Official Step 2 CK Practice Exam - Answers & Explanations

Updated: Aug 28

Practice exam: http://orientation.nbme.org/Launch/USMLE/STPF1

Please note: The HY Medicine is in no way affiliated with the Federation of State

Medical Boards (FSMB) or the National Board of Medical Examiners® (NBME®)


BLOCK 1


1) Alcohol

• Alcohol → ↑ GGT


2) Herpes Zoster • Vesicular rash in a dermatomal distribution • Shingles can be triggered by severe physical stress (eg, chemotherapy) or immunosuppressed states


3) Haemophilus ducreyi • Multiple ulcers with gray/yellow exudate • Chancroid (H ducreyi) and HSV present with painful initial lesions; Granuloma inguinal (Klebsiella granulomatis), Syphilis (Treponemia pallidum), and Lymphogranuloma venereum (C trachomatis) do not have initial painful lesions


4) Excision of the lesion

• This lesion is concerning for cancer and should be completely excised


5) Adverse effects of medication • ACEi (eg, lisinopril) and potassium-sparing diuretics (eg, spironolactone) → hyperkalemia


6) Compression of the lateral femoral cutaneous nerve • Lateral femoral cutaneous nerve provides sensory innervation to the anterior and lateral thigh • Hematoma → compression of the lateral femoral cutaneous nerve → ↓ sensation (hematoma doesn’t directly cause ↓ sensation, but rather through nerve compression)


7) Reassurance • Moro reflex is normal until ~4 months


8) Ultrasonography of the upper abdomen • Intermittent, acute RUQ pain in an obese woman = biliary colic • RUQ ultrasound → visualization of biliary stones; HIDA scan is useful when U/S findings are equivocal • Tx: Elective cholecystectomy


9) Arteriovenous fistula

• Post-traumatic AV fistula → continuous bruit (→ buzzing sensation) + palpable thrill + no mass

• DDx: pseudoaneurysm → systolic bruit + pulsatile mass


10) Ultrasonography

• Ultrasound should be used to accurately assess this woman gestational age (LMP unknown)

• The most common cause of abnormal MSAFP is incorrect dating (ie, underestimation of gestational age)


11) Thrombotic thrombocytopenic purpura • Pentad: fever, microangiopathic hemolytic anemia (→ ↑ LDH & fragmented erythrocytes), thrombocytopenia (→ scattered petechiae), acute kidney injury (↑ BUN & creatinine), neurologic symptoms (confusion)


12) Systemic lupus erythematosus • ⊕ ANA (sensitive) and ⊕ anti-DNA (specific) = SLE


13) Measurement of serum insulin and C-peptide concentrations • Hypoglycemia in a nurse is suspicious for factitious disorder imposed on self (aka Munchausen syndrome)

• Exogenous insulin use: ↑ serum insulin, ↓ C-peptide

• C-peptide level helps distinguish exogenous insulin use from insulinoma (high C- peptide)


14) Exercise and weight reduction program

• In obese individuals, the most effective non-pharmacologic approach to reduce blood pressure is weight loss

• Urinalysis and renal U/S exclude renal HTN (eg, fibromuscular dysplasia, Conn syndrome)


15) Mastoiditis

• Complication of acute otitis media → otalgia, deviation of ear, inflammation of mastoid

• Tx: IV antibiotics


16) Vasculitis • Granulomatosis with polyangiitis (Wegener) → upper respiratory tract (eg, sinus congestion), lower respiratory tract (eg, cough + sputum), and renal (eg, hematuria, ↑ BUN & creatinine) involvement

• ⊕ c-ANCA • Tx: cyclophosphamide, corticosteroids


17) Decreased gluconeogenesis • Von Gierke disease: deficiency of glucose-6-phosphatase → inability of liver to regulate blood glucose → hepatomegaly + severe fasting hypoglycemia

18) Ventilation-perfusion mismatch • Pulmonary embolism → pleuritic chest pain, shortness of breath, tachypnea


19) Endometriosis

• Dysmenorrhea + Infertility

• Presence of secretory endometrium rules out anovulation; Progesterone (secreted by the corpus luteum during ovulatory cycles) → differentiation of proliferative endometrium into secretory endometrium


20) Decreasing myocardial contractility • β-bockers (and ynon-dihydropyradine CCBs) → ↓ contractility & heart rate → ↓ myocardial O2 demand



21) Alcohol withdrawal

• Agitation, tremulousness, uncooperative, and lack of orientation after an unexpected admission to the hospital (unanticipated detox) • DDx: fate embolism → respiratory distress, petechial rash, neurologic dysfunction


22) Dermatomysositis • Proximal muscle weakness + Gottron papules (flat-topped red papules over all knuckles) + heliotrope rash (purple-red discoloration over the eyelids)


23) Metabolic acidosis, respiratory compensation • ↓ pH = acidosis • ↓ HCO3− = metabolic acidosis, ↓ CO2 = respiratory compensation

Winter formula → predicted respiratory compensation


24) Cryptosporidium parvumCryptosporidium → severe watery diarrhea + weight loss • Mycobacterium avium complex and CMV diarrhea present once CD4 <50


25) ErythromycinMycoplasma pneumonia → indolent malaise, fever, persistent dry cough

• CXR: interstitial infiltrate • Tx: Macrolide or respiratory fluoroquinolone


26) Tetralogy of Fallot

• Most common cyanotic congenital heart condition

• Pulmonary stenosis → harsh systolic ejection murmur over left upper sternal border

• RV hypertrophy → upturning of cardiac apex → “boot-shaped” heart on CXR


27) Arthrocentesis of the knee

• Any patients with possible septic arthritis should have urgent synovial fluid analysis; septic arthritis is more likely to occur in joints that have pre-existing abnormalities (eg, osteoarthritis)

• Dx: synovial fluid analysis showing leukocytosis (>50,000), gram stain, culture


28) Culture for bacteria • Septic arthritis dx: synovial fluid analysis showing leukocytosis (>50,000), gram stain, culture


29) Potassium decreased, Bicarbonate increased • Vomiting (eg, bulimia) → metabolic alkalosis (loss of gastric HCl → ↑ HCO3−) and hypokalemia (hypovolemia → ↑ aldosterone → ↑ K+ secretion)


30) Chronic lymphocytic thyroiditis (Hashimoto disease)

• Hypothyroid features + diffuse goiter


31) Vitamin D deficiency

• Excessive alcohol consumption, previous hospitalizations for abdominal pain, and steatorrhea = pancreatic insufficiency → fat-soluble vitamin (A, D, E, K) deficiency

• ↓ vitamin D → ↓ Ca2+ and PO43− absorption from gut → symptoms of hypocalcemia


32) Pseudogout

• Pseudogout (calcium pyrophosphate dehydrate crystal deposition disease) → chonedrocalcinosis (ie calcified articular cartilage)


33) Bone marrow aspiration • Thrombocytopenia, ⊖ splenomegaly, ⊖ antiplatelet antibodies = problem with platelet production (eg, myelofibrosis)


34) Assess for suicidal ideation • Suicide risk should be assessed in patients with depression • Depression is commonly under diagnosed and underrated in cancer patients and those with terminal diseases


35) Intramuscular ceftriaxone and oral doxycycline • Outpatient antibiotic therapy for patients with PID: IM ceftriaxone + oral doxycycline or azithromycin


36) History of gastrectomy

• Gastrectomy → loss of intrinsic factor → vitamin B12 deficiency → impaired DNA synthesis

• ↑ immature megaloblasts in marrow → ↑ intramedullary hemolysis → indirect hyperbilirubinemia & ↑ LDH

37) Decrease in cardiac output • Pneumothorax → compression of IVC → impaired RV filling → hypotension & tachycardia


38) Echocardiography • Ehlers-Danlos syndrome can cause dilation and rupture of blood vessels. Aortic and Mitral valves are often affected.


39) Subarachnoid hemorrhage • Sudden “thunderclap” headache + nuchal rigidity (meningeal irritation)


40) Diabetic nephropathy • Microalbuminemia, HTN, mesangial expansion, GBM thickening, arteriolar hyalinosis




BLOCK 2


1) Adjusting her medication regimen • This patient with chronic symptomatic hypotension is taking 3 anti-hypertensives (diuretic, β-blocker, ACEi)


2) Incision and drainage

• Symptomatic Bartholin duct cysts → incision & drainage → placement of Word catheter

• Asymptomatic Bartholin duct cysts → observation


3) Parkinson disease

• Pill-rolling tremor • ↓ dopamine neurons in substantia nigra → Parkinson disease


4) Intravenous methylprednisolone • Rapidly progressive (crescentic) glomerulonephritis; poor prognosis


5) Selection bias • Cohort study with matching of some factors (eg, age, gender) doesn’t control for all possible confounders • Randomized control trial can prevent selection bias


6) Chance of a type II error • Type II error (β) = false-negative error

• ↓ sample size (n) → ↓ power (1-β) & ↑ chance of type II error (β); in other words, a smaller sample size may not be able to detect an effect when one really exists

7) Preterm labor and delivery • Most common complication of twin pregnancies = preterm delivery (likely due to uterine crowding and overdistension) • Twin-twin transfusion syndrome may occur in monochorionic (single, shared placenta) diamniotic twins


8) Regular activity • Patients with lumbar strain should maintain moderate activity level; periods of bed rest or reductions in activity are associated with prolonged pain and stiffness


9) Colonoscopy • Weight loss, ⊕ occult blood, and iron deficient anemia (↓ MCV, ↑ RDW) are concerning for colon cancer


10) Attention-deficit/hyperactivity disorder • Hyperactive symptoms for ≥6 months in ≥2 locations with onset before age 12


11) Pericardiocentesis

• Cardiac tamponade - Becks triad: hypotension, JVD, ↓ heart sounds

• Symptoms are due to an exaggerated shift of the interventricular septum toward the LV cavity → ↓ LV preload, ↓ stroke volume, ↓ cardiac output


12) Decreased conjugation of bilirubin

• Gilbert syndrome: mild ↓ UDP-glucuronyltransferase conjugation

• Asymptomatic or mild jaundice with stress (eg, illness or fasting)


13) Cryotherapy • HPV 6 & 11 → genital warts (condylomata acuminata) • Tx: podophyllin resin, trichloroacetic acid, imiquimod, cryotherapy, laser therapy


14) 20000, Needle-shaped, no organisms

• Acutely swollen, painful great toe = podagra

• Surgery, trauma, recent hospitalization → ↑ risk of gout

• Synovial fluid analysis: monosodium urate needle-shaped crystals that are ⊖ birefringent


15) CT scan of the head • Non-contrast CT of the head is the initial diagnostic test of choice for a patient with a suspected stroke (evaluates ischemic vs hemorrhagic, which determines further management)


16) Adhere to the patient’s wishes and discuss home-care options

• This patient has decision-making capacity (ie, understands disease & consequences) and is not a imminent harm to himself or others, thus his autonomy should be respected


17) Combination oral contraceptive

• Signs of androgen excess, obesity, menstrual irregularity, ↑ testosterone, LH/FSH imbalance = polycystic ovary syndrome (PCOS)

• Tx: weight loss, OCPs (menstrual regulation), clomiphene citrate (ovulation induction)

18) Approve basketball participation

• Healthy child, ⊖ family history of sudden cardiac death, benign vibratory flow murmur at LLSB

• HOCM would present with a systolic ejection murmur


19) Frequent turning

• ↓ mobility (eg, quadriplegic) → ↑ risk of pressure ulcers


20) Placenta previa • Painless 3rd trimester bleeding with normal fetal heart tracing = placenta previa

• Placental abruption would be painful • Vasa previa would have fetal bradycardia because hemorrhage is of fetal origin (versus maternal origin in placenta previa)



21) Diabetic ketoacidosis

• ↑ anion-gap (>12) metabolic acidosis, ⊕ ketones, glucose > 250


22) Impaired phagocytic oxidative metabolism

• Defect in NADPH oxidase → chronic granulomatous disease (CGD)

• CGD → ↓ formation of superoxide anions → ↑ susceptibility to catalase ⊕ bugs (eg, S aureus, Aspergillus)

• Dx: nitroblue tetrazolium test (dye turns blue if NADPH oxidase is functional; stays colorless if NADPH oxidase is defective)


23) Polysomnography • Diagnostic test for OSA (obstructive sleep apnea)


24) Axillary-subclavian venous thrombosis • Paget-Schroetter disease (upper extremity DVT)

• Repeated micro-trauma from repetitive stress (eg, jackhammer) → thrombosis → venous engorgement and erythema


25) Administer intravenous fluids

• Airway, breathing, and circulation take precedence over correction of hyperthermia

• Hypotension and tachycardia indicate needs for IV fluid resuscitation


26) Paroxetine therapy • Major depressive disorder (MDD) ± panic disorder

• Tx: SSRI


27) Herpes simplex encephalitis • Fever, altered mental status, seizures = Viral (HSV) encephalitis • CSF analysis: ↑ RBCs, ↑ WBCs (lymphocytic predominance), Protein < 100

• Tx: IV acyclovir, after obtaining CSF fluid


28) Topical corticosteroid therapy • Eczema (atopic dermatitis) appears on flexor surfaces in adults - “fleczema”

• Allergic triad: asthma, allergic rhinitis, atopic dermatitis • Tx: topical emollient ± steroid ointment


29) Sweat chloride test • Cystic fibrosis → absent vas deferens (azoospermia) → infertility


30) Multinodular goiter • Multiple, nodular areas of high uptake on radioactive iodine scan + symptoms of hyperthyroidism = toxic multinodular goiter


31) Epithelial tissue proliferation • Cholesteatoma = overgrowth of desquamated keratin debris within middle ear

• Recurrent otitis media → ↑ risk of cholesteatoma


32) Adrenal medulla

• Pheochromocytoma (adrenal medulla tumor) → episodic catecholamine secretion → intermittent headaches, sweating, pallor

• Thyroid would causes constant symptoms, rather than intermittent symptoms


33) Pulmonary embolus

• Acute (3 days) shortness of breath, non-productive cough, tachycardia, OCP use

• DDx: Hypersensitivity pneumonitis & Interstitial pulmonary disease would have a more gradual presentation (longer than 3 days). Pneumonia would present with fever and ↓ resonance to percussion. Bronchitis usually presents with a productive cough


34) Paroxetine • Panic disorder tx: SSRI

35) Detrusor instability • Detrusor hyperactivity → urge incontinence • Urge incontinence tx: bladder training, antimuscarinic drugs (eg, oxybutynin)

• DDx: Neurogenic bladder → overflow incontinence


36) Intravenous immune globulin • IVIG → ↓ risk of coronary artery aneurysm in Kawasaki disease


37) Multiple myeloma • Hypercalcemia, renal insufficiency, anemia, bone pain/lytic lesions


38) Femoral popliteal stenosis

• Palpable femoral pulses with absent pedal pulses = stenosis somewhere in between (ie, femoropopliteal)

• Peripheral artery disease (PAD) → claudication and vascular insufficiency

• Diabetes & smoking → ↑ risk of PAD


39) Non-small cell lung cancer • Smoking, weight loss, lung mass = lung cancer


40) Nasogastric intubation

• Previous hysterectomy → adhesions → small-bowel obstruction (SBO) → dilated small bowel

• SBO in a stable patient can be treated with nasogastric decompression and bowel rest (NPO)

• Absence of distal colonic dilation rules out paralytic ileus




BLOCK 3


1) Meniere’s disease • Triad: vertigo, tinnitus, hearing loss • Due to imbalance of the fluid and electrolyte composition of endolymph


2) Mitral valve stenosis • Opening snap following S2 with mid-to-late diastolic rumble

• Mitral stenosis → left atrial enlargement → ↑ risk of arrhythmia and/or thromboembolic complications (eg, stroke)


3) Acute stress disorder • PTSD like symptoms lasting ≥3 days and ≤1 month

• Tx: trauma-focused CBT


4) Amniotic fluid embolism

• Clinical presentation: cardiogenic shock, hypoxemic respiratory failure, DIC, coma or seizure


5) Atrial septal defect • Wide, fixed split S2 (↑ blood in right heart delays closure of pulmonic valve)


6) Presynaptic neuromuscular junction

• Lambert-Eaton syndrome → proximal limb weakness, ↓ or absent reflexes, autonomic dysfunction (eg, dry mouth)

• Antibodies to presynaptic voltage-gated calcium channels; ↑ action potential amplitude with repetitive nerve stimulation


7) Candidiasis • Candida vaginitis → thick “cottage cheese” discharge, vaginal inflammation, normal pH (3.8 - 4.5)

• Candidiasis tx: fluconazole • DDx: Bacterial vaginosis (Gardnerella vaginalis) and Trichomoniasis (Trichomonas vaginalis) lead to a vaginal pH >4.5


8) Carrying self-injectable epinephrine

• Anaphylaxis tx: Intramuscular epinephrine


9) Streptococcus pneumoniae

• Nontypeable Haemophilus influenzae is the most common (~45%) organism associated with acute bacterial rhinosinusitis

Strep pneumoniae is second most common (~25%) and Moraxella catarrhalis is

third most common (~20%)

• Of the answer choices listed, Strep pneumoniae is the most likely cause


10) Measured outcomes were not important to patients • Statistical significance (low p-value) ≠ clinical significance


11) Left ventricular end-systolic volume decreased by a greater amount in patients treated with spironolactone than in patients treated with placebo


12) Abdominal ultrasonography of the right upper quadrant • Intermittent, postprandial RUQ pain in an obese woman = biliary colic • RUQ ultrasound → visualization of biliary stones; HIDA scan is useful when U/S findings are equivocal • Tx: Elective cholecystectomy


13) Nonphysiologic ADH (vasopressin) secretion • SIADH is a paraneoplastic syndrome of small cell lung cancer


14) Aortic dissection

• Involvement of aortic root → aortic regurgitation (→ new murmur)

• Involvement of descending aorta → diminished femoral pulses


15) Beginning folic acid supplementation prior to conception

• Folate prevents neural tube defects (NTDs)


16) Left tube thoracostomy

• Thoracostomy should precede intubation (this is an important exception to the typical order of establishing the airway first (ie, airway, breathing, circulation) but is necessary because positive-pressure ventilation (eg, intubation and mechanical ventilation) → accumulation of air and ↑ intrathoracic pressure → exacerbation of the tension pneumothorax → cardiovascular collapse


17) Persistence of a patent processes vaginalis

• Incomplete obliteration of the processes vaginalis → hydrocele


18) Ulnar nerve at the elbow

• Most common site of ulnar entrapment is where the ulnar nerve lies in the medial epicondylar groove (elbow)

• Ulnar nerve compression → ↓ sensation over 4th & 5th digits and weak grip

• Prolonged, inadvertent compression of the nerve by leaning on the elbows while working at a desk is the typical scenario


19) Hypothyroidism

• Hypothyroidism → ↓ LDL receptor expression → hypercholesterolemia


20) Offer insulin but allow the patient to refuse it • Patients with capacity are allowed refuse medical treatment, but you should still offer



21) Neuroleptic malignant syndrome

• Secondary to antipsychotic use

• Signs/symptoms: fever, confusion, muscle rigidity, autonomic instability (abnormal vitals), ↑ CK and WBCs

• Tx: stop antipsychotics, dantrolene or bromocriptine if refractory


22) CT scan of the abdomen with contrast • Chronic constipation (→ ↑ intraluminal pressure), LLQ pain, fever, leukocytosis ≈ diverticulitis


23) Phlebotomy • Hemochromatosis triad: cirrhosis, diabetes mellitus, skin pigmentation (“bronze diabetes) • Tx: repeated phlebotomy, iron chelation (eg, deferoxamine)

24) Impaired contractility of the left ventricle • Myocardial infarction → myocyte death → systolic heart failure


25) Asthma

• Coughing episodes with triggers such as cold weather or exercise is a classic history for undiagnosed asthma

• The most common etiologies of chronic cough include asthma, GERD, and upper airway cough syndrome (postnasal drip)


26) Endometrial biopsy • Endometrial biopsy is indicated in women age <45 with abnormal bleeding plus: unopposed estrogen (eg, obesity, anovulation), failed medical management (eg, abnormal bleeding after trial of OCPs), or Lynch syndrome


27) Laparotomy • Laparotomy allows access to the esophageal hiatus of the diaphragm to repair the esophageal perforation (→ greenish fluid)


28) Exercise program

• This patients insulin resistance, as evidenced by his ancanthosis nigricans (velvety hyper-pigmented rash over neck and axillae), is consistent with his symptoms of diabetes

• Diet and exercise should be attempted to ↑ insulin sensitivity before pharmacotherapy is initiated


29) Arrange for the regional organ procurement organization to address the issue with the patient’s family

• Organ procurement organization (OPO) are non-profit organizations that evaluate procure deceased-donor organs for transplant


30) Ceftriaxone • Meningitis with gram-negative cocci in a college student = meningococcal meningitis • Tx: Third-generation cephalosporins (eg, ceftriaxone)


31) Acute tubular necrosis

• Rhabdomyolysis → myoglobinuria → acute tubular necrosis

• Standard urinalysis can’t distinguish between hemoglobin and myoglobin, but microscopic exam for RBCs can add clarity


32) Influenza virus vaccine • Should be given annually


33) The findings are clinically insignificant but statistically significant

• P-value < 0.05 indicates statistical significance, however, there is no clinical significance between resolution of the common cold in 6.4 days versos 6.7 days


34) Na+ 130, K+ 2.8, Cl− 88, HCO3− 32 • Vomiting → hypochloremic metabolic alkalosis (loss of gastric HCl → ↑ HCO3−) and hypokalemia (hypovolemia → ↑ aldosterone → ↑ K+ secretion)


35) Oral amoxicillin therapy

• Asymptomatic bacteriuria is only treated during pregnancy (to ↓ risk of pyelonephritis, preterm birth, and low birth weight)

• First-line tx: Amoxiciliin-clavulanate, Nitrofurantoin


36) Heroin • Opioid intoxication → ↓ respiratory rate, bradycardia, miosis, ↓ bowel sounds


37) Iron deficiency • This patient likely had Crohn disease that affected the duodenum (area of small intestine responsible for iron absorption) → iron deficient anemia → fatigue


38) Bipolar disorder

• Patient is experiencing a manic episode


39) Toxic epidermal necrolysis • Bullae and sloughing of skin with mucosal involvement • <10% = Stevens-Johnson syndrome; >30% = toxic epidermal necrolysis


40) Nortriptyline • Irritable bowel syndrome symptoms can be improved by TCA therapy





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