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

USMLE USMLE-STEP-3 Online Questions & Answers

• Question 231:

  A65-year-old White female presents to the office for her annual gynecologic examination. She has been a patient of yours for many years. She also sees you on a routine basis for treatment of hypertension and hypothyroidism. Her last pap smear was 5 years ago and she has never had an abnormal pap smear. She had a mammogram 1 year ago that was normal. She does not perform self- breast examination. She is without complaint today.

  Past medical 1. Hypertension for 15 years history: 2. Graves' disease, treated with radioactive iodine thyroid ablation at age 50 OB/GYN history: 1.

  Menarche at age 14 2. Four term pregnancies with vaginal deliveries (at age 22, 25, 27, and 32) 3. Total abdominal hysterectomy and bilateral salpingo oophorectomy (TAH/BSO) age 47 for fibroids 4. On estrogen replacement therapy from age 47 to 55 Past surgical 1. Appendectomy at age 16 history:

  2. TAH/BSO as noted above Medications: 1. Hydrochlorothiazide 25 mg daily 2. Levothyroxine 0.1 mg daily 3. Potassium chloride 20 meq daily Allergies: None Family history: Parents, siblings unknown as patient was adopted Children are alive and well without known chronic medical conditions Social history: Widowed for 5 years, has not been involved in a sexual relationship since the death of her husband; retired school teacher; college educated; does not smoke cigarettes, drink alcohol, or use drugs; walks 3045 min a day for exercise

  At this visit you should do which of the following?

  A. perform a pap smear
  B. recommend that she restart estrogen replacement therapy
  C. tell her that she can reduce her risk of dying of breast cancer by performing self-breast examinations monthly
  D. order a bone density test to screen for osteoporosis
  E. send a urine culture as a screening test for asymptomatic bacteruria
  D. order a bone density test to screen for osteoporosis

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  Explanation

  Explanations:

  Screening for osteoporosis in women 65 years old or older is a level B recommendation of the USPSTF, as detection and treatment of osteoporosis may reduce fracture risk. In women who have had a hysterectomy (with removal of the cervix) for reasons other than cervical cancer, pap smear screening of the vaginal cuff is not recommended and cytologic screening can be discontinued. Therapy with either estrogen alone (in women who do not have a uterus) or combined estrogen and progesterone (in women who have a uterus) in postmenopausal women is controversial. Based on findings of the Women's Health Initiative and other studies, the USPSTF gives a level D recommendation to the use of combined estrogen and progesterone therapy and level I recommendation for estrogen therapy alone for the prevention of chronic conditions. Screening for asymptomatic bacteruria in all populations other than pregnant women is given a level D recommendation. No benefit from the intervention has been found and overtreatment with antibiotics may produce harm. While mammography for breast cancer screening has been given a level B recommendation, both self-breast examination and clinical breast examination are level I recommendations, with insufficient evidence to show any benefit in morbidity or mortality.

  According to the Centers for Disease Control, diseases of the heart make up the most common cause of death in women in this age group. Heart disease is responsible for approximately one-third of all deaths in women aged 65 and older. Malignant neoplasms make up the next largest cause of death, followed by cerebrovascular diseases and chronic lower respiratory diseases. PPV-23 is recommended for all adults over the age of 65 and at younger ages for individuals at high risk for pneumonia or complications of pneumonia. These include persons with diabetes mellitus, chronic obstructive pulmonary disease, coronary artery disease, and those who have had a splenectomy or are functionally asplenic. The PCV-7 is recommended for the routine vaccination of children. Hepatitis B vaccine is recommended universally for children and for adults who are at high risk for the disease based on profession or lifestyle. Hepatitis A vaccine is recommended for children who live in certain areas of the United States in which the disease is prevalent and may be offered electively to persons traveling to endemic areas. The MMR vaccine is recommended to all children but is not indicated in adults. Rubella vaccination is recommended for women of childbearing age who may become pregnant and who do not have immunity to rubella, in an effort to reduce the risk of congenital rubella infection

• Question 232:

  A young White female, age unknown, is brought into the emergency room after being found unresponsive at the bus station. She is obtunded and her vitals signs are temperature 97.8, blood pressure (BP) 9 4/60, pulse 55, and respirations 8. Her physical examination is notable for a markedly underweight, poorly groomed woman. She appears pale with cold, dry skin and mucous membranes. She is uncooperative with the examination. Her pupils are pinpoint and minimally reactive to light. Her cardiac examination demonstrates bradycardia without murmurs or rubs. Her lungs are clear with shallow breathing. Her abdomen appears to be slightly distended.

  Intake of which of the following substances would most likely account for her presentation?

  A. alcohol
  B. anticholinergic
  C. benzodiazepine
  D. heroin
  E. phencyclidine (PCP)
  D. heroin

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  Explanation

  Alcohol and benzodiazepine intoxication commonly present with disinhibited behavior, slurred speech, poor coordination, and nystagmus, but not typically with dry mucous membranes or constricted pupils. Patients with anticholinergic overdose classically demonstrate psychotic symptoms and dry skin, similar to the above case. However, physical examination usually shows dilated pupils, warm skin, and tachycardia. PCP intoxication also manifests itself with vertical or horizontal nystagmus, dysarthria, and even coma, but it will usually cause hypertension or tachycardia (DSM IV-TR). This case is a typical presentation of opiate (such as heroin) overdose. The clinical triad is coma/unresponsiveness, pinpoint pupils, and respiratory depression. Other signs may include hypothermia, hypotension, and bradycardia. Disulfiram is an oral, nonemergent medication that blocks aldehyde dehydrogenase to cause a noxious reaction in those who consume alcohol while taking it. It is useful as a deterrent to drinking alcohol but not indicated for alcohol or opiate overdose.

  Flumazenil is a benzodiazepine receptor antagonist used to reverse the symptoms of overdose with benzodiazepines, especially the sedation and respiratory depression. It would have no effect on overdose on opiates unless benzodiazepines have been ingested concurrently. Intravenous thiamine is indicated for the treatment of Wernicke's encephalopathy, due to the thiamine deficiency seen in alcoholics. The classic triad seen in Wernicke encephalopathy consists of oculomotor disturbances, ataxia, and delirium. Although individuals with chronic opiate dependence are often malnourished, thiamine would not prevent complications seen with overdose. Physostigmine is an anticholinesterase inhibitor used in the emergent treatment of anticholinergic toxicity, but it could be dangerous in opiate overdose since it can cause further hypotension. Intravenous naloxone, an opiate antagonist, is the treatment of choice for the urgent management of heroin overdose, as it rapidly reverses the sedation, respiratory depression, hypotension, and bradycardia seen in cases similar to the patient above.

• Question 233:

  An 18-year-old female presents for evaluation of facial acne. On examination, she has multiple comedones, papules, and pustules on her forehead, nose, cheeks, and chin. She also has several distinct nodules, each greater than 5 mm in diameter. Which of the following is most appropriate for initial inclusion in a regimen to treat this patient's acne?

  A. erythromycin gel
  B. tretinoin 0.025% cream
  C. clindamycin lotion
  D. oral tetracycline
  E. oral isotretinoin
  D. oral tetracycline

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  Explanation

  This patient has nodulocystic acne which is characterized by the presence of multiple comedones, inflammatory papules, pustules, and large nodules. Characteristically, the nodules measure greater than 5 mm in diameter. Initial therapy should include a systemic antibiotic such as tetracycline or erythromycin. Use of local therapy alone may be adequate in individuals with comedonal acne. In cases of acne which feature more of an inflammatory component (with papules and pustules), topical and oral antibiotics are useful. Oral isotretinoin is indicated for severe nodulocystic acne that is unresponsive to other therapies.

• Question 234:

  A 49-year-old male postal worker presents to your office for the evaluation of a lesion on his left arm. The lesion started about a week ago as a red pustule but has grown and now has a thick black scab. The lesion is painless. A coworker showed the patient a similar appearing lesion that she developed on her arm for which her doctor prescribed an oral antibiotic. Examination reveals a 5 cm circular black eschar with some surrounding vesicles. A Gram stain of fluid drained from a vesicle reveals chains of gram-positive bacilli.

  What is the most appropriate management at this point?

  A. topical mupirocin ointment tid for 10 days
  B. oral cephalexin 500 mg qid for a week
  C. oral clindamycin 300 mg tid for 10 days
  D. urgent quarantine of patient's coworkers and family contacts
  E. immediate notification of Public Health Authorities
  E. immediate notification of Public Health Authorities

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  Explanation

  B. anthracis causes three diseases in humans: cutaneous, inhalation, and gastrointestinal anthrax. Cutaneous anthrax is the most common of the naturally occurring anthrax diseases. The spores of the gram-positive bacillus can survive for years in soil. The disease cutaneous anthrax occurs when the spores contaminate a wound on the skin of the victim and then start to grow. This disease occurs most commonly in agricultural areas where the soil becomes contaminated by the presence of animals. Initially

  a painless papule develops, followed by vesicles which then ulcerate and a black eschar forms. In the setting of cutaneous anthrax in a postal worker who has a coworker with an apparently similar disease, bioterrorism must be suspected. This type of attack occurred in the Fall of 2001, when anthrax spores were sent through the U.S. Postal system and over 20 persons were infected. In this setting, the most appropriate initial management is to immediately contact the appropriate Public Health Authorities,

  usually the local or state health department. Appropriate treatment will also need to be instituted, under the guidance of the public health specialists, as untreated cutaneous anthrax may carry a 20% mortality rate. Antibiotic therapy would usually be with ciprofloxacin, penicillin, or doxycycline. Anthrax does not spread from person to person, so quarantine is not necessary. Inhalation anthrax is caused by the direct inhalation of spores into the lungs and gastrointestinal anthrax, the least common of the anthrax

  syndromes, is caused by ingestion. Smallpox does not occur naturally anywhere in the world. Therefore, any suspicion of smallpox must be assumed to be a bioterror event and must be reported immediately to public health officials. Physicians should be able to recognize the signs and symptoms of smallpox and be able to distinguish them from the common occurrence of chickenpox. Chickenpox lesions tend to occur in clusters and evolve asynchronously. They are often described as "dew drops on a rose

  petal" as they are vesicles occurring on an erythematous base. The lesions tend to start on the trunk and rapidly spread outward. The rash will be associated with a fever but there are usually few to no prodromal symptoms. Because of the asynchronous growth and outbreaks, a patient will typically have lesions in different stages of evolution. In contrast, smallpox lesions tend to occur synchronously and the lesions tend to be uniform. The rash frequently occurs on the palms and soles. It typically starts on the

  face and arms and then spreads to the trunk and legs. The development of the rash tends to be slower than that of chickenpox. There is often a dramatic prodrome of high fever, malaise, headache, and backache for 24 days prior to the onset of the rash. Smallpox carries an approximately 30% mortality, while mortality associated with chickenpox is very low.

• Question 235:

  You had previously seen a 24-year-old male in your office for evaluation of a suspicious looking mole. He had undergone a punch biopsy, which demonstrated a melanoma. He has no prior history of skin cancer, no family history of skin cancer, nor any history of blistering sunburns. Which of the following results in the pathology report are most predictive of outcome?

  A. size of the melanoma
  B. color of the melanoma
  C. depth of the melanoma
  D. presence of ulceration
  E. site of the melanoma
  C. depth of the melanoma

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  Explanation

  When assessing the prognosis for a patient diagnosed with melanoma, there are many factors that are involved. Tumor thickness, the presence of ulceration, the location of the lesion, the age of the patient, and the gender can all contribute. The most predictive factor is the tumor thickness. There are two measurement systems that have been developed to classify melanoma. The Clark level refers to the depth of invasion of the melanoma in terms of the anatomical layers of the skin. A second system, known as the Breslow depth, simply measures the overall tumor thickness in millimeters. Since the Breslow depth is more reproducible among pathologists, it has proven to be more accurate in the prediction of outcomes.

• Question 236:

  A 74-year-old female with a history of hypertension and hypothyroidism is admitted with easy bruising, guaiac positive stools, and anemia (Hgb 8.1 g/dL). Screening coagulation tests reveal a prolonged activated partial thromboplastin time (aPTT) with a normal prothrombin time (PT) and platelet count.

  What is the next step in the diagnosis of this woman's problem?

  A. Perform upper and lower endoscopy with biopsies.
  B. Check factors II, VII, IX, and X levels.
  C. Check factor VII level.
  D. Check factors XI, VII, IX, and VIII levels
  E. Check an aPTT 1:1 mix with normal plasma and 1-hour incubation.
  E. Check an aPTT 1:1 mix with normal plasma and 1-hour incubation.

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  Explanation

  A 1:1 mixing study is done when the PT or PTT is prolonged. The patient's plasma is mixed with normal plasma and the abnormal test is repeated. If the mixing of normal plasma corrects the abnormal test (PT or PTT), then a factor deficiency is suggested; otherwise, an inhibitor is suspected. Similarly, an incubated mixing study is done 1 hour (and occasionally 2 hours) after mixing of the patient plasma with normal plasma. It is used to differentiate a lupus anticoagulant from factor inhibitors.

• Question 237:

  The patient is a 9-year-old girl brought into the urgent care clinic by both of her parents. Over the past 18 months, they have noticed emerging "habits" including repetitive squinting and grimacing, along with associated clearing of her throat and grunting noises. These behaviors occur almost every day and frequently occur together. She has gotten increasingly teased because of her peculiarities and her anxiety has only worsened her symptoms. She has no major illnesses and is not taking any medications.

  Her physical examination is within normal limits with the exception of the above stereotypes.

  A history of infection with which of the following organisms would be most likely in this patient?

  A. herpes simplex virus
  B. HIV
  C. influenza virus
  D. Staphylococcus
  E. Streptococcus
  E. Streptococcus

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  Explanation

  This patient has Tourette disorder, characterized by the existence of both motor and vocal tics which have been present for 1 year. There is not a significantly increased comorbidity for autistic disorder, major depressive disorder, panic disorder, or conduct disorder. There is a very high comorbidity, however, for both ADHD and OCD in individuals with Tourette's disorder. Lorazepam, a benzodiazepine, may be useful in the short-term management of the anxiety associated with Tourette's disorder, but it is not indicated for the treatment of the tics themselves. Methylphenidate, a stimulant, may be used if there is associated ADHD along with the tic disorder, but it may increase the frequency of tics. Paroxetine, a SSRI, is used in treating both depressive disorders and OCD, but it is not indicated for treatment of Tourette disorder. Clonidine, an alpha-2 adrenergic agonist, can be somewhat helpful in reducing some symptoms of Tourette's disorder. The most efficacious, and first-line, treatment for Tourette's disorder is the use of dopamine antagonists such as antipsychotics (e.g., haloperidol). The etiology of several disorders, among them Tourette's and OCD, may be related to an autoimmune process. It is believed that infection with certain microorganisms, specifically streptococcal infections, may act synergistically with a genetic vulnerability to cause those mental illnesses. The full significance of this in terms of diagnosis, prevention, and treatment of these conditions has yet to be determined.

• Question 238:

  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. The most appropriate measure, after IV hydration and nasogastric decompression, in the initial management of this patient is which of the following?

  A. upper GI endoscopy
  B. supine and erect x-rays of the abdomen
  C. abdominal sonography
  D. antiemetic agents
  E. promotility drugs
  B. supine and erect x-rays of the abdomen

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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 239:

  A 17-year-old boy is reluctantly taken to the family medicine clinic by his mother, who is upset as "he is hanging out with the wrong crowd." She strongly believes that he has been smoking marijuana every day after school and on weekends with his friends. The patient appears irritated about the appointment but denies using any drugs or alcohol. His mother would like him to be counseled about the potential dangers of "smoking pot."

  Which of the following would be the most serious potential long-term consequence of smoking cannabis in this individual?

  A. amotivational syndrome
  B. cerebral atrophy
  C. chromosomal damage
  D. lung cancer
  E. seizures
  D. lung cancer

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  Explanation

  Cannabis is one of the few substances of abuse that does not affect the respiratory rate. Consuming marijuana classically produces symptoms of a dry mouth and increased appetite (the munchies). Contrary to what is sometimes claimed, intoxication with cannabis does significantly impair motor function and, therefore, interferes with driving ability. It also can cause tachycardia (DSM IV- TR). Amotivational syndrome is a potential, but controversial, long-term effect of heavy cannabis use. It is characterized by apathy and boredom. Cerebral atrophy, chromosomal damage, and seizures have also been reported, but not confirmed, in individuals with chronic cannabis use. The most concerning medical consequences of smoking cannabis over the long term are similar to those from smoking tobacco, such as lung cancer and respiratory disease.

• Question 240:

  A 19-year-old newly married female presents to the emergency room, accompanied by her spouse. She states that she awoke this morning to find that she could not move her legs. She denies any pain but claims that she is unable to feel anything below her abdomen. She denies any trauma or past medical history. She is 24 weeks' pregnant, has had an uneventful pregnancy, and only takes prenatal vitamins. She is concerned if her symptoms will get better and wonders whether the "baby is pulling on my spinal cord." Her neurologic examination is remarkable for 0/5 motor strength in her lower extremities bilaterally, with decreased sensation to light touch and pinprick below the level of her umbilicus. Her cranial nerves and reflexes are normal, and she does not display any upper motor neuron signs. A STAT MRI performed is read as normal.

  Which of the following is the most likely explanation for her current symptoms?

  A. conscious production of symptoms to assume the sick role
  B. conscious production of symptoms to obtain secondary gain
  C. pathology involving the central nervous system
  D. pathology involving the peripheral nervous system
  E. unconscious production of symptoms due to unconscious conflict
  E. unconscious production of symptoms due to unconscious conflict

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  Explanation

  This young woman would be diagnosed with conversion disorder. The conscious production of symptoms to assume the sick role is the motivation underlying factitious disorder. Malingering is not a diagnosable mental illness but is the conscious inventing or exaggerating of physical or psychiatric symptoms in order to obtain secondary gain, such as disability benefits, or avoidance of work or a prison sentence. Given her unremarkable MRI, normal reflexes, absence of pathologic reflexes, and hemianesthesia along her umbilicus, her presentation is not consistent with either central or peripheral nervous system pathology. The apparent stressors of a new marriage and pregnancy are likely related to the genesis of her symptoms. Conversion symptoms are created through the unconscious production of neurologic symptoms due to unconscious conflict. While administering a "placebo," such as intravenous saline, may resolve her symptoms, it is both dishonest and unethical. Admission to neurology is unnecessary unless there is a concern regarding an actual underlying or comorbid disease. It may also serve to reinforce the somatization of her conflict. Confronting a patient with conversion disorder often results in a subsequent worsening of symptomatology. Consultation with a psychiatrist may be useful in helping the patient cope with the stress of her dysfunction but, in the emergency room, may also lead to feelings of not being believed and an increase in symptoms. Many cases of conversion disorder spontaneously remit, but recovery may be significantly facilitated through support, reassurance, and actual suggestion that improvement will occur.