What is the passing score for USMLE Step 2 CK?

The minimum passing score for USMLE Step 2 CK is 218, effective for exams taken on or after July 1, 2025 (raised from 214). It is a three-digit, criterion-referenced score, so there is no fixed percentage set to fail — you pass by meeting the standard. Verify the current standard on usmle.org, as the program reviews it periodically.

How many questions are on USMLE Step 2 CK?

Step 2 CK has no more than 318 multiple-choice questions, all clinical vignettes, delivered in one 9-hour computer-based session at a Prometric center. For exams on or after May 7, 2026, the day is 16 blocks of 30 minutes (up to 20 questions each), a short tutorial, and a 55-minute break allotment. Earlier administrations used 8 blocks of 60 minutes.

What does USMLE Step 2 CK cover?

Step 2 CK tests applied clinical knowledge across the core clerkship disciplines: Medicine (55–65%), Pediatrics (17–27%), Obstetrics & Gynecology (10–20%), Psychiatry (10–15%), and Surgery (5–15%). The competencies are dominated by Patient Care — diagnosis, ordering and interpreting tests, and management — plus communication, professionalism, and patient safety.

How is Step 2 CK different from Step 1?

Step 1 tests foundational basic science (pathology, physiology, pharmacology) and is now Pass/Fail. Step 2 CK tests clinical knowledge for patient care under supervision — diagnosis and management across the clerkship disciplines — and is still scored with a three-digit number. Where Step 1 rewards mechanism, Step 2 CK rewards the next clinical decision.

How is Step 2 CK different from Step 3?

Step 2 CK is a one-day multiple-choice exam of clinical knowledge, usually taken during medical school. Step 3 is a two-day exam taken during residency that adds Computer-based Case Simulations (CCS) and focuses on independent, unsupervised practice — patient management over time, not just the single best answer.

What are the eligibility requirements for USMLE Step 2 CK?

You must be enrolled in, or a graduate of, a qualifying medical school: a US or Canadian MD program accredited by the LCME, a US DO program accredited by the COCA, or an international medical school listed in the World Directory of Medical Schools that meets ECFMG eligibility requirements.

How much does USMLE Step 2 CK cost?

The USMLE Step 2 CK registration fee for US and Canadian students and graduates (through the NBME) is about $1,020 (a dated anchor — verify on usmle.org, as fees change). International medical graduates pay the same base through ECFMG plus an international test-delivery surcharge of roughly $235 when testing outside the US and Canada.

What is the USMLE Step 2 CK pass rate?

For the most recent reporting period, first-time pass rates were about 98% for US and Canadian MD students, 96% for US and Canadian DO students, and 90% for international (non-US) students. The standard is criterion-referenced, so the rate reflects whether candidates meet the minimum proficiency standard rather than a fixed quota.

Is this USMLE Step 2 CK study guide free?

Yes — the full guide, the glossary, the concept questions, the practice questions, and the flashcards are 100% free with no account required.

What is the first-line reperfusion strategy for a STEMI?

Primary percutaneous coronary intervention (PCI) is first-line for ST-elevation myocardial infarction when it can be done promptly — ideally with a door-to-balloon time under 90 minutes at a PCI-capable center. Fibrinolytic (clot-busting) therapy is reserved for when timely PCI is not available. Give aspirin and start anticoagulation immediately. A STEMI is diagnosed on ECG by ST-segment elevation in a coronary territory; obtain the ECG within 10 minutes of arrival. Every minute of delay costs myocardium — 'time is muscle' — so reperfusion is the time-critical decision.

How is diabetic ketoacidosis (DKA) managed?

Diabetic ketoacidosis is treated with aggressive IV fluids first, then an insulin infusion, with close potassium monitoring and replacement. Insulin drives potassium into cells, so total-body potassium falls — give potassium once it is below the upper-normal range, and hold insulin if potassium is dangerously low. Correct the precipitant (often infection). DKA is defined by hyperglycemia, anion-gap metabolic acidosis, and ketones; it occurs mainly in type 1 diabetes. Switch to subcutaneous insulin only after the anion gap closes and the patient can eat.

What is the stepwise approach to managing asthma?

Asthma is managed in steps based on symptom frequency and control. A short-acting beta-agonist (SABA) relieves acute symptoms; an inhaled corticosteroid (ICS) is the cornerstone controller, stepped up to a higher-dose ICS plus a long-acting beta-agonist (LABA) as severity increases. Step down once control is sustained. Frequent reliever (SABA) use signals poor control and the need to step up controller therapy. Assess control and inhaler technique at every visit before escalating.

What are the priorities in the first hour of sepsis management?

In suspected sepsis, the early bundle is to measure lactate, draw blood cultures before antibiotics, give broad-spectrum antibiotics rapidly, and start crystalloid fluid resuscitation for hypotension or a raised lactate. Add vasopressors (norepinephrine first-line) if the patient stays hypotensive despite fluids, targeting adequate perfusion. Cultures must be drawn before antibiotics, but antibiotics should not be delayed waiting for them. Septic shock is sepsis with persistent hypotension requiring vasopressors plus an elevated lactate.

How do you work up a high anion-gap metabolic acidosis?

First confirm the acidosis with pH and bicarbonate, then calculate the anion gap (sodium minus chloride plus bicarbonate); a high gap means an unmeasured acid. Use MUDPILES — methanol, uremia, DKA, propylene glycol, isoniazid/iron, lactic acidosis, ethylene glycol, salicylates — to find the cause. A normal-gap acidosis instead points to bicarbonate loss (diarrhea, renal tubular acidosis). Check whether respiratory compensation is appropriate; if not, a mixed disorder is present.

What is the routine childhood immunization schedule based on?

The childhood immunization schedule is set annually by the CDC's Advisory Committee on Immunization Practices (ACIP). It includes vaccines such as hepatitis B at birth, DTaP, Hib, pneumococcal, polio, rotavirus, and MMR and varicella at about 12–15 months. Live vaccines (MMR, varicella) are generally avoided in pregnancy and significant immunocompromise. Step 2 CK frequently asks which vaccine is due at a given age or which is contraindicated. MMR and varicella are live attenuated vaccines, so timing and contraindications are high-yield.

What defines preeclampsia and how is it managed?

Preeclampsia is new-onset hypertension after 20 weeks of pregnancy with proteinuria or signs of end-organ dysfunction (e.g., thrombocytopenia, renal or liver involvement, or neurologic symptoms). Management is blood-pressure control, magnesium sulfate for seizure prophylaxis, and timely delivery — the only definitive cure. Magnesium sulfate prevents and treats eclamptic seizures; monitor for toxicity (loss of reflexes, respiratory depression). Severe features or worsening status push toward earlier delivery regardless of gestational age.

What are the most common causes of postpartum hemorrhage?

The classic causes of postpartum hemorrhage are the 'four Ts': Tone (uterine atony, the most common), Trauma (lacerations), Tissue (retained placenta), and Thrombin (coagulopathy). Atony is treated with uterine massage and uterotonics (oxytocin first-line), escalating to other agents, balloon tamponade, or surgery if bleeding continues. Always estimate blood loss and resuscitate while treating the cause. Uterine atony — a soft, 'boggy' uterus — is the first thing to address in postpartum bleeding.

What is first-line treatment for major depressive disorder?

First-line pharmacotherapy for major depressive disorder is a selective serotonin reuptake inhibitor (SSRI), often combined with psychotherapy such as cognitive behavioral therapy. Antidepressants take several weeks for full effect, so set expectations and follow up; assess for suicidality at the start and during dose changes. Diagnosis requires ≥5 of 9 SIG-E-CAPS symptoms for ≥2 weeks, including depressed mood or anhedonia. If one SSRI fails after an adequate trial, switch agents or augment before concluding it is treatment-resistant.

How do serotonin syndrome and neuroleptic malignant syndrome differ?

Serotonin syndrome develops within hours of a serotonergic drug and causes agitation, autonomic instability, and neuromuscular hyperactivity with clonus and hyperreflexia (lower limbs more than upper). Neuroleptic malignant syndrome develops over days after a dopamine antagonist and causes 'lead-pipe' rigidity, high fever, autonomic instability, and a markedly elevated creatine kinase. Serotonin syndrome features hyperreflexia and clonus; NMS features rigidity and hyporeflexia. Both are managed by stopping the offending drug and giving supportive care; specific agents differ (e.g., cyproheptadine vs dantrolene/bromocriptine).

How does acute appendicitis present and how is it managed?

Classic appendicitis begins as vague periumbilical pain that migrates to the right lower quadrant (McBurney point), with anorexia, nausea, low-grade fever, and rebound tenderness. CT confirms the diagnosis in adults (ultrasound first in children and pregnancy). Definitive treatment is appendectomy, with perioperative antibiotics. Rovsing, psoas, and obturator signs support the diagnosis. Delay risks perforation and peritonitis, so timely surgical evaluation is essential.

What is neuroleptic malignant syndrome's emergency management?

Neuroleptic malignant syndrome is a medical emergency: stop the causative dopamine antagonist immediately and provide aggressive supportive care — cooling, IV fluids, and monitoring for rhabdomyolysis and renal failure. Dantrolene and bromocriptine are used in severe cases. Recognize the tetrad of rigidity, fever, autonomic instability, and altered mental status. A very high creatine kinase and the recent start or dose increase of an antipsychotic are key clues. Untreated NMS carries significant mortality, so early recognition and drug withdrawal are critical.

What is the difference between sensitivity and specificity?

Sensitivity is the proportion of people with a disease who test positive (the true-positive rate); a highly sensitive test, when negative, helps rule a disease OUT (SnNout). Specificity is the proportion of people without the disease who test negative (the true-negative rate); a highly specific test, when positive, helps rule a disease IN (SpPin). Highly sensitive tests make good screening tests; highly specific tests make good confirmatory tests. Sensitivity and specificity are properties of the test and do not change with prevalence; predictive values do.

The second examination in the three-step United States Medical Licensing Examination sequence (Clinical Knowledge) — a one-day, computer-based test of no more than 318 clinical-vignette questions that assesses applying clinical science to patient care under supervision. It is still reported as a 3-digit numeric score.

The National Board of Medical Examiners — co-sponsor of the USMLE (with the FSMB) and the organization through which US and Canadian medical students register for the Step exams.

The Federation of State Medical Boards — co-sponsor of the USMLE; international medical graduates register for the Step exams through ECFMG/FSMB.

The standard Step 2 CK question format: a patient scenario (history, exam, vitals, labs, imaging) that requires you to choose the most likely diagnosis, the next best test, or the best management — applied clinical reasoning, not isolated recall.

The single most appropriate immediate action given the vignette — order the discriminating test, give the first-line treatment, or stabilize the patient — the most common task on Step 2 CK.

ST-elevation myocardial infarction — a complete coronary occlusion shown as ST-segment elevation on ECG; the time-critical treatment is reperfusion, ideally primary percutaneous coronary intervention (PCI) within 90 minutes.

diabetic ketoacidosis

A hyperglycemic emergency (mainly type 1 diabetes) with anion-gap metabolic acidosis and ketones; treated with IV fluids first, then an insulin infusion, with close potassium replacement.

Serum sodium minus (chloride plus bicarbonate); normally about 8–12 mEq/L. A high anion gap signals an added acid (the MUDPILES causes of metabolic acidosis).

Life-threatening organ dysfunction from a dysregulated host response to infection; managed with early cultures, broad-spectrum antibiotics, fluids, and lactate measurement, adding vasopressors for septic shock.

The ordered primary trauma assessment — Airway (with C-spine protection), Breathing, Circulation (hemorrhage control), Disability (neurologic), and Exposure/Environment — completed before moving to the secondary survey.

Acute inflammation of the appendix, classically periumbilical pain migrating to the right lower quadrant (McBurney point) with anorexia and rebound; treated with appendectomy and perioperative antibiotics.

A 0–10 newborn assessment at 1 and 5 minutes scoring Appearance, Pulse, Grimace, Activity, and Respiration; it guides resuscitation but does not predict long-term outcome.

developmental milestone

An age-expected skill (gross motor, fine motor, language, social) used to screen infants and children; a delay across domains prompts evaluation.

Newborn hyperbilirubinemia; physiologic jaundice appears after 24 hours and resolves in about two weeks, while jaundice in the first 24 hours or conjugated hyperbilirubinemia is pathologic.

New-onset hypertension after 20 weeks of pregnancy with proteinuria or end-organ dysfunction; managed with blood-pressure control, magnesium sulfate for seizure prophylaxis, and timely delivery.

postpartum hemorrhage

Excessive bleeding after delivery; the four Ts are Tone (atony, most common), Trauma, Tissue (retained placenta), and Thrombin (coagulopathy). Atony is treated with massage and uterotonics.

Maternal anti-Rh antibody formation when an Rh-negative mother is exposed to Rh-positive fetal blood; prevented with anti-D immune globulin (RhoGAM), which can cause hemolytic disease of the newborn in later pregnancies.

Selective serotonin reuptake inhibitor — the first-line drug class for major depressive disorder and many anxiety disorders; effects build over several weeks.

An acute, potentially life-threatening reaction to serotonergic drugs with agitation, autonomic instability, clonus, and hyperreflexia (lower limbs more than upper).

neuroleptic malignant syndrome

A reaction to dopamine-blocking drugs over days with 'lead-pipe' rigidity, high fever, autonomic instability, altered mental status, and a markedly elevated creatine kinase; stop the drug and give supportive care.

The proportion of people WITH a disease who test positive (true-positive rate); a highly sensitive test, when negative, helps rule a disease OUT (SnNout).

The proportion of people WITHOUT a disease who test negative (true-negative rate); a highly specific test, when positive, helps rule a disease IN (SpPin).

number needed to treat

The number of patients who must receive a treatment to prevent one additional bad outcome; it equals the reciprocal of the absolute risk reduction — a lower NNT means a more effective treatment.

A patient with decision-making capacity voluntarily agreeing to a treatment after disclosure of the diagnosis, risks, benefits, and alternatives; capacity is a clinical, decision-specific judgment, distinct from legal competency.

What is the first-line reperfusion strategy for a STEMI?

Primary percutaneous coronary intervention (PCI) is first-line for ST-elevation myocardial infarction when it can be done promptly — ideally with a door-to-balloon time under 90 minutes at a PCI-capable center. Fibrinolytic (clot-busting) therapy is reserved for when timely PCI is not available. Give aspirin and start anticoagulation immediately.

How is diabetic ketoacidosis (DKA) managed?

Diabetic ketoacidosis is treated with aggressive IV fluids first, then an insulin infusion, with close potassium monitoring and replacement. Insulin drives potassium into cells, so total-body potassium falls — give potassium once it is below the upper-normal range, and hold insulin if potassium is dangerously low. Correct the precipitant (often infection).

FREE USMLE Step 2 CK Study Guide 2026 + Readiness Score

Q: Is USMLE Step 2 CK pass/fail or scored?

Step 2 CK is still scored. It is reported as a three-digit numeric score (the same scale the old Step 1 used) — not Pass/Fail. Only Step 1 became Pass/Fail (in January 2022). Because Step 1 is now Pass/Fail, Step 2 CK has taken on added importance for residency applications, since it is the main numeric USMLE score programs see.

This free USMLE Step 2 CK study guide walks through the highest-yield clinical knowledge the exam tests — organized by the clerkship disciplines you rotate through, the way the exam asks them.^[1]

It is interactive, not a wall of text: every discipline has worked clinical reasoning, comparison tables, labeled diagrams, and built-in flashcards — taught to the level a future physician needs to manage patients under supervision.

Read it discipline by discipline, then round out your prep with our practice questions and flashcards. Step 2 CK has no more than 318 questions in a single 9-hour day and — unlike Step 1 — is still reported as a 3-digit numeric score, with a minimum passing score of 218.^[3]

USMLE Step 2 CK Exam Snapshot

USMLE Step 2 CK at a glance (2026)
Detail	USMLE Step 2 CK
Questions	No more than 318 multiple-choice clinical vignettes
Format	One 9-hour computer-based session at a Prometric center
Blocks	On/after May 7, 2026: 16 blocks of 30 min (≤20 Qs each); earlier: 8 blocks of 60 min
Scoring	3-digit numeric score (still scored — NOT pass/fail)
Minimum passing score	218 (effective July 1, 2025; raised from 214)
Application fee	~$1,020 via NBME (dated anchor — verify on usmle.org)
Eligibility	LCME (MD), COCA (DO), or ECFMG-eligible international medical student/graduate
Issued by	USMLE program — a joint program of the FSMB and NBME

Step 2 CK is a clinical-reasoning exam. Its competencies are dominated by Patient Care — diagnosis (16–20%), interpreting laboratory and diagnostic studies (13–17%), and management (12–16%) — not the foundational-science recall that ruled Step 1.^[2] Every question is a that usually asks for the in a patient’s care.

How USMLE Step 2 CK Is Built

Step 2 CK is constructed from an integrated content outline that classifies every question along several dimensions at once.^[2] The clinical-science (discipline) dimension is the rotation the question belongs to; the physician-competency dimension is the clinical task it measures; and the organ-system dimension is the body system it concerns. This guide teaches by discipline — internal medicine, surgery and emergency medicine, pediatrics, OB/GYN, and psychiatry, plus a cross-cutting module — because that is how you build clinical knowledge and how the largest exam shares are organized.

Step 2 CK weighting by clinical discipline (official ranges)

Medicine (Internal Medicine)

55–65%

Pediatrics

17–27%

Obstetrics & Gynecology

10–20%

Psychiatry

10–15%

Surgery

5–15%

Medicine alone is the majority of the exam — master it first, then pediatrics, OB/GYN, psychiatry, and surgery.

The five Step 2 CK clinical sciences and their official weight ranges. Medicine alone is the majority of the exam; pediatrics is second. These six teaching modules cover all five disciplines plus a cross-cutting module for biostatistics, ethics, safety, and prevention.

Step 2 CK is a Patient Care exam (competency ranges)

Patient Care: Diagnosis

16–20%

Patient Care: Laboratory / Diagnostic Studies

13–17%

Patient Care: Mixed Management

12–16%

Patient Care: Pharmacotherapy

8–12%

Patient Care: Clinical Interventions

6–10%

Patient Care: Health Maintenance / Prevention

5–10%

Patient Care: Prognosis / Outcome

5–9%

Systems-based Practice & Patient Safety

5–7%

Professionalism

5–7%

Practice-based Learning & Improvement

3–5%

Where Step 1 rewarded mechanism, Step 2 CK rewards the next clinical decision — diagnosis, the right test, and management.

The physician competencies Step 2 CK measures, dominated by Patient Care — diagnosis, interpreting tests, and management. Unlike Step 1, applying foundational science and the history/physical are coded at roughly 0%, because Step 2 CK is about the next clinical decision.

Step 2 CK is reported as a 3-digit numeric score — it did not become pass/fail. The minimum passing score is 218 (effective July 1, 2025; previously 214).^[3]

Because Step 1 is now pass/fail, residency programs lean on the Step 2 CK number, so it carries real weight for the Match. Step 2 CK sits between Step 1 (foundational sciences) and Step 3 (independent practice).

How to attack any Step 2 CK clinical vignette

1
Read the last line first
Identify the task: most likely diagnosis, the next best test, the best management, or the prognosis.
2
Build the patient picture
Age, sex, vitals, risk factors, the key history, exam finding, and the most discriminating lab or image.
3
Narrow the differential
From the vignette, list the 2–3 likeliest diagnoses before reading the options.
4
Confirm or treat
Choose the next best step — order the discriminating test, or, when the diagnosis is clear and time-critical, treat first.
5
Pick the single best answer
Match the choice to the exact task asked — most-likely cause, first-line management, or correct interpretation.

Step 2 CK almost never asks a fact in isolation — it gives you a patient and asks for the next clinical decision.

A repeatable five-step method for any Step 2 CK vignette: read the task, build the patient picture, narrow the differential, confirm or treat, then pick the single best answer.

Internal Medicine

Internal medicine is the single largest discipline on Step 2 CK (55–65%) — master it and you have most of the exam.^[2] Think in organ systems and, for each presentation, the diagnostic test that confirms it and the first-line treatment.

Cardiology & Pulmonology

In cardiology, anchor on chest-pain triage: get an ECG within 10 minutes and a troponin. means a — reperfuse immediately with primary PCI (goal under 90 minutes); a rising troponin without ST-elevation is NSTEMI; ischemic symptoms with normal troponin are unstable angina.

Know heart-failure management (diuretics for congestion; ACE inhibitors, beta-blockers, and aldosterone antagonists improve survival in reduced ejection fraction), atrial fibrillation (rate control plus anticoagulation by CHA₂DS₂-VASc), and the murmurs (aortic stenosis: a crescendo-decrescendo systolic murmur radiating to the carotids). In pulmonology, separate obstructive disease (asthma, COPD; a low FEV₁/FVC ratio) from restrictive disease, and learn the asthma step-up: a short-acting beta-agonist reliever plus an inhaled corticosteroid controller.

Acute chest pain → suspected ACS (high-yield pathway)

1
Acute chest pain → immediate ECG (within 10 min) + troponin
Stabilize: oxygen if hypoxic, aspirin, nitrates, pain control. Continuous monitoring.
2
ST-elevation (STEMI)?
If yes → reperfuse NOW: primary PCI (goal <90 min). Fibrinolytics only if timely PCI is unavailable.
3
No ST-elevation → trend troponin + risk-stratify
Rising troponin = NSTEMI; normal troponin with ischemic symptoms = unstable angina.
4
NSTEMI / unstable angina
Antiplatelet + anticoagulation; early invasive angiography for high-risk features.
5
Low-risk, troponin negative
Consider stress testing or CT coronary angiography to rule out coronary disease before discharge.

ECG first, then split on ST-elevation. STEMI = reperfuse now (PCI); no elevation = trend troponin and risk-stratify.

The high-yield acute chest-pain pathway: ECG first, then split on ST-elevation. A STEMI is reperfused immediately (primary PCI); without ST-elevation, trend troponin and risk-stratify into NSTEMI, unstable angina, or a low-risk rule-out.

Renal, Endocrine, GI, Heme & Infectious Disease

Work through the remaining systems by topic:

For renal and acid–base questions, classify with pH, PCO₂, and bicarbonate, then use the for metabolic acidosis (MUDPILES), and manage acute kidney injury by cause (prerenal, intrinsic, postrenal).
In endocrine, recognize — IV fluids first, then insulin, with potassium replacement — and the thyroid patterns (low TSH with high T₄ in hyperthyroidism).
In GI, know GI bleeding triage, cirrhosis complications, and pancreatitis.
In hematology, work up anemia by mean corpuscular volume (microcytic: iron deficiency, thalassemia; macrocytic: B₁₂/folate).
For infectious disease, start care early: cultures before antibiotics, then broad-spectrum antibiotics, fluids, and a lactate, adding norepinephrine for septic shock.^[8]

High-yield internal-medicine 'best test / first treatment' pairs
Presentation	Confirming test	First-line management
STEMI (ST-elevation on ECG)	ECG + troponin	Primary PCI (goal <90 min); aspirin + anticoagulation
Suspected pulmonary embolism	CT pulmonary angiography	Anticoagulation (heparin/DOAC)
Diabetic ketoacidosis	Glucose, anion gap, ketones, K⁺	IV fluids → insulin infusion → replace K⁺
Community-acquired pneumonia	Chest X-ray	Empiric antibiotics per severity/site
Acute kidney injury	BUN/creatinine, urinalysis, FeNa	Treat the cause; avoid nephrotoxins
Iron-deficiency anemia	Ferritin (low), microcytic MCV	Oral iron; find the source of loss

Checkpoint · Internal Medicine

Question 1 of 10

A 62-year-old woman arrives at a rural hospital with 50 minutes of chest pain and 2-mm ST elevations in leads II, III, and aVF. The nearest PCI-capable center is a 3-hour transfer away. She has no contraindications to thrombolytics. What is the best immediate reperfusion treatment?

Surgery & Emergency Medicine

Surgery is 5–15% of Step 2 CK, but it overlaps heavily with the acute-care questions woven through medicine.^[2] The recurring task is recognizing a surgical emergency and choosing whether to image, operate, or stabilize first.

Acute Abdomen & Perioperative Care

Localize abdominal pain: right-lower-quadrant migration suggests (confirm with CT in adults, ultrasound in children and pregnancy; treat with appendectomy)^[9]; right-upper-quadrant pain after fatty food suggests cholecystitis (ultrasound first); and sudden, severe, diffuse pain with free air under the diaphragm suggests a perforated viscus (emergency surgery).

Bowel obstruction shows distension, vomiting, and air-fluid levels. Perioperatively, know the common postoperative fevers by timeline (the “five Ws”: Wind/atelectasis days 1–2, Water/UTI days 3–5, Wound, Walking/DVT, and Wonder-drugs), and prevent venous thromboembolism in surgical patients.

Trauma & Emergencies (ABCDE)

For trauma, work the in order and fix each life threat before moving on: Airway with cervical-spine protection, Breathing (treat a tension pneumothorax with needle decompression then a chest tube), Circulation (two large-bore IVs, control hemorrhage, give blood), Disability (a rapid neurologic check), and Exposure with hypothermia prevention.

Recognize the high-mortality emergencies that demand immediate action: tension pneumothorax, cardiac tamponade (Beck triad: hypotension, distended neck veins, muffled heart sounds), and massive hemorrhage. Anaphylaxis is treated with intramuscular epinephrine first, before anything else.

The trauma primary survey — ABCDE, in order

1
A — Airway (with C-spine protection)
Is the airway patent? Talk to the patient. Intubate if obstructed or GCS ≤ 8; keep the cervical spine immobilized.
2
B — Breathing
Inspect, auscultate, and treat life threats now — tension pneumothorax (needle then chest tube), open chest wound, flail chest.
3
C — Circulation (control hemorrhage)
Two large-bore IVs, stop external bleeding, give blood/fluids; find occult bleeding (chest, abdomen, pelvis, long bones).
4
D — Disability
Rapid neurologic check: GCS, pupils, gross motor — screen for a focal deficit or rising intracranial pressure.
5
E — Exposure / Environment
Fully undress to find every injury, then prevent hypothermia (warm the patient and the fluids).

Work A→B→C→D→E and fix each life threat before moving on — never skip ahead to a later letter.

The trauma primary survey — Airway, Breathing, Circulation, Disability, Exposure — performed strictly in order, fixing each life threat before moving to the next letter.

Surgical and emergency 'can't-miss' diagnoses
Emergency	Key clue	Immediate action
Tension pneumothorax	Hypotension, absent breath sounds, tracheal deviation	Needle decompression, then chest tube
Cardiac tamponade	Beck triad; pulsus paradoxus	Pericardiocentesis
Perforated viscus	Sudden diffuse pain, free air under diaphragm	Emergency laparotomy
Anaphylaxis	Urticaria, wheeze, hypotension after exposure	Intramuscular epinephrine
Appendicitis	Periumbilical → RLQ pain, rebound	Appendectomy + perioperative antibiotics

Checkpoint · Surgery & Emergency Medicine

Question 1 of 10

A 19-year-old college athlete reports one day of periumbilical pain that has now settled into the right lower quadrant, along with loss of appetite and one episode of vomiting. He has rebound tenderness at a point two-thirds of the way from the umbilicus to the anterior superior iliac spine. Which physical exam landmark is being described?

Pediatrics

Pediatrics is the second-largest discipline (17–27%).^[2] It rewards knowing the age-appropriate normal — milestones, vaccines, and growth — so you can spot the abnormal.

Newborn, Development & Vaccines

At birth, the (at 1 and 5 minutes) guides resuscitation. Distinguish : jaundice after 24 hours that resolves within about two weeks is physiologic, while jaundice in the first 24 hours or conjugated (direct) hyperbilirubinemia is pathologic and needs prompt workup (treat unconjugated hyperbilirubinemia with phototherapy to prevent kernicterus).

Know the major (social smile ~2 months, sits unsupported ~6 months, first words ~12 months, two-word phrases ~24 months) and the routine childhood vaccine schedule set by the CDC’s ACIP — hepatitis B at birth; DTaP, Hib, pneumococcal, polio, and rotavirus in infancy; MMR and varicella (both live vaccines) around 12–15 months.^[10]

Common Illness & Pediatric Emergencies

Recognize the classic pediatric infections by their patterns: croup (barking cough, “steeple sign,” parainfluenza), epiglottitis (drooling, tripod posture, a now-rare emergency), bronchiolitis (RSV in infants), and the childhood exanthems.

High-yield emergencies include intussusception (“currant-jelly” stool, a target sign on ultrasound), pyloric stenosis (non-bilious projectile vomiting, an “olive” mass, hypochloremic hypokalemic metabolic alkalosis), and febrile seizures (usually benign, ages 6 months to 5 years). Always weigh non-accidental trauma when an injury pattern does not match the history.

High-yield pediatric milestones and patterns
Finding / age	Pattern	Significance
Social smile	~2 months	Earliest social milestone
Sits unsupported	~6 months	Gross-motor milestone
First words	~12 months	Language milestone
Projectile non-bilious vomiting	3–6 weeks old, 'olive' mass	Pyloric stenosis
Currant-jelly stool + target sign	6–36 months	Intussusception
Barking cough + steeple sign	Parainfluenza	Croup

Checkpoint · Pediatrics

Question 1 of 10

A 10-month-old boy is brought to the emergency department after his parents found him drowsy and difficult to rouse following a morning of episodic screaming. He has had no diarrhea or vomiting. On examination he is pale and lethargic, but his abdomen is soft with a vague fullness on the right. The triage nurse is focused on the altered mental status and orders a head CT. Which alternative diagnosis must be actively excluded before pursuing a neurologic workup?

Obstetrics & Gynecology

Obstetrics and gynecology is 10–20% of Step 2 CK.^[2] Obstetrics rewards a timeline — what to screen for and when — and the recognition of the dangerous complications.

Prenatal Care, Labor & Complications

Know the prenatal timeline: confirm pregnancy and dating, screen for gestational diabetes at 24–28 weeks, and give to Rh-negative mothers (around 28 weeks and after delivery of an Rh-positive infant) to prevent isoimmunization.

The high-yield complications are (new-onset hypertension after 20 weeks with proteinuria or end-organ dysfunction — control blood pressure, give magnesium sulfate for seizure prophylaxis, and deliver)^[11], gestational diabetes, the third-trimester bleeds (placenta previa: painless bleeding; placental abruption: painful bleeding with a rigid uterus), and (the four Ts — Tone, Trauma, Tissue, Thrombin — with uterine atony the most common cause).

Gynecology & Contraception

On the gynecology side, work up abnormal uterine bleeding by age, evaluate an adnexal mass with the patient’s age and ultrasound features in mind, and rule out ectopic pregnancy in any reproductive-age woman with pelvic pain and a positive pregnancy test (a positive test with an empty uterus on ultrasound is ectopic until proven otherwise).

Know cervical-cancer screening (Pap smear with HPV co-testing on the recommended interval), the menopause transition, and the contraceptive options with their key contraindications (combined estrogen-containing methods are avoided with a history of venous thromboembolism, migraine with aura, or heavy smoking over age 35).

High-yield obstetric complications
Complication	Key clue	Management
Preeclampsia	BP ≥140/90 after 20 wk + proteinuria/end-organ	BP control, magnesium sulfate, deliver
Placenta previa	Painless third-trimester bleeding	Ultrasound; no digital exam; plan delivery
Placental abruption	Painful bleeding, rigid uterus	Stabilize; deliver if unstable
Postpartum hemorrhage (atony)	Soft 'boggy' uterus after delivery	Massage + uterotonics (oxytocin first)
Ectopic pregnancy	Positive βhCG, empty uterus, pelvic pain	Methotrexate or surgery by stability

Checkpoint · Obstetrics & Gynecology

Question 1 of 10

A 23-year-old woman presents to the emergency department with 1 day of right-sided pelvic pain and a small amount of dark vaginal spotting. Her last menstrual period was about 6 weeks ago, and a urine pregnancy test is positive. Her vital signs are stable. Which single test best determines whether the pregnancy is inside or outside the uterus?

Psychiatry

Psychiatry is 10–15% of Step 2 CK.^[2] It rewards the diagnostic criteria (especially the time courses) and the first-line treatments, plus a short list of dangerous drug reactions.

Mood, Anxiety, Psychotic & Substance Disorders

Master the time courses that separate the diagnoses: major depressive disorder requires symptoms for at least 2 weeks (≥5 of 9, including depressed mood or anhedonia — the SIG-E-CAPS mnemonic); a manic episode lasting at least a week defines bipolar I; schizophrenia requires at least 6 months of symptoms (schizophreniform 1–6 months, brief psychotic disorder under a month).

For anxiety, distinguish generalized anxiety, panic disorder, OCD, and PTSD by their features. In substance use, recognize the intoxication and withdrawal syndromes — alcohol withdrawal can progress to life-threatening delirium tremens (treat with benzodiazepines), and opioid overdose (pinpoint pupils, respiratory depression) is reversed with naloxone.

Psychopharmacology & Emergencies

An is first-line for major depression and most anxiety disorders; antidepressants take several weeks to work, so set expectations and reassess for suicidality at the start and during dose changes.

Know the two psychiatric drug emergencies cold: (within hours of a serotonergic drug; agitation, autonomic instability, clonus and hyperreflexia) and (over days after a dopamine antagonist; “lead-pipe” rigidity, high fever, autonomic instability, and a markedly elevated creatine kinase).

Both are treated by stopping the offending drug and giving supportive care, with specific agents in severe cases. Lithium and the antipsychotics carry high-yield monitoring requirements and side effects (tardive dyskinesia, metabolic effects).

Psychiatric diagnoses by time course
Disorder	Required duration	First-line treatment
Major depressive disorder	≥2 weeks (≥5/9 symptoms)	SSRI + psychotherapy
Manic episode (bipolar I)	≥1 week	Mood stabilizer / antipsychotic
Brief psychotic disorder	<1 month	Antipsychotic; supportive care
Schizophreniform disorder	1–6 months	Antipsychotic
Schizophrenia	≥6 months	Antipsychotic (long-term)
Generalized anxiety disorder	≥6 months	SSRI/SNRI + CBT

Checkpoint · Psychiatry

Question 1 of 10

A 35-year-old man with major depressive disorder has taken sertraline at a maximal dose for 8 weeks with only minimal improvement and good adherence. He tolerates the medication well. According to a measurement-based stepwise approach, which next step is most appropriate?

Cross-Cutting Clinical Science

A predictable cluster of points threads through every discipline: biostatistics and evidence-based medicine, medical ethics, patient safety and systems-based practice, and preventive medicine.^[2] These are reliable, rule-based points — learn them once and bank them across the exam.

Biostatistics & Evidence-Based Medicine

Know the test-performance quartet cold: (a negative on a sensitive test rules OUT, “SnNout”), (a positive on a specific test rules IN, “SpPin”), and the predictive values, where rises with prevalence.^[12] Sensitivity and specificity are fixed properties of the test; predictive values depend on prevalence.

For study design, the cohort study yields relative risk and the case-control study yields the odds ratio, and the randomized controlled trial is the gold standard for causation. Calculate the as the reciprocal of the absolute risk reduction. Recognize the common biases (selection, recall, lead-time, length-time).

Reading a diagnostic test — sensitivity, specificity & predictive value

Sensitivity (SnNout)TP ÷ (TP + FN)

A NEGATIVE on a highly sensitive test rules a disease OUT. Good for screening.

Specificity (SpPin)TN ÷ (TN + FP)

A POSITIVE on a highly specific test rules a disease IN. Good for confirmation.

Positive predictive valueTP ÷ (TP + FP)

Probability a positive test is a true case — rises with disease prevalence.

Negative predictive valueTN ÷ (TN + FN)

Probability a negative test is truly disease-free — falls with prevalence.

Sensitivity and specificity are properties of the TEST; predictive values depend on PREVALENCE.

Reading a diagnostic test: sensitivity (SnNout) and specificity (SpPin) are fixed properties of the test, while positive and negative predictive value depend on disease prevalence.

Ethics, Safety & Preventive Medicine

Ethics is heavily tested. requires decision-making capacity, disclosure, understanding, and voluntariness; capacity is a clinical, decision-specific judgment (distinct from legal competency), and a patient with capacity may refuse treatment. Honor autonomy, confidentiality (with its safety exceptions), and the minor-consent exceptions (emergencies, STIs, contraception, pregnancy, substance use).

For patient safety, distinguish errors and the systems response — the “Swiss cheese” model, root-cause analysis (reactive) versus failure mode and effects analysis (proactive), and the duty to disclose errors honestly. In preventive medicine, know the major USPSTF-style screenings (colorectal cancer from age 45, cervical and breast cancer screening, lipid and diabetes screening) and the levels of prevention (primary prevents disease, secondary detects it early, tertiary limits its impact).

Cross-cutting high-yield facts
Concept	Definition	Exam pearl
Sensitivity (SnNout)	TP ÷ (TP + FN)	Negative on a sensitive test rules a disease OUT
Specificity (SpPin)	TN ÷ (TN + FP)	Positive on a specific test rules a disease IN
Number needed to treat	1 ÷ absolute risk reduction	Lower NNT = more effective treatment
Decision-making capacity	Clinical, decision-specific judgment	A patient with capacity may refuse care
Primary prevention	Prevents disease before it occurs	Vaccination, smoking cessation counseling

Checkpoint · Cross-Cutting Clinical Science

Question 1 of 10

A 60-year-old woman presents with suspected pulmonary embolism, and a high-sensitivity D-dimer is markedly elevated, but she has a high pretest probability. How should the elevated D-dimer be interpreted in this context?

How to Use This Study Guide

Work through the guide one discipline at a time. After each one, check it off in the contents to raise your exam-readiness score, then drill the same content in our free practice questions and flashcards — timed practice with reasoned explanations is what moves clinical knowledge into exam-day performance.

Lead with internal medicine. At 55–65% it is the majority of the exam — the deepest understanding pays off most here.
Think in next steps. For each presentation, learn the confirming test and the first-line treatment, because Step 2 CK almost always asks for the next best action.
Use the time courses. In psychiatry especially, the duration of symptoms usually pins the diagnosis before you read the options.
Bank the rule sets. ABCDE, the four Ts of postpartum hemorrhage, MUDPILES, and the sensitivity/specificity rules are guaranteed, reliable points.
Aim for a strong number. Because Step 1 is pass/fail, the Step 2 CK three-digit score carries real weight for residency — build a comfortable margin above 218.
Then prove it. When a discipline feels solid, confirm with our practice questions before exam day, and revisit Step 1 mechanisms or Step 3 management as needed.

Common concepts USMLE Step 2 CK candidates study and get asked — each answered briefly and backed by an official source (NIH/NCBI, MedlinePlus, or CDC). Tap any card to test yourself.

USMLE Step 2 CK Concept Questions

USMLE Step 2 CK Glossary

Key USMLE Step 2 CK terms in one place. Hover any dotted term throughout the guide for its definition; the full list is below.

USMLE Step 2 CK: The second examination in the three-step United States Medical Licensing Examination sequence (Clinical Knowledge) — a one-day, computer-based test of no more than 318 clinical-vignette questions that assesses applying clinical science to patient care under supervision. It is still reported as a 3-digit numeric score.
NBME: The National Board of Medical Examiners — co-sponsor of the USMLE (with the FSMB) and the organization through which US and Canadian medical students register for the Step exams.
FSMB: The Federation of State Medical Boards — co-sponsor of the USMLE; international medical graduates register for the Step exams through ECFMG/FSMB.
clinical vignette: The standard Step 2 CK question format: a patient scenario (history, exam, vitals, labs, imaging) that requires you to choose the most likely diagnosis, the next best test, or the best management — applied clinical reasoning, not isolated recall.
next best step: The single most appropriate immediate action given the vignette — order the discriminating test, give the first-line treatment, or stabilize the patient — the most common task on Step 2 CK.
STEMI: ST-elevation myocardial infarction — a complete coronary occlusion shown as ST-segment elevation on ECG; the time-critical treatment is reperfusion, ideally primary percutaneous coronary intervention (PCI) within 90 minutes.
diabetic ketoacidosis: A hyperglycemic emergency (mainly type 1 diabetes) with anion-gap metabolic acidosis and ketones; treated with IV fluids first, then an insulin infusion, with close potassium replacement.
anion gap: Serum sodium minus (chloride plus bicarbonate); normally about 8–12 mEq/L. A high anion gap signals an added acid (the MUDPILES causes of metabolic acidosis).
sepsis: Life-threatening organ dysfunction from a dysregulated host response to infection; managed with early cultures, broad-spectrum antibiotics, fluids, and lactate measurement, adding vasopressors for septic shock.
ABCDE survey: The ordered primary trauma assessment — Airway (with C-spine protection), Breathing, Circulation (hemorrhage control), Disability (neurologic), and Exposure/Environment — completed before moving to the secondary survey.
appendicitis: Acute inflammation of the appendix, classically periumbilical pain migrating to the right lower quadrant (McBurney point) with anorexia and rebound; treated with appendectomy and perioperative antibiotics.
APGAR score: A 0–10 newborn assessment at 1 and 5 minutes scoring Appearance, Pulse, Grimace, Activity, and Respiration; it guides resuscitation but does not predict long-term outcome.
developmental milestone: An age-expected skill (gross motor, fine motor, language, social) used to screen infants and children; a delay across domains prompts evaluation.
neonatal jaundice: Newborn hyperbilirubinemia; physiologic jaundice appears after 24 hours and resolves in about two weeks, while jaundice in the first 24 hours or conjugated hyperbilirubinemia is pathologic.
preeclampsia: New-onset hypertension after 20 weeks of pregnancy with proteinuria or end-organ dysfunction; managed with blood-pressure control, magnesium sulfate for seizure prophylaxis, and timely delivery.
postpartum hemorrhage: Excessive bleeding after delivery; the four Ts are Tone (atony, most common), Trauma, Tissue (retained placenta), and Thrombin (coagulopathy). Atony is treated with massage and uterotonics.
Rh isoimmunization: Maternal anti-Rh antibody formation when an Rh-negative mother is exposed to Rh-positive fetal blood; prevented with anti-D immune globulin (RhoGAM), which can cause hemolytic disease of the newborn in later pregnancies.
SSRI: Selective serotonin reuptake inhibitor — the first-line drug class for major depressive disorder and many anxiety disorders; effects build over several weeks.
serotonin syndrome: An acute, potentially life-threatening reaction to serotonergic drugs with agitation, autonomic instability, clonus, and hyperreflexia (lower limbs more than upper).
neuroleptic malignant syndrome: A reaction to dopamine-blocking drugs over days with 'lead-pipe' rigidity, high fever, autonomic instability, altered mental status, and a markedly elevated creatine kinase; stop the drug and give supportive care.
sensitivity: The proportion of people WITH a disease who test positive (true-positive rate); a highly sensitive test, when negative, helps rule a disease OUT (SnNout).
specificity: The proportion of people WITHOUT a disease who test negative (true-negative rate); a highly specific test, when positive, helps rule a disease IN (SpPin).
positive predictive value: The probability that a person with a positive test truly has the disease; it rises as disease prevalence rises (and falls as prevalence falls).
number needed to treat: The number of patients who must receive a treatment to prevent one additional bad outcome; it equals the reciprocal of the absolute risk reduction — a lower NNT means a more effective treatment.
informed consent: A patient with decision-making capacity voluntarily agreeing to a treatment after disclosure of the diagnosis, risks, benefits, and alternatives; capacity is a clinical, decision-specific judgment, distinct from legal competency.

USMLE Step 2 CK Study Guide FAQ

Step 2 CK is still scored. It is reported as a three-digit numeric score (the same scale the old Step 1 used) — not Pass/Fail. Only Step 1 became Pass/Fail (in January 2022). Because Step 1 is now Pass/Fail, Step 2 CK has taken on added importance for residency applications, since it is the main numeric USMLE score programs see.

References

1.USMLE Program (FSMB and NBME). “Step 2 CK Overview.” usmle.org. ↑
2.USMLE Program (FSMB and NBME). “Step 2 CK Content Outline and Specifications.” usmle.org. ↑
3.USMLE Program (FSMB and NBME). “Change to Step 2 CK Passing Standard Begins July 1, 2025.” usmle.org. ↑
4.USMLE Program (FSMB and NBME). “Test Delivery Software Updates: Step 2 CK and Step 1 Coming May 2026.” usmle.org. ↑
5.USMLE Program (FSMB and NBME). “Bulletin of Information: Eligibility.” usmle.org. ↑
6.USMLE Program (FSMB and NBME). “Performance Data.” usmle.org. ↑
7.National Institutes of Health (NIH). “ST-Segment Elevation Myocardial Infarction (StatPearls).” ncbi.nlm.nih.gov. ↑
8.National Institutes of Health (NIH). “Sepsis (StatPearls).” ncbi.nlm.nih.gov. ↑
9.National Institutes of Health (NIH). “Appendicitis (StatPearls).” ncbi.nlm.nih.gov. ↑
10.Centers for Disease Control and Prevention (CDC). “Child and Adolescent Immunization Schedule.” cdc.gov. ↑
11.National Institutes of Health (NIH). “Preeclampsia (StatPearls).” ncbi.nlm.nih.gov. ↑
12.Centers for Disease Control and Prevention (CDC). “Principles of Epidemiology: Validity of Screening Tests.” cdc.gov. ↑
101.National Institutes of Health (NIH). “Diabetic Ketoacidosis (StatPearls).” ncbi.nlm.nih.gov, accessed 19 June 2026. ↑
102.National Institutes of Health (NIH). “Asthma (StatPearls).” ncbi.nlm.nih.gov, accessed 19 June 2026. ↑
103.National Institutes of Health (NIH). “High Anion Gap Metabolic Acidosis (StatPearls).” ncbi.nlm.nih.gov, accessed 19 June 2026. ↑
104.National Institutes of Health (NIH). “Neonatal Jaundice (StatPearls).” ncbi.nlm.nih.gov, accessed 19 June 2026. ↑
105.National Institutes of Health (NIH). “Postpartum Hemorrhage (StatPearls).” ncbi.nlm.nih.gov, accessed 19 June 2026. ↑
106.National Institutes of Health (NIH). “Major Depressive Disorder (StatPearls).” ncbi.nlm.nih.gov, accessed 19 June 2026. ↑
107.National Institutes of Health (NIH). “Serotonin Syndrome (StatPearls).” ncbi.nlm.nih.gov, accessed 19 June 2026. ↑
108.National Institutes of Health (NIH). “Neuroleptic Malignant Syndrome (StatPearls).” ncbi.nlm.nih.gov, accessed 19 June 2026. ↑

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