- UHM here means Certification in Undersea and Hyperbaric Medicine, administered through the American Board of Preventive Medicine (ABPM).
- The exam is 150 single-best-answer, closed-book questions delivered in three one-hour blocks at Pearson VUE.
- Content covers three domains: Fundamentals, Diving Medicine, and Clinical Hyperbaric Medicine.
- The ABPM route costs $2,650 total; the separate ABEM route costs $2,215 total.
What UHM Means Here
"UHM" is shorthand for Undersea and Hyperbaric Medicine, a physician subspecialty built around two overlapping bodies of knowledge: the medicine of exposure to increased ambient pressure (diving and compressed-gas work) and the therapeutic use of hyperbaric oxygen in a clinical setting. The credential this article covers is the Certification in Undersea and Hyperbaric Medicine, a subspecialty certificate earned by physicians who already hold primary board certification in another specialty.
That last point matters. This is not an entry-level credential, and it is not a technician or operator certificate. It is a physician-level subspecialty certification that sits on top of a primary specialty. If you are searching for the meaning of the acronym, our companion pages on UHM meaning, what UHM stands for, and what UHM certification is cover the terminology from other angles. This article focuses on how the certification actually works: who administers it, what the exam contains, what it costs, and who qualifies.
Who Certifies It and Where You Test
The certificate is administered by the American Board of Preventive Medicine (ABPM). Examinations are delivered at Pearson VUE test centers, so candidates schedule a seat at a proctored testing site rather than sitting for the exam at a hospital or conference.
There is also a separate pathway through the American Board of Emergency Medicine (ABEM). ABEM diplomates apply through ABEM rather than through ABPM, and the fee structure differs (covered below). If your primary certification is in emergency medicine, it is worth confirming which application route applies to you before you pay anything. The full eligibility picture is laid out in our guide to UHM requirements.
What the Exam Looks Like
The format is straightforward, and knowing it removes a lot of avoidable test-day stress.
| Feature | Detail |
|---|---|
| Number of questions | 150 |
| Question style | Single-best-answer multiple choice |
| Structure | Three one-hour testing blocks |
| Total appointment | 3 hours 30 minutes, including tutorial and break |
| Reference materials | Closed-book |
| Revisiting answers | Completed blocks cannot be revisited |
| Delivery | Pearson VUE test centers |
Two format details deserve attention. First, because prior completed blocks cannot be revisited, you cannot bank hard questions for later across blocks. Within a block you manage your own pacing, but once you close it, those answers are final. Second, the exam is closed-book, so recall of numbers, thresholds, and treatment parameters has to come from memory rather than a reference. I could not verify a published policy on initial remote delivery, adaptive testing, or an on-screen calculator, so do not assume any of those; check the current ABPM candidate materials before exam day.
A single-best-answer item gives you a clinical or physiological stem and several plausible options, only one of which is the best. In UHM, distractors are often technically defensible in a different context, such as a treatment that is appropriate for one indication but not the one in the stem. That is a skill separate from raw recall, and it is why practice with realistic questions matters. For a sense of the difficulty, see how hard the UHM exam is.
The Three Content Domains
The current public outline organizes the exam into three domains. Our deeper walkthrough is in the complete guide to all three UHM content areas; here is the orientation.
Domain 1: Fundamentals
The scientific foundation under everything else. Candidates need to be comfortable with how pressure, gases, and physiology interact, because the other two domains lean on this material constantly.
- Gas laws and how partial pressures change with depth and with chamber pressure
- Oxygen physiology and the effects of elevated oxygen delivery to tissue
- Hyperbaric chamber types, safety, and operational principles
- Mechanisms by which hyperbaric exposure produces its physiologic effects
Domain 2: Diving Medicine
The undersea half of the specialty: the injuries, illnesses, and fitness questions that arise from breathing compressed gas underwater.
- Decompression illness, including arterial gas embolism and decompression sickness, and their recognition and recompression-based management
- Barotrauma across the ears, sinuses, lungs, and other gas-containing spaces
- Inert gas narcosis and oxygen toxicity as they relate to different breathing gases
- Fitness-to-dive evaluation and the medical conditions that complicate it
Domain 3: Clinical Hyperbaric Medicine
The therapeutic half: when hyperbaric oxygen is indicated, how it is delivered, and what can go wrong.
- Accepted indications for hyperbaric oxygen therapy and how to match a patient to an appropriate treatment approach
- Wound and tissue-related indications, infections, and acute emergent conditions
- Treatment protocols, patient selection, and monitoring during therapy
- Contraindications, complications, and adverse effects of treatment
The domains are not isolated. A single question can start in Fundamentals (a gas-law calculation or physiologic principle) and finish in Domain 2 or 3 (what that means for a diver or a patient in a chamber). Studying them as a connected system, rather than three separate silos, tends to pay off.
Eligibility and Pathways
Eligibility is the part of this credential that most often surprises candidates, because it involves both training and prior certification. The requirements include:
- Qualifying medical education and unrestricted licenses
- An accepted primary certification in another specialty
- Completion of a 12-month ACGME UHM fellowship or an approved COLT pathway
- Training verification, plus elapsed-training reference rules that can affect candidates whose training ended some time ago
The practical takeaway: do not treat eligibility as an afterthought you sort out after choosing an exam date. Confirm that your primary certification is accepted, that your training will be verified in time, and that any elapsed-time rules do not catch you out. Our UHM requirements guide goes through the prerequisites step by step, and the UHM training page covers fellowship and pathway options.
Fees: ABPM Route vs. ABEM Route
The cost differs depending on which board you apply through. Both routes charge an application fee plus a separate examination fee.
| Route | Application Fee | Examination Fee | Total |
|---|---|---|---|
| ABPM | $500 | $2,150 | $2,650 |
| ABEM (for ABEM diplomates) | $470 | $1,745 | $2,215 |
The $435 difference between the two totals is real, but it only applies if you are an ABEM diplomate eligible for that route; the ABEM pathway is not a discount anyone can choose. Many candidates also need to budget for travel, lodging, and time away from clinical work around the test date. For the full picture of ongoing costs beyond the exam itself, see our UHM certification cost breakdown.
Pass Rate and Exam Window
The official 2024 combined ABPM/ABEM pass rate was 94%, or 29 of 31 candidates. Two cautions apply when reading that number. The sample is small, so a single result moves the percentage noticeably. And the figure is not labeled as first-time-only, so it should not be read as a first-attempt pass rate. A high pass rate is also a reflection of a self-selected, already-board-certified, fellowship-trained candidate pool, not evidence that the exam is easy. We unpack this further in what the pass-rate data shows, and the scoring threshold is discussed in UHM passing score.
For scheduling, the 2026 examination window is October 12 to November 1, and ABPM currently describes the exam as administered annually. Because it is offered once a year, missing your window or an application deadline can mean waiting a full year. Registration timing and deadlines are covered in UHM exam dates.
Who Uses This Credential
This section heading is intentionally brief; the section below carries the detail.
Who Uses This Credential
Because the certification is a physician subspecialty, the people who hold it are practicing doctors who add hyperbaric and diving expertise to a primary specialty. Typical settings include:
- Hospital-based hyperbaric and wound-care programs, where a physician directs or supervises hyperbaric oxygen therapy
- Dedicated hyperbaric treatment centers, including outpatient facilities focused on wound and tissue indications
- Emergency and critical-care departments that manage acute hyperbaric emergencies and need physicians who can run a chamber
- Diving-medicine practices that evaluate divers for fitness and treat dive-related injuries
- Occupational and commercial diving operations, which need medical oversight for compressed-gas work
The credential tends to matter most where an organization needs a qualified physician to serve as medical director or to lead a program. Compensation varies with practice setting, primary specialty, and the share of time spent on hyperbaric work, so we avoid quoting a single figure here; see the UHM salary guide and UHM jobs for more context, and the ROI analysis if you are weighing whether the investment pays off for your situation.
Keeping the Certificate Current
Earning the certificate is not the end of the obligation. The Continuing Certification Program (CCP) for 2025-2029 sets ongoing requirements:
- An annual unrestricted license requirement
- 20 Category 1 CME credits, including at least six that are relevant to the specialty
- 30 longitudinal questions per certificate
- An annual fee of $150, $175, or $200, depending on the payment quarter
Individual certificate expiry dates are not something to guess at. Confirm yours directly through your ABPM account, since the account is the authoritative source for your specific timeline.
Key Takeaway
Treat the annual fee tiers as a small incentive to pay early in the year, and track your 20 CME credits (with the six relevant ones) as you go rather than scrambling at the end of a cycle.
Sequencing Your Preparation
Because the domains build on each other, order matters more than intensity. A reasonable approach is to lead with Fundamentals, since gas laws and oxygen physiology are the vocabulary the other two domains speak, then layer Diving Medicine, then Clinical Hyperbaric Medicine, and finish with mixed-domain practice questions under timed conditions. Practicing in one-hour blocks of roughly fifty questions mirrors the real structure, including the fact that you cannot return to a finished block.
Fundamentals
- Gas laws, partial pressures, and oxygen physiology
- Chamber operation and safety principles
Diving Medicine
- Decompression illness and barotrauma
- Breathing-gas toxicities and fitness-to-dive questions
Clinical Hyperbaric Medicine
- Indications, protocols, and patient selection
- Contraindications, complications, and adverse effects
Timed mixed practice
- Three one-hour blocks of single-best-answer questions
- Review misses by domain to find weak areas
For a fuller plan, read the UHM study guide, keep the UHM cheat sheet handy for last-minute review, and run realistic practice on the UHM practice test site. If you want a domain-by-domain question bank, our practice exam is built around the same three content areas.
Frequently Asked Questions
It stands for Undersea and Hyperbaric Medicine. This article covers the Certification in Undersea and Hyperbaric Medicine, a physician subspecialty certificate administered through the American Board of Preventive Medicine.
The exam has 150 single-best-answer multiple-choice questions in three one-hour blocks. The full appointment is 3 hours 30 minutes, including the tutorial and a break. It is closed-book, and completed blocks cannot be revisited.
Through ABPM, the application fee is $500 and the examination fee is $2,150, for $2,650 total. ABEM diplomates apply through ABEM, where the fees are $470 plus $1,745, or $2,215 total.
The current public outline has three domains: Fundamentals, Diving Medicine, and Clinical Hyperbaric Medicine. Questions often cross domains, so connected study works better than treating each in isolation.
The 2026 examination window runs October 12 to November 1. ABPM currently describes the exam as administered annually, so confirm deadlines early to avoid waiting another year.