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

USMLE USMLE-STEP-3 Online Questions & Answers

• Question 761:

  Which of the following is the most appropriate treatment for a 32-year-old male with a toxic nodular goiter and compressive airway symptoms?

  A. radioactive iodine therapy
  B. propranolol
  C. propylthiouracil
  D. Lugol's solution
  E. total lobectomy
  E. total lobectomy

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  Explanation

  Toxic nodular goiter, also known as Plummer's disease, is a consequence of one or more thyroid nodules secreting inappropriately high levels of thyroid hormone independently of thyroid-stimulating hormone (TSH) control. Hyperthyroidism in patients with toxic nodular goiter is milder than in those with Graves' disease, and the condition is not accompanied by extrathyroidal manifestations such as ophthalmopathy, pretibial myxedema, vitiligo, or thyroid acropathy. Patients with toxic multinodular goiter are older at presentation than those with Graves' disease. The thyroid gland characteristically has one or more nodules on palpation. Local symptoms of compression, such as dysphagia and dyspnea, may occur. The diagnosis is suggested by a thorough history and physical examination and confirmed by documenting suppressed serum TSH level and raised serum thyroid hormone level.

• Question 762:

  In January, you see an 18-month-old boy in the middle of the night in the pediatric emergency department. The father relates that 1 hour ago his son started coughing. The father describes the cough as barking ("seal" like). The child has mild stridor at rest, but otherwise is not in respiratory distress. His RR is 45 breaths per minute. He has a temperature of 103.4 .

  What is the most common x-ray finding in this illness?

  A. swollen adenoids
  B. the "thumb" sign
  C. a lobar pulmonary infiltrate
  D. a deviated tracheal air column
  E. the "steeple" sign
  E. the "steeple" sign

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  Explanation

  This case is a common presentation for viral croup, with the symptoms of a seal-barking cough, stridor, tachypnea, and fever in the winter. Pneumonia must also be considered with tachypnea, cough, and fever, but it is less likely to cause stridor and may not have the seal-bark type of cough. Sinusitis may cause cough and fever, but would be more likely to have a purulent nasal discharge and less likely to have the typical croupy cough. Bronchiolitis due to RSV is a common cause of wintertime cough and fever. It is less likely to have stridor and more likely to have wheezing. Children with epiglottitis are typically found in the "tripod position" and may be drooling. It is, fortunately, becoming rare with the widespread use of the H. influenzae vaccine. Parainfluenza types 1 and 2 account for 6070% of all viral croup. HIB was a common cause of epiglottitis, but is now rare because of widespread vaccinations. Influenza B and RSV can cause croup, but not as commonly as parainfluenza types 1 and 2. S. pneumoniae would be the most common bacterial cause of pneumonia or sinusitis. (American Academy of Pediatrics, 2003, pp. 454455) The steeple sign is subglottic narrowing of the trachea seen on an AP view of the trachea or a CXR. The trachea is seen to narrow, almost to a point, like the steeple of a church. Swollen adenoids are difficult to identify in lateral neck x-rays. The presence of swollen adenoids is unrelated to the airway narrowing seen in croup. The thumb sign is a swollen epiglottis seen with epiglottitis.

  Alobar pulmonary infiltrate may be seen with a typical bacterial pneumonia

• Question 763:

  A67-year-old female with past medical history of rheumatoid arthritis on chronic steroid treatment and past surgical history (PSH) of complete hysterectomy secondary to fibroids presents for routine visit. Patient states that she has had multiple arthralgias worsening over the last 2 years. She had a DEXA scan done that showed a T score of -1.5. She has been taking calcium + vitamin D, and even started an exercise program at her local gym. She was started on bisphosphonates, which she has tolerated well. Prior to discharging the patient, how soon would you counsel her to repeat the DEXA scan?

  A. never: although she has risk for osteoporosis, she has already made all the lifestyle changes and is on pharmacotherapy
  B. 6 months
  C. repeat in 1 year
  D. repeat in 2 years
  D. repeat in 2 years

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  Explanation

  Osteoporosis is generally defined as a T score of -2.5 SD or greater on assessment of BMD. Osteopenia is generally defined as a T score between 1 and 2.5 SD below the peak BMD for a healthy young person of the same gender. Osteoporosis screening with an assessment of BMD should be offered to the following groups:

  ?All women 65 years old or older ?All adult women with a history of a fracture (or fractures) not caused by severe trauma (such as a motor vehicle accident) ?Younger postmenopausal women who have clinical risk factors for fractures ?Modifiable risk factors:

  current cigarette smoking, low body weight (<127 lbs), estrogen deficiency, premature menopause, excessive thyroid hormone replacement, chronic corticosteroid therapy, low calcium intake (life-long), alcoholism, uncorrected visual impairment, inadequate physical activity, recurrent falls ?Nonmodifiable risk factors: personal or family history of fragility, family history of osteoporosis, White or Asian race, age, gender, poor health/frailty, dementia, hypogonadism in males, fracture without substantial trauma Serial assessments for BMD may be useful but one must remember the precision error among the tests. Using DEXA, a BMD must have a 35% difference to be clinically significant. Patients who are on pharmacologic treatment with bisphosphonates may only show this much change in 1 year. Therefore, static BMD or slight reduction should not be regarded as treatment failure. At present, there are no hard evidencebased guidelines for the most efficient use for BMD monitoring. However, the following guidelines are generally accepted:

  ?For patients with";norma"; baseline BMD (T score more than -1.0), consider a followup measurement every 35 years. Patients whose bone density is well above the minimal acceptable level may not need further bone density testing.

  ?For patients in an osteoporosis prevention program, perform a follow-up measurement every 12 years until bone mass stability is documented. After BMD has stabilized, perform follow-up measurements every 23 years.

  ?For patients on a therapeutic program, perform a follow-up measurement yearly for 2 years. If bone mass has stabilized after 2 years, perform a follow-up measurement every 2 years. Otherwise, continue with annual follow-up measurements until stability of bone mass is achieved.

• Question 764:

  An 8-year-old male presents to your office complaining of a 1-week history of painful knee and elbow joints. On examination, you find a painful, hot, and swollen knee. He also has multiple erythematous macules with pale centers on his trunk and extremities. The laboratory work you order reveals elevated antistreptococcal antibodies.

  Which of the following information is required to make this diagnosis?

  A. The child must currently have a fever.
  B. The child must have arthritis.
  C. The presence of a group A streptococcal (GAS) infection must be documented.
  D. The child may have chorea alone.
  E. Aspiration of fluid from the swollen knee is required to confirm the diagnosis.
  D. The child may have chorea alone.

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  Explanation

  ARF is clinically diagnosed by using the Jones criteria. The Jones criteria are separated into major and minor findings. The major criteria are arthritis (not simply arthralgia), carditis, Sydenham chorea, erythema marginatum, and subcutaneous nodules. The minor criteria include the presence of a fever, arthralgias, documentation of a GAS infection (either currently or in the past), or laboratory evidence of inflammation (increased ESR). Two major criteria, or one major and two minors, are required for the diagnosis of ARF. The only exception to this rule is that the presence of Sydenham chorea alone will make the diagnosis. While the documentation of a prior, or current, GAS infection is compelling, it is not a requirement for the diagnosis of ARF. Children with rheumatic fever are not considered contagious.

• Question 765:

  Several days following an uneventful laparoscopic cholecystectomy, the pathology report reveals gallbladder cancer that is invasive into the submucosa of the specimen. The most appropriate management is which of the following?

  A. observation and close follow-up
  B. chemotherapy with a 5-fluorouracil (5-FU)-based regimen
  C. laparotomy with 23 cm wedge resection of the gallbladder liver bed
  D. laparotomy with 23 cm wedge resection of the gallbladder liver bed and regional lymphadenectomy including the portal and hepatic nodal basins
  E. radiation to the gallbladder liver bed
  A. observation and close follow-up

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  Explanation

  Carcinoma of the gallbladder accounts for 24% of GI malignancies. Fewer than 1% of patients undergoing biliary tract operations have carcinoma either as an anticipated diagnosis or as an incidental finding. The calcified "porcelain" gallbladder is associated with a 20% incidence of gallbladder carcinoma. Signs and symptoms of carcinoma of the gallbladder are generally indistinguishable from those associated with cholecystitis and cholelithiasis. They include abdominal discomfort, right upper quadrant pain, nausea, and vomiting. Most long-term survivors are patients who underwent cholecystectomy for cholelithiasis and in whom the malignancy was an incidental finding on the pathology report. The management of these patients is based on the depth of tumor penetration into the wall of the gallbladder

• Question 766:

  A 42-year-old woman who previously underwent a vaginal hysterectomy for persistent cervical dysplasia presents to your office for vaginal cytology. Her vaginal cytology is shown in Figure.

  Which of the following is the most appropriate next step in management?

  

  A. repeat vaginal cytology in 6 months
  B. observation
  C. random vaginal biopsies
  D. intravaginal estrogen cream followed by repeat cytology
  E. colposcopic examination of the vaginal canal
  E. colposcopic examination of the vaginal canal

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  Explanation

  VAIN is frequently found in women who have a history of cervical dysplasia. Although the etiology of VAIN has not been thoroughly elucidated, like cervical intraepithelial neoplasia (CIN), it is thought that HPV is the carcinogenic agent. Thus, when vaginal cytology is abnormal, the evaluation is very similar to that of an abnormal pap smear. It is important to assess the histologic severity and the extent of the lesion. To do this, the next step in management is a thorough colposcopic evaluation of the entire vaginal canal, especially because many patients will have multifocal disease.

  During colposcopy the application of acetic acid (4%) is useful. The speculum should be fully inserted to visualize the upper vagina and then slowly removed while rotating the speculum, being careful to view the entire vaginal mucosal surface. Most vaginal lesions are not grossly visible. However, a raised white epithelium may occasionally be seen. If a lesion is visible, then directed biopsy of the lesion is indicated to confirm the diagnosis. The image provided shows HGSIL. In the presence of high-grade vaginal cytology, repeat cytology in 6 months, and observation are not viable management options given the concern for carcinoma in situ or for invasive carcinoma of the vagina. Random vaginal biopsies are also not likely to be helpful since they will most likely miss the involved area and lead to a false negative result. Intravaginal estrogen cream is reserved for postmenopausal women with vaginal atrophy and low-grade VAIN without evidence of invasion. Estrogen is not a treatment for VAIN 3, or high- grade VAIN.

• Question 767:

  Which of the following is the most common characteristic of a serous cystadenocarcinoma of the ovary?

  A. It causes pseudomyxoma peritonei.
  B. It is composed of transitional epithelial cells.
  C. It is frequently bilateral.
  D. It is most common in children and young adults.
  E. It often metastasizes to the brain.
  C. It is frequently bilateral.

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  Explanation

  Serous cystadenocarcinoma of the ovary is the most common malignant ovarian tumor and is frequently bilateral. Microscopically, they show a variegated appearance with papillary pattern. Different degrees of anaplasia of the cuboidal to columnar cells cover the papilla and occasional calcified concretions (Psammoma bodies) are present. These tumors almost never metastasize to the brain and they are not seen in children or young adults.

• Question 768:

  A woman with type 1 diabetes is at increased risk for having a fetus with which of the following congenital anomalies?

  A. gastroschisis
  B. duodenal atresia
  C. cleft lip and palate
  D. congenital heart defects
  E. diaphragmatic hernia
  D. congenital heart defects

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  Explanation

  In general, women with diabetes mellitus are at increased risk for congenital abnormalities as well as spontaneous abortion, with the risk rising in direct relationship to the maternal hemoglobin A1C. The risk is particularly increased when the periconception hemoglobin A1C value exceeds 10%. In addition to congenital heart defects, which are increased approximately fivefold over the general population (2.5% vs. 0.5%), open neural defects are thought to be 10 times more common

• Question 769:

  The patient is a 25-year-old woman recently released from the hospital after her first manic episode. She is currently taking lithium 1200 mg/day, and her lithium level is 1.1 meq/L. She has a slight, but tolerable, tremor and has gained 5 lbs, but she is otherwise tolerating the medication. She claims her mood is "pretty good." She is sleeping approximately 7 hours per night. Her energy and concentration are adequate, and she denies racing thoughts, talkativeness, or increased activity. She has no major medical problems, and her only other medication is birth control pills. She does not consume alcohol or drugs. She wonders, "How long will I have to take medications for this problem?" How long should she be recommended to continue on maintenance therapy?

  A. 6 months
  B. 1 year
  C. 2 years
  D. 5 years
  E. lifelong
  E. lifelong

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  Explanation

  Explanations:

  This woman has bipolar disorder, most recent episode manic, and she has been stabilized on lithium. Bipolar disorder is a chronic mental illness, with a high number of future episodes (mania and depression) likely. Because of this, after one episode of mania, it is generally recommended to continue on maintenance treatment indefinitely in order to minimize the risk of future recurrences. This woman has now developed an episode of bipolar disorder, depressed. While adding an antidepressant such as sertraline may help the depression, there is always a risk\ of provoking a manic episode. Adding another mood stabilizer in order to treat the depression has little data to support it. Decreasing the lithium will not help her depression, and it may make her more vulnerable to a switch into mania. As her lithium level is therapeutic, increasing the dose will likely only add to her side effects and may lead to toxicity. Lamotrigine has been found to be beneficial in treating bipolar depression and does not appear to increase the likelihood of causing a manic episode, as other antidepressants do. It is recommended as a first-line treatment for depressive episodes in bipolar patients. In fact, it has been shown to be useful in maintenance treatment of bipolar disorder by decreasing the likelihood that a patient experiences a depressive, manic, or mixed episode.

• Question 770:

  While you are working in the community health center, a 40-year-old male presents to you as a referral from the dental clinic. The patient reported on the intake history form at the dental office that he had rheumatic fever at the age of 7. The dentist refused to allow him to have a dental examination and cleaning until he was cleared by a medical doctor. Other than rheumatic fever, the patient has no medical history and does not take any medications. He denies chest pain, palpitations, dyspnea, or any other symptoms. On examination, he has normal vital signs and a normal general examination. On auscultation of his heart, you hear a 2/6 systolic ejection murmur at the left upper sternal border without radiation. Review of his chart shows that he had an echocardiogram approximately 9 months ago that revealed mild mitral valve prolapse without evidence of mitral regurgitation, but otherwise normal valves and cardiac function For which of the following cardiac conditions is bacterial endocarditis prophylaxis recommended?

  A. cardiac pacemaker
  B. isolated secundum atrial septal defect
  C. previous coronary artery bypass graft
  D. bicuspid aortic valve
  E. the presence of any cardiac murmur
  D. bicuspid aortic valve

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  Explanation

  Explanations:

  Bacterial endocarditis is a rare, but life-threatening, disease. It occurs primarily in persons with underlying structural heart defects who develop bacteremia with organisms that are likely to cause endocarditis. Most cases of endocarditis are not a complication of invasive medical or dental procedures. Because of the risks associated with the disease, efforts should be made to prevent bacterial endocarditis when appropriate. The American Heart Association has published updated, evidence- based recommendations on the prevention of bacterial endocarditis. These guidelines are available at the American Heart Association web site (www.americanheart.org). These guidelines outline conditions for which endocarditis prophylaxis is appropriate, procedures for which endocarditis prophylaxis is necessary, and antibiotic regimens that are recommended.

  Cardiac conditions are stratified into high-risk, moderate-risk, and negligible risk. Negligible risk conditions are those in which, although endocarditis may develop, the risk is no greater than in the general population. This patient has a history of rheumatic fever, which can potentially result in high- risk valvular damage. However, his echocardiogram did not reveal any such condition. Mitral valve prolapse without a regurgitant jet (which is not a complication of rheumatic fever) is considered a negligible risk condition, so the proposed dental work can proceed without delay. Of the conditions listed, only bicuspid aortic valve would require antibiotic prophylaxis, as it is a moderate-risk congenital cardiac malformation. All of the other conditions listed are considered to be of negligible risk. Procedures which require antibiotic prophylaxis are those which produce a significant bacteremia with organisms commonly causing endocarditis. For dental procedures, those that tend to cause significant bleeding from hard or soft tissues would necessitate prophylaxis. Of the procedures listed, only dental extraction is likely to do this. During the course of other procedures, if unexpected significant bleeding occurs, antibiotics within 2 hours following the procedure would be recommended