USMLE USMLE Certifications USMLE-STEP-2 Questions & Answers

• Question 51:

  A 23-year-old G1P0010 woman complains of severe dysmenorrhea (i.e., pain with menses). She misses work for the first 3 days of her menstrual cycle almost every month and states that this has been a problem for about 3 years, now getting worse. She is not currently sexually active and is not using any hormonal contraception. She complains of occasional deep abdominal pain after bowel movements. Subsequent laparoscopic evaluation reveals endometriosis. Which of the following is a true statement regarding this condition?

  A. Smoking is a strong risk factor for the development of endometriosis.

  B. There is a direct relationship between perceived pain and the amount of endometriosis noted at the time of surgery.

  C. Most women with endometriosis also have infertility.

  D. Medical and surgical management are equally effective in restoring fertility in the patient with endometriosis.

  E. The most common sites of endometriosis implants are the ovaries and anterior and posterior cul-desacs.

  Correct Answer: E

  Endometriosis is a complex condition affecting women of reproductive age, most commonly diagnosed between the ages of 20 and 40. True incidence rates are hard to estimate because direct visualization is necessary to confirm the diagnosis, but the disease likely affects 710% of women. Because smoking is associated with reduced body mass index and reduced estrogen levels, it is negatively associated with the risk of endometriosis. Symptoms include ysmenorrhea (most common), dyspareunia (i.e., pain with intercourse), or dyschezia (i.e., pain with efecation). There appears to be little correlation between the amount of disease noted at the time of surgery and the patient's report of pain. Infertility affects up to 3050% of women with endometriosis and surgical resection appears to be more effective in promoting fertility than does medical management alone. In order, the most common sites for endometriosis implants are the ovaries, anterior and posterior cul-de- sacs, broad ligaments, uterosacral ligaments, uterus, tubes, colon, and appendix.

• Question 52:

  A 55-year-old male who is a former IV drug user presents with jaundice, ascites, and leg edema. A CT scan of the abdomen reveals a malignant-appearing mass in the liver. According to the above findings of patient having hepatitis virus, select the most likely type of viral hepatitis.

  A. hepatitis A

  B. hepatitis B

  C. hepatitis C

  Correct Answer: C

  Hepatitis A is transmitted almost exclusively by the fecal-oral route. Large outbreaks have been linked to contaminated food products. Intrafamily and intrainstitutional spread also is common. Clinical severity usually is mild, and hepatitis A does not progress to chronicity. Hepatitis C more commonly progresses to chronicity (5070% develop chronic hepatitis and 8090% of these patients have evidence for chronic infection). Hepatitis C can lead to cirrhosis and hepatocellular carcinoma. Chronicity occurs in only 110% of patients with hepatitis B

• Question 53:

  On the second day after an appendectomy, a 33-year-old man complains of chest pain. Vital signs are: temperature 102°F, BP 130/70 mmHg, pulse rate 100/m in, and respiration rate 22/min. Room air ABG reveals a pH of 7.50, PCO2 of 29, and PO2 of 49. His WBC count is elevated and CXR shows a right lower lobe infiltrate. Which of the following is the most likely diagnosis?

  A. pulmonary embolism

  B. myocardial infarction

  C. pneumonia

  D. asthma

  E. congestive heart failure

  Correct Answer: C

  Asthma is characterized by bronchospasm and typically causes a prolonged expiratory phase and retention of carbon dioxide. This degree of hypoxia (PO2 of 49) generally would not be seen with asthma. Pulmonary embolism, congestive heart failure, myocardial infarction, or pneumonia all could lead to this degree of hypoxia. The constellation of fever, elevated white count, and localized infiltrate on CXR is most characteristic of pneumonia. The most likely etiology is perioperative aspiration related to general anesthesia.

• Question 54:

  A62-year-old woman with a long-standing history of diabetes and hypertension presents for evaluation of hyperkalemia. Her room air arterial blood gas (ABG) and electrolytes are the following: pH 7.38/PCO2 34/PO2 89 Na 140 Cl 106 BUN 51 K 5.9 CO2 20 Cr 2.8

  Which of the following is the underlying renal abnormality?

  A. renal tubular acidosis (RTA), type 2

  B. focal segmental glomerulonephritis

  C. interstitial nephritis

  D. RTA, type 4 E. Barter syndrome

  Correct Answer: D

  In type 4 RTAassociated with diabetes and hypertension, damage to the juxtaglomerular apparatus in the glomeruli leads to decreased renin production. This results in a state of hypoaldosteronism, causing hyperkalemia and a nongap metabolic acidosis.

• Question 55:

  A 58-year-old man is establishing care with you because his insurance changed. His old records have not yet arrived, but he is complaining of palpitations and lightheadedness, so you order the ECG shown in

  Figure

  What is the underlying abnormality?

  

  A. right bundle branch block (RBBB)

  B. left bundle branch block (LBBB)

  C. accelerated junctional rhythm

  D. left anterior fascicular block

  E. intraventricular conduction delay

  Correct Answer: B

  The prolonged, negative QRS vector anteriorly (V1-V3) and wide notched R waves in V5 and V6 are characteristic for LBBB. In RBBB, there is an rSR' complex in V1 and QRS pattern in V6. Accelerated junctional rhythm would not have P waves. Partial blocks, such as left anterior fascicular block, generally do not prolong the QRS duration substantially, but are associated with shifts in the frontal plane QRS axis (left axis deviation). With intraventricular conduction delay, the QRS is between 100 and 120 ms. LBBB is a marker of one of four conditions: severe aortic valve disease, ischemic heart disease, long-standing hypertension, and cardiomyopathy. RBBB is seen more commonly than LBBB in patients without structural heart disease, although RBBB also occurs with congenital heart disease and ASD or valvular heart disease. Hyper- but not hypokalemia may cause intraventricular conduction delay. Myocarditis does not usually lead to LBBB.

• Question 56:

  A 30-year-old woman who has been human immunodeficiency virus (HIV) positive for 4 years was recently diagnosed with AIDS. Which of the following meets the criteria for the case definition?

  A. oral thrush

  B. herpes zoster

  C. persistent lymphadenopathy

  D. peripheral neuropathy

  E. pulmonary tuberculosis

  Correct Answer: E

  The new case definition for AIDS in 1993 added pulmonary tuberculosis, invasive cervical cancer, and recurrent pneumonia. This CDC classification system is divided into three categories: category A is symptomatic infection with HIV and includes acute illness and persistent lymphadenopathy; category B includes conditions attributed to HIV infection, such as oral thrush, herpes zoster, and peripheral neuropathy; category C is the AIDS surveillance cases. Anergy to common skin test antigens is a common finding with HIV infection. There is a decline in CD4 cell numbers, a relative increase in the number of T8 cells, which results in a decreased T4:T8 ratio of less than 1. Functional abnormalities occur in both B cells and natural killer cells, which accounts for the increase in certain bacterial infections seen in advanced HIV disease. Elevation of beta2 submicroglobulin, a serologic finding reflecting immunologic dysfunction, is a fairly reliable marker of progressive immunologic decline and the subsequent development of AIDS.

• Question 57:

  A54-year-old woman with diabetes is noted to have BP in the range of 140/90 mmHg on several occasions. Which of the following is the best next step in management?

  A. initiate antihypertensive therapy

  B. advise weight loss and recheck BP in 3 months

  C. advise regular exercise and recheck BP in 3 months

  D. no further intervention is necessary

  E. follow-up in 6 months for recheck of BP

  Correct Answer: A

  The Hypertension Optimal Treatment Study and the U.K. Prospective Diabetes Study both showed benefit in targeting BP to the normal range in patients with diabetes (i.e., 130/85 mmHg). This patient has multiple readings of 140/90 mmHg and should be treated with antihypertensive medication.

• Question 58:

  While examining a 46-year-old woman, you hear a diastolic murmur that is increased when the patient is in the left lateral decubitus position. You ask her to run in place for 3 minutes, and the murmur is found to be accentuated as well by exercise. What is the most likely valvular defect?

  A. aortic regurgitation

  B. mitral stenosis

  C. tricuspid stenosis

  D. pulmonic regurgitation

  E. VSD

  Correct Answer: B

  Heart sounds and murmurs can often be accentuated by various physiologic and pharmacologic maneuvers. These maneuvers aid in the differentiation of multiple valvular and other organic lesions from ordinary sounds. Mitral stenosis is a diastolic murmur that grows louder with increased flow across the stenotic valve, as in exercise. Tricuspid stenosis is heard best at the lower left sternal border. Aortic regurgitation is generally reduced by dynamic exercise due to shortened diastole. AVSD may be small, and causes a systolic murmur; its murmur will fade with maneuvers favoring forward flow, such as vasodilatation with amyl nitrate. The murmur of aortic stenosis is systolic and will grow louder with increased flow across the valve, as with amyl nitrate; it will diminish with maneuvers that decrease flow across the valve, as in stage two of the Valsalva maneuver.

• Question 59:

  A 75-year-old man who developed diabetes within the last 6 months was found to be jaundiced. He has remained asymptomatic, except for weight loss of about 10 lbs in 6 months. On physical examination, he is found to have a nontender, globular, right upper quadrant mass that moves with respiration. A CT scan shows enlargement of the head of the pancreas, with no filling defects in the liver. What is the most likely cause of his painless jaundice?

  A. malignant biliary structure

  B. carcinoma of the head of the pancreas

  C. choledocholithiasis

  D. cirrhosis of the liver

  E. pancreatitis

  Correct Answer: B

  Adenocarcinoma of the pancreas arises from ductal epithelium. Because of fibrous tissue formation, the terminal bile duct occludes, causing jaundice. Typically, in the early stages, the patient is free of pain. With invasion of retroperitoneal structures, the patient may sometimes have severe and constant pain. Often, patients have a history of weight loss and present with unexplained diabetes. Because of gradual obstruction, the gallbladder distends, unless it has lost its distensibility because of previous scarring. Malignant biliary stricture, choledocholithiasis, and cirrhosis of the liver are ruled out by the appearance of the CT. Pancreatitis is rarely associated with jaundice and would be painful.

• Question 60:

  A22-year-old man complains of low back pain and stiffness that is worse on arising and improves with exercise. On examination, he is found to have limited mobility of the sacroiliac joints and lumbar spine. A serum test for histocompatibility antigen HLA-B27 is positive. What is the most common extraskeletal manifestation of this disease?

  A. premature cataracts

  B. splenomegaly

  C. acute iritis

  D. aortic insufficiency

  E. pulmonary fibrosis

  Correct Answer: C

  The clinical features of the patient described in the question are most compatible with ankylosing spondylitis, an inflammatory arthritis that occurs most often in young men. Early findings of low back pain and stiffness may progress to involve the entire spine with straightening (poker spine). The most common extraskeletal manifestation is acute anterior iridocyclitis, occurring in 2530% of patients. Additional manifestations, which occur rarely, include heart block, aortitis with aortic insufficiency, and upper-lobe pulmonary fibrosis. Splenomegaly is associated with rheumatoid arthritis (Felty syndrome) but is not a feature of ankylosing spondylitis, nor are cataracts.