- What Primary Certification in Cardiothoracic Surgery Actually Is
- Who Certifies It: The AOBS and AOA Connection
- The Two Stages: Written and Oral
- How the Written Exam Divides Its Content
- What Candidates Must Master in the Two Heaviest Areas
- The Smaller Domains That Still Matter
- Eligibility and the ABTS Written-Exam Pathway
- What the Exams Cost
- After You Pass: Maintaining Certification
- Sequencing Your Preparation Around the Blueprint
- Who Hires Certified Cardiothoracic Surgeons
- Frequently Asked Questions
- This credential is Primary Certification in Cardiothoracic Surgery, issued by the American Osteopathic Board of Surgery (AOBS) with AOA certification approval.
- The written exam has 200 multiple-choice questions over four hours 30 minutes; a scaled score of 500 on a 200-800 scale passes.
- Cardiac & Cardiac Surgery (49-53%) and Thoracic (23-27%) together make up roughly three-quarters of the written blueprint.
- Written and oral stages are each $1,500, so standard fees add up to $3,000 before other costs.
What Primary Certification in Cardiothoracic Surgery Actually Is
Primary Certification in Cardiothoracic Surgery is a board certification credential for surgeons who treat diseases of the heart, lungs, esophagus, mediastinum and chest wall. It is not a degree, a license or a residency completion certificate. It is an independent, board-administered verification that a surgeon has completed approved training, holds an active unrestricted license and can demonstrate command of the specialty's knowledge base and clinical judgment through examination.
The phrase "cardiothoracic surgery" is also the name of the specialty itself, which causes confusion in search results. If you want the broader terminology explained, our articles on the meaning of cardiothoracic surgery and what the term stands for cover the vocabulary. This article focuses on the certification itself: who issues it, how it is tested, what it costs and how it is maintained. For a more focused treatment of the credential's lifecycle, see our overview of cardiothoracic surgery certification.
Who Certifies It: The AOBS and AOA Connection
The issuing body is the American Osteopathic Board of Surgery (AOBS), operating with certification approval from the American Osteopathic Association (AOA). That detail matters because it determines the exam content outline, the fee schedule, the proctoring rules and the maintenance requirements you will follow. Candidates should treat the AOBS and AOA pages as the authoritative sources and should not assume that rules from any other board apply.
The Two Stages: Written and Oral
The certification process has two examination stages. Both must be completed, and they test different skills.
The written stage
The written exam consists of 200 multiple-choice questions delivered over four hours and 30 minutes. Scoring is scaled, with a passing score of 500 on a 200-800 scale. Because the score is scaled, you cannot convert it into a simple percent-correct target; our guide to the cardiothoracic surgery passing score explains how to think about it.
Remote delivery follows the AOA's remote-proctoring instructions, which name the MonitorEDU Secure Browser and PARADIGM testing. Candidates who sit remotely should complete the technical checks well in advance rather than discovering a compatibility problem on exam day.
The oral stage
The oral exam is criterion-referenced and built around clinical cases. Examiners assess how you approach diagnosis, investigations, differential diagnosis and management. The published materials do not specify a number of oral questions or a timer, so you should not plan around an assumed format. The 2026 oral sitting was held September 30 in person in New Orleans.
Oral preparation is different from written preparation. Instead of recognizing a correct option among distractors, you must articulate a reasoned workup and plan aloud, defend your choices and handle follow-up questions about complications and alternatives.
| Feature | Written Stage | Oral Stage |
|---|---|---|
| Format | 200 multiple-choice questions | Clinical cases, criterion-referenced |
| Time | Four hours 30 minutes | No timer or question count published |
| Fee | $1,500 | $1,500 |
| Scoring | Scaled; 500 on a 200-800 scale passes | Criterion-referenced assessment of diagnosis, investigations, differential and management |
| Delivery | Remote proctored per AOA instructions | 2026 sitting in person, New Orleans, September 30 |
How the Written Exam Divides Its Content
The AOBS publishes an exam content outline with ten content areas and a percentage range for each. The ranges below are the published figures; they are ranges rather than fixed counts, so the number of questions you see in any area can vary.
| Content Area | Published Range |
|---|---|
| Basic Science | 1-3% |
| Cardiac & Cardiac Surgery | 49-53% |
| Chest | 1-5% |
| Esophagus | 2-5% |
| Mediastinal (Mediastinum) | 1-4% |
| Osteopathic Manipulative Medicine | 1-3% |
| Other | 6-8% |
| Pulmonary | 2-6% |
| Thoracic | 23-27% |
| Trauma | 1-3% |
The distribution is strongly top-heavy. Cardiac & Cardiac Surgery is by far the largest area, and Thoracic is a clear second. For a deeper walk through each area, see our complete guide to all 10 content areas.
What Candidates Must Master in the Two Heaviest Areas
Cardiac & Cardiac Surgery (49-53%)
Roughly half the exam lives here, so depth in this area is non-negotiable. Expect questions that move from physiology and pathology to operative decision-making and perioperative care.
- Coronary artery disease: indications for surgical revascularization versus other strategies, conduit selection and graft considerations
- Valvular disease: indications and timing for repair versus replacement across aortic, mitral, tricuspid and pulmonic pathology, plus prosthesis selection
- Aortic disease: aneurysm and dissection management, and the logic of urgent versus elective repair
- Congenital heart disease encountered in surgical practice
- Cardiopulmonary bypass, myocardial protection and mechanical circulatory support
- Postoperative critical care: arrhythmias, bleeding, low cardiac output, and complication recognition
Thoracic (23-27%)
The second-largest area covers the operative and decision-making side of general thoracic surgery.
- Lung cancer: staging, resectability, and selection of operative approach
- Surgical management of benign and malignant pleural disease
- Airway problems, including tracheal pathology
- Chest wall conditions and their reconstruction
- Perioperative physiology: pulmonary function assessment and risk stratification before resection
Because these two areas dominate, your preparation should reflect that weight. A candidate who spends equal time on every area will be underprepared where the points are concentrated. Our cardiothoracic surgery study guide builds a full plan around this reality.
The Smaller Domains That Still Matter
The remaining areas are individually small, but together they account for a meaningful share of the exam, and they can separate a borderline result from a passing one.
Other (6-8%)
The "Other" category is the largest of the minor areas. Because it is a catch-all, it rewards broad surgical and perioperative knowledge rather than a single narrow topic. Treat it as a reminder that the exam can reach into territory adjacent to your daily practice.
Pulmonary (2-6%), Esophagus (2-5%), Chest (1-5%) and Mediastinal (1-4%)
These areas reflect the breadth of the specialty. Pulmonary overlaps with thoracic work but emphasizes the medical and physiologic side of lung disease. Esophagus covers disease of the foregut that thoracic surgeons commonly manage. Chest and Mediastinal (Mediastinum) address structures and conditions within the thoracic cavity beyond the lungs and heart, including mediastinal masses.
Basic Science (1-3%), Trauma (1-3%) and Osteopathic Manipulative Medicine (1-3%)
Basic Science tests the foundational physiology, anatomy and pathology that underpin clinical decisions. Trauma addresses thoracic injury recognition and management. The Osteopathic Manipulative Medicine area is a distinctive feature of this osteopathic-board credential and is worth a short, targeted review so that a small domain does not become an avoidable loss.
Eligibility and the ABTS Written-Exam Pathway
Eligibility requires approved training, active unrestricted licensure and the required documentation. The specialty page describes four years of AOA-approved general surgery plus two years of cardiothoracic training with program-director documentation, while current AOBS Board Policies recognize qualifying DO/MD and ACGME routes. Because these sources describe the requirements differently, verify your specific situation against the current policies. Our requirements and eligibility guide walks through the prerequisites in more detail.
One notable development is the April 29, 2026 AOA announcement that AOBS expanded certification eligibility. Under it, a passed ABTS written examination is recognized for the AOBS cardiothoracic oral-stage application. It is important to read this precisely: it is credit within the selected AOBS pathway. It does not make an ABTS credential interchangeable with AOBS certification, and it does not mean the two exams share a syllabus or a pass rate. Candidates receiving written-exam credit should also confirm their fee path with the AOBS rather than assuming it matches the standard schedule.
On timing, the specialty pages conflict on whether the application lead time is five or six months, and they retain April scheduling, while the board homepage lists May 1-3, 2027 for the remote Spring Qualifying Examination. The protocol document is also noted as under revision. The practical takeaway is to resolve your own deadlines through current notices and the application portal; see our exam dates and scheduling guide for how to approach it.
What the Exams Cost
The standard AOBS fee is $1,500 for the written stage and $1,500 for the oral stage, which sums to $3,000 for the pair. That figure covers examination fees only and excludes other costs such as travel to an in-person oral sitting, lodging, review materials and any time away from clinical work. Candidates receiving written-exam credit should not assume the same fee path applies. For a fuller picture, see our certification cost breakdown, and for the value question, our ROI analysis.
If you do not pass
The written-exam page requires reapplication after a failure and describes a two-year retake window after the first or second failure. After a third written or oral failure, documented board-review study is required before another written attempt. Plan your first attempt seriously, because retakes add cost and delay. For perspective on difficulty, read how hard the exam is. No AOBS cardiothoracic-specific pass rate was verified, so be cautious about any figure you see quoted; our pass rate article explains what is and is not known.
After You Pass: Maintaining Certification
The specialty timeline describes primary active status for one year, subject to OCC (Osteopathic Continuous Certification). Maintenance has several components:
- Licensure: an active license must be maintained.
- CME: 60 credits per three-year cycle, confirmed by the current CME Requirements by Specialty Board document for 2025-2027.
- Longitudinal assessment: an annual assessment of 15 questions.
- QI/QA attestation: required every three years.
One source caveat is worth knowing: the Component 4 page still contains legacy wording about a 10-year cycle, but that wording does not establish a new ten-year validity term. Rely on the current OCC pages for your own maintenance planning.
Sequencing Your Preparation Around the Blueprint
Rather than a generic schedule, let the content outline drive your order of study. The logic is simple: allocate the most time to the areas with the most points, and revisit the small domains briefly but deliberately.
Cardiac & Cardiac Surgery foundation
- Coronary and valvular disease first, since they anchor the largest domain
- Cardiopulmonary bypass and myocardial protection
Cardiac depth and critical care
- Aortic and congenital disease
- Postoperative complications and mechanical support
Thoracic
- Lung cancer staging and resection logic
- Pleural, airway and chest wall problems
Smaller domains and oral practice
- Esophagus, Pulmonary, Mediastinal, Chest, Trauma, Basic Science, Osteopathic Manipulative Medicine
- Verbal case walk-throughs for the oral stage
Interleave timed multiple-choice sets throughout so the 200-question, four-hour-30-minute pacing feels familiar. You can build that stamina with the practice questions on our main practice test site, and keep our one-page cheat sheet handy for last-week review.
Who Hires Certified Cardiothoracic Surgeons
Board certification is a credentialing requirement that hospitals and health systems commonly look for when granting privileges and hiring. Typical employers include academic medical centers, large community hospitals with cardiac and thoracic programs, tertiary referral centers and integrated health systems. Certification can also matter for privileging, payer participation and professional standing. Compensation varies widely by setting, region and practice model, and no specific figures are asserted here; our salary guide and jobs overview discuss the market, and our training article covers the path that leads to eligibility.
Frequently Asked Questions
The American Osteopathic Board of Surgery (AOBS) issues it, with AOA certification approval. The exam content outline, fees and maintenance rules come from the AOBS and AOA, so use their official pages as your authority.
It contains 200 multiple-choice questions over four hours and 30 minutes. Scoring is scaled, and a score of 500 on a 200-800 scale is passing. The fee is $1,500.
Cardiac & Cardiac Surgery is the largest at 49-53%, followed by Thoracic at 23-27%. The other eight areas are each far smaller, with Other at 6-8% being the biggest of them.
It uses criterion-referenced clinical cases to assess diagnosis, investigations, differential diagnosis and management. The fee is $1,500, and no oral question count or timer is published, so avoid assuming a format.
Per the April 29, 2026 AOA announcement, AOBS recognizes a passed ABTS written examination for the AOBS cardiothoracic oral-stage application. It is credit within the AOBS pathway, not a substitution of an ABTS credential, and you should confirm your fee path with the AOBS.
If you are weighing whether this credential fits your career, start with the overview of cardiothoracic surgery certification, then check your eligibility, confirm your deadlines in the application portal and begin building question stamina with the practice tests on our practice platform.