USMLE USMLE Certifications USMLE-STEP-2 Questions & Answers

• Question 71:

  A previously healthy 45-year-old woman is involved in a motor vehicle crash, sustaining multiple rib fractures, a complex duodenal injury, and a fractured pelvis. She is ventilated in the ICU. Because of a persistent high-output duodenal fistula, the patient has required prolonged parenteral alimentation. During her ICU course, the patient develops diarrhea, mental depression, alopecia, and perioral and periorbital dermatitis. Administration of which of the following trace elements are most likely to reverse these complications?

  A. iodine

  B. zinc

  C. selenium

  D. silicon

  E. tin

  Correct Answer: B

  Symptoms of zinc deficiency include diarrhea, depression, alopecia, and perioral and periorbital dermatitis. Patients at greater risk for developing this syndrome include those with high gastrointestinal fluid losses, patients with multisystem trauma, and patients on prolonged parenteral nutrition. The symptoms resolve with zinc supplementation. Iodine deficiency results in hypothyroidism. Deficiency syndromes for selenium, silicon, and tin have not been described

• Question 72:

  A22-year-old professional basketball player falls on his outstretched hand during a scrimmage game. He has mild swelling at the wrist and tenderness to palpation in the anatomic snuffbox. No fracture is visible on multiple radiographs of the wrist and hand. Which of the following is the most appropriate management of this patient?

  A. anti-inflammatory medication and application of ice

  B. elastic wrist support, analgesics, and restricted activity for 12 weeks

  C. presumptive diagnosis of a scaphoid fracture, with application of a wrist splint, and repeat x-rays in 1014 days

  D. presumptive diagnosis of a scaphoid fracture, with application of a short-arm cast including the thumb

  E. presumptive diagnosis of a scaphoid fracture, application of a short-arm cast including the thumb, and removal of the cast, with repeat x-rays in 1014 days

  Correct Answer: E

  Any patient with this history and point tenderness in the anatomic snuffbox must be assumed to have a scaphoid fracture. Undisplaced fractures may be difficult to visualize on initial radiographs, even when multiple views are obtained. The appropriate management is full immobilization of the scaphoid, which is achieved only with a cast that extends to include the thumb. X-rays should be repeated in 1014 days, and if the fracture is confirmed, immobilization should be continued. Avascular necrosis is a common complication. Minor wrist injury with ligamentous sprain may be adequately treated with anti- inflammatory medication, application of ice, an elastic wrist support, and restricted activity. However, these are not adequate therapy for a suspected scaphoid fracture. Furthermore, a wrist splint does not provide adequate immobilization of the scaphoid.

• Question 73:

  A50-year-old man is admitted to the hospital with a UGI bleed from acute erosive gastritis, secondary to chronic nonsteroidal anti-inflammatory use. His hematocrit is 28%. With fluid resuscitation, his blood pressure normalizes, but he has a persistent hyperdynamic precordium, tachycardia, and flow murmur on auscultation. He complains of shortness of breath on ambulation. An ECG shows depressed ST-T segments. Which of the following is the next appropriate step in management?

  A. initiation of iron supplementation therapy

  B. supplemental oxygen

  C. continued IV fluid resuscitation

  D. initiation of a calcium channel blocker

  E. blood transfusion

  Correct Answer: C

  This patient has symptomatic anemia. The decreased oxygen-carrying capacity has resulted in decreased tissue perfusion. The heart attempts to compensate with increased contractility and heart rate, in an attempt to improve cardiac output and oxygen delivery. In this patient, however, this is inadequate and has also placed excess metabolic demands on the myocardium with signs of ischemia. These changes can be ameliorated with a blood transfusion. Iron supplementation is indicated in the treatment of chronic iron-deficiency anemia. Restoration of iron stores and a normal red cell mass usually takes several months. Therefore, it is not appropriate in a patient with symptomatic anemia. Supplemental oxygen will not improve oxygen delivery in a patient with limited oxygen-carrying capacity and compensatory maximum oxygen extraction at the tissue level. IV fluid resuscitation will increase circulating blood volume, resulting in hemodilution and decreased red cell concentration. Calcium channel blockade is indicated for management of myocardial ischemia from primary coronary or myocardial pathology.

• Question 74:

  Apreviously healthy 28-year-old woman develops significant postpartum hemorrhage, with a rapid drop in hematocrit to 18%. Despite aggressive IV fluid resuscitation, the patient has a persistent tachycardia, labile systolic blood pressure, and poor urine output. Ongoing resuscitation includes emergency transfusion with 2 units of O-negative packed red blood cells. During transfusion of the second unit, the patient develops chills, fever, vomiting, and hypertension. These symptoms are most likely the result of which of the following?

  A. a febrile nonhemolytic transfusion reaction

  B. an anaphylactic transfusion reaction

  C. ABO incompatibility with acute hemolytic transfusion reaction

  D. delayed hemolytic transfusion reaction

  E. acute bacterial infection transmitted in the blood product

  Correct Answer: A

  Afebrile nonhemolytic transfusion reaction is usually caused by an interaction between recipient antibodies and leukocytes in the transfused blood. Treatment is discontinuation of the transfusion and antipyretics. If further transfusion is required, further reactions can be prevented by filtration of blood products for leukocyte reduction. Anaphylactic transfusion reactions are rare. Patients develop urticaria, flushing, hypotension, and bronchospasm. O blood type is characterized by the absence of ABO antigens on the red blood cell surface. Therefore, type O blood is universally accepted as the donor type for transfusion therapy, making an acute hemolytic transfusion reaction from ABO incompatability impossible. Delayed hemolytic reactions usually occur 13 weeks after a first transfusion and are manifested by an unexplained drop in hematocrit, associated with unconjugated hyperbilirubinemia. Acute bacterial infection transmitted through blood products is extremely rare and has been reported only in association with platelet concentrates stored at room temperature

• Question 75:

  During diagnostic evaluation, a 14-year-old girl with menorrhagia, frequent nosebleeds, and irondeficiency anemia is found to have a low platelet count with a normal coagulation profile. Bone marrow biopsy reveals abundant megakaryocytes. On abdominal examination, no organomegaly is noted. The patient has a satisfactory response to the initial therapeutic intervention, but over 612 months' time, the response is less dramatic and shorter in duration. There are signs and symptoms of increasing side effects from therapy. The next step in management should be to recommend which of the following?

  A. partial splenectomy

  B. splenectomy

  C. increase in steroid dose and frequency

  D. bone marrow transplant

  E. plasmapheresis

  Correct Answer: B

  This patient has idiopathic thrombocytopenic purpura (ITP), a disease characterized by a low platelet count, normal coagulation profile, increased megakaryocytes, and a normal-sized spleen. Patients with ITP will often demonstrate excessive bleeding in response to a minor injury. Circulating antiplatelet antibodies coat normal platelets, which are then sequestered by the spleen, with resultant platelet destruction. The majority of patients respond to initial therapy with systemic steroids. Splenectomy is indicated in patients who become steroid dependent with significant side effects or in patients requiring increasing doses of steroids to maintain a satisfactory platelet count. The entire spleen must be excised, including any accessory spleens found at surgery. Residual splenic parenchyma would result in persistent platelet sequestration. Splenectomy is not indicated in the initial management of ITP. Platelet transfusion is rarely required. Spontaneous bleeding is unusual unless the platelet counts drop below 20,000/L. When this occurs, if the patient is not responsive to steroids, platelet transfusion and urgent splenectomy is indicated. Antineoplastic chemotherapy is not used in the management of ITP. Expectant management is associated with significant risk, as the most life- threatening complication of ITP is spontaneous intracerebral hemorrhage. Bone marrow transplant is not indicated. ITP is a disease of peripheral platelet destruction, with normal or increased platelet production.

• Question 76:

  During diagnostic evaluation, a 14-year-old girl with menorrhagia, frequent nosebleeds, and irondeficiency anemia is found to have a low platelet count with a normal coagulation profile. Bone marrow biopsy reveals abundant megakaryocytes. On abdominal examination, no organomegaly is noted. Which of the following is the most appropriate initial therapy for this patient?

  A. splenectomy

  B. platelet transfusion when peripheral platelet count drops below 50,000/mL

  C. systemic steroids

  D. chemotherapy

  E. expectant, with intervention only if the patient develops significant clinicalbleeding

  Correct Answer: C

  This patient has idiopathic thrombocytopenic purpura (ITP), a disease characterized by a low platelet count, normal coagulation profile, increased megakaryocytes, and a normal-sized spleen. Patients with ITP will often demonstrate excessive bleeding in response to a minor injury. Circulating antiplatelet antibodies coat normal platelets, which are then sequestered by the spleen, with resultant platelet destruction. The majority of patients respond to initial therapy with systemic steroids. Splenectomy is indicated in patients who become steroid dependent with significant side effects or in patients requiring increasing doses of steroids to maintain a satisfactory platelet count. The entire spleen must be excised, including any accessory spleens found at surgery. Residual splenic parenchyma would result in persistent platelet sequestration. Splenectomy is not indicated in the initial management of ITP. Platelet transfusion is rarely required. Spontaneous bleeding is unusual unless the platelet counts drop below 20,000/L. When this occurs, if the patient is not responsive to steroids, platelet transfusion and urgent splenectomy is indicated. Antineoplastic chemotherapy is not used in the management of ITP. Expectant management is associated with significant risk, as the most life- threatening complication of ITP is spontaneous intracerebral hemorrhage. Bone marrow transplant is not indicated. ITP is a disease of peripheral platelet destruction, with normal or increased platelet production.

• Question 77:

  A 7-week-old, breast-fed, term infant presents with increasing jaundice, abdominal distention, and abnormal stools. Liver function tests demonstrate a conjugated hyperbilirubinemia, mildly elevated transaminases, and an elevated gamma-glutamyl transpeptidase. TORCH (congenital infection complex, including toxoplasmosis, rubella, cytomegalovirus, and hepatitis) serology and screening for inborn errors of metabolism are negative. As part of the diagnostic evaluation, the most sensitive imaging study in this clinical setting would be which of the following?

  

  A. radioisotope scanning

  B. radioisotope scanning with preimaging phenobarbital administration

  C. abdominal ultrasound

  D. CT scan of the abdomen

  E. MRI scan of the abdomen

  Correct Answer: B

  This child presents with progressive cholestatic jaundice, as indicated by the elevated conjugated hyperbilirubinemia. Metabolic screening for inborn errors of metabolism and serologic evaluation for intrauterine infections are important to exclude these causes of intrahepatic cholestasis. Figure depicts an acholic stool (absence of bile pigments), which is usually indicative of complete biliary tract obstruction. In this clinical setting, biliary atresia is the most probable diagnosis. The most sensitive imaging study is radioisotope scanning. Preimaging phenobarbital increases the diagnostic yield by stimulating hepatic microsomal enzymes. Abdominal ultrasound may show absence of the gallbladder, but this study is operator dependent and does not evaluate hepatocyte function and bile excretory pattern. CT or MRI scans may demonstrate hepatic parenchymal changes (e.g., extensive cirrhosis) and the presence or absence of bile duct dilatation, but do not evaluate and differentiate abnormalities of hepatocyte function or bile excretory pattern.

• Question 78:

  A 70-year-old man with a 50 pack-year history of smoking presents with a 6-week history of intermittent,

  painless, gross hematuria and urinary frequency. There are no masses palpable on abdominal

  examination, and rectal examination is normal. Urinalysis confirms the presence of hematuria, and urine

  culture is negative.

  The initial diagnostic evaluation does not reveal any abnormalities. Which of the following is the best next

  step in the diagnostic workup?

  A. an abdominal CT scan

  B. cystourethroscopy and urinary cytology

  C. a transrectal ultrasound

  D. exploratory laparoscopy

  E. re-evaluation in 24 weeks, with repeat urinalysis and urine culture

  Correct Answer: B

  Patients with gross hematuria require aggressive diagnostic evaluation. A careful, planned approach will yield the cause in the majority of patients. Painless hematuria is often the first sign of a urinary tract malignancy. After confirmation of hematuria, and exclusion of infection, all patients should have plain radiographs and IVP. This is the optimal initial diagnostic approach to aid in distinguishing between upper tract (renal) pathology and lower tract (lower ureteric and bladder) pathology. Further diagnostic evaluation will be guided by these noninvasive studies. A voiding cystourethrogram is invasive. It is a limited examination of bladder function and anatomy, and although advanced invasive bladder tumors may be demonstrated as a filling defect, it is not sensitive for lower stages of bladder neoplasms.

  Cystourethroscopy is invasive and is, therefore, not the initial examination in the evaluation of hematuria. It is indicated in the evaluation of gross hematuria in patients with a normal IVP. It is the optimal tool for evaluation of potential bladder pathology. An abdominal ultrasound or CT scan is indicated in patients with a suspected renal mass, either by clinical examination or demonstrated on IVP. Urine for cytology is useful for screening of patients with suspected urinary tract malignancy, but it is falsely negative in approximately 20% of patients and should not be used as the only diagnostic evaluation. Atransrectal ultrasound may be helpful in evaluating the extent of invasion of a bladder or prostatic neoplasm. Abdominal CT scan is a superior imaging study for this purpose.

• Question 79:

  A 70-year-old man with a 50 pack-year history of smoking presents with a 6-week history of intermittent,

  painless, gross hematuria and urinary frequency. There are no masses palpable on abdominal

  examination, and rectal examination is normal. Urinalysis confirms the presence of hematuria, and urine

  culture is negative.

  Which of the following is the most appropriate initial diagnostic evaluation of this patient?

  A. plain abdominal radiographs and an intravenous pyelogram (IVP)

  B. voiding cystourethrogram

  C. cystourethroscopy

  D. abdominal ultrasound

  E. urine for cytology

  Correct Answer: A

  Patients with gross hematuria require aggressive diagnostic evaluation. A careful, planned approach will yield the cause in the majority of patients. Painless hematuria is often the first sign of a urinary tract malignancy. After confirmation of hematuria, and exclusion of infection, all patients should have plain radiographs and IVP. This is the optimal initial diagnostic approach to aid in distinguishing between upper tract (renal) pathology and lower tract (lower ureteric and bladder) pathology. Further diagnostic evaluation will be guided by these noninvasive studies. A voiding cystourethrogram is invasive. It is a limited examination of bladder function and anatomy, and although advanced invasive bladder tumors may be demonstrated as a filling defect, it is not sensitive for lower stages of bladder neoplasms. Cystourethroscopy is invasive and is, therefore, not the initial examination in the evaluation of hematuria. It is indicated in the evaluation of gross hematuria in patients with a normal IVP. It is the optimal tool for evaluation of potential bladder pathology. An abdominal ultrasound or CT scan is indicated in patients with a suspected renal mass, either by clinical examination or demonstrated on IVP. Urine for cytology is useful for screening of patients with suspected urinary tract malignancy, but it is falsely negative in approximately 20% of patients and should not be used as the only diagnostic evaluation. Atransrectal ultrasound may be helpful in evaluating the extent of invasion of a bladder or prostatic neoplasm. Abdominal CT scan is a superior imaging study for this purpose.

• Question 80:

  In a 6-month-old previously healthy male infant, an abnormality is revealed during a routine diaper change, as illustrated in Figure. The parents have noted this finding on and off on several occasions over the last month. On each occasion, the child has been feeding well, and is content and playful.

  

  Several weeks later, the child presents to the emergency department with a 4-hour history of irritability. He has had one episode of nonbilious vomiting and has refused to breast-feed. In the emergency department, the infant appears inconsolable. He is afebrile, and his abdomen is mildly distended but soft. On removal of his diaper, the same abnormality is documented (see Figure. Which of the following is the most appropriate management at this time?

  A. urgent surgical exploration

  B. systemic antibiotics

  C. elective surgical repair

  D. sedation with manual reduction and arrangements for elective surgical repair

  E. sedation with manual reduction, admission, rehydration, and surgical repair within 2448 hours

  Correct Answer: E

  This patient has an inguinoscrotal mass from an indirect inguinal hernia. His initial presentation is one of a reducible inguinal hernia. Repair is indicated because of the risk of incarceration. He should be referred for early elective surgery. The second presentation several weeks later is at the time of incarceration of the hernia. This has resulted in pain, irritability, and reflex vomiting. Prolonged incarceration increases the risk of bowel ischemia. The appropriate management is sedation with manual reduction, admission with observation in hospital, and surgical repair within 2448 hours. Delaying repair after an initial episode of incarceration increases the risk of further episodes of incarceration, with potential bowel or testicular compromise. Failure to reduce an incarcerated hernia successfully mandates urgent surgical intervention. Testicular torsion is uncommon in this age group and presents with a tender, high-riding testicle. When suspected, urgent surgical exploration is indicated. Inguinal adenitis may be the result of an inflammatory focus in the diaper area, with resultant adenopathy, and secondary infection of the inguinal nodes with a gram-positive organism. The infant is usually febrile, with a tender inguinal mass. Therapy includes systemic antibiotics. An undescended testicle may present as an inguinal mass, with an empty hemiscrotum. It is usually asymptomatic. Management is elective orchiopexy at approximately 1 year of age. A noncommunicating hydrocele presents as an asymptomatic, fluctuant scrotal mass that transilluminates. Surgical intervention is not required, because most will resolve spontaneously by 1 year of age