation mistakes
The first mistake is catalogue study of anomalies: long lists of conditions, each with a memorized description, detached from the survey views in which they appear. It produces a recognizable failure mode — the candidate can describe a condition fluently and cannot find it on an image, or finds a finding and cannot name what produces it. The repair is the one the content walk above prescribes: no anomaly is finished until it is attached to its system, its view, and the normal appearance it departs from.
The second mistake is preparing the obstetric content without its timeline discipline. Early pregnancy is a sequence in which the same finding changes meaning with timing and measurement, and later pregnancy judges growth and wellbeing against references that only make sense in sequence. Candidates who learn the trimesters as three unrelated blocks lose exactly the items that test the joins between them: dating carried forward, development carried forward, a pregnancy’s own history carried forward. Keep a single timeline document through your whole preparation and add to it at every phase, so the joins are studied as often as the blocks.
The third mistake is treating the image-based item types as a test-day novelty rather than a study method. Hotspot items ask you to locate, on an image, what a text item would ask you to name; simulated cases ask you to work material in the order a case presents it. Both reward a candidate whose ordinary study was already image-first and case-shaped. If your preparation has been predominantly verbal — notes, summaries, definitions — convert it deliberately in the later phases: identify on images rather than diagrams, state where you would place a marker and why, and work case material as a unfolding encounter, committing to an interpretation before the next piece of information arrives.
The fourth mistake is letting physics and safety drift into generic revision borrowed from another examination’s preparation. The physics that matters here is the physics of these examinations — the choices this specialty’s scanning presents, the artifacts this anatomy produces, and above all the exposure discipline that obstetric scanning demands. Attach every principle to the pelvic or obstetric situation that tests it, as the walk above advises, and treat output awareness not as a topic among topics but as a habit the items will probe from several directions.
The fifth mistake is administrative, and it is the most avoidable: discovering late that a verification form, a prerequisite document, or a partner-examination deadline needed attention months earlier. The fee structure described in this guide makes documentation errors expensive, and the five-year pairing window makes calendar errors slow to repair. Fix the frame in the first week, as the study plan directs, and then let the content phases run without an administrative surprise waiting underneath them.
Frequently asked questions
How many questions are on the OB/GYN exam? Approximately 170 questions in three hours, including a five-minute survey.
What question types are used? Multiple-choice, hotspot (answered by marking directly on an image), and PACSim simulated clinical scenario questions.
What score passes? 555 or better on ARDMS’s 300-to-700 point scale. It is not a percentage.
How much does the OB/GYN exam cost? $275 including a $100 non-refundable processing fee, as ARDMS publishes it; add $50 at test centers outside the U.S., Canada, and Mexico. Confirm the current fee when you apply.
Do I need the SPI as well? Yes — both examinations, passed within five years of each other, in either order, earn the RDMS credential with the OB/GYN specialty.
Who can apply? Candidates meeting one of ARDMS’s published prerequisite pathways (education and clinical experience). A current OB/GYN Clinical Verification form may be part of the application; if one is on file, you submit the application and fee only.
If I fail, when can I retake? Reapply after three days; retake after a 60-day wait. The five-year SPI window keeps running.
What does the exam cover? The female reproductive system; the fetus in the first, second, and third trimesters; protocols and procedures; and physics and instrumentation, under the domains of ARDMS’s OB content outline.
Where does ARDMS say the content comes from? All questions fall under the domains and subdomains of the OB content outline, which ARDMS maintains through periodic practice analyses of the specialty. Review the current outline before you test.
Is OB/GYN the same specialty as Abdomen? No. They are separate ARDMS specialty examinations sharing the same SPI partner and the same RDMS credential family. This guide covers OB/GYN only.
Are PassProfessor’s questions the real exam questions? No. They are original practice questions written to the content ARDMS publishes for the examination. ARDMS does not release its examination questions.
When will the PassProfessor RDMS OB/GYN program open? The program is in the works. Join the notify list on this page or on the program page and we will email you when enrollment opens.
Disclaimer
PassProfessor is an independent exam-preparation provider; this guide and the companion program are not endorsed by, affiliated with, or sponsored by the American Registry for Diagnostic Medical Sonography (ARDMS), Inteleos, or Pearson VUE. ARDMS, RDMS, and SPI are marks of the ARDMS. The details in this guide are drawn from the official sources recorded below and are current as of November 2026; ARDMS’s official publications govern if anything here differs from them. The credential is awarded by ARDMS alone.