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

USMLE USMLE-STEP-3 Online Questions & Answers

• Question 311:

  A 32-year-old woman presents with complaints of irritability, heat intolerance, hyperdefecation, and frequent palpitations. She has lost 20 lb over the past six months. She has always been in good health and does not take any prescription or OTC medications. She denies any prior history of thyroid disease or exposure to head/neck irradiation, but she states that one of her relatives was diagnosed with a thyroid disorder at roughly the same age. Vital signs are as follows: BP 138/78, HR 112, RR 22, temp.

  98.8. On examination, her thyroid is diffusely enlarged and smooth. Auscultation of the thyroid reveals a bruit. Her hair is fine in texture, and she has warm velvety skin. She has hyperactive deep tendon reflexes. There is a fine tremor in her outstretched hands. Which of the following is a common finding in this condition?

  A. macroglossia
  B. hyperkeratosis
  C. infiltrative ophthalmopathy
  D. cerebellar ataxia
  E. pericardial effusion
  C. infiltrative ophthalmopathy

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  Explanation

  This patient's presentation is consistent with Graves' disease. Infiltrative ophthalmopathy is a common finding in this condition. Approximately 2040% of patients with Graves' disease possess clinically evident eye disease. Complaints include photophobia, diplopia, reduced visual acuity, and easy tearing; and, signs of corneal or conjunctival irritation are oftentimes present. Periorbital edema, chemosis, lid retraction with restricted ocular movement, proptosis, and upward gaze impairment may also be found.

  Optic nerve compression may also arise, leading to decreased visual acuity, visual field defects, impaired color vision, and papilledema. Macroglossia, hyperkeratosis, cerebellar ataxia, and pericardial effusion are all findings in hypothyroidism. (Ceci Textbook of Medicine, pp. 13961400) Free T3 levels are elevated in all patients with Graves' disease. Most patients also have elevated free T4 levels, but occasionally this level will remain within the normal reference range in a state known as T3 toxicosis. This generally occurs during the initial phases of Graves' disease or at the onset of a relapse. TSH levels are suppressed by the elevated thyroid hormone levels.

• Question 312:

  A 21-year-old male presents to the ED after sustaining a gunshot wound to the neck. After evaluation, it is determined that he has C6 quadriplegia.

  Which of the following activities will be limited by this injury?

  A. wrist extension
  B. elbow extension
  C. elbow flexion
  D. shoulder flexion
  E. raising his arms above his shoulders
  B. elbow extension

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  Explanation

  This patient should be able to perform any activity that requires innervation from C6 or above. The biceps and deltoid are innervated by C5, so he should be able to lift his arms above his head, have shoulder flexion, and elbow flexion. C6 innervates the extensor carpi radialis, so wrist extension should be preserved. The triceps rely on C7, so he would not be able to perform elbow extension.

• Question 313:

  One of your responsibilities at the community health center is to serve as director of the tuberculosis (TB) screening and prevention program.

  You see a 2-week-old child for a routine wellbaby check-up. The mother is feeding him formula that she prepares by mixing powdered formula with her home tap water that comes from a well. The local health department considers the water to be nonfluoridated. Which of the following suggestions would be appropriate?

  A. She should start giving her baby a fluoride supplement now.
  B. Powdered infant formula contains an adequate amount of fluoride, so a supplement will not be required as long as she continues formula feeding.
  C. A fluoride supplement would be recommended starting at age 6 months.
  D. She should take a fluoride supplement during subsequent pregnancies for the benefit of the fetus.
  E. There is no risk to fluoride supplementation, so any dosage may be used.
  C. A fluoride supplement would be recommended starting at age 6 months.

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  Explanation

  The widespread use of fluoride has been a major factor in the decline in the prevalence and severity of tooth decay in the United States. In most communities public water supplies are fluoridated. Supplementation is recommended by the Centers for Disease Control, American Academy of Pediatrics, American Academy of Family Physicians, and other authorities, for those who do not have access to fluoridated water. Fluoride supplementation can occur from both ingestion and from topical supplementation, such as in fluoride-containing toothpaste. Current guidelines recommend no supplementation until 6 months of age and then a dietary fluoride supplement of 0.25 mg/day from the age of 6 months to 3 years, 0.5 mg/day for ages 36 years, and 1.0 mg/day for ages 616 years for those persons who do not have access to fluoridated water. Current powdered infant formulas do not provide a significant amount of fluoride because of the risk of a child receiving too much fluoride if the formula is mixed with fluoridated water. The chronic ingestion of high levels of fluoride can result in fluorosis, a state of hypomineralization of tooth enamel. Studies have shown that fluoride supplements taken by pregnant women do not benefit their offspring.

• Question 314:

  A 50-year-old male presents to your office for a routine annual physical examination. He has no specific complaints for this visit other than wanting to be checked for all the usual stuff. His last visit with you was a year ago for a physical examination. At that time his examination was normal. You performed blood work that was within normal limits and included a total cholesterol of 172 with a high-density lipoprotein (HDL) of 45 and low-density lipoprotein (LDL) of 100. He reports that he had a tetanus shot 5 years ago.

  Past medical history: Unremarkable Past surgical history: 1. Appendectomy at age 17 2. Vasectomy at age 43 Medications: Daily multivitamin Allergies: NKDA (no known drug allergies) Family history: Father died at age 78 of a heart attack Mother is alive at age 76. She has hypertension and osteoarthritis Brother aged 48 without known chronic medical condition Children aged 16, 14, and 8--no known chronic medical illness Social history: Married, employed as an accountant; college graduate Denies tobacco or recreational drug use Drinks one alcoholic drink (either beer or wine) a day Does not exercise on a regular basis

  Which of the following interventions would be recommended for this patient?

  A. pneumococcal vaccine
  B. tetanus toxoid vaccine
  C. complete cessation of all alcohol intake
  D. beta-carotene supplementation to prevent cancer and heart disease
  E. screening for depression with a patientcompleted questionnaire
  E. screening for depression with a patientcompleted questionnaire

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  Explanation

  Explanations:

  The United States Preventative Services Task Force (USPSTF) is an independent panel of experts in primary care and prevention that systematically reviews the evidence of effectiveness and develops recommendations for clinical preventative services. By carefully and systematically reviewing the available literature, the USPSTF makes recommendations on the effectiveness of screening, counseling, immunization, and chemoprevention using the following rating system:

  A. The USPSTF strongly recommends that clinicians provide the service to eligible patients.

  B. The USPSTF recommends that clinicians provide this service to eligible patients.

  C. The USPSTF makes no recommendation for or against routine provision of the service.

  D. The USPSTF recommends against routinely providing the service to asymptomatic patients.

  I. The USPSTF concludes that the evidence is insufficient to recommend for or against routinely providing the service. All of the recommendations of

  the USPSTF are available free of charge at their web site www.preventiveservices.ahrq.gov. In a 50-year-old male who is generally healthy and does not present any apparent high-risk personal or family history, the USPSTF gives a level A recommendation to blood pressure measurement as a screening tool for hypertension in adults over the age of 18, as there is good evidence that screening for, and treating, hypertension can reduce the incidence of cardiovascular disease. There is insufficient evidence to

  recommend for or against screening for abdominal aortic aneurysm by abdominal palpation or for screening for skin cancer by a whole body skin examination (level I recommendation).

  This suggests that the evidence is lacking that performing these interventions will reduce the morbidity or mortality associated with these conditions. The USPSTF gives level D recommendations to screening for thyroid cancer by palpation and for screening for testicular cancer by palpation. Fecal occult blood testing using three selfcollected stool cards as a screening test for colon cancer has been given a level A recommendation, with good data to support reduction in colon cancer mortality from periodic screening. There is also evidence to support screening for colon cancer by flexible sigmoidoscopy or colonoscopy, with double-contrast barium enema as a possible alternative as well. Screening for lipid disorders in men over the age of 35 and women over the age of 45 also receives a level A recommendation. In general, the interval for repeat screening for an otherwise low-risk patient with lipid levels within the goal range, based on the National Cholesterol Education Project's Consensus opinion statement, would be 5 years. As this patient had lipid levels within the goal range 1 year ago, it would not be necessary to repeatthis blood test at this visit. Screening for cardiovascular disease by the routine use of electrocardiography in asymptomatic, lowrisk patients has been given a D recommendation, as there is an absence of evidence of improved health outcomes from this intervention. Screening for lung cancer by chest x-ray and for glaucoma by measurement of intraocular pressure are level I recommendations, with insufficient evidence to recommend for or against these interventions.

• Question 315:

  The predicted length of the follicular phase of a patient with a consistent 34-day menstrual cycle is which of the following?

  A. 14 days
  B. depends on the length of the luteal phase
  C. 16 days
  D. 18 days
  E. 20 days
  E. 20 days

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  Explanation

  The luteal phase of the menstrual cycle, defined as beginning with the LH surge and ending with onset menses, is normally fixed at 14 + 2 days. Therefore, the length of the follicular phase can fairly accurately be determined by subtracting 14 days from the total length of the cycle. In this case, the length of the follicular phase is: 34 - 14 = 20 days.

• Question 316:

  You are called to the trauma bay to evaluate a 42-year-old male who suffered a blow to his knee at the construction site where he works. He is awake, alert, and his vital signs have been stable in transport. After completing your primary survey, you continue with your secondary survey and determine that his only injury is to his right leg. It is clear that he has suffered a posterior knee dislocation. As part of your examination, you determine that you cannot feel a pulse in his right foot.

  Later that night after the patient had been treated and stabilized, you are called to the patient's room to evaluate severe pain in his right lower leg. Upon examining the patient, you determine that he has a bounding pulse in his right foot. However, the patient does state that he has a tingling sensation in his foot and he is in excruciating pain when you flex his foot. Which of the following should be the next step in his treatment?

  A. Increase the dose of intravenous narcotics to help control the pain.
  B. Prescribe an anti-inflammatory drug to enhance the effects of the narcotics.
  C. Order a series of right foot x-rays looking for an occult fracture.
  D. Obtain an emergent arteriogram looking for missed vascular injury.
  E. Emergently take the patient to the OR.
  E. Emergently take the patient to the OR.

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  Explanation

  It is important to consider vascular injuries in the setting of extremity trauma. This is particularly true in the setting of fractures, dislocations, or penetrating trauma in the vicinity of major vascular structures. When evaluating patients for traumatic vascular injuries, the first step is evaluation of peripheral pulses. This should be done after the initial resuscitation in order to rule out hypovolemia as the source for diminished peripheral perfusion. In the presence of fractures or dislocations, if diminished or absent pulses are identified, it is critical to reduce the fracture or the dislocation and then re-evaluate the perfusion. By placing the bony structures in the anatomical position, you rule out a kink in the vessel as the source of the arterial obstruction. After reduction or relocation, if the pulse is still absent or diminished compared to an uninjured extremity, then further investigation of the vasculature is indicated. In the case described, posterior knee dislocations have a very high incidence of concomitant popliteal artery injury. If vascular compromise is identified after relocation of the knee, operative exploration is indicated for emergent repair of the popliteal artery with a venous interposition graft. It would not be indicated in this setting to delay operative repair for an arteriogram. Arteriograms are indicated in the evaluation of extremity trauma if there are diminished distal pulses after restoring anatomical alignment and the ankle-brachial indices are <0.9.

• Question 317:

  A14-year-old male is evaluated for thigh pain. He has no history of injury. An x-ray of the leg shows a mass in the distal femur that extends into the soft tissue. Abiopsy is performed and cytogenetic studies show translocation of chromosomes 11 and 22. What is this patient's diagnosis?

  A. osteosarcoma
  B. osteoblastoma
  C. metastatic carcinoma
  D. multiple myeloma
  E. Ewing sarcoma
  E. Ewing sarcoma

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  Explanation

  Ewing sarcoma is a malignant neoplasm of the bone that originates in the medullary canal and is composed of small uniform round cells. This tumor belongs to the primitive neuroectodermal tumors (PNET) of childhood. Approximately, 85% of these tumors show the C-MYC oncogene expression and there is a reciprocal transformation of chromosomes 11 and 22.

• Question 318:

  In your role as a physician in a community health center, you agree to perform sports preparticipation examinations on students from the local high school. You have several scheduled for today. Your first appointment is with a 16-year-old male who is planning to run on the cross-country team in the Fall and play baseball in the Spring. He reports that one time he "blacked out" while running, but he has never had chest pain while exercising and he is one of the top runners on the team. He has no known medical history, denies alcohol, tobacco, recreational drug, or performance-enhancing drug use. He has a cousin who died at the age of 21 of "some kind of heart disease," although your patient is not sure of any details. On examination, he is healthy appearing and has normal vital signs, with a pulse rate of 72 and a blood pressure of 100/65. Auscultation of his heart reveals no cardiac murmur while he is lying down, a soft systolic murmur when he stands which increases on having the patient perform a Valsalva maneuver. The remainder of his examination is normal Your next appointment is with a 15-year-old female who plans to play basketball and volleyball. She has no significant medical history, denies a family history of premature cardiac deaths, and denies tobacco, alcohol, recreational drug, or performance-enhancing drug use. She reports having regular menstrual cycles. On examination, she is 72 in. tall, weighs 150 lbs, and has an arm-span of 77 in. Her vital signs are normal. She has a high-arched palate, pectus excavatum, and long, slender fingers. Her cardiac, pulmonary, abdominal, and dermatologic examinations are normal.

  Your management at this point should include further evaluation for the possible diagnosis of which of the following?

  A. Turner syndrome
  B. Marfan syndrome
  C. the female athlete's triad
  D. type 1 diabetes mellitus
  E. atlantoaxial instability
  B. Marfan syndrome

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  Explanation

  Explanations:

  Primary care physicians are frequently called on to perform preparticipation examinations on young athletes. These types of encounters can be used to serve a number of purposes, including attempting to identify conditions that may adversely affect the athlete during participation, identify conditions that may predispose the athlete to injury, provide anticipatory guidance on high-risk behaviors common to the age group being addressed, and fulfill legal conditions of the institution involved. Fortunately, the rate of sudden death in young athletes is low.

  In those under the age of 35, the most common cause of sudden death is congenital cardiac anomalies. Hypertrophic cardiomyopathy (HCM) is responsible for about onethird of these deaths. Unfortunately, sudden death may be the presenting symptom of HCM. Apersonal or family history of congenital heart disease, symptoms of chest pain or tightness, palpitations, dyspnea, syncope or near-syncope are important. A family history of HCM or unexplained sudden death in someone under the age of 50 is significant as well. The murmur of HCM may not be present in all persons with this disorder.

  To identify the murmur, dynamic auscultation is often necessary. The heart should be auscultated while the patient is lying and then standing. As this murmur is accentuated by maneuvers which reduce cardiac preload, the murmur will get louder when the patient stands or performs a Valsalva maneuver and will diminish as the patient lies or squats. As the patient has the concerning historical point of exertional syncope and a family history of an unexplained, early death along with a characteristic murmur on examination, further evaluation is warranted. In the 26th Bethesda Conference report, the American College of Cardiology recommends that persons with HCM should be restricted from all, except possibly for the least strenuous, athletic activity. In this case, restriction of all athletic activity until the patient can be further evaluated by a cardiologist--preferably one with experience in dealing with the evaluation of athletes--would be the most appropriate option of the choices given.

  Marfan syndrome is a connective tissue disorder that typically affects the eyes, skeletal system, and cardiovascular system. Persons with Marfan syndrome are typically tall and have arm spans that are greater than their height. Signs include long, slender digits, high-arched palates, and pectus deformities of the chest. Lens dislocations in the eye are common. Detecting Marfan syndrome during a preparticipation examination is important because of the occurrence of aortic\ root dilation and the risk of sudden death caused by aortic rupture. The patient in questions 23 and 24 has multiple signs of Marfan syndrome and further evaluation would be indicated. Of the options given, an echocardiogram to evaluate the aortic root and to look for other valvular abnormalities would be indicated. These persons usually require referral to an ophthalmologist as well for a dilated eye examination to evaluate for lens dislocations. Turner syndrome is a syndrome of gonadal dysgenesis, associated with a 45, X karyotype (or another defect of the X chromosome). This syndrome is typically associated with a short stature and multiple anomalies including a webbed neck and "shield" chest. The female athlete triad is a syndrome of disordered eating, amenorrhea, and osteoporosis. It is seen most often in participants in activities that emphasize low body weights, such as gymnastics or ballet. The presence of regular menstrual cycles makes this diagnosis unlikely. Atlantoaxial instability can be associated with Down syndrome.

  Physicians performing preparticipation examinations on someone with Down syndrome must consider performing lateral cervical spine x-rays with flexion and extension views. This patient does not have any of the classic findings of Down syndrome. Similarly, she does not exhibit any of the classic symptoms of type 1 diabetes polydipsia, polyphagia, and polyuria. Performing serum glucose testing would therefore not be indicated. The patient is the most typical type of patient who presents for a preparticipation examination-- the healthy adolescent. This may be the only encounter that a physician will have with an adolescent, especially an adolescent male. It is in this population where a physician can use this encounter to address other age appropriate health maintenance issues. As the patient had a Td booster 3 years ago, another one at this point would not be indicated (although consideration could be given to providing a Tdap). Other vaccinations to consider would be hepatitis B and MMR, if he has not previously been adequately immunized. As he has had two MMR vaccines, he has completed the recommended series. There is no history given regarding hepatitis B vaccination and this would be something to address clinically. A nonjudgmental discussion of sexual behaviors, drug use, alcohol use, and other high-risk behaviors would also be appropriate. Screening athletes who have neither concerning symptoms nor signs with ECGs is not recommended because of the poor predictive values and significant costs involved with mass screening. ECGs should be performed without hesitation in any athlete who has a history, examination finding, or preexisting diagnosis of a potentially high-risk condition. Although some localities may require a urinalysis as part of a preparticipation examination, there is no evidence to recommend universal screening

• Question 319:

  A54-year-old woman has a dilation and curettage procedure for the evaluation of postmenopausal bleeding. Which of the following pathologic diagnoses would carry the most favorable prognosis for the patient?

  A. well-differentiated adenocarcinoma with a squamous differentiation
  B. serous carcinoma
  C. clear cell adenocarcinoma
  D. carcinosarcoma
  E. carcinosarcoma with heterologous elements
  A. well-differentiated adenocarcinoma with a squamous differentiation

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  Explanation

  One-third of all endometrial adenocarcinomas contain squamous cells, in addition to glandular elements. If the squamous element is well differentiated with no more than minimal atypia, the tumor is called well- differentiated adenocarcinoma with squamous differentiation. These tumors enjoy a better prognosis stage- by-stage compared with all of the others listed in the question. These tumors are less common and they show an aggressive behavior. The histologic grading, therefore, is not of clinical value.

  These aggressive tumors are serous carcinoma, clear cell adenocarcinoma, carcinosarcoma.

• Question 320:

  A 4-year-old is brought to your office by his mother for evaluation. She is concerned because the child has been spiking fevers and pulling on his left ear. Your examination reveals a bulging and erythematous tympanic membrane (TM).

  You determine that the child should receive antibiotics. The initial antibiotic of choice should be?

  A. amoxicillin
  B. azithromycin (Zithromax)
  C. erythromycin
  D. trimethoprim/sulfamethoxazole (Septra)
  E. tetracycline
  A. amoxicillin

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  Explanation

  The most common cause of otitis media in children is pneumococcus (S. pneumoniae). This is also the most common cause of sinusitis and pneumonia. Otitis media is usually seen in conjunction with an upper respiratory tract infection. Pressure from extensive use of antimicrobials has resulted in a dramatic increase in penicillin resistance in pneumococcus. Amoxicillin remains the recommended initial antibiotic of choice for the treatment of otitis media in children. In an effort to reduce the incidence of antibiotic resistance, and because of the high spontaneous cure rate of otitis media, many authorities are advocating withholding antimicrobial treatment unless symptoms persist for several days in spite of symptomatic treatment.