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

USMLE USMLE-STEP-3 Online Questions & Answers

• Question 111:

  Mr. Jones is a 34-year-old married businessman. He and his wife are both patients in your practice. As part of his annual physical, you screen for high-risk behaviors and he admits to receiving confidential treatment at a public health clinic for gonorrhea and genital herpes. He has not revealed this information to his wife even though they are planning to have a baby. He did not return for the results of HIV screening at the public health clinic. On physical examination, you note that he has cervical and axillary lymphadenopathy, oral thrush, and seborrheic dermatitis. Mr. Jones returns to your office for a follow-up visit. He adamantly refuses to discuss his HIV status with his wife and threatens to sue if you reveal the test results. What is your role as a physician?

  A. Respect Mr. Jones' patient autonomy.
  B. Protect Mr. Jones' confidentiality.
  C. Contact Mrs. Jones and ask her to come in for an annual examination.
  D. Advise Mr. Jones you have a responsibility to notify his wife.
  E. Refer Mr. Jones to an HIV specialist.
  D. Advise Mr. Jones you have a responsibility to notify his wife.

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  Explanation

  Although Mycelex troches would be appropriate in the management of his oral candidiasis and the Lotrisone would treat his seborrheic dermatitis, the patient has previously described risk factors for HIV infection and physical symptoms of immunodeficiency. Accurate knowledge of his HIV status is essential in the appropriate long-term management of this patient. In fact, his current physical examination suggests long-standing HIV infection. A lymph node biopsy is not warranted. His wife will eventually need screening for STDs since active STDs increase her risk of cotransmission of HIV. The patient's refusal to discuss his situation with his wife raises many controversial issues with no simple solution. There are multiple arguments which support the ethical guidelines for supporting patient confidentiality.

  These include:

  ?An appeal to consequences (potential patient discrimination secondary to health information; importance of trust) ?Appeal to virtue (physician fidelity) ?Respect (awareness and compassion for patient vulnerability) ?Do no harm (breach of medical information may lead to discrimination) Respect for patient autonomy incorporates the patient in the treatment process and is based on mutual trust. Referring Mr. Jones to another physician doesn't address the concerns involved in the care of Mrs. Jones. The Tarasoff case (1976) established the following precedent: Patient confidentiality must be upheld as part of the protected clinicianpatient relationship but the physician has a duty to warn specific, innocent third parties of potential harm threatened or posed by the patient. In fact, failure to warn by the physician may constitute negligence. This is not the law in all states. Some states interpret the standard as a strict duty to warn; other states permit physicians to warn affected third parties but not require it. If the physician unilaterally discloses the HIV status, it would represent a breach of confidentiality. However, their marital status may allow this disclosure. Even if the patient is adamant in his refusal, the physician needs to determine the reasons for his reticence. As his physician, you can provide additional information about HIV prevention and treatment. It would be highly unusual for Mr. Jones to ultimately refuse notification of his spouse once he has been urged to do so by his physician. The mechanism for how these complex issues are addressed has potential ramifications for his future trust of physicians, consent to HAART (highly active antiretroviral therapy) treatment, and medication compliance. If these barriers to disclosure cannot be addressed within the physician-patient relationship, the health department can provide a mechanism for contact testing. Although you could ask Mrs. Jones to come in for a physical examination, she might refuse to have STD tests performed, especially if she perceives herself to be at minimal risk. Ideally, this assessment should be performed prior to a pregnancy. If she is currently HIV negative, then protective measures against future infection can be introduced.

• Question 112:

  A 60-year-old man with hypertension, hyperlipidemia, and peripheral vascular disease requires coronary artery bypass graft surgery.

  Which of the following vessels would be the most appropriate conduit for his coronary artery bypass graft?

  A. left axillary artery
  B. internal mammary arteries
  C. ulnar artery
  D. common femoral vein
  E. femoral artery
  B. internal mammary arteries

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  Explanation

  Finding a conduit for use in coronary artery bypass grafting can sometimes be a challenge since these patients often have diffuse atherosclerotic disease. The left internal mammary artery is most commonly used. Bilateral internal mammary arteries can be used, however this increases the chances of sternal healing problems. Saphenous vein grafts are used in patients with multivessel disease, although this may not be an option in patients with deep vein thrombosis (DVT), venous insufficiency, or arterial insufficiency to the legs (because they will not heal the harvest wound). Radial arteries, the right gastroepiploic artery, and inferior epigastric arteries have also been used.

• Question 113:

  On your surgery rotation you are assisting in a gastric surgical procedure. The attending surgeon asks you to describe the vascular supply to the stomach. You reply with which of the following?

  A. The right gastric artery arises from the celiac axis.
  B. The left gastric artery arises from the common hepatic artery.
  C. The right gastroepiploic arises from the right hepatic artery.
  D. The short gastric arteries arise from the splenic artery.
  E. The left gastroepiploic arises from the left gastric artery.
  D. The short gastric arteries arise from the splenic artery.

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  Explanation

  The main blood supply to the stomach comes from the right gastric artery (from the hepatic artery), the left gastric artery (from the celiac axis), the right gastroepiploic artery (from the gastroduodenal artery), the left gastroepiploic (from the splenic artery), and the short gastric arteries from the splenic artery.

• Question 114:

  A 24-year-old G1 presents to you for initiation of obstetric care. She informs you that she is on a medication that was prescribed for acne. The drug is listed as category X in your pharmacy book.

  The pregnancy risk factor category X for a drug indicates which of the following?

  A. Controlled human studies demonstrate no risk to a fetus.
  B. This drug should never be used by a pregnant female under any circumstances.
  C. Evidence of human teratogenic risk exists but in some cases the known risks may be outweighed in some serious situations, such as life-threatening disease.
  D. Animal reproduction studies have not demonstrated fetal risk but there are no controlled human studies to assess the risk.
  E. Animal reproduction studies have demonstrated risk to a fetus and no controlled human studies are available.
  B. This drug should never be used by a pregnant female under any circumstances.

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  Explanation

  The pregnancy risk factor category assists the physician and patient to understand the safety of the use of a medication during pregnancy. The summary of the categories is as follows: category A-- controlled human studies demonstrate no risk to a fetus. Category B--animal-reproduction studies have not demonstrated fetal risk but there are no controlled human studies to assess the risk. Category C-- animal- reproduction studies have demonstrated risk to a fetus and no controlled human studies are available. Category D--evidence of human teratogenic risk exists but in some cases the known risks may be outweighed in serious situations, such as lifethreatening disease. Class X--this drug should never be used by a pregnant female under any circumstances. The principle of autonomy states that the patient has the right and capability to control the course of her medical care and to participate in the decision-making process.

• Question 115:

  A 26-year-old man is brought into the emergency room via ambulance, minimally responsive to questioning or examination. According to his girlfriend, he has a history of major depressive disorder as well as alcohol dependence. He was found unconscious with a suicide note and many empty beer bottles. She also believes that he had taken "some other drug" that he purchased from a local drug dealer. Which of the following substances found in urine toxicology would be the most dangerous in this patient?

  A. barbiturate
  B. cannabis
  C. cocaine
  D. opiate
  E. PCP
  A. barbiturate

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  Explanation

  Explanations:

  Even large amounts of cannabis do not cause death. Cocaine, PCP, and opiates can certainly be lethal in overdose, particularly when combined with alcohol. However, because of their similar effects on the GABA (gammaaminobutyric acid) receptors in the brain, barbiturates (and benzodiazepines) are especially deadly when added to alcohol in an overdose

• Question 116:

  A 4-year-old boy is brought to the emergency room by his mother after the child spontaneously admitted to swallowing part of a toy. The child is unable to describe what he ate further, although he appears to be in no distress. His vital signs are normal and his respiratory and abdominal examinations are unremarkable. The child is hungry and is demanding to eat something. ACXR reveals what appears to be a watch battery ("button battery") in the patient's esophagus. What is the best course of action in this situation?

  A. admit the child to the hospital and allow him to eat
  B. admit the child to the hospital but keep him in a fasting state
  C. induce vomiting
  D. emergency endoscopy
  E. discharge the patient with instructions to look in his stools for the battery to confirm passage
  D. emergency endoscopy

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  Explanation

  The child has ingested a button battery which has lodged in the esophagus. This constitutes a medical emergency and immediate emergency endoscopy is warranted. Button batteries can cause severe esophageal injury and tissue necrosis via electrical current discharge as well as burns from alkali chemicals contained within the battery itself. Severe burns and perforation can occur within hours. Admission for observation is inadequate, and vomiting should not be induced as this could promote aspiration of the battery or gastric contents. Emergency surgery should be reserved for patients in whom endoscopy fails. The patient cannot be discharged with a button battery in the esophagus.

• Question 117:

  A well-appearing 6-year-old presents to your office with a chief complaint of bruising. The parents report that the child had a cold 2 weeks ago but completely recovered. The child is sitting on the examining table, in no distress, discussing her favorite cartoons. On examination, you find mucosal bleeding and bruises on the child's arms and chest. You order a complete blood count (CBC) that has the following results: WBC 12,000, hemoglobin 11 g/dL, and a platelet count of 45,000.

  Following your initial evaluation and treatment, you see the child for follow-up in 1 week. She continues to appear well but still has obvious purpura and her platelet count is now 17,000. All other cell lines are normal. Of the options listed below, what is your most appropriate management at this time?

  A. admission to the regional children's hospital for a platelet transfusion
  B. admission to the children's hospital for a splenectomy
  C. reassurance to the parents and close outpatient follow-up
  D. admission to the children's hospital for IVIG and steroids
  E. whole-blood transfusion with several hours of observation to ensure that there is no transfusion reaction
  D. admission to the children's hospital for IVIG and steroids

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  Explanation

  The hallmark of immune (also known as idiopathic) thrombocytopenia purpura (ITP) is the otherwise healthy appearing child with isolated thrombocytopenia. ITP is the most common cause of isolated thrombocytopenia in childhood. It occurs with equal frequency in both boys and girls. The presence of thrombocytopenia in a patient with otherwise normal cell lines, and a normal physical examination is enough to make the diagnosis, so further evaluation, such as a bone marrow biopsy, is unnecessary. Which children to treat and which treatment to use are areas of controversy in the management of ITP. Most acute ITP will resolve spontaneously, so many will recommend observation for children who appear well, are asymptomatic, and have platelet counts above 30,000. Platelet transfusions should be reserved only in the instance of ongoing or imminent bleeding. When a decision is made to treat, usually when the platelet count falls below 20,000, there are several options available. Treatment involves using IVIG, steroids, anti-D immunoglobulins, or combinations thereof. Combinations of medications may work synergistically. Prednisone is often used initially, as it can be given orally and is inexpensive. Typically, it will be tapered over 2 weeks to 3 months. By using combination therapy when needed, splenectomy can be avoided in the vast majority of cases. When it is necessary, it should be delayed, if at all possible, for at least a year after diagnosis.

• Question 118:

  A 72-year-old male presented with nonspecific symptoms of easy fatigability, weight loss, and anorexia. On physical examination, generalized lymphadenopathy and hepatosplenomegaly were present. On the peripheral blood, he was found to have a marked lymphocytosis and in the serum, a small monoclonal spike was present.

  The clinical behavior of this disease can best be described by which of the following?

  A. rapidly progressive
  B. never relapses
  C. can be completely eradicated by chemotherapy
  D. the median survival is 46 years
  E. never responds to chemotherapeutic agents
  D. the median survival is 46 years

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  Explanation

  Chronic lymphocytic leukemia is a disease that presents generally over the age of 50 with a male predominance. For a long time many of these patients remain asymptomatic and, when they do present, the symptomatology is nonspecific, with generalized lymphadenopathy and hepatosplenomegaly. The peripheral lymphocyte count is generally high and composed of small lymphocytes. A low percentage of patients develop autoantibodies directed against red cells or platelets, which produces autoimmune hemolytic anemia or thrombocytopenia. Although the disease progresses and relapses in spite of the chemotherapy treatment, the overall median survival is 46 years, but this appears to be very variable. Some patients may survive longer than 10 years. All of the parameters for a worse prognosis have to be measured before a final statement of prognosis can be made. The lymph node architecture is diffusely effaced by a population of small lymphocytes, which contain nondiscernible cytoplasm and inconspicuous nucleoli. Mitotic activity is rare, focal proliferation centers with an increase in the number of mitotic activity cells are seen.

• Question 119:

  A49-year-old female noticed that, in the morning, the small joints of her hands are swollen, painful, and stiff. Her rheumatoid factor is reportedly strongly positive. Citruline tests (cyclic citrullinated peptide [CCP]) are also positive.

  What disease does the patient most likely have?

  A. degenerative joint disease
  B. rheumatoid arthritis
  C. spondyloarthritis
  D. tennis elbow
  E. septic arthritis
  B. rheumatoid arthritis

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  Explanation

  In this case, the patient most likely has rheumatoid arthritis, an autoimmune chronic relapsing disorder that mostly affects the joints. The disease is usually seen in Western European and North American White females between the ages of 30 and 50. The clinical hallmark of the disease is symmetric swelling of the small joints of the hands and feet, particularly the proximal and interphalangeal joints. Swelling, pain, and stiffness are most severe in the morning. Pathologically, a pannus, or hypertrophic inflamed synovium, is produced that may eventually erode into the articular cartilage, with subsequent fibrosis, restriction of movements, and deformity.

• Question 120:

  You are asked to perform a high school physical examination for a 16-year-old female patient. She is on the track team. By history, she is healthy except for the fact that she has been amenorrheic for 4 months. She denies current or past sexual activity. On examination, she is 5 ft 9 in. tall and weighs 115 lbs. Her heart rate is 50 bpm. She has dry skin with lanugo. She has several sores in her mouth and obvious dental caries. She has several scratches on the backs of her hands. She is tanner stage III on breast examination. Her pelvic examination is remarkable for findings of urogenital atrophy. Her urine -hCG is negative.

  At this point in time, appropriate management of this patient would include which of the following?

  A. laboratory assessment of electrolytes and an electrocardiogram
  B. intensive care unit (ICU) admission
  C. antipsychotic medication
  D. reassurance
  E. IM Depo-Provera injection
  A. laboratory assessment of electrolytes and an electrocardiogram

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  Explanation

  Menstrual disorders, primarily oligo- and amenorrhea, are particularly common among women with eating disorders and are thought to be the result of hypothalamic hypoestrogenism. This patient demonstrates estrogen deficiency (decreased breast size, urogenital atrophy). Her dental caries, oral sores, and hand sores might be a result of self-induced vomiting. Hyperthyroidism would be considered in the differential diagnosis of a young woman with weight loss and menstrual irregularities. In contrast to persons with a medical condition that causes weight loss, those with an eating disorder express a disordered body image and, often, a desire to be underweight. This patient requires additional investigation to assess for the possibility of inpatient admission. Patients with a prolonged, severe eating disorder are at risk for developing dehydration, electrolyte imbalance (especially hypokalemia), cardiac dysrhythmias, and hypothermia. Hospitalization would be considered for those who are severely dehydrated, who have marked electrolyte abnormalities who are <75% of their ideal body weight, or who have a comorbid condition that would require hospitalization, such as a severe psychiatric disorder. Although weight-bearing exercise favors bone formation, when excessive exercise and/or an eating disorder results in amenorrhea, estrogen levels fall. Subsequently, bone mineral density decreases. Persons with eating disorders are at increased risk for comorbid psychiatric conditions including depression, anxiety, obsessive-compulsive disorder, and personality disorders.