- What This Cheat Sheet Covers (and What It Doesn't)
- Credential Snapshot: Who Certifies, What Stages Exist
- Domain 1: Foundational Reproductive Endocrinology
- Domain 2: Reproductive Endocrine Function and Disease
- Domain 3: Conception and Pregnancy
- Domain 4: Fertility and Infertility
- Domain 5: Anatomic Reproductive Disorders
- Domain 6: Reproductive Genetics
- The Only Numbers Worth Memorizing
- Sequencing Your Review by Domain
- Frequently Asked Questions
- REI certification runs through ABOG: a written Qualifying Examination (QE) followed by an oral Certifying Examination (CE).
- The ABOG REI blueprint lists six primary categories and 27 subcategories, with no published percentage weights.
- Fellowship graduates from 2026 onward move the thesis from CE eligibility to QE eligibility.
- The 2025 first-time REI pass rates reported by ABOG were 100% on the QE (N=55) and 94.7% on the CE (N=57).
What This Cheat Sheet Covers (and What It Doesn't)
This page is a compressed review of Reproductive Endocrinology & Infertility, the three-year fellowship-trained subspecialty within obstetrics and gynecology. It follows the six domain headings and 27 subcategories in the American Board of Obstetrics and Gynecology (ABOG) REI blueprint, which is a four-page document and is the closest thing to an official scope statement candidates have.
Two cautions shape how to use it. First, the blueprint publishes no percentage weights and does not split coverage between the written and oral stages, so any claim that "Domain 4 is worth X% of the exam" is invented. Second, a cheat sheet is a retrieval aid, not a teaching tool. If a bullet below feels unfamiliar, treat it as a flag and go deeper using the REI study guide or the full breakdown of all six REI content areas.
Credential Snapshot: Who Certifies, What Stages Exist
Training context comes from the ASRM 2025 scope-of-practice statement: medical school, a four-year obstetrics and gynecology residency, then a three-year REI fellowship. Certification is administered by ABOG and has two distinct stages. For deeper eligibility detail, see REI requirements and how to qualify.
| Element | What the Sources Establish |
|---|---|
| Certifying body | American Board of Obstetrics and Gynecology (ABOG) |
| Written stage | Qualifying Examination (QE), delivered through Pearson VUE |
| Oral stage | Certifying Examination (CE) |
| Thesis timing | Moves from CE eligibility to QE eligibility for fellowship graduates from 2026 onward; earlier graduates keep prior requirements |
| Blueprint structure | Six primary categories, 27 subcategories, no weights, no QE/CE split |
| Staying certified | Continuing-certification participation is required |
Domain 1: Foundational Reproductive Endocrinology
This domain covers REI1.1 Hormone Structure and Function, REI1.2 Basic Pharmacology, and REI1.3 Laboratory Assays. It is the vocabulary layer beneath everything else.
Hormone Structure and Function (REI1.1)
Know the hypothalamic-pituitary-gonadal axis cold, including feedback logic.
- Steroid versus peptide versus glycoprotein hormones, and why receptor location differs
- Shared alpha subunit and unique beta subunit across the glycoprotein family
- Steroidogenic pathway order and which enzyme deficiencies shunt precursors where
Basic Pharmacology (REI1.2)
Expect mechanism-of-action reasoning, not just drug lists.
- Ovulation-induction agents: how each changes feedback or follicular stimulation
- GnRH agonists versus antagonists: flare effect, down-regulation, and clinical timing
- Gonadotropin preparations and trigger options, including their implications for ovarian hyperstimulation risk
Laboratory Assays (REI1.3)
Interpretation and pitfalls matter more than technique.
- Cycle-timed hormone interpretation and what a single value can and cannot tell you
- Immunoassay limitations such as cross-reactivity and interference
- Ovarian reserve markers and their appropriate (and inappropriate) uses
Domain 2: Reproductive Endocrine Function and Disease
Five subcategories live here: REI2.1 Reproductive Physiology Across the Lifespan, REI2.2 Neuroendocrine Disorders, REI2.3 Thyroid Disorders, REI2.4 Endometrial Physiology and Abnormal Uterine Bleeding, and REI2.5 Ovarian and Adrenal Disorders (Idiopathic and Iatrogenic).
Lifespan physiology (REI2.1)
- Sequence and mechanism of puberty, including precocious and delayed presentations
- The menopausal transition and its hormonal signature
- Primary versus secondary amenorrhea as an organized work-up, not a memorized list
Neuroendocrine and thyroid disease (REI2.2, REI2.3)
- Hyperprolactinemia: causes, medication effects, imaging indications, and treatment logic
- Hypothalamic amenorrhea versus pituitary or structural causes
- Hypo- and hyperthyroidism effects on ovulation, menses, and pregnancy outcomes
Endometrium and bleeding (REI2.4)
- Proliferative and secretory endometrial physiology and the hormonal drivers of each phase
- Structured approach to abnormal uterine bleeding by etiology category
- When hormonal management is appropriate and when structural evaluation must come first
Ovarian and adrenal disorders (REI2.5)
- Diagnostic criteria logic for polycystic ovary syndrome and the conditions that must be excluded
- Primary ovarian insufficiency: evaluation, associated conditions, and counseling
- Nonclassic congenital adrenal hyperplasia and androgen-excess differentials
- Iatrogenic causes, such as effects of surgery, chemotherapy, or radiation on ovarian function
Domain 3: Conception and Pregnancy: Physiology and Pathology
This domain includes REI3.1 Gamete Biology, REI3.2 Early Embryo Development, REI3.3 Endocrinology of Pregnancy, REI3.4 Early Pregnancy, and REI3.5 Recurrent Pregnancy Loss.
Gametes and Early Embryo (REI3.1, REI3.2)
Cell-biology questions reward understanding of timing and checkpoints.
- Oocyte meiotic arrest points and resumption triggers
- Folliculogenesis stages and gonadotropin dependence at each stage
- Fertilization events, cleavage, compaction, blastocyst formation, and implantation
- Spermatogenesis timing and the Sertoli/Leydig cell roles
Endocrinology of Pregnancy (REI3.3)
Know which tissue makes what, and when function transfers.
- Corpus luteum support and the luteal-placental transition
- hCG physiology, expected trajectories, and discordant patterns
- Maternal endocrine adaptations, including thyroid and glucose metabolism
Early Pregnancy and Loss (REI3.4, REI3.5)
Management reasoning is the point: what to test, what to treat, what to leave alone.
- Pregnancy of unknown location, ectopic pregnancy, and management options
- Early pregnancy failure evaluation and counseling
- Recurrent pregnancy loss work-up: parental karyotype, uterine evaluation, antiphospholipid testing, and endocrine factors
- Which commonly ordered tests lack strong evidence of benefit
Domain 4: Fertility and Infertility
The clinical heart of the specialty, with five subcategories: REI4.1 Female Fertility and Infertility, REI4.2 Male Infertility, REI4.3 Fertility Treatment: Special Considerations, REI4.4 Assisted Reproductive Technology (ART) Techniques, and REI4.5 Fertility Preservation.
Female and male evaluation (REI4.1, REI4.2)
- Standard infertility work-up: ovulatory assessment, tubal and uterine evaluation, ovarian reserve, and male semen analysis
- Age-related decline in oocyte quality and quantity and how it should shape counseling and timing
- Male factor: semen parameter interpretation, hormonal causes, obstructive versus nonobstructive azoospermia, and genetic contributors
Treatment and ART (REI4.3, REI4.4)
- Stepwise logic from ovulation induction through intrauterine insemination to in vitro fertilization
- Stimulation protocols, trigger selection, and ovarian hyperstimulation syndrome prevention and management
- Laboratory steps: insemination versus intracytoplasmic sperm injection, embryo culture, biopsy, and cryopreservation concepts
- Special populations, such as patients with diminished reserve, same-sex couples, and those using donor gametes or gestational carriers
- Multiple-gestation risk and strategies to reduce it
Fertility preservation (REI4.5)
- Oocyte, embryo, and ovarian tissue approaches and the patient scenarios that favor each
- Timing of preservation relative to gonadotoxic therapy
- Counseling on expected outcomes without overpromising
Key Takeaway
Domain 4 is where oral-exam performance is most visible. Practice narrating a complete case aloud: history, targeted work-up, diagnosis, treatment options with trade-offs, and risks. If you can do that for ovulatory dysfunction, tubal disease, male factor, and diminished reserve, you are covering most of the realistic case space.
Domain 5: Anatomic Reproductive Disorders
REI5.1 through REI5.7 form the longest subcategory run: pelvic adhesive disease, endometriosis, adenomyosis, congenital anomalies of the reproductive tract, Asherman syndrome, leiomyomas, and endometrial polyps.
| Subcategory | Core Concepts to Own |
|---|---|
| REI5.1 Pelvic Adhesive Disease | Causes, impact on tubal function, role of surgery versus bypassing via IVF |
| REI5.2 Endometriosis | Diagnostic approaches, effects on fertility and pain, medical versus surgical management, treatment before ART |
| REI5.3 Adenomyosis | Imaging features, symptoms, and possible impact on implantation and outcomes |
| REI5.4 Congenital Anomalies | Müllerian development, classification, imaging choice, and associated renal anomalies |
| REI5.5 Asherman Syndrome | Causes, hysteroscopic diagnosis and treatment, post-operative strategies to limit recurrence |
| REI5.6 Leiomyomas | Location-based effect on fertility, when removal helps, myomectomy considerations |
| REI5.7 Endometrial Polyps | Association with bleeding and infertility, evaluation, and resection indications |
The pattern across this domain is location and distortion. Whether a lesion distorts the uterine cavity, obstructs tubes, or affects the peritoneal environment usually determines whether treatment improves fertility. Build every answer around that question.
Domain 6: Reproductive Genetics
The shortest domain by subcategory count, with REI6.1 Understanding of Genetic Testing and Screening and REI6.2 Application of Genetic Screening and Testing to Patient Care. Because the blueprint is unweighted, do not assume it is lightly tested.
Concepts Versus Application
REI6.1 is about knowing what a test measures; REI6.2 is about using it for a real patient.
- Karyotype, microarray, sequencing, and carrier screening: what each detects and misses
- Embryo biopsy testing: aneuploidy, monogenic, and structural-rearrangement indications and their limitations
- Sex chromosome and structural disorders presenting with amenorrhea or infertility, such as Turner syndrome and Y-chromosome material
- Genetic contributors to male infertility, including Y microdeletions and CFTR-related conditions
- Pre- and post-test counseling, including interpreting uncertain results
The Only Numbers Worth Memorizing
Credential logistics change, and this page deliberately avoids numbers that the sources do not support. The figures below are the ones documented in ABOG's 2026 program directors update and the blueprint itself.
- 6 primary blueprint categories and 27 subcategories
- 2025 first-time REI QE pass rate: 100% (N=55)
- 2025 REI CE pass rate: 94.7% (N=57)
- 2026 dates cited by ABOG: subspecialty QE on July 20; CE April 13-17. These are historical 2026 dates, not guarantees about future windows
Sequencing Your Review by Domain
Because the blueprint has no weights, an even, dependency-ordered pass beats guessing at what is "high yield." Foundations first, because Domains 2 through 4 assume you can reason from hormone physiology and assay interpretation.
Domain 1 and Domain 2
- Rebuild the axis, steroidogenesis, pharmacology, and assay interpretation (REI1.1-1.3)
- Work through amenorrhea, prolactin, thyroid, bleeding, and PCOS/POI frameworks (REI2.1-2.5)
Domain 3 and Domain 4
- Gamete, embryo, and pregnancy endocrinology, then loss work-ups (REI3.1-3.5)
- Full infertility evaluation, ART, and preservation case narration (REI4.1-4.5)
Domain 5, Domain 6, and Integration
- Anatomic disorders by location and distortion (REI5.1-5.7)
- Genetics concepts and counseling application (REI6.1-6.2)
- Mixed-domain questions and spoken case practice for the oral stage
Adjust the length to your own timeline. Test your retention with timed sets in the REI practice test platform, and review misses by subcategory code so gaps map directly back to the blueprint. For a longer plan, the REI study guide goes further.
Where This Credential Leads
REI-certified physicians typically practice in fertility centers, academic medical centers, and hospital-affiliated reproductive programs, combining clinical care, procedures, and often laboratory oversight. If you are weighing the career side, the REI salary guide, REI jobs overview, and ROI analysis of REI certification cover it in more depth. If you landed here wondering about the acronym itself, start with what REI is.
Frequently Asked Questions
No. The current ABOG REI blueprint lists six primary categories and 27 subcategories but publishes no percentage weights and no separate allocation for the written QE versus the oral CE. Any weighting you see elsewhere is an editorial estimate.
The written Qualifying Examination (QE), delivered through Pearson VUE, and the oral Certifying Examination (CE). They are distinct stages. For fellowship graduates from 2026 onward, the thesis requirement moves from CE eligibility to QE eligibility; earlier graduates keep their prior requirements.
ABOG's 2026 program directors update reported a 2025 first-time REI QE pass rate of 100% (N=55) and a CE pass rate of 94.7% (N=57). The cohorts are small, and the presentation's repeat and overall counts are inconsistent, so avoid drawing strong conclusions from them.
The blueprint doesn't rank them, so prioritize by personal weakness rather than assumed weight. Use practice questions tagged to subcategories (REI1.1 through REI6.2) to find gaps, and keep Domain 1 solid since Domains 2 through 4 depend on it.
The ASRM 2025 scope-of-practice statement describes the pathway as medical school, a four-year obstetrics and gynecology residency, and a three-year REI fellowship. That is professional-society context rather than an ABOG blueprint, which is why this sheet is organized by the ABOG domains instead.