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

USMLE USMLE-STEP-2 Online Questions & Answers

• Question 391:

  Children with sickle cell disease are at risk for certain conditions with characteristic presentation.

  Match the clinical scenario with the syndrome.

  A 12-month old patient presents with a 3-day history of lethargy and fever. He has also had rhinorrhea and a cough. On physical examination, he is pale, tachycardic, and has a left upper quadrant mass. His hemoglobin is 4 g/dL, platelet count is 100,000, and WBC is 15,000 with 50% segmented neutrophils.

  His reticulocyte count is 15%.

  A. acute chest syndrome
  B. acute splenic sequestration
  C. aplastic crisis
  D. hand-foot syndrome
  E. Salmonella osteomyelitis
  F. vasoocclusive crisis
  B. acute splenic sequestration

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  Explanation

  This is the classic presentation of splenic sequestration which occurs in these patients in the first few years of life, before the spleen autoinfarcts. This often occurs following an acute febrile illness. Blood pools in the spleen, which becomes enlarged; signs of circulatory collapse may develop. In an aplastic crisis, a very low reticulocyte count would be expected, and there is no such splenic enlargement.

• Question 392:

  Afamily is scheduled to move into a home that is 15 years old. Its water supply is a well, and sewage is discharged to an on-site septic system. In preparation for the move, they obtain a series of water tests from the well. All of the results show the presence of coliform bacteria.Which of the following is the implication of these data?

  A. They are at risk of acquiring a coliform bacterial infection.
  B. The well water has been mixed with untreated surface or groundwater.
  C. Nothing--this is a common finding in the country.
  D. The groundwater is extensively contaminated and the house is unlivable.
  E. They can live in the house but must seek medical care at the first sign of illness.
  B. The well water has been mixed with untreated surface or groundwater.

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  Explanation

  Testing for the presence of coliform bacteria is a standard bacterial test of water quality. Since coliform bacteria are ubiquitous in nature, their presence means only that the water has been contaminated with water from the ground surface or the septic system. It is only an indicator. Coliform bacteria are not the principal agents of disease. It is the other agents introduced into the water by the contamination that create the risk. The problem should be resolved before using the well water. A common cause of contamination is poor well construction, resulting in surface water moving down the outside of the well casing and into the water source.

• Question 393:

  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. Which of the following is the best diagnostic test to confirm the diagnosis?

  A. repeat CT scan with delayed imaging
  B. ultrasonography
  C. sigmoidoscopy
  D. colonoscopy
  E. small-bowel radiography
  E. small-bowel radiography

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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 394:

  With reference to the above patient, you tell her that her expected delivery date (EDD) is which of the following?

  A. May 18
  B. August 18
  C. May 11
  D. August 11
  E. May 25
  F. June 1
  E. May 25

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  Explanation

  Calculation of the EDD is by using Naegele's rule. Seven days are added to the first day of the LMP, then 3 months are subtracted. Application of Naegele's rule is accurate only for women who have regular menstrual cycle intervals of 2830 days.

• Question 395:

  A2-year-old child presents with a 2-day history of painless rectal bleeding. On examination, the child is pale with tachycardia. The abdomen is nondistended and nontender. There is dark blood on rectal examination. The child has the following imaging study. Which of the following is the most appropriate management?

  

  A. surgical exploration
  B. aggressive resuscitation followed by surgical exploration
  C. colonoscopy
  D. acid suppression therapy
  E. IV steroids
  B. aggressive resuscitation followed by surgical exploration

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  Explanation

  Meckel's diverticulum typically presents in young children with painless rectal bleeding. The etiology of the bleeding is from ulceration of the adjacent ileum that is bathed by the acid produced from the ectopic gastric mucosa in the diverticulum. Bleeding may result in hypovolemia, requiring aggressive resuscitation before any surgical intervention. Diagnosis is made by technetium scan, with the child pretreated with H2 blocks to increase the sensitivity. Colonoscopy is reserved for those children with a negative Meckel's scan. Acid suppression therapy is not indicated. At surgical exploration, the diverticulum and adjacent ileum are removed.

• Question 396:

  A 55-year-old man presents to the physician's office with complaints of hoarseness and left neck fullness for the past month. On examination, a firm, movable, left submandibular mass is noted. Past history is pertinent for a 30 packyear smoking history with occasional alcohol intake. For the above patient with a neck mass, select the most likely diagnosis.

  A. thyroid carcinoma
  B. cystic hygroma
  C. acute suppurative lymphadenitis
  D. thyroglossal duct cyst
  E. lipoma
  F. carotid artery aneurysm
  G. mixed parotid tumor (pleomorphic adenoma)
  H. laryngeal carcinoma
  I. parathyroid adenoma
  J. branchial cleft cystK. tuberculosis
  H. laryngeal carcinoma

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  Explanation

  Laryngeal carcinoma is the most common malignancy of the upper aerodigestive tract in the United States. Presenting symptoms include hoarseness of the voice and, for supraglottic lesions, early metastatic disease to the neck. Risk factors include exposure to tobacco and alcohol.

• Question 397:

  A 69-year-old woman with diabetes mellitus complains of urinary incontinence. Her diabetesis well controlled with oral hypoglycemic agents. She has no complaints other than the wetness. Which of the following tests is most likely to demonstrate the cause?

  A. urinalysis
  B. urine culture and sensitivity
  C. intravesical instillation of methylene blue
  D. the Q-tip test
  E. measurement of residual urine volume
  E. measurement of residual urine volume

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  Explanation

  The combination of aging and diabetes suggests the likelihood of a neurologic defect in the bladder, resulting in overflow incontinence. This occurs when the detrusor muscle becomes hypotonic or atonic. Such women complain of voiding small amounts but still having the feeling of a full bladder. In addition, these women are incontinent of small amounts of urine and are unable to stop the flow. This helps to distinguish those with overflow incontinence from those with GSI; the latter are able to voluntarily increase urethral pressure enough to stop urine flow. Cystitis commonly causes urgency and increased urinary frequency, but not incontinence. Urinalysis and urine culture are not likely to be revealing in this patient, but should be done routinely in all incontinent women. Instillation of methylene blue into the bladder after placement of a vaginal tampon should be done when a vesicovaginal fistula is suspected. This occurs most often following gynecologic surgery and should be suspected in women complaining of constant urine leakage. The Q- tip test is useful to demonstrate posterior urethral rotation found in women with GSI.

• Question 398:

  For each newborn with vomiting and illustrated radiographs, select the most likely diagnosis. A 10- day-old infant presenting with bilious vomiting, paucity of gas on plain radiographs, and duodenal obstruction on UGI contrast study

  

  A. congenital hypertrophic pyloric stenosis
  B. annular pancreas
  C. duodenal atresia
  D. midgut volvulus
  E. intussusception
  F. imperforate anus
  G. Meckel's diverticulum
  H. meconium ileus
  I. Hirschsprung's disease
  J. jejunal atresia
  D. midgut volvulus

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  Explanation

  Pyloric stenosis presents with nonbilious vomiting and gastric distention. An annular pancreas does not result in obstruction, except when it is associated with an underlying duodenal abnormality. Duodenal atresia is associated with Down syndrome. It results in early onset of bilious vomiting from complete duodenal obstruction distal to the ampulla. There is a "double bubble" sign on plain abdominal radiographs from air in the stomach and proximal duodenum. Midgut volvulus is a life-threatening complication of malrotation. It presents with acute onset of bilious vomiting, usually in infants in the first year of life. There is a paucity of gas on plain radiographs, with evidence of duodenal obstruction. UGI contrast study will confirm the abnormal position of the duodenaljejunal junction and may demonstrate a corkscrew of the duodenum from volvulus. Intussusception is uncommon in newborns. Bilious vomiting is unusual at the outset, but may develop if the intussusception has been present for a significant time.

  Imperforate anus can be excluded by clinical examination.

  If unrecognized, the infant will develop a clinical picture of a distal bowel obstruction, with dilated small and large bowel. Meckel's diverticulum can present with obstruction secondary to volvulus around a Meckel's band, with a distal small-bowel obstruction. Contrast enema will demonstrate a normal-caliber decompressed colon, with proximal dilated small bowel. Meconium ileus is associated with cystic fibrosis. Obstruction occurs from inspissated meconium in the terminal ileum. Plain radiographs may demonstrate a "soap bubble" pattern in the right lower quadrant, with a decompressed colon on contrast enema. Hirsch- sprung's disease presents with a distal bowel obstruction and delayed passage of meconium. A contrast enema may demonstrate a transition zone, with a narrow distal aganglionic segment, and proximal colonic dilatation. Jejunal atresia is a result of an intrauterine vascular accident. Infants present with bile- stained vomiting and abdominal distention early after birth. The colon is unused, and characteristically, on contrast enema, it is abnormally small in caliber

• Question 399:

  A healthy 27-year-old male and his partner have been attempting to conceive for more than 1 year. As part of their evaluation he has a semen analysis. His ejaculate volume is 3.5 mL, sperm concentration is 8 million/mL, sperm motility is 65%, oval forms comprise 60% of the sperm, and fructose is present in the ejaculate. Which of these semen parameters is abnormal and suggests that this couple's infertility may be due to a male factor?

  A. ejaculate volume
  B. sperm concentration
  C. sperm motility
  D. sperm morphology
  E. presence of fructose
  B. sperm concentration

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  Explanation

  The WHO suggests a minimal sperm concentration of 20 million/mL for normal conception rates of 1520% per ovulation. However, sperm motility (percentage and velocity; >50% with forward progression), sperm morphology (30% or more oval forms, using strict criteria), coital frequency, and others must be considered. Stated otherwise, a sperm concentration of 10 million/mL may be associated with normal fertility if the sperm motility and morphology are better than average and coital frequency is three to four times per week. Any abnormality of a semen analysis should be confirmed by a repeat semen analysis no sooner than 4 weeks after the initial analysis.

• Question 400:

  A 24-year-old nullipara is being evaluated for infertility. On pelvic examination, she has a single cervix. A diagnostic laparoscopy shows a double uterine fundus. Which of the following is the most likely diagnosis of her uterine anomaly?

  A. septate uterus
  B. unicornuate uterus
  C. bicornuate uterus
  D. didelphic uterus
  E. a diethylstilbestrol (DES) exposed uterus
  C. bicornuate uterus

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  Explanation

  Asingle cavity uterus forms from fusion of paired Müllerian ducts followed by dissolution of the fused medial walls. Uterine anomalies can be divided into five distinct categories: A. failure of formation of one or both Müllerian ducts (unicornuate uterus or absent uterus, respectively); B. failure of fusion of the Müllerian ducts (didelphic uterus, with two cervixes and two vaginal canals separated by a longitudinal septum); C. partial fusion of the Müllerian ducts (bicornuate uterus); D. failure of dissolution of the fused medial walls of the Müllerian ducts (septate uterus); and E. DES exposed uterus. Afetus exposed to DES (or any estrogen) in the first trimester will often develop a T-shaped uterine cavity. The pathophysiology of this abnormality is unknown. In this patient, a single cervix and a double uterine fundus indicate a bicornuate uterus.