USMLE USMLE-STEP-2 Online Practice Questions and Exam Preparation

USMLE USMLE-STEP-2 Online Questions & Answers

• Question 511:

  A 44-year-old man presents with fears that his mathematical abilities have been slowly sucked out of his brain for the last 4 years. He believes an "alien force disguised as a human being" is responsible. To avoid contacting this being, he has isolated himself in a room in a boarding house. His wife divorced him and left with their children. After 10 years teaching math at a local high school, he resigned about 3 years ago. He supports himself by "collecting cans." His affect is blunted. His appearance is disheveled, unshaven, and unwashed.

  Considering the information learned thus far, which of the following would be an appropriate first-line treatment for this patient?

  A. thiamine
  B. olanzapine
  C. amitriptyline
  D. lithium carbonate
  E. fluoxetine
  B. olanzapine

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  Explanation

  The treatment of choice for patients with a schizophrenic disorder is an antipsychotic drug. Of the medications listed, only olanzapine is an antipsychotic drug. Olanzapine causes relatively fewer EPS than traditional neuroleptics, such as haloperidol, and seems to be substantially less likely to cause tardive dyskinesia than typical neuroleptics. Olanzapine blocks both dopamine D2 receptors and serotonin 5- HT2 receptors. Its use is often associated with some weight gain by patients.

• Question 512:

  A term infant is born at a small community hospital by cesarean section for failure to progress. The infant is noted to have the following abnormality at birth

  

  Which of the following is the most likely diagnosis?

  A. umbilical hernia
  B. omphalitis
  C. omphalocele
  D. gastroschisis
  E. traumatic evisceration
  C. omphalocele

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  Explanation

  This infant has an omphalocele. This is a result of failure of the abdominal muscles to close in the midline at the umbilical cord. The abdominal wall defect is therefore midline, with viscera enclosed in a sac composed of amniotic membranes. Children with omphalocele may have other associated anomalies. Infants with abdominal wall defects are at risk for fluid and temperature loss, and infection. Therefore, the initial management consists of measures to decompress the gastrointestinal tract, fluid resuscitation, IV antibiotics, and placing the viscera in a warm, moist occlusive dressing. An umbilical hernia results when the umbilical ring does not close, with viscera enclosed in a sac covered by peritoneum and skin. Many of these may spontaneously close on their own. Therefore, surgical intervention is restricted to those children with a persistent fascial defect. Omphalitis results from bacterial infection at the base of the cord and is well treated with antibiotics to cover skin organisms. Gastroschisis is a congenital evisceration, located to the right of the umbilical cord, and thought to be related to obliteration of one of the umbilical veins prior to birth. As with omphalocele, the child needs NG decompression, IV fluids and antibiotics, and a warm moist occlusive dressing. In gastroschisis, the bowel may be at risk of mechanical or vascular compromise, thus urgent surgical intervention is required.

• Question 513:

  A 40-year-old woman presents to the emergency room with a 3-day history of worsening abdominal pain, with nausea and vomiting. Examination reveals a low-grade fever and abdominal tenderness in the right upper quadrant with guarding, especially during inspiration. Laboratory findings include a mild leukocytosis and a slightly elevated bilirubin. For the above patient with abdominal pain, select the most likely diagnosis.

  A. gastroenteritis
  B. regional enteritis
  C. acute appendicitis
  D. perforated peptic ulcer
  E. sigmoid diverticulitis
  F. acute pancreatitis
  G. acute cholecystitis
  H. superior mesenteric artery embolism
  I. ruptured abdominal aortic aneurysm
  J. ruptured ovarian cystK. cecal volvulus
  G. acute cholecystitis

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  Explanation

  Acute appendicitis initially presents with periumbilical pain secondary to obstruction of the appendiceal lumen. This is mediated through visceral pain fibers, and because the appendix is from the embryologic midgut, the pain is referred to the umbilicus. With obstruction of a hollow viscus, there may be associated nausea. As the inflammatory process progresses to involve the visceral and parietal peritoneal surfaces, the pain becomes localized directly over the appendix in the right lower quadrant. Fever and leukocytosis are nonspecific signs of an inflammatory process. Gastroenteritis may be associated with nausea, anorexia, and lowgrade fever. Periumbilical pain is colicky and secondary to increased peristalsis. Localized pain and signs of peritoneal irritation are uncommon. Aruptured right ovarian cyst may mimic appendicitis. Patients may exhibit right lower abdominal peritoneal irritation. However, the onset of pain is usually sudden, and the pain is initially felt in the right lower quadrant.

  These patients do not have anorexia or other gastrointestinal symptoms. The clinical picture of regional enteritis (Crohn's disease) is one of a chronic illness, often associated with weight loss, intermittent cramps, and diarrhea. Fever, tenderness, and a palpable right lower quadrant inflammatory mass may result from complications of ileal involvement. Sigmoid diverticulitis is more common in older patients, often with a prodromal history of irregular bowel habits. There may be left lower quadrant pain and tenderness, with a palpable left-sided inflammatory mass. A cecal volvulus presents with sudden onset of colicky abdominal pain and signs and symptoms of a bowel obstruction, including bilious emesis and abdominal distention. Alcohol-related acute pancreatitis presents with pain referred to the epigastrium, with radiation to the back mediated through the celiac ganglia. The patient may develop abdominal distention secondary to the associated paralytic ileus. Hyperamylasemia and an elevated serum lipase, in this clinical setting, are suggestive of pancreatitis. Perforated peptic ulcer and acute cholecystitis may also present with epigastric pain, and elevations of both serum lipase and amylase. Pain from a perforated ulcer, however, is sudden in onset and may be associated with shoulder-tip pain from diaphragmatic irritation. About 75% of patients with perforated duodenal ulcers have pneumoperitoneum on chest and abdominal radiographs.

  Acute cholecystitis will usually commence after a large meal and initially presents as colicky epigastric pain, progressing to pain localized in the right upper abdomen when transmural inflammation of the gallbladder wall produces peritoneal irritation. Acute mesenteric occlusion presents with sudden onset of severe but poorly localized periumbilical abdominal pain, associated with acidosis. There may be elevation of serum amylase and lipase. A ruptured abdominal aortic aneurysm will present with sudden onset of midabdominal pain, back pain, and hemodynamic instability.

• Question 514:

  A 38-year-old G4P3013 woman is seeing you for her annual gynecologic examination. She has no specific complaints, but notes that her menses have gradually become heavier over the past 23 years. Your pelvic examination is normal aside from an enlarged uterus, which you estimate at 12 weeks' size. Office ultrasonography confirms that she has multiple uterine fibroids. Which of the following statements is true regarding leiomyomata?

  A. OCs cause leiomyomata to grow more rapidly.
  B. Leiomyomata not removed by hysterectomy may eventually degenerate into malignant tumors (i.e., leiomyosarcoma).
  C. Submucosal fibroids are more likely to cause painful, heavy periods than are subserosal fibroids.
  D. Leiomyomata occur in up to 5% of all women.
  E. Typical bleeding abnormalities seen with uterine fibroids are heavy menstrual bleeding as well as frequent intermenstrual bleeding episodes.
  C. Submucosal fibroids are more likely to cause painful, heavy periods than are subserosal fibroids.

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  Explanation

  Leiomyomata lead to more hysterectomies than any other gynecologic condition and can be found in up to 50% of all women. Most are asymptomatic, but symptoms can include heavy menstrual bleeding, pelvic pain, "pressure symptoms," and even preterm birth. Symptoms depend on where the fibroids are located-- those closest to the endometrial cavity cause more problems with bleeding and dysmenorrhea, while those closest to the serosa can be expected to cause more pressure symptoms such as bladder frequency or constipation. However, the typical bleeding disturbance associated with uterine fibroids is heavy regular bleeding as opposed to bleeding or spotting between periods, which deserves separate evaluation. Leiomyosarcomas are malignant tumors that appear very similar to benign leiomyomata-- however, they are now felt to arise de novo and not from degeneration of a benign fibroid. Leiomyomata do seem to respond to sex steroids but oral contraceptives do not cause more rapid growth or regression.

• Question 515:

  A 59-year-old woman complains of shortness of breath and aching left-sided chest pain that radiates to the left shoulder. Physical examination shows no abnormalities; her CXRs are shown in Figure below. Which of the following statements is true concerning this disease?

  

  A. This tumor frequently metastasizes to distant sites.
  B. Direct exposure to asbestos is required.
  C. Most cases are associated with recent, massive exposure to asbestos.
  D. Diffuse forms may be cured by chemotherapy alone.
  E. Localized forms may be cured by surgery alone.
  E. Localized forms may be cured by surgery alone.

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  Explanation

  The x-ray in Figure shows a large, pleural based tumor in the left upper chest; this is most likely a mesothelioma. The tumor is locally invasive, so there are no signs of extrathoracic disease. Direct exposure or contact with asbestos is not required-tumors have occurred in families of asbestos workers. The exposure may be brief and mild, and there is typically a long latent period before appearance of the tumor, about 2040 years. Surgery is curative in local cases. Diffuse malignant mesothelioma responds poorly to all treatments (surgery, radiotherapy, and chemotherapy).

• Question 516:

  A 16-year-old girl presents with a history of primary amenorrhea. On examination, short stature and a short neck with a low posterior hairline are noted. Chromosomal analysis most likely would reveal which of the following?

  A. fragile X
  B. trisomy 18
  C. trisomy 21
  D. 45,XO
  E. XXY
  D. 45,XO

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  Explanation

  Turner syndrome (usually 45,XO karyotype) occurs in 1 of 3000 live births. The hallmark of this genetic disease is gonadal dysgenesis. Although sexual maturation usually does not occur, a girl with Turner syndrome occasionally will have menstrual periods but rarely will be fertile. Treatment may include estrogen replacement or growth hormone usage. Psychosocial support is extremely important.

• Question 517:

  A 55-year-old woman presents with a 6-month history of weight loss, abdominal cramps, and intermittent nonbloody diarrhea. On examination, her abdomen is mildly distended and there is a palpable mass in the right lower quadrant. Stool cultures yield normal fecal flora. CT scan with oral contrast demonstrates an inflammatory mass in the right lower quadrant, with thickening of the terminal ileum and ileocecal valve.

  Initial management should include which of the following?

  A. antibiotics and IV fluids
  B. lactose-free diet
  C. antispasmodics
  D. nutritional supplementation and systemic steroids
  E. laparotomy
  D. nutritional supplementation and systemic steroids

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  Explanation

  Crohn's disease is a chronic inflammatory disease of the gastrointestinal tract that presents with intermittent crampy abdominal pain and diarrhea. It most commonly involves the terminal ileum and right colon. Because eating can exacerbate symptoms, oral intake may be decreased, contributing to the associated weight loss. Transmural inflammation leads to bowel wall thickening, and with adjacent mesenteric inflammation, the patient may develop a palpable mass. It may be difficult to differentiate Crohn's disease from ulcerative colitis on the basis of history and clinical examination.

  However, ulcerative colitis is a mucosal disease that is limited to the colon and nearly always involves the rectum. Diarrhea is usually bloody, and hemorrhage may be significant enough to require transfusion therapy. Complicated appendicitis may present with a right lower quadrant mass and diarrhea if there is perforation with abscess formation. The history is that of an acute illness in a previously well patient. Irritable bowel syndrome is associated with intermittent crampy abdominal pain, and diarrhea alternating with constipation. There is no inflammatory process, and weight loss is not a clinical feature. Evaluation of the small bowel is best accomplished with contrast radiography, such as a small-bowel follow-through study or enteroclysis. Radiographic abnormalities of small-bowel Crohn's disease are often distinctive and can demonstrate complications such as strictures and fistulae. CT scanning does not assist in confirming the diagnosis, but is helpful in detecting such complications as abscess.

  Ultrasonography has limited value. Sigmoidoscopy may not be useful, because Crohn's disease commonly spares the rectum and may be worse on the right side of the colon. Colonoscopy may be helpful when the colon is involved and when intubation of the ileocecal valve can be achieved; however, the disease may be limited to the small bowel resulting in a nondiagnostic examination.

  The principle of initial management of Crohn's disease is relief of symptoms, nutritional therapy, and suppression of the inflammatory process. Nutritional supplementation may require TPN in conjunction with bowel rest. Acute exacerbations of the disease are initially treated with systemic steroids. The use of antispasmodics may be effective in the treatment of irritable bowel syndrome. In Crohn's disease, however, antispasmodics may lead to an ileus or toxic bowel dilatation. Surgery in Crohn's disease is indicated for the management of complications, including fistula or abscess formation, stricture with obstruction, and perforation.

• Question 518:

  The mother of a 3-year-old girl brings her daughter to see you because the girl developed breasts 6 months ago. The girl has had no vaginal bleeding, and there is no pubic hair. She takes no medication

  The tests you ordered are normal for a prepubertal girl. Which of the following is the most likely diagnosis?

  A. ingestion of the mother's OC pills
  B. a granulosa cell tumor
  C. 21-hydroxylase deficiency
  D. polycystic ovary syndrome
  E. premature thelarche
  E. premature thelarche

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  Explanation

  Premature thelarche is a disorder that probably occurs as a consequence of increased sensitivity of breast tissue to the low levels of circulating estradiol in prepubertal girls. The disorder occurs most commonly before the age of 3 years. The estradiol concentration may be normal in young girls ingesting estrogen if the serum estrogen concentration is not obtained at the time the estrogen is ingested. A negative medication history is helpful to exclude this possibility. The absence of a palpable lower abdominal mass and a prepubertal concentration of estradiol exclude a granulosa cell tumor. Adrenal 21-hydroxylase deficiency and polycystic ovary syndrome are function disorders that require the stimulation of adrenocorticotropic hormone (ACTH) and pituitary gonadotropins (FSH and LH), respectively, to become clinically apparent. Neither disorder appears until after the onset of puberty. Moreover, both are associated with androgen excess and masculinization, not estrogen excess and precocious breast development.

• Question 519:

  A5-year-old child was hit in the right eye by a toy. He is rubbing at his eye, which is watering profusely. There is a small abrasion at the corner of the eye. He is mildly photophobic, but his pupils are equal, symmetric, and reactive to light and accommodation. His vision is normal.

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

  A. Perform a fluorescein dye stain of the cornea to determine if there is a corneal abrasion.
  B. Refer him immediately to an ophthalmologist.
  C. Irrigate the eye with sterile normal saline.
  D. Discharge him to home with antibiotic eye ointment.
  E. Apply a patch to the eye and follow-up in a week.
  A. Perform a fluorescein dye stain of the cornea to determine if there is a corneal abrasion.

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  Explanation

  Superficial corneal injuries expose underlying layers causing pain, photophobia, tearing, and decreased vision. Irrigation is recommended only if a foreign body is suspected. Abrasions are detected by instilling fluorescein dye and inspecting the cornea using blue-filtered light. Treatment consists of frequent applications of topical antibiotic ointment until the epithelium is healed. The use of a patch does not accelerate healing, and if improperly applied, may abrade the cornea. Referral to an ophthalmologist should be considered if there are significant changes in vision, or signs of deeper or more penetrating injury which often result in papillary bnormalities.

• Question 520:

  A 62-year-old man is undergoing neurologic evaluation. His arteriogram demonstrates the lesion shown in the figure below. Which of the following deficits is compatible with this lesion?

  

  A. diplopia
  B. transient monocular blindness
  C. ataxia
  D. vertigo
  E. dysarthria
  B. transient monocular blindness

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  Explanation

  The cerebral arteriogram shown in Figure reveals severe stenosis of the common carotid artery proximal to its bifurcation, as well as small lesions in the more distal vessels. Common manifestations are transient monocular blindness (amaurosis fugax), hemiparesis, hemisensory loss, aphasia, and homonymous visual field defects. Ataxia would be an unusual feature of carotid disease and, if present, would suggest involvement of the vertebrobasilar arteries, which results in dysarthria, diplopia, and vertigo.