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

USMLE USMLE-STEP-3 Online Questions & Answers

• Question 801:

  In order to prevent unintended pregnancy following an episode of unprotected intercourse, by when is it recommended that "emergency" oral contraception should be initiated?

  A. 12 hours
  B. 24 hours
  C. 48 hours
  D. 72 hours
  E. 1 week
  D. 72 hours

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  Explanation

  The U.S. Food and Drug Administration (FDA) has approved the use of oral contraceptives as an effective method of postcoital contraception, often termed emergency contraception. The most common regimens involve two to four oral contraceptive tablets, depending on the dosage of the brand used, repeated 12 hours later. Progestin-only regimens are also highly effective. Initiating treatment greater than 72 hours after the event of unprotected intercourse is associated with a lower success rate.

• Question 802:

  A 65-year-old man presents to your office for evaluation of abdominal pain. The patient states that he has epigastric pain that radiates to his back. The pain is worse with eating and improves with fasting. The pain has been present for 6 months and is gradually worsening. The patient has lost 15 lbs but feels his oral intake has been adequate. He complains of greasy stools and frequent thirst and urination. Examination reveals a thin male with temporal wasting and oderate abdominal pain with palpation. The patient consumes approximately 1015 beers per day and smokes a pack of cigarettes per day for the past 20 years.

  The patient's weight loss would be best treated by which of the following regimens?

  A. pancreatic enzyme replacement therapy
  B. liquid caloric supplementation by mouth
  C. liquid caloric supplementation via gastrostomy tube
  D. total parenteral nutrition (TPN)
  E. partial parenteral nutrition (PPN)
  A. pancreatic enzyme replacement therapy

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  Explanation

  The patient's history and examination are worrisome for pancreatic disease, and he has strong signs of pancreatic insufficiency. His long history of alcohol use suggests the possibility of chronic pancreatitis or pancreatic cancer. Fecal fat studies would only confirm or quantify his steatorrhea. ACT scan would image the pancreas for changes consistent with chronic pancreatitis (duct dilation, calcifications, pseudocysts) and could look for a neoplasm of the pancreas as well. ERCP is not indicated as a first- line test in patients with abdominal pain given its risk of causing acute pancreatitis. Upper endoscopy would be helpful to rule out peptic ulcer disease and other gastric complaints, but would not provide more global information about the abdomen.

  The patient has greasy stools and weight loss, findings seen in patients with steatorrhea due to chronic pancreatitis.

  Patients with steatorrhea malabsorb fat-soluble vitamins (vitamins A, D, E, and K). "Night blindness" (poor night vision) due to vitamin Adeficiency is common among patients with advanced chronic pancreatitis and likely led to this patient's motor vehicle accident. The patient has DM as a consequence of pancreatic endocrine insufficiency, another feature of chronic pancreatitis. Diabetes develops when greater than 80- 90% of the gland has been destroyed. Patients with chronic pancreatitis have a coexisting loss of glucagon from islet cells and, thus, often become brittle diabetics, with hypoglycemia seen after insulin administration. Vitamin K and B12 deficiency, which the patient may have, do not cause hypoglycemia. The patient was previously noted to eat well, so inadequate oral intake is unlikely. Diabetic education should decrease the rate of chronic insulin overdosage.

  The patient has pancreatic exocrine insufficiency and thus cannot produce enough pancreatic enzymes to digest his food. Pancreatic enzyme replacement therapy in tablet form is a mainstay of therapy for chronic pancreatitis. It can rapidly reverse this problem by providing exogenously produced pancreatic enzymes to break down fats, carbohydrates, and proteins for absorption in the small bowel. The patient would not benefit from additional oral feedings without enzyme supplementation and would only worsen his steatorrhea by doing so. He can take food orally, so feeding via gastrostomy, TPN, or PPN are not indicated. The patient's worsening pain and weight loss despite therapy is worrisome for the development of pancreatic cancer. CA-19-9 is frequently (but not universally) elevated in pancreatic cancers, although it can be elevated in cholangiocarcinoma as well. PSA is associated with prostate cancer. CEA is associated with colon cancer. CA-125 is associated with ovarian cancer. AFP is associated with hepatocellular carcinoma.

• Question 803:

  A 60-year-old male is evaluated following a pathologic fracture of his humerus. As part of the workup, a bone biopsy is performed and the photomicrograph is shown in Figure below

  

  Which of the following is the most likely diagnosis?

  A. benign neoplasm
  B. cellular hyperplasia
  C. osteogenic sarcoma
  D. metastatic lesion
  E. chronic leukemia
  D. metastatic lesion

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  Explanation

  The photomicrograph accompanying the question shows bone marrow spaces replaced by a well- differentiated adenocarcinoma. The bone spicules are normal. The glandular structures replacing the interspicular spaces and replacing the marrow elements are diagnostic of metastatic adenocarcinoma.

• Question 804:

  A 38-year-old married female is brought in to the primary care clinic by her husband. She is minimally responsive to questioning, head bowed, and staring at the floor. Most of the history is obtained from her spouse. He denies any known personal or family history of mental illness, but he claims for the past several months his wife has become increasingly depressed and withdrawn. Instead of taking part in her usual hobbies, she is lying around the house. "She tosses and turns" throughout the night. Her husband ensures that she eats a limited amount of food, but she has lost a significant amount of weight. She has been ruminating about guilty feelings regarding a number of issues and recently has been speaking about suicide, although she has no plan or intent. She has refused to come in to see a doctor. Her husband insisted that she come today, as she informed him that the devil has possessed her and told her she will "go to hell."

  What is the most effective pharmacologic treatment for this patient?

  A. antidepressant alone
  B. antidepressant and antipsychotic
  C. antipsychotic alone
  D. mood stabilizer alone
  E. mood stabilizer and antipsychotic
  B. antidepressant and antipsychotic

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  Explanation

  While patients with bipolar depression do present with psychotic features, this individual does not give any history of manic episodes, making the diagnosis difficult at this time. The bizarre delusions (those that cannot possibly exist in life) and auditory hallucinations that this patient has are not consistent with delusional disorder. Schizoaffective disorder, depressed type, includes both psychotic as well as depressive symptoms. However, the psychotic symptoms must last at least 1 month and occur in the absence of a depressed mood. The diagnosis of schizophrenia also requires at least 1 month of active psychosis but a total of 6 months of attenuated or residual symptoms. Although a depressed mood is very commonly seen in schizophrenia, the total duration of depression is brief overall compared to the psychotic symptoms. This patient presents with major depression with psychotic features, consisting of a depressed mood with neurovegetative symptoms for at least 2 weeks, as well as psychotic symptoms, which are only present along with the mood symptoms (DSM IV-TR).

  Mood stabilizers alone or with antipsychotic medications are not the first-line treatments for major depression with psychotic features, but rather for mania with or without psychotic features. Studies have demonstrated that the combination of antidepressants and antipsychotics is more effective in treating major depression with psychotic features than either pharmacotherapy alone.