USMLE USMLE-STEP-3 Online Practice Questions and Exam Preparation

USMLE USMLE-STEP-3 Online Questions & Answers

• Question 1:

  A 19-year-old (G2P1001) female at 354/7 weeks EGA presents for a routine prenatal visit. Her pregnancy has been uncomplicated. She reports good fetal movement and denies vaginal bleeding, loss of fluid, or contractions. She is excited about the arrival of her baby and is planning to breast-feed. Her past medical history is significant for chlamydia that was treated approximately 1 year ago. She is otherwise healthy. Her blood pressure today is 110/60. Fundal height is appropriate. UA is negative.

  The patient would like to discuss options for postpartum birth control. Which of the following would be an appropriate and effective option for postpartum birth control for this patient?

  A. combined OCP
  B. intrauterine device (IUD)
  C. progesterone-only pill
  D. no birth control is necessary as the patient will be breast-feeding
  E. rhythm method
  C. progesterone-only pill

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  Explanation

  The patient would be best served by a progesterone-only pill as it will be less likely to interfere with breast milk production. The rhythm method cannot be reliably used in the early postpartum period as normal menstrual cycles may not have resumed. An IUD would be contraindicated in this patient because of her recent history of chlamydia infection. Patients may not ovulate during breastfeeding but should not rely on breast-feeding alone as a form of contraception, as pregnancy can occur while breast- feeding.

  Mastitis is a common complication of breast-feeding. It is characterized by fever, myalgias, and redness with pain in the affected breast. Antibiotic options include penicillin V, ampicillin, or dicloxacillin. Studies show that patients may continue to breast-feed while undergoing treatment for mastitis

• Question 2:

  A 22-year-old male is brought into the emergency room by the police as he was found yelling in the middle of the street, naked. In the quiet room, he is unpredictable during the examination. He displays extreme lability, alternating between agitation with kicking the bed and listlessness. He is observed responding to internal stimuli and appears paranoid. A limited physical examination demonstrates mildly elevated BP and heart rate, nystagmus, ataxia, and muscle rigidity. Intoxication with which of the following substances is most likely in this patient?

  A. alcohol
  B. cannabis
  C. heroin
  D. lysergic acid diethylamide (LSD)
  E. PCP
  E. PCP

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  Explanation

  This patient presents with agitation and psychosis, likely caused by intoxication with a substance of abuse. While intoxication with alcohol can cause unsteadiness and belligerence, it does not present with hypertension and tachycardia. Cannabis can cause tachycardia and feelings of paranoia but, by itself, does not usually spur violence or grossly disorganized behavior. Intoxication with heroin or other opiates more often presents with drowsiness or apathy rather than the overt psychotic symptoms and sympathetic discharge seen in the above case. While LSD and other hallucinogens obviously cause psychotic symptoms, the nystagmus and muscular rigidity are not as common. Patients are not characteristically as hostile as in the case example. PCP use classically presents with the unpredictability, paranoia, and aggressiveness similar to the above case. It is not uncommonly mistaken for schizophrenia. Physical findings may include nystagmus, hypertension, tachycardia, ataxia, and muscular rigidity (DSM IV-TR).

• Question 3:

  A 56-year-old man comes to the hospital. For the past 5 days he has had colicky abdominal pain, vomiting, abdominal distention, and constipation

  He undergoes barium enema examination. The findings on barium enema, shown in Figure, are most compatible with which of the following diagnoses?

  

  A. mechanical small bowel obstruction
  B. intussusception
  C. volvulus
  D. carcinoma of the colon
  E. diverticulitis
  D. carcinoma of the colon

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  Explanation

  This patient presents with classic symptoms of a bowel obstruction. The diagnosis is often made by a thorough history and physical examination. Following the initial evaluation, an acute abdominal x-ray series should be obtained, which includes supine and erect views of the abdomen. The diagnosis is confirmed with the presence of dilated loops of bowel with the presence of air-fluid levels. These plain films may also suggest the location of the obstruction (small vs. large intestine). Abdominal ultrasonography has limited role in the diagnosis or management of intestinal obstruction. Serum electrolyte determination helps in identifying the electrolyte disturbances that have taken place. Fluid loss needs to be corrected with rehydration, and nasogastric suction helps in decreasing abdominal distention. Upper GI endoscopy would increase distention, and is contraindicated. Antiemetics should not be given until a definitive diagnosis is made, and then only if indicated; promotility agents have little to no role in the management of a patient with bowel obstruction, and may even be contraindicated.

  An annular constricting lesion with overhanging edges is typical of annular carcinoma of the colon. Mechanical small bowel obstruction results in multiple air-fluid levels in distended small bowel loops. Intussusception produces a "corkscrew" appearance on barium enema, and sigmoid volvulus produces a "bird's beak" appearance. In diverticulitis, extravasation of barium outside the lumen of the colon typically is seen.

• Question 4:

  Preconception counseling is an important component of health care encounters with reproductive age women. As a general recommendation, women of childbearing age should be advised to consume what dose of folic acid for prevention of neural tube defects?

  A. 0.1 mg
  B. 0.4 mg
  C. 1 mg
  D. 4 mg
  E. folic acid has only been shown to prevent the recurrence of neural tube defects in women who have previously had an affected child
  B. 0.4 mg

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  Explanation

  In randomized-controlled trials, the daily administration of 0.4 mg of folic acid in the periconception period was shown to prevent the first occurrence of open neural tube defects by approximately 70% as compared to placebo. For women who have previously had a fetus with an open neural defect, the recommended dose for prevention of recurrence is 4 mg and has been shown to have approximately 70% effectiveness in preventing recurrence.

• Question 5:

  Which of the following has a carrier state that is not considered contagious?

  B. HSV
  C. Chlamydia trachomatis
  D. GAS
  E. RSV
  D. GAS

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  Explanation

  GAS pharyngitis ("strep throat") is a common cause of tonsillitis requiring antibiotics. GAS continues to be very susceptible to penicillin, which still remains the treatment of choice. Occasionally, children will have a persistently positive throat culture for GAS and are considered carriers. This carrier state is not a risk for rheumatic disease and is felt not to be contagious to others. The presence of E. coli in the intestinal tract is considered colonization and not carrier state. An example of an enteric bacterium which does have a carrier state would be Salmonella typhi (typhoid fever).

• Question 6:

  A 60-year-old morbidly obese man presents with complaints of fatigue, worsening exertional dyspnea, three-pillow orthopnea, lower extremity edema, and cough occasionally productive of frothy sputum. He has a long-standing history of type II diabetes and hypertension. On examination, you note the presence of bibasilar rales, an S3 gallop, jugular venous distention, and 2+ pitting edema in both legs up to the knees. There does not appear to be an arrhythmia present. Which of the following medications should be given initially?

  A. metoprolol
  B. diltiazem
  C. furosemide
  D. carvedilol
  E. lisinopril
  C. furosemide

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  Explanation

  This patient's presentation is most consistent with pulmonary edema from decompensated CHF. The BNP test has been found to be both sensitive and specific for the diagnosis of CHF. It can be a very useful test to order when a patient is dyspneic to help to determine if CHF is the cause. Troponin, CK- MB, and LDH are markers of damage to cardiac muscle and can be diagnostic in a MI. While MI can be a cause of CHF, and most patients presenting with CHF will have cardiac enzymes drawn as part of their evaluation, cardiac enzymes are neither sensitive nor specific for CHF. Similarly, a CXR can determine the presence of pulmonary edema but not its cause.

  Acute pulmonary edema secondary to CHF will require management with diuresis for acute symptomatic relief. ACE inhibitors and beta-blockers do decrease mortality and morbidity in CHF; however their use in acute decompensated heart failure is suspected as they may induce hypotension and further cardiogenic shock. Digoxin is used for symptomatic relief either when other modalities fail or when rate control from atrial fibrillation is an issue. In patients with CHF and atrial fibrillation, beta- blockers have shown better effect and reduced morbidity than digoxin. Nevertheless, in the acute setting of decompensated heart failure with pulmonary edema, diuresis is the optimal initial treatment, not digoxin. In chronic heart failure, digoxin is reserved for patients with systolic failure that are symptomatic despite adequate ACE inhibitor and beta-blocker use. Furosemide is effective in treating the acute pulmonary edema associated with CHF by virtue of its potent diuretic action, which rapidly eliminates excess body fluid volume.

• Question 7:

  An 86-year-old woman is brought to the emergency room by her daughter. The patient is a poor historian with limited insight. Her daughter understands that she has a history of high BP and is treated with an unknown medication. The patient has been living by herself in a retirement community. The daughter became concerned a year prior, when she noticed that her mother seemed more confused. She had attributed this to "old age," but 2 weeks ago she noticed an abrupt worsening in her condition. Her mother now has difficulty recognizing close relatives and remembering information. For the past 2 weeks, she has been getting lost, forgetting to turn off the stove, and has been unable to bathe herself. The daughter is concerned that she may inadvertently harm herself.

  Which of the following will be the most likely course of her illness?

  A. gradual improvement
  B. rapid decline
  C. stable course
  D. steady worsening
  E. stepwise deterioration
  E. stepwise deterioration

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  Explanation

  This is a case of dementia, vascular type (multiinfarct dementia), caused by poorly controlled hypertension. Atrophy of the caudate nucleus is seen in Huntington chorea, which accounts for the movement disorder and dementia that are seen in that illness. Dilated ventricles without atrophy are characteristic of normal pressure hydrocephalus (NPH), one of the potentially reversible causes of dementia. The triad seen in NPH consists of dementia, gait disturbance, and urinary incontinence. Pick's disease is a gradually progressing dementia, displaying marked but preferential atrophy of the frontal and temporal lobes of the brain. Generalized atrophy can often be seen with neuroimaging in Alzheimer dementia. Vascular dementia classically will show lacunar infarcts of the white matter on MRI. With the exception of reversible causes (e.g., NPH, metabolic causes, or heavy metal toxicity), improvement is unusual in dementing illnesses. A rapid decline is common in dementias due to prion infection, such as Creutzfeldt-Jakob disease. Stable dementias are also unusual, most notably seen in dementia due to a head injury. Both Alzheimer's and Pick's dementias demonstrate a steady worsening of the illness over many years. The multiple small infarcts causing vascular dementia correspond to a stepwise deterioration in functioning of the patient

• Question 8:

  A42-year-old male presents to the office for a refill of the nasal steroid medication that he uses every spring to control his allergies. You notice on the vital signs taken by the nurse that his blood pressure is 150/95. Except for some sneezing and nasal congestion, the patient has no symptoms. He has no other medical history and his only medication is a nasal steroid. He does not smoke cigarettes, does not drink alcohol, and does not exercise. His body mass index is 24 kg/m2.

  The patient returns for a follow-up visit and his blood pressure is 165/105 mmHg. You diagnose him with which of the following?

  A. elevated blood pressure without hypertension
  B. prehypertension
  C. stage 1 hypertension
  D. stage 2 hypertension
  E. stage 3 hypertension
  D. stage 2 hypertension

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  Explanation

  Explanations: The Seventh Report of the Joint National Committee on the Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7) was released in May, 2003. It provides evidence-based guidelines for the detection, evaluation, and treatment of hypertension, the most common primary diagnosis in the United States. One of the key guidelines presented in this report is the classification of blood pressure for adults. The classification is based on the average of two or more properly measured, seated, blood pressure readings on each of two or more office visits. The proper measurement of blood pressure is critical. Blood pressure should be measured using a properly calibrated instrument in a patient who has been seated quietly in a chair for at least 5 minutes, with his feet on the floor and arm supported at heart level. The blood pressure cuff should encircle at least 80% of the arm. The systolic blood pressure is the point at which the first of two or more sounds is heard and the diastolic Where an incidentally noted elevated blood blood pressure is the point before the sounds disappear.

  pressure reading is found, it is then necessary to perform blood pressure measurements following the JNC 7 guidelines--two or more readings after the patient has been seated quietly in a chair for 5 or more minutes. Institution of antihypertensive medications would be inappropriate based on one blood pressure reading in this range, as the patient has not been diagnosed as hypertensive as of yet. Aspirin therapy is recommended for most persons over the age of 50 for the primary prevention of CHD events and would be recommended for others at high risk of heart disease.

  In persons with hypertension, it is recommended to start aspirin after their blood pressure is controlled because the risk of hemorrhagic stroke is increased in uncontrolled hypertension. Risk stratification with an exercise stress test at this point is not supported by evidence showing a reduction of morbidity or mortality and is likely to have many false positive results. Discontinuation of his nasal steroid is unnecessary as it is unlikely to be affecting his blood pressure adversely and should provide good symptomatic relief of his seasonal allergy symptoms. The blood pressure classifications from the JNC 7 report are as follows:

  

  This classification regimen represents a change from previous JNC guidelines with the designation of a prehypertension classification and the combination of the previous stage 2 and stage 3 into a single stage 2 category. By this categorization, the patient in this question has stage 2 hypertension. Recommended evaluation of patients with hypertension includes an ECG, measurement of blood glucose, hematocrit, serum potassium, creatinine and calcium, urinalysis, and a fasting lipid profile. Other testing is not indicated unless suggested by the presence of symptoms or if blood pressure control cannot be achieved. The management of hypertension involves the institution of lifestyle recommendations and, frequently, the use of antihypertensive medications. Lifestyle modifications can lower blood pressure, enhance the effectiveness of medications, and reduce cardiovascular risks. A low salt diet by itself may lower systolic blood pressure by 28 mmHg and is not likely to bring this patient to a goal blood pressure

  if that is the only modification made. Other lifestyle modifications, including the DASH (dietary approaches to stop hypertension) eating plan and increasing physical

• Question 9:

  A 60-year-old male with a history of hypertension and hyperlipidemia undergoes an evaluation for angina. He states that he routinely experiences dyspnea, fatigue, and retrosternal chest discomfort when performing activities such as walking around the block on which his house is located or climbing the flight of stairs within his home. Besides taking medications for his blood pressure and cholesterol, he uses nitroglycerin which successfully alleviates his symptoms.

  The patient undergoes a cardiac catheterization and is found to have 70% narrowing of the left anterior descending and proximal left circumflex arteries. Which of the following would be the most appropriate management of this condition?

  A. percutaneous transluminal coronary angioplasty (PTCA)
  B. medical management with a beta-blocker, statin, and aspirin
  C. medical management with an ACE inhibitor, statin, and aspirin
  D. referral for coronary artery bypass grafting (CABG)
  E. placement of a cardiac defibrillator
  D. referral for coronary artery bypass grafting (CABG)

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  Explanation

  Two generally accepted conventions for grading the severity of angina pectoris are those of the Canadian Cardiovascular Society (CCS) and the NYHA. The NYHA classification attempts to quantify the functional limitations imposed on an individual by their symptoms. Class I angina is defined as angina which does not appear as a patient undertakes ordinary physical activity. Symptoms caused by ordinary physical activity characterize class II angina. In class III angina, there is a moderate limitation of activity such that a patient remains comfortable at rest but symptoms appear during less-than- ordinary activities. In class IV angina, symptoms are present at rest so a patient is unable to perform any physical activity without feeling discomfort. Prinzmetal angina describes a syndrome of ischemic pain occurring at rest but not necessarily with exertion; it is diagnosed with detection of transient ST-T elevation with rest pain.

  The goal of treatment of angina is to relieve symptoms and prolong exercise capacity by improving the relationship of oxygen demand and supply. Nitroglycerin is a smooth muscle relaxant that produces both venodilation (reduced preload) and arteriolar dilation (reduced afterload). Although the combined effect is to reduce myocardial oxygen demands, the potential exists for reflex tachycardia and increased contractility. To avoid the potential for increased oxygen demand and decreased coronary blood flow, a beta-blocker such as propranolol may be used concurrently with nitroglycerin. Another option is the careful titration of the nitroglycerin dose used. Discontinuation of nitroglycerin without further intervention would inappropriately leave the patient's angina pain untreated. Replacing nitroglycerin with the calcium channel blocker nifedipine may not address the problem of reflex tachycardia as nifedipine can also lead to a rapid vasodilation and subsequent drop in blood pressure (which, in turn, leads to increased sympathetic outflow and an increase in heart rate). Addition of isoproterenol would be inappropriate since it increases myocardial oxygen demand.

• Question 10:

  A34-year-old woman was found to have a 2-cm right thyroid nodule at the time of a well woman examination. The remainder of the thyroid was palpably normal and there were no lymph nodes palpable. There was no history of thyroid disease or radiation therapy to her head or neck. She was clinically euthyroid. Thyroid-stimulating hormone (TSH) was normal. Which of the following tests would be the most useful in establishing a specific diagnosis?

  A. ultrasound of the thyroid
  B. nuclear scan of the thyroid
  C. thyroid antibody studies
  D. fine needle aspiration of the nodule
  E. CT of the neck
  D. fine needle aspiration of the nodule

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  Explanation

  In evaluating a sporadic thyroid nodule in a patient who is euthyroid, it is critical to determine whether the nodule is malignant or benign. The most diagnostic test is the fine needle aspiration. Ultrasound will only distinguish between cystic and solid structures, and most nodules have some solid component. The nuclear scan will demonstrate a photopenic area in over 85% of patients. Neither these tests nor CT scan will reliably separate benign from malignant nodules. Thyroid antibody studies do not play a role in the evaluation of a thyroid nodule in a euthyroid patient. They are sometimes used in the evaluation of thyroiditis.