- The written exam has 150 multiple-choice questions; passing requires a scaled score of 500 on a 200-800 scale.
- Fundamentals is the largest domain at 40%, followed by Diving medicine at 30.5%.
- Exam and recertification fees are each published at $1,100.
- Eligibility requires a one-year AOA- or ACGME-approved hyperbaric fellowship plus primary certification through AOBEM, AOBFP, AOBIM, or AOBPM.
Certification Snapshot
This cheat sheet condenses the core facts of AOA Subspecialty Certification in Undersea and Hyperbaric Medicine (UHM) into a single reference page. It is built specifically around the American Osteopathic Conjoint Undersea & Hyperbaric Medicine Examination Committee's written examination - not the separate ABPM/ABEM pathway. If you already know what the credential entails and just need the numbers, this page is your quick-reference companion to the longer UHM Study Guide 2026: How to Pass on Your First Attempt.
| Item | Detail |
|---|---|
| Certifying body | American Osteopathic Conjoint Undersea & Hyperbaric Medicine Examination Committee (AOA board certification) |
| Question count | 150 multiple-choice questions |
| Passing standard | Scaled score of at least 500 on a 200-800 scale |
| Exam fee | $1,100 (published) |
| Recertification fee | $1,100 (published) |
| Recert cycle | 10-year cycle via the OCC pathway with a written recertification assessment |
Domain Weights at a Glance
The official written-examination page lists a four-category outline. Memorize the order and rough proportions before you build a study plan - this single table drives most scheduling decisions.
Domain 1 - Fundamentals (40%)
The largest tested area by a wide margin. Expect coverage of physics, physiology of gas exposure, decompression theory basics, and the mechanistic underpinnings that connect diving and clinical hyperbaric practice.
- Highest point value on the exam - prioritize accordingly
- Foundational for correctly answering Domains 2 and 3
Domain 2 - Diving Medicine (30.5%)
Covers dive-related pathology, fitness-to-dive evaluation, and injury management specific to underwater exposure.
- Second-largest domain - nearly a third of the exam
- Distinct from clinical hyperbaric chamber-based treatment content
Domain 3 - Clinical Hyperbaric Medicine (26.5%)
Focuses on indications, protocols, and monitoring for hyperbaric oxygen therapy delivered in a clinical chamber setting.
- Nearly as large as Diving medicine - do not under-study it
- Ties directly to the 13 treatment indications referenced in eligibility documentation
Domain 4 - Research (3%)
The smallest domain. Expect a handful of questions on research literacy relevant to hyperbaric and diving medicine practice.
- Lowest weight - allocate proportionally light study time
- Still worth reviewing once, since every point counts toward the scaled score
For a deeper breakdown of subtopics inside each category, see UHM Exam Domains 2026: Complete Guide to All 4 Content Areas. If you're trying to gauge overall difficulty before committing study hours, How Hard Is the UHM Exam? Complete Difficulty Guide 2026 puts the domain weights in context.
Key Takeaway
Fundamentals and Diving medicine together account for over 70% of the exam. If your study time is limited, these two domains deserve the majority of your review hours before you touch Clinical hyperbaric medicine or Research.
Eligibility Checklist
Before you can register, the published eligibility requirements must all be satisfied. Use this as a pre-application checklist:
- COCA-accredited osteopathic medical degree
- One-year AOA-approved internship
- One-year AOA- or ACGME-approved hyperbaric medicine fellowship
- Primary certification through AOBEM, AOBFP, AOBIM, or AOBPM
- Unrestricted medical licensure
- Good ethical standing
Full detail on how each requirement is documented - including what counts as an acceptable fellowship and how primary board certification is verified - is covered in UHM Requirements 2026: Eligibility, Prerequisites & How to Qualify.
Application & Fee Mechanics
The application packet is document-heavy and case-log-heavy. Plan to assemble these pieces well ahead of any submission deadline:
- Current CV
- Proof of unrestricted medical license
- Fellowship completion documentation
- Case log documenting supervision of at least 500 treatments distributed across the 13 treatment indications specified in the published requirements, according to institutional case frequency
The published examination fee is $1,100. Recertification carries the same published fee of $1,100. Neither figure should be confused with fees from a differently-named "UHM" credential elsewhere - these numbers apply specifically to the AOA Conjoint pathway. A complete fee-by-fee walkthrough, including what's billed at application versus recertification, lives in UHM Certification Cost 2026: Complete Pricing Breakdown.
Exam Format & Scoring
The written exam is a fixed-format, 150-question multiple-choice assessment. There is no essay or oral component in this written examination pathway. Scoring is reported on a 200-800 scale, and a scaled score of at least 500 is required to pass.
- 150 total multiple-choice items
- Scaled scoring, 200-800 range
- Passing threshold: 500
- Four content domains, weighted as shown above
Because the exam is scaled rather than raw-scored, don't try to reverse-engineer "how many questions you can miss." Focus instead on domain mastery. For a full explanation of how the scaled score works and what it means practically, see UHM Passing Score 2026: Exactly What You Need to Pass. If you're trying to plan around a specific testing window, check UHM Exam Dates 2026: Testing Windows, Deadlines & Scheduling - note that the official written-examination page still carries 2024 scheduling text at the time of writing, so treat any listed date there as outdated rather than a confirmed 2026 appointment, and verify current windows directly with the certifying committee.
Recertification (OCC)
UHM recertification runs on a 10-year cycle through the published Osteopathic Continuous Certification (OCC) pathway, which includes a written recertification assessment. Outside of that assessment, the conjoint committee does not impose an additional UHM-specific CME requirement - instead, diplomates maintain:
- CME required by their primary board (AOBEM, AOBFP, AOBIM, or AOBPM)
- General OCC compliance
- Active, unrestricted licensure
The recertification fee is published at $1,100, matching the initial exam fee. This structure is meaningfully different from certifications that layer on separate specialty-specific CME hour minimums, so don't import assumptions from other credentials when planning your 10-year cycle.
One-Week Cram Alignment
If you're using this cheat sheet in the final stretch before an exam date, align a short review block to domain weight rather than splitting time evenly across all four areas.
Fundamentals (40%)
- Review core physics and physiology of gas exposure
- Drill decompression theory basics until recall is automatic
Diving Medicine (30.5%)
- Review fitness-to-dive criteria and dive-injury management
- Cross-check against Fundamentals concepts already reviewed
Clinical Hyperbaric Medicine (26.5%) + Research (3%)
- Review indications and protocols tied to the 13 treatment categories
- Skim research literacy topics last - lowest weight, lowest priority
This sequencing mirrors point value: Fundamentals gets the most days because it's worth the most on the exam, and Research is reviewed last because a light pass is proportionally appropriate at 3%. For a longer-horizon plan spanning weeks rather than days, the UHM Study Guide 2026 lays out a fuller schedule.
Why This Credential Matters to Employers
Hospitals and multi-specialty groups operating hyperbaric chambers look for AOA-board-certified physicians who hold both a primary osteopathic board certification and this UHM subspecialty credential as evidence of fellowship-level training in hyperbaric and diving medicine. If you're weighing whether pursuing certification fits your career plans, Is the UHM Certification Worth It? Complete ROI Analysis 2026 and UHM Salary Guide 2026: Complete Earnings Analysis walk through the practical considerations. For a look at where UHM-certified physicians typically practice, see UHM Jobs.
Before diving deeper into study logistics, it's worth confirming you understand the credential itself. If any of the terminology feels unfamiliar, start with What Is UHM Certification? or the shorter primers What Is UHM? and UHM Meaning.
Frequently Asked Questions
The exam contains 150 multiple-choice questions covering four content domains: Fundamentals, Diving medicine, Clinical hyperbaric medicine, and Research.
You need a scaled score of at least 500 on a 200-800 scale. See UHM Passing Score 2026 for a full explanation of how scaling works.
The published examination fee is $1,100, and the recertification fee is also published at $1,100. Full cost breakdowns are available in UHM Certification Cost 2026.
Fundamentals, at 40% of the exam, carries the most weight, followed by Diving medicine at 30.5%. Together they represent over 70% of scored content.
No. Beyond the written recertification assessment within the 10-year OCC cycle, the conjoint committee does not add a UHM-specific CME requirement on top of your primary board's CME and OCC compliance.