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

USMLE USMLE-STEP-3 Online Questions & Answers

• Question 361:

  A54-year-old Asian female with no significant medical history presents with frontal headache, eye pain, nausea, and vomiting. Her abdominal examination shows mild diffuse tenderness but no rebound or guarding. Her mucous membranes are dry. Her vision is blurry in both eyes, her eyes are injected but her extraocular muscles are intact. Her pupils are mid-dilated and fixed Which of the following is appropriate initial management of this patient?

  A. urgent consultation of a general surgeon
  B. urgent consultation of an ophthalmologist
  C. prescription of an antiemetic with follow-up the next day in the office
  D. bed rest with head of bed elevated to45 degrees
  E. performance of a dilated eye examination prior with referral if abnormalities seen
  B. urgent consultation of an ophthalmologist

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  Explanation

  The presence of headache, eye pain, nausea, and vomiting should prompt the consideration of the diagnosis of acute angle closure glaucoma. This is a rare but serious condition in which the aqueous outflow is obstructed, and the intraocular pressure abruptly rises. Susceptible eyes have a narrow anterior chamber and when the pupil becomes dilated, the peripheral iris blocks the outflow via the anterior chamber angle. Edema of the cornea occurs, resulting in cloudiness on examination. Diagnosis is made by measuring the intraocular pressure during an acute attack. Treatment includes medications to induce miosis in an effort to relieve the blockage or, if that fails, surgical intervention. In some patients, the headache or GI symptoms can overshadow the ocular symptoms, resulting in a delay in diagnosis and unnecessary workup for other conditions. In this case, the lack of findings on abdominal examination makes appendicitis or perforated bowel unlikely. DKA can present with primary GI symptoms, but would not explain the ocular symptoms. Similarly, cerebellar or other brain tumors may cause headache, nausea, and vomiting, but would not be causes of a painful, red eye.

• Question 362:

  A 14-year-old girl is admitted to the medical unit due to dehydration. She is found to be severely underweight, at 75% of expected weight. She has no significant medical problems, but she stopped menstruating 9 months ago after having regular periods since age 12. She has no prior psychiatric history and is a very successful student and athlete at school. She denies feeling depressed but does admit to feeling tired. When confronted about her weight loss, she does not appear concerned, stating, "I was very fat and still have more weight to lose." Which of the following treatment modalities is the most effective for her gaining weight?

  A. amitriptyline (Elavil)
  B. behavioral therapy
  C. fluoxetine (Prozac)
  D. growth hormone
  E. lithium
  B. behavioral therapy

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  Explanation

  Explanations:

  This girl meets criteria for anorexia nervosa, restricting type. The efficacy for tricyclic antidepressants such as amitriptyline in anorexia nervosa is quite limited. While some studies have demonstrated benefit with SSRIs such as fluoxetine in anorexia after adequate weight has been restored, the evidence for gains in weight restoration is lacking. Neither growth hormone injections nor lithium have promoted weight gain in anorexic patients. The best evidence for the short-term treatment of anorexia nervosa lies with behavioral interventions while the patient is in a structured inpatient or partial hospital setting; the treatment modalities often include individual (cognitive-behavioral), group, and family therapies.

• Question 363:

  A 12-month-old male child is brought to your office for a well-child examination and immunizations. You have been following the child since delivery and are aware that he has acquired immune deficiency syndrome (AIDS) and a markedly reduced T-cell count. Which of the following vaccinations should he not receive?

  A. diphtheria, tetanus, and acellular pertussis (DTaP)
  B. diphtheria tetanus (dT)
  C. hepatitis B
  D. injectable polio vaccine (IPV)
  E. varicella
  E. varicella

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  Explanation

  All of the vaccines mentioned, except varicella, are killed or synthetic vaccines. Varivax is an attenuated varicella strain (OKA) from Japan. Live virus vaccines are contraindicated in the case of AIDS with a markedly reduced T-cell count. The IPV is the inactivated version of the live polio vaccine, oral polio vaccine (OPV).

• Question 364:

  A25-year-old African American female develops a large lesion on her ear lobe after having it pierced (see Figure). How would you advise this patient?

  

  A. Surgical excision is curative.
  B. This resulted from an infection that occurred when she had her ear pierced.
  C. Recurrences of this problem are common.
  D. She is likely to have reduced fertility.
  E. Oral corticosteroids have been effective.
  C. Recurrences of this problem are common.

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  Explanation

  Keloids occur at the site of injury, predominately in people with dark skin who have a genetic predisposition. The keloid is a form of benign tumor that consists of an overabundance of collagen that extends beyond the margins of the incision. Treatment options have only moderate success and include excision of the keloid with intralesional steroid injections. Recurrences of keloids, both at the original site and with subsequent injury/incision elsewhere in the body, are common. They are not associated with decreased fertility or other systemic processes

• Question 365:

  A husband and wife, both aged 30, come to the community health center for advice and evaluation prior to a month-long mission trip to central Africa. Both are in good health. She takes oral contraceptive pills and he is on no prescription medication. Review of their records shows that they have had all of the appropriate vaccinations for their ages, have completed a three dose hepatitis B series and had dT boosters 2 years ago. Their mission will involve building a school and health clinic in a rural area of Cameroon. Which of the following immunizations would be recommended prior to the trip?

  A. MMR booster
  B. dT booster
  C. hepatitis B booster
  D. injectable polio vaccine
  E. smallpox vaccine
  D. injectable polio vaccine

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  Explanation

  Encounters with persons traveling to other countries are common in primary care or community health settings. The advice and interventions provided are dependent on where the person is going, what he or she will be doing, and for how long he or she will be there. The most accessible and up-to-date source of this information in the United States is at the Centers for Disease Control web site, which provides detailed recommendations on vaccinations, health, and safety risks involved in overseas travel. In this series of questions, the travelers are going to the region of central Africa and, more specifically, to a rural area of Cameroon. This is an area of the world where polio remains a risk. As most Americans have not been vaccinated against polio since childhood, booster immunization against polio is recommended. The injectable polio vaccine is recommended as it does not carry with it the risk of vaccine-induced disease that the oral (live virus) vaccine does. Smallpox has been eliminated as a naturally occurring disease, although it remains of importance in bioterrorism discussions. The smallpox vaccine is not necessary for travel to any part of the world, but is used by the military or medical first responders who may be exposed in the event of a biowarfare attack. The traveling couple is up-to-date on their dT status with boosters within the past 2 years. They have completed a series of both MMR and hepatitis B, which is felt to confer lifetime immunity. Malaria prevention is an important consideration for travel to many areas of the developing world. Different regimens may be used depending on the area to which the travel will occur. All regimens, however, require the institution of prophylaxis prior to travel and the continuation of prophylaxis for up to 4 weeks after completion of travel. This is due to the life cycle of organisms that cause the disease. Prevention of malaria also involves attempts to reduce one's risk of exposure to the Ixodes mosquito which can transmit the disease. This mosquito tends to be more active early in the morning and at dusk, and less active in the middle of the day. Wearing long sleeved clothing, using mosquito nets, and insect repellent is important. DEET-containing insect repellents are recommended as the most effective products available and are safe when used appropriately. The most common cause of injury during travel is motor vehicle accidents. The risk of injury is higher in many developing countries than in the United States due to poor roads, poor vehicle maintenance, lack of seat belts, and other issues. Very cautious driving and avoidance of driving after dark may help to reduce the risk somewhat. While swimming is an ideal exercise in such hot climates as central Africa, freshwater lake swimming should be avoided due to the risk of exposure to schistosomiasis. The Schistosoma species that cause this disease are endemic in standing freshwater bodies. Swimming or bathing in salt water or chlorinated swimming pools is safer. Traveler's diarrhea and exposure to foodborne pathogens is a common cause of illness during travel to developing countries. The guideline with food is to cook it, peel it, purify it, or forget it. Fruits that can be peeled, such as oranges or bananas, are generally safe to eat. Carbonated beverages are also safe. However, ice cubes made from local water supplies are a common, and sometimes ignored, source of infection. Water purification can be accomplished by boiling or by filtering through an absolute 1 m filter and then purifying with iodine.

  Filtering alone does not provide adequate protection. Salads that are not made of carefully cleaned vegetables should be avoided and salad dressings may also be contaminated. Meats that are well cooked and served hot would be considered less likely to transmit an infection. Finally, brushing one's teeth with unpurified water carries a significant risk of transmission of waterborne illness and should be avoided. Purified water or bottled water should be used instead.

• Question 366:

  A 45-year-old woman undergoes an uncomplicated thyroidectomy for a goiter. Later that night, she becomes agitated and complains of difficulty breathing. The surgeon notices some neck swelling at the incision site, but the dressing is clean.

  What should the next step be?

  A. start oxygen by nasal cannula
  B. check STAT serum calcium level
  C. endotracheal intubation to protect her airway
  D. open the incision
  E. administer propranolol and morphine
  D. open the incision

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  Explanation

  One of the most feared complications of neck surgery is postoperative hemorrhage causing airway compromise. Any patient with neck swelling and dyspnea must be assessed for this emergently. The treatment is to immediately open up the neck wound to release the hematoma and relieve the tracheal compression.

• Question 367:

  The patient is a 7-year-old boy brought in for evaluation by his father. He has been concerned with his son's behavior. At school conferences, he has been told that his son will not stay in place and moves around the room despite being informed about the rules. He neither listens at home nor at school when given feedback. For example, he continues to have difficulty waiting in line, completing his homework, and cleaning up his toys, regardless of numerous consequences. In department stores, he will run around and grab at items, and this has resulted in his breaking merchandise on many occasions. The father states that his son has been this way "since he could walk" and is worried about his son's future.

  After further history is obtained and consultation with the school is initiated, a definitive diagnosis is made. The recommendation to begin a stimulant is presented to the father, but he has concerns regarding that treatment choice. How should he be counseled regarding the use of this medication?

  A. It may cause paradoxical sedation.
  B. It only improves behavior and not school performance.
  C. It requires regular BP monitoring.
  D. It should be taken daily, throughout the year.
  E. It will increase the risk of future addiction.
  C. It requires regular BP monitoring.

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  Explanation

  This patient suffers from ADHD as evidenced by numerous inattentive and hyperactive/ impulsive symptoms and signs. Autistic disorder is a pervasive developmental disorder (PDD) consisting of impairments in social interaction and communication, in addition to stereotyped behaviors. Conduct disorder is a disruptive behavior disorder characterized by aggression and violation of the rights of others. While oppositional defiant disorder is also a disruptive behavior disorder, it is not as severe as conduct disorder, occurring at an earlier age and demonstrating a pattern of negativistic and defiant behaviors. OCD is an anxiety disorder not uncommonly seen in children, diagnosed by the presence of recurrent, distressing obsessions and/or compulsions.

  Stimulants are the first-line treatment for ADHD. However, there are many misconceptions regarding their use, which may necessitate the use of more detailed psychoeducation.

  It was previously believed that stimulants exert their clinical effect through sedation, but this is no longer considered to be true. Stimulants not only improve behavior, but there is evidence that they actually "normalize" school performance as well. The use of drug holidays, such as weekends and during the summer, is recommended in order to make up for any growth suppression.

• Question 368:

  A 74-year-old male with gout, osteoporosis, and type II diabetes presents for routine followup. As you review his medication list you note that he is on insulin, vitamin D, glypizide, quinidine, and allopurinol. You now diagnose him with hypertension that requires pharmacologic management. Which of the following medications would be contraindicated in this patient?

  A. enalapril
  B. hydrochlorothiazide
  C. diltiazem
  D. losartan
  E. atenolol
  B. hydrochlorothiazide

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  Explanation

  Quinidine can prolong the Q-T interval resulting in the development of polymorphic ventricular tachycardia (torsade de pointes). Hypokalemia, a side effect of thiazide diuretics, increases the risk of torsade de pointes, which can then degenerate into fatal ventricular fibrillation. Thiazide diuretics may decrease the effectiveness of uricosuric agents, insulin, and sulfonylureas and may increase the effects of vitamin D.

  However, these effects tend not to be life threatening

• Question 369:

  You are called to see a 12-hour-old male infant who was born to a 19-year-old G1 woman with no prenatal care. She presented to the emergency room completely dilated and crowning. The baby was born minutes later. On examination, the baby is febrile and tachypneic. A CXR confirms the presence of pneumonia.

  What is the most likely infectious agent?

  A. group B Streptococcus (GBS)
  B. HSV
  D. respiratory syncytial virus (RSV)
  E. Streptococcus pneumoniae
  A. group B Streptococcus (GBS)

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  Explanation

  GBS is the most common cause of infection in the newborn infant, followed by E. coli and L. monocytogenes. GBS is the most common cause of pneumonia, septicemia, UTI, and meningitis. The risk of early-onset (within the first 7 days of life) GBS infection can be reduced with the antenatal administration of appropriate antimicrobials. The use of perinatal antimicrobials has no effect on the occurrence of late- onset (after 7 days of life) GBS disease.

• Question 370:

  A 48-year-old woman presents for evaluation of progressively worsening dyspnea. She relates the onset of symptoms to a "walking pneumonia" that she had a year ago. Her breathing has worsened progressively since that time. She has a "smoker's cough" productive of some clear or white phlegm, for which she frequently sucks on cough drops. She started smoking regularly at the age of 18. She currently smokes about a pack of cigarettes a day, down from as much as two packs per day. She is not on

  any medications regularly. She has no history of heart disease and has always had normal blood pressure

  Which of the following is most likely to be found on a CXR?

  A. cardiomegaly
  B. residual infiltrate from inadequately treated pneumonia
  C. a pulmonary mass with hilar adenopathy
  D. hyperinflation of the lungs
  E. Kerley B lines
  D. hyperinflation of the lungs

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  Explanation

  COPD is a group of chronic and progressive pulmonary disorders that cause reduced expiratory flow. Most of the obstruction is fixed, although some reversibility can be found. COPD affects approximately 16 million Americans and smoking is, by far, the greatest risk factor. Onset is typically in the fifth decade and the typical presenting symptoms are dyspnea and cough. Patients often relate these to an acute illness (walking pneumonia in this case) but the decline in pulmonary function has been present for some time prior to the onset of symptoms. The physical examination has poor sensitivity and may, in early disease, only show wheezing on forced expiration and a prolonged expiratory phase of respiration. Clubbing is not typically a manifestation of COPD and its presence should lead to a search for another cause, such as lung cancer. In the setting of pulmonary hypertension, sometimes one can hear a pronounced pulmonic component to the second heart sound, although hyperinflation may obscure this finding. Bilateral pulmonary crackles would be more consistent with pulmonary edema. Supraclavicular adenopathy should lead to a workup to exclude cancer, especially of breast, lung, ovarian, or GI origin. Hyperinflation of the lungs is the most likely CXR finding in this case. This would manifest as flattened diaphragms with elongated lungs and a long, narrow cardiac shadow. Kerley B lines would be more characteristic of pulmonary edema from left-sided heart failure, rather than COPD. A pulmonary mass with adenopathy would be more consistent with lung cancer--certainly a possibility in a long-time smoker, but much less common than COPD. A residual infiltrate from pneumonia a year ago would be highly unlikely.