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

USMLE USMLE-STEP-3 Online Questions & Answers

• Question 401:

  A38-year-old woman presents to the ER with heavy vaginal bleeding. A pelvic examination using a speculum to visualize the cervix reveals a large, friable, fungating cervical mass. On bimanual examination, the mass extends to the right pelvic sidewall. A biopsy from a recent gynecologic visit reveals invasive squamous cell carcinoma of the cervix. An abdominal/pelvic CT scan shows enlarged pelvic lymph nodes and right hydronephrosis. Her hematocrit (HCT) in the ER is 24%, but she is hemodynamically stable with a BP of 124/70 and a pulse of 73. The cervical mass is actively bleeding.

  Which of the following is the most appropriate immediate management of the vaginal bleeding in the ER?

  A. vaginal packing soaked with Monsel solution
  B. vitamin K
  C. transfusion of fresh frozen plasma (FFP)
  D. uterine massage
  E. supportive care with transfusion of packed red blood cells
  A. vaginal packing soaked with Monsel solution

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  Explanation

  A woman with advanced cervical cancer may present emergently with heavy vaginal bleeding. Often, the bleeding can be controlled for 24 hours by packing the vagina with a packing soaked in Monsel solution. The patient is kept on bedrest, and the packing is changed every 24 hours. If packing the vagina does not control the bleeding, then emergent radiation therapy is warranted if the patient has not had previous radiation treatment. Hemorrhage is usually controlled within 2448 hours of initiating external beam therapy. If radiation therapy fails, then the next best treatment is arterial embolization of either the uterine or hypogastric arteries. However, embolization may result in tumor hypoxia and decrease the sensitivity of the tumor to radiation.

  Arteriography with embolization may allow visualization of the bleeding vessel with direct embolization of the source. Arterial embolization has several risks including infarction of distal tissue, infection, and femoral artery thrombosis. If embolization is not available or not successful, bilateral hypogastric artery ligation is an option. In this patient, surgical therapy with radical hysterectomy is not an appropriate treatment because this patient's disease has spread beyond the cervix. This procedure would result in transection of the tumor and lead to further bleeding complications. This patient has at least a stage IIIB tumor, and the best treatment for her is chemoradiation.

• Question 402:

  A 53-year-old Black male, with a history of hypertension, hepatitis C, and newly diagnosed nonsmall cell lung cancer, undergoes his first round of chemotherapy, which includes cisplatin. You are called to see this patient 5 days into his hospitalization for oliguria and laboratory abnormalities. Other than the chemotherapy, he is receiving lansoprazole, acetaminophen, and an infusion of D5-- 0.9% normal saline at 50 mL/h. On examination, his BP is 98/60 and heart rate is irregular, between 40 and 50 bpm. His physical examination shows a middle-aged male in no acute distress. His cardiac examination is unremarkable, his lungs show bibasilar crackles, and the abdominal examination is positive for a palpable spleen tip without any hepatomegaly or abdominal tenderness. He has trace bilateral ankle edema. His distal pulses are irregular. The neurologic examination was unremarkable. His laboratory (serum sample) results are as follows

  

  What is the most likely etiology of this patient's acute renal failure?

  A. renal tubular deposition of uric acid
  B. calcium oxalate kidney stones causing partial urinary tract obstruction
  C. renal tubular injury due to cisplatin
  D. ischemic acute tubular necrosis from a decreased cardiac output
  E. type II cryoglobulinemia due to hepatitis C
  A. renal tubular deposition of uric acid

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  Explanation

  The patient has tumor lysis syndrome. The destruction of malignant cells by chemotherapeutic agents will lead to the release of intracellular contents, including potassium, phosphorus, and uric acid (from nucleic acids). This can result in hyperkalemia, hyperuricemia, and hyperphosphatemia. Hyperkalemia will produce significant ECG abnormalities, including peaked T waves and widened QRS complexes. The presence of bradycardia and irregular heart rate on physical examination are suggestive of the cardiac effects of hyperkalemia, which can lead to lifethreatening arrhythmias if not addressed. Patients with tumor lysis syndrome can develop a severe hyperuricemia. The kidneys are responsible for the excretion of uric acid. In acidic urine, the uric acid can crystallize in collecting tubules, resulting in intratubular obstruction and acute kidney failure. Calcium oxalate stones are not a part of this entity. Cisplatin can cause renal potassium and magnesium losses, which is not the case in this patient. The laboratory data suggest the release of intracellular contents (high LDH, uric acid, potassium, and phosphate) and the diagnosis of urate nephropathy as the cause of his acute kidney failure. As mentioned before, hyperkalemia will produce significant ECG abnormalities, including peaked T waves and widened QRS complexes. Prominent U waves are found in hypokalemia, not hyperkalemia. Atrial fibrillation is not typically seen in hyperkalemia

• Question 403:

  A 70-year-old male is seen in the office for chest pain. He reports that he is getting substernal chest pain, without radiation, when he mows his lawn. The pain resolves with 1015 minutes of rest. He has never had pain at rest. He has no other cardiac complaints and his review of systems is otherwise negative. He has an unremarkable medical history and takes only a baby aspirin a day. On examination, his blood pressure is 160/70, pulse 85, and respiratory rate 16. His cardiac examination is notable for a harsh, 3/6 systolic ejection murmur along the sternal border that radiates to the carotid arteries. His carotid pulsation is noted to rise slowly and is small and sustained. His lungs are clear. The remainder of his examination is normal.

  Which of the following would be the most appropriate test to order next?

  A. echocardiogram
  B. exercise stress test
  C. cardiac catheterization
  D. 24-hour Holter monitor
  E. electrophysiologic studies
  A. echocardiogram

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  Explanation

  Aortic stenosis is one of the most common valvular abnormalities found in adults. It can be congenital -- such as a unicuspid or bicuspid valve--or acquired. In young adults, acquired aortic stenosis is often seen as a consequence of rheumatic fever. This is becoming less common in developed nations. In adults over the age of 65, the most common cause of aortic stenosis is age-related degenerative, calcific aortic stenosis. The valvular cusps are immobilized and the stenosis caused by calcium deposits along the flexion lines of the valves. Acquired aortic stenosis typically has a prolonged asymptomatic period. During this time the stenosis may be found incidentally by auscultation of the characteristic harsh, holosystolic murmur in the aortic valve area that radiates to the carotid arteries. There may also be a slow, small, and sustained arterial pulsation (pulsus parvus and tardus) due to the relative outflow obstruction. The cardinal symptoms of aortic stenosis that signal advancing disease, and increased risk of mortality, are angina, heart failure, and syncope. An ECG will show left ventricular hypertrophy in approximately 85% of symptomatic cases of aortic stenosis.

  A normal ECG is possible but would be more likely in early, asymptomatic stages. S-T segment elevation would be more consistent with acute cardiac ischemia and Q waves would be more consistent with a completed MI. Low-voltage QRS complexes can be seen in several conditions, including pericardial effusion, COPD, or obesity. When considering the diagnosis of aortic stenosis, the initial diagnostic test of choice would be echocardiography. It would provide information on both the structure (bicuspid, tricuspid, and the like) and the function (valve area, pressures) of the valve. The size and function of the left ventricle can also be determined. If aortic stenosis is found on echocardiogram and the patient is symptomatic, the next test would be cardiac catheterization.

  This would allow for direct measurement of the pressure gradient across the valve. It would also allow for evaluation of the status of the coronary arteries in order to determine whether CABG would need to be performed along with valve replacement. Exercise stress testing is relatively contraindicated in the setting of symptomatic aortic stenosis. Holter monitoring would only be useful if there were a concomitant arrhythmia. Electrophysiologic studies would not play a role in the typical evaluation of aortic stenosis.

• Question 404:

  A 40-year-old male comes to your office as a new patient to get established for care, as he recently moved into your city from another state. He has been on medical therapy for type 2 diabetes mellitus for 3 years and has had good glycemic control. He takes metformin 500 mg bid and reports having fasting glucose levels of less than 100 on home monitoring. He has records from his previous physician that show that he had a dilated eye examination 6 months ago that was normal and a hemoglobin A1C (HgbA1C) level of 6.2 that was taken 3 months ago. He has no known history of coronary artery disease. His last fasting lipid measurement was 14 months ago. You order a fasting lipid panel today and get the following results:

  Total cholesterol: 235 mg/dL Triglycerides: 210 mg/dL HDL cholesterol: 45mg/dL LDL cholesterol: 162 mg/dL

  He states that he has not had any immunizations in "longer than I can remember." Which of the following would be recommended for him?

  A. hepatitis A and hepatitis B vaccines
  B. herpes zoster vaccine (Zostavax)
  C. tetanus, diphtheria, and acellular pertussis (Tdap) vaccine
  D. tetanus and diphtheria (Td) vaccine
  E. Tdap and PPV-23
  E. Tdap and PPV-23

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  Explanation

  Explanations:

  The Third Report of the National Cholesterol Education Program Expert Panel on the Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (ATP III) was published in May 2001 by the National Heart, Lung, and Blood Institute of the National Institutes of Health. This evidence-based report provides guidelines for the evaluation and management of blood lipid levels for the primary and secondary prevention of heart disease. The basis of the recommendations for management is an overall evaluation of an individual's risk factors for developing cardiovascular disease. Persons at the highest risk for future cardiac events are those with already established coronary artery disease or "coronary artery disease equivalents," which include diabetes mellitus, other forms of atherosclerotic disease, or multiple risk factors that confer a 10-year CHD risk of greater than 20%. Multiple studies have shown that elevated LDL cholesterol levels are a risk for coronary artery disease and that lowering LDL levels can reduce the risk of events.

  ATP III goals are targeted at LDL levels. For persons with LDL levels above this goal, the options for lowering LDL can include therapeutic lifestyle changes, lipid-lowering medications, or a combination of both. In a patient with coronary artery disease, diabetes mellitus, or other CHD equivalents, the LDL goal level is 100 mg/dL. In this population, therapeutic lifestyle changes alone would be recommended for those with LDL levels of 100130 and medication could be started concomitantly with lifestyle changes for those with LDL above 130, as most persons would require medication to achieve the recommended goal. For the patient in this question with an LDL of 160 mg/dL, therapy with an HMG- CoA reductase inhibitor would be recommended first-line therapy to try to get his LDLto goal. Therapeutic lifestyle changes alone would be very unlikely to reduce his LDL to less than 100 mg/dL, but are still an important part of his overall lipid management program and should be recommended along with medication therapy. Neither increasing his dosage of metformin nor adding insulin would be recommended as they would not be expected to improve his dyslipidemia significantly and because his diabetic control is appropriate. At his follow-up visit, the patient's lipid levels have met the recommended guidelines; therefore, the recommendation would be to continue with his current therapy. Increasing the dosage of his statin, adding a fibric acid, nicotinic acid, or referring the patient to a dietician would all be appropriate considerations in someone who had not successfully reached his goal lipid levels.

  A recent addition to the ATP III provides an option for changing the target LDL goal for those at the highest of risk for coronary events. For persons with known coronary artery disease, or CAD equivalent, and multiple risk factors, such as diabetes or continued smoking, one could consider using an LDL of 70 as a goal. For this patient, with diabetes but no history of CAD or equivalent, the recommended goal would remain an LDL of 100 or less. Immunizations should be a routine part of the adult health maintenance evaluation. All patients with diabetes are recommended to be vaccinated with the pneumococcal vaccine (PPV-23) both because of the incidence of pneumonia in diabetics and the increased risk of complications should infection occur. A recent recommendation for all adults is to provide a single dose of Tdap vaccine in place of one booster dose of Td. The rationale for this is to attempt to reduce the incidence of pertussis in the population, as pertussis has been recurring in the United States in spite of routine childhood vaccination. Hepatitis A and B are routine vaccinations for children. The current recommendation for adult immunizations against these diseases is to target high- risk adults. Diabetes is not considered a high risk for these infections. Herpes zoster vaccine is recommended for adults over the age of 60

• Question 405:

  Of the following conditions, which results in the most deaths each year in the United States?

  A. acquired immunodeficiency syndrome (AIDS)
  B. breast cancer
  C. motor vehicle accidents
  D. occupational injuries
  E. medical errors
  E. medical errors

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  Explanation

  Explanations:

  The landmark 1999 Institute of Medicine report, To Err is Human: Building a Safer Health System, estimated that between 44,000 and 98,000 Americans died each year in hospitals as a result of medical errors. Even using the lower number, this represents more deaths than breast cancer, motor vehicle accidents, and AIDS. About 7000 deaths are attributable to medication errors. This number alone is greater than the number of deaths in work-related injuries. Errors in diagnosis, treatment, prevention, communication, equipment failure, and other system failures result not only in significant morbidity and mortality, but also an estimated 1729 billion dollars in costs. Further, there is a significant loss in trust in the health system by patients and loss in satisfaction by patients, their families, and health care providers. Unfortunately, many of these errors that occurred, and continue to occur, are preventable. Many hospitals, health care organizations, and oversight agencies, including the Quality Interagency Coordination Task Force of the Federal Government, are actively pursuing mechanisms of quality improvement to reduce this epidemic.

• Question 406:

  A 23-year-old female graduate student with acne and asthma presents to you with a chief complaint of headaches. She has noted a gradual increase in the intensity and frequency of the headaches to the point where they are interfering with her daily activities and studies. Your examination shows an obese young lady with papilledema. The remainder of your physical examination is normal Which of the following is most commonly associated with this condition?

  A. obesity
  B. steroid use during asthma attacks
  C. tetracycline treatment for acne
  D. oral contraceptives
  E. pregnancy
  A. obesity

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  Explanation

  Papilledema is optic disc swelling and implies raised intracranial pressure. Headache is a common associated symptom. The initial evaluation of papilledema should involve imaging, either by MRI or CT scan with and without contrast, to exclude mass lesions. If these studies are negative, then the subarachnoid opening pressure should be measured by lumbar puncture. An ESR is unlikely to be diagnostic in this case. It would be more important in the evaluation of vision loss or headache in a person over the age of 50. Neither a pregnancy test nor a glucose tolerance test would provide information on the cause of increased intracranial pressure. Pseudotumor cerebri is a condition of idiopathic intracranial hypertension. It is a diagnosis of exclusion that would be made in the presence of papilledema, normal imaging studies, and elevated opening pressure on lumbar puncture with normal CSF studies. The majority of patients with pseudotumor cerbri are young, female, and obese. This condition is treated with a carbonic anhydrase inhibitor, such as acetazolamide, which lowers intracranial pressure by reducing the production of CSF. Weight reduction, while important, is often unsuccessful in improving the condition by itself. Steroids, tetracycline, pregnancy, and oral contraceptives are not associated with the development of pseudotumor cerbri. Pseudotumor cerebri may ultimately resolve spontaneously, but there is a significant risk for development of impaired vision or even blindness if left untreated. The goal of treatment is the reduction of intracranial pressure. This may be accomplished in a number of ways. Use of medications such as acetazolamide or furosemide is considered a first-line therapy, with the aim of reducing CSF production. If pharmacologic treatment proves unsuccessful, alternative treatment options include surgical options such as optic nerve fenestration or creation of a ventricular-peritoneal shunt. Performing serial lumbar punctures is also possible but carries a number of associated risks including development of infections or headaches

• Question 407:

  A 55-year-old male is brought to the ED, by ambulance, because of crushing chest pain radiating to his left shoulder and arm that started 1 hour ago. He has a history of hypertension, high cholesterol, and has smoked a pack of cigarettes a day for 30 years. He has never had symptoms like this before. The patient's rhythm converts to asystole. What is the most appropriate first action to take?

  A. IV epinephrine
  B. IV atropine
  C. discontinuation of resuscitation
  D. direct current (DC) cardioversion
  E. check a second monitor lead
  E. check a second monitor lead

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  Explanation

  The clinical scenario described is classic for an acute MI. The patient has multiple risk factors, including smoking, hypertension, and elevated cholesterol. His symptoms of crushing chest pain radiating to the left arm is commonly seen in this setting. Often the first electrocardiographic sign of acute ischemia is the development of hyperacute T waves. The ECG will usually show S-T segment elevations in the area of the involved occluded vessel, with reciprocal S-T segment depressions in uninvolved areas.

  This can be followed by the eventual resolution of S-T segment abnormalities and the development of T wave inversions and Q waves. Diffuse P-R depressions are often the initial manifestation of pericarditis, a less common cause of acute chest pain. This often progresses to diffuse S-T segment elevations, the presence of which helps to distinguish pericarditis from the focal S-T elevations more classically associated with a thrombosed coronary artery. Q waves would be unlikely to occur within 1 hour of the onset of symptoms. In this clinical setting, a normal ECG, while possible, would be less likely to occur.

  Ventricular arrhythmias, both tachycardia and fibrillation, are recognized complications of acute MI. The presence of ventricular fibrillation or pulseless ventricular tachycardia should lead to the primary "ABCD" survey, as outlined in the American Heart Association's ACLS protocols. The mnemonic stands for airway, breathing, circulation, and defibrillation. Epinephrine, lidocaine, or amiodarone are reserved for the setting where defibrillation is ineffective. Synchronized cardioversion would be used in efforts to convert a patient's rhythm in the setting of a stable tachycardia.

• Question 408:

  An amenorrheic 17-year-old female is diagnosed with Kallmann syndrome. Blood testing of this patient would indicate which of the following results?

  A. FSH, LH, normal estradiol
  B. high FSH, high LH, low estradiol
  C. normal FSH, normal LH, normal estradiol
  D. low FSH, low LH, normal estradiol
  E. low FSH, low LH, low estradiol
  E. low FSH, low LH, low estradiol

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  Explanation

  Kallmann syndrome is a genetic problem due to failure of migration of olfactory and GnRH secreting neurons to make their appropriate connections in the brain. Classically, this leads to anosmia (inability to smell), delayed puberty, and amenorrhea. The GnRH is not secreted, and pituitary FSH and LH release does not occur. In the absence of stimulation the ovaries do not produce significant estrogen. This is an example of hypogonadotropic hypogonadism, also termed hypothalamic amenorrhea.

• Question 409:

  A man who underwent total thyroidectomy 24 hours ago now complains of a generalized "tingling" sensation and muscle cramps. Appropriate treatment would include which of the following?

  A. intravenous infusion of calcium gluconate
  B. administration of oxygen by mask
  C. administration of an anticonvulsant
  D. administration of a tranquilizer
  E. neurologic consultation
  A. intravenous infusion of calcium gluconate

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  Explanation

  During total thyroidectomy, parathyroid glands may inadvertently be removed or their vascular supply interrupted. Hypoparathyroidism may then develop, the manifestations of which include tingling, muscle cramps, convulsions, and a positive Chvostek's sign (contraction of facial muscles after tapping the facial nerve). These symptoms are dramatically relieved by intravenous administration of calcium. Oral calcium and vitamin D are administered for long-term correction of hypocalcemia.

• Question 410:

  Which of the following maternal cardiac conditions is associated with the highest mortality rate during pregnancy?

  A. mitral stenosis, New York Heart Association class 12
  B. corrected tetralogy of Fallot
  C. porcine prosthetic heart valve
  D. mechanical prosthetic heart valve
  E. pulmonary hypertension
  E. pulmonary hypertension

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  Explanation

  Many women with underlying cardiac disease have increased risk for serious complications during the pregnancy, including maternal mortality. Clark et al. have classified maternal cardiac conditions into mortality groups. Group 1 conditions (including mild mitral stenosis, corrected tetralogy of Fallot, and porcine prosthetic valves) have a maternal mortality rate of less than 1%. Group 2 conditions, which include mechanical prosthetic heart valves, more severe degrees of mitral stenosis, uncorrected congenital heart disease, and mild Marfan syndrome, have a mortality rate of 515%. Group 3 conditions include those that have a mortality risk of 50% or higher and include pulmonary hypertension, complicated coarctation of the aorta, and Marfan syndrome with an abnormal aortic root.