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

USMLE USMLE-STEP-3 Online Questions & Answers

• Question 541:

  A35-year-old woman with two prior term pregnancies presents for her first prenatal visit at 12 weeks' gestation. She recalls having had hypertension near the end of her first pregnancy. She believes her blood pressure has been normal since, but admits that she rarely seeks preventive health care visits, and that her last examination by a physician was more than 2 years ago. Today, you find her blood pressure to be 160/100.

  Her blood pressure comes under good control after initiating medication and remains well controlled until the 36th week, when her blood pressure is noted to have risen again to 170/110. She is also noted to have 3+ proteinuria on urine dipstick testing.

  For which of the following complications is she at risk?

  A. eclampsia
  B. fetal macrosomia
  C. abnormal progress of labor
  D. postpartum hemorrhage
  E. breech presentation
  A. eclampsia

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  Explanation

  The angiotensin-converting enzyme inhibitors (and angiotensin receptor blockers) are contraindicated in pregnancy due to their potential to cause decreased fetal renal perfusion, ultimately resulting in fetal oliguria, oligohydramnios, renal tubular dysplasia, and neonatal anuric renal failure, as well as defects in ossification of the fetal skull. These adverse effects occur during the second and third trimesters of pregnancy. If a woman conceives while taking an angiotensin-converting enzyme inhibitor, she should be changed to another agent during the first trimester.

  Preeclampsia causes 5070% of cases of hypertension in pregnancy. Mild preeclampsia is characterized by an increase in systolic BP of 30 mmHg, an increase in diastolic BP of 15 mmHg, or an absolute reading of 140/90 mmHg in a pregnant patient with minimal proteinuria and pathologic edema. A systolic BP greater than 160/110 mmHg with significant proteinuria (>5000 mg/24 h) and evidence of end-organ damage indicate severe preeclampsia. End organ damage results from increased vascular reactivity, third spacing of fluids, and platelet activation. Complications include oliguria, the syndrome of hemolysis, elevated liver function tests, and low platelets (HELLP) and eclamptic seizures. Seizure prophylaxis is effective in both primary prevention of eclampsia and in prevention of recurrent seizures. Fetal macrosomia occurs more commonly in pregnancies complicated by diabetes. Abnormal labor progress and postpartum hemorrhage as well as breech presentation are not more common in pregnancies complicated by preeclampsia.

• Question 542:

  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.

  After discussing various options with a regional pediatric hematologist and the patient's parents, your most appropriate initial management would be which of the following?

  A. a platelet transfusion at the regional children's hospital
  B. an IM dose of methylprednisolone as an outpatient
  C. reassurance to the parents with close outpatient follow-up
  D. intravenous immunoglobulin (IVIG) at the regional children's hospital
  E. bone marrow biopsy at the regional children's hospital
  C. reassurance to the parents with close outpatient follow-up

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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 543:

  A62-year-old female with a history of a recent pulmonary embolus presents to your office for follow- up on anticoagulation treatment. She takes warfarin on a daily basis. She reports that for the last week she has noticed mild rectal bleeding and multiple bruises over the extremities with minimal trauma. She is comfortable appearing with normal vital signs and is not orthostatic. You ordered a stat CBC and PT/INR which revealed a mildly decreased Hgb at 11 g/dL and an elevated INR of 7. Which of the following would be the most appropriate intervention?

  A. subcutaneous injections of heparin
  B. oral allopurinol
  C. intravenous protamine sulfate
  D. oral vitamin E
  E. oral vitamin K
  E. oral vitamin K

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  Explanation

  Warfarin acts as a vitamin K antagonist by blocking the regeneration of the reduced form of the vitamin. The result is a decrease in clotting factors II, VII, IX, and X leading to an increase in bleeding time. Warfarin toxicity can be alleviated by increasing the availability of vitamin K.

• Question 544:

  A6-month-old boy is brought to the office for a routine check-up by his mother. They have recently moved to the area and are new to your practice. He is the product of an uncomplicated term pregnancy, has grown and developed appropriately for his age, and is up-to-date on his immunizations. He has had two cases of otitis media in his life. Neither of his parents has been diagnosed with any chronic medical conditions. Both of his parents smoke cigarettes, but "not in the same room" as the child.

  Which of the following statements is true?

  A. Children of parents who smoke become smokers less often than children of nonsmokers.
  B. Chemicals from cigarette smoke do not get into breast milk.
  C. More than 95% of the smoke from a cigarette is out of a room within 30 minutes of smoking cessation.
  D. The United States Environmental Protection Agency (EPA) does not consider secondhand smoke to be a carcinogen.
  E. Parental smoking may be considered as a factor in assessing the "best interest" of a child in child custody hearings.
  E. Parental smoking may be considered as a factor in assessing the "best interest" of a child in child custody hearings.

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  Explanation

  Environmental tobacco smoke, or "secondhand smoke," consists of both "mainstream smoke" which is exhaled by the smoker and "sidestream smoke" which comes from the burning cigarette between puffs. About half of the smoke from a cigarette is sidestream smoke, which consists of the same chemicals as the mainstream smoke that is inhaled by the user. Nonsmokers exposed to secondhand smoke absorb nicotine, carcinogens, and other chemicals from the smoke just as the smoker does. While the concentration of the chemicals absorbed is less than in a smoker, the levels absorbed increase as exposure increases and there are significant health risks involved. The EPAconsiders secondhand smoke to be a class A carcinogen a substance that causes cancer in humans. Among the health risks are increased incidences of asthma, respiratory infections, otitis media, and SIDS in children exposed to secondhand smoke. Nursing mothers can pass harmful chemicals from cigarette smoke in breast milk.

  While separating smokers and nonsmokers in the same airspace may reduce the exposure to secondhand smoke, the exposure is not eliminated. It is estimated to take 3 hours to remove 95% of the cigarette smoke from a room once smoking is completed, so there is still significant risk for exposure even though the nonsmoker is not in the same room. Courts in the United States and Canada have considered the smoking behaviors of parents as factors in determining the "best interests" of a child during custody hearings. Finally, parental smoking is an important predictor of the smoking behaviors of their children as they become adolescents.

• Question 545:

  A 42-year-old man presents to your clinic with a 1-week history of pain and inflammation involving his right first metatarsophalangeal (MTP) joint. He describes the pain as sudden in onset and worse at night. He denies experiencing any fever or traumatic injury to the joint and states that he has never had this type of pain before. He denies any chronic medical conditions, any prior surgery, and any current medication use. Besides an erythematous and exquisitely tender right first MTP joint, the remainder of his physical examination is unremarkable.

  Aspiration of the patient's right first MTP joint space is likely to reveal which of the following?

  A. negatively birefringent crystals
  B. positively birefringent crystals
  C. nonbirefringent crystals
  D. acellular synovial fluid
  E. gram-positive cocci in clusters
  A. negatively birefringent crystals

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  Explanation

  This patient's presentation is consistent with gout. Aspiration of his first MTP joint is likely to reveal the presence of needle-shaped, negatively birefringent crystals. Rhomboid-shaped, positively birefringent crystals are characteristic of calcium pyrophosphate deposition disease, or pseudogout, with the knee being the joint most commonly affected. Nonbirefringent crystals are found in hydroxyapatite crystal deposition disease. The synovial fluid from joints affected by gout typically show evidence of inflammation in the form of leukocytosis with a predominance of polymorphonuclear neutrophils. The presence of bacteria in synovial fluid is characteristic of infection rather than gout, although gout and infectious arthritis may coexist. (Cecil Textbook of Medicine, pp. 17031708) Acute gouty arthritis usually presents in a monoarticular or oligoarticular distribution, with the first MTP joint most commonly affected. The diagnostic gold standard is detection of urate crystals within the synovial fluid of affected joints.

  It most commonly affects adult men with a peak incidence in the fifth decade of life. While patients with gout typically also have hyperuricemia, only a small fraction of the people with hyperuricemia actually have or will develop gout.

  Tophi are primarily seen in patients with long-standing hyperuricemia and is considered a finding of chronic gouty arthritis. As the disease progresses, acute attacks become more frequent and last longer if left untreated. Indomethacin inhibits the prostaglandin synthesis that facilitates the inflammation of acute gout and inhibits the phagocytosis of urate crystals by leukocytes. This inhibits the cell lysis and release of cytotoxic factors that initiate the inflammatory cascade. Allopurinol (an inhibitor of urate synthesis) and probenecid and sulfinpyrazone (promoters of urate excretion) are useful for preventing gout but are not effective during an acute gout attack. Aspirin is inappropriate in the treatment of gout since it can inhibit urate elimination and, therefore, increase hyperuricemia.

• Question 546:

  A40-year-old single male with chronic schizophrenia is seen for a routine primary care clinic appointment for diabetes management. He is currently taking glyburide 5 mg bid and aripiprazole (Abilify) 20 mg daily. He claims to be compliant with his medications but appears poorly groomed with noticeable body odor. He is reluctant to talk, being somewhat guarded, but he eventually confides that he has been programmed by the government to kill his landlord, who he is convinced is working for Al Qaeda. His orders have been transmitted through his apartment walls to a receiver in his brain. He has been informed that if he does not comply, he will be sent to hell, so he has recently purchased several knives and plans to carry out "my mission" as soon as possible. When the subject of voluntary admission is brought up, he adamantly refuses.

  What is the most appropriate next step in his management?

  A. admit the patient involuntarily
  B. call the landlord and warn him
  C. continue current medications with close follow-up
  D. discuss the potential legal issues with the patient
  E. switch the patient to another atypical antipsychotic
  A. admit the patient involuntarily

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  Explanation

  The patient has chronic schizophrenia with an acute exacerbation consisting of disorganization, paranoia, persecutory delusions, and command hallucinations to kill his landlord. Although all of the choices may be indicated, this patient appears to be at significant risk of harm to others, namely his landlord. Therefore, only admission to the hospital for treatment (either voluntary or involuntary) would adequately protect the landlord. The Durham rule refers to criminal responsibility, that one is not criminally responsible if the illegal act was a product of a mental disease or defect. The M'Naghten rule was established by the British courts and posits that one is not guilty by reason of insanity if, due to a mental disease, one was unaware of the nature of the act or was incapable of realizing the act was wrong. Testamentary capacity refers to one's competence to make a will. The Tarasoff I and Tarasoff II rulings refer to the duty to warn others of danger and duty to protect others from danger, respectively.

• Question 547:

  Which of the following can induce menstrual bleeding in a 21-year-old anovulatory, amenorrheic woman with PCOS?

  A. administration of progestins
  B. administration of estrogens
  C. withdrawal of progestin therapy
  D. withdrawal of estrogen therapy
  E. danazol
  C. withdrawal of progestin therapy

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  Explanation

  Apatient who is anovulatory due to PCOS would be expected to have normal estrogen production. However, without corpus luteum formation following ovulation there is no significant progesterone production. Therefore, the discontinuation of a period of progestin therapy would initiate menstrual flow

• Question 548:

  A 72-year-old man comes to your clinic for the first time, accompanied by his wife. His wife states that she is concerned because he has been growing increasingly forgetful over the past year. Within the past month, he has forgotten to turn off the stove and has got lost while walking to the post office one block away from their home. His past medical history is significant for well-controlled diabetes and chronic lower back pain. He has no history of falls or traumatic injury to the head. Examination of the patient is significant for a score of 18 on a Mini Mental Status Examination (MMSE). During the administration of the MMSE, the patient blurts out that his wife brought him to the doctor because she is having an extramarital relationship.

  Use of which of the following medications would be the most likely to lead to worsening of symptoms in this patient?

  A. risperidone
  B. amitriptyline
  C. olanzapine
  D. quetiapine
  E. trazodone
  B. amitriptyline

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  Explanation

  This patient's symptoms are most consistent with Alzheimer disease. Alzheimer disease is a prominent condition in developed nations, ranking as the third most common terminal illness behind heart disease and cancer. It is the most common form of dementia, with over 4 million Americans having the condition in the United States alone. There is a direct correlation between advanced age and increasing prevalence of Alzheimer disease. While there is an early-onset form of familial Alzheimer disease that may appear as early as the third decade of life, this accounts for only a small percentage of total Alzheimer cases. There does appear to be a genetic component to the development of Alzheimer disease, as it has been demonstrated that first-degree relatives of Alzheimer patients possess an increased risk for development of the condition. Genes on chromosomes 1, 14, and 21 have been implicated in this association. While age and family history are important risk factors, there is no evidence proving that environmental factors lead to an increased chance for development of the disease. Progression of Alzheimer dementia is typically insidious, spanning as many as several years.

  Anticholinergic agents and any other medication with anticholinergic effects are contraindicated in the setting of Alzheimer dementia. Their use may lead to worsening of cognition and may contribute to decreased efficacy of medications used in the treatment of Alzheimer dementia. Tricyclic antidepressants such as amitriptyline should be avoided for this reason. Risperidone, olanzapine, and quetiapine are atypical antipsychotic medications which are useful in the treatment of emotional withdrawal and delusions which may arise in Alzheimer patients. Trazodone, carbamazepine, and divalproex are moodstabilizing medications which are useful in patients who display marked agitation. While trazodone does display some anticholinergic side effects, they are far less pronounced than those seen with amitriptyline.

• Question 549:

  A32 year-old male presents to the primary care clinic with recurrent episodes of bronchitis. He is otherwise healthy but admits to a 14 packyear history of cigarette smoking. He is prescribed another trial of appropriate antibiotics, but he has "had enough" of smoking and wants to quit. Use of which of the following modalities would most likely give him the best chance of quitting?

  A. bupropion
  B. nicotine gum
  C. nicotine inhaler
  D. nicotine nasal spray
  E. nicotine patch plus behavioral therapy
  E. nicotine patch plus behavioral therapy

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  Explanation

  Any of the nicotine replacement therapies (gum, patch, or inhaler) have been found to double cessation rates. Bupropion has also been shown to double quit rates. Several studies have demonstrated that the combination of nicotine replacement and behavior therapy increases quit rates over either alone.

• Question 550:

  A 53-year-old female has made an appointment to see you concerning the recent onset of menopause. Her last menstrual period was 8 months ago and, over the last year, she had noticed that her periods were becoming lighter and less frequent. In addition, she has developed frequent hot flashes, and her mood has become very labile. She wishes to know what your advice is regarding hormone replacement therapy (HRT). She has heard recent reports in the news concerning an increased risk of developing cardiovascular complications, especially heart attacks and strokes. Although she is in great health, her father died at age 50 of a massive heart attack. Her mother is alive and well, and there is no history of breast cancer among the females in her family

  Which of the following would be the strongest argument to avoid HRT in this patient?

  A. HRT is unlikely to relieve her hot flashes.
  B. She has a positive family history of CAD.
  C. She is at high risk for developing breast cancer.
  D. She is at high risk for developing venous thromboembolism.
  E. She probably would develop breast tenderness and bloating.
  B. She has a positive family history of CAD.

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  Explanation

  Despite recent findings from the Women's Health Initiative (WHI) study, which show that HRT may not be cardioprotective and may increase the risk for cardiovascular events (MI and stroke) in postmenopausal women with a known history of cardiovascular disease, HRT remains an effective way to treat and alleviate vasomotor instability and reduce the risk of osteoporosis and bone fractures (particularly hip fractures). In addition, there is evidence to support that this effect, along with improvement in affect and mood stability, is long lived and persists during the course of therapy. The incidence of endometrial cancer appears to be reduced in those taking HRT. The use of HRT in those with risk factors for cardiovascular disease must be made on an individual case base, with carefully considering the risks versus the potential benefits of the intervention.

  The WHI study has demonstrated an added risk for developing cardiovascular events, such as MI and stroke, among those with known coronary disease or populations at high risk for CAD. A significant family history of CAD (father died at early age of an MI) would place this patient in the category of higher risk. Although patients taking HRT are at an increase risk for developing venous thromboembolism, this would not preclude its use unless the patient had a known history of the disease. The incidence of breast cancer in women on HRT remains controversial and, in our patient's case, we are told that there is a negative family history, hence making it less of a concern. Bloating and breast tenderness may develop in patients taking HRT, but its occurrence would not be a reason not to start therapy on our patient.