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

USMLE USMLE-STEP-3 Online Questions & Answers

• Question 441:

  A55-year-old man with hepatic cirrhosis from alcohol abuse presents with a massive hematemesis. This is his third admission for upper GI hemorrhage in the past 2 months. He is currently receiving appropriate therapy for liver failure, including a beta-blocker and diuretics. He is lethargic and confused. His pulse is 100 and blood pressure is 85/40. His initial hematocrit is 20. After fluid resuscitation, which of the following is the most appropriate management strategy?

  A. The transplant team should be called immediately.
  B. The bleeding is probably secondary to an uncontrolled duodenal ulcer related to his alcohol use.
  C. Red blood cells should be administered immediately, but fresh frozen plasma should be withheld if possible.
  D. Endoscopic control options include sclerotherapy and banding.
  E. Transjugular intrahepatic portal systemic shunt (TIPS) is not an option in the immediate period.
  D. Endoscopic control options include sclerotherapy and banding.

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  Explanation

  In patients with liver failure, the source of an upper GI bleed is esophageal varices in 50%, gastritis in 30%, and duodenal ulcers in only about 10%. Esophageal variceal bleeding is a potentially fatal complication of portal hypertension. The initial management should include fluid resuscitation and replacement of blood and clotting factors as needed. The second step is to control the source of bleeding. Medical management may include vasopressin or octreotide. Once the patient is stabilized, endoscopic evaluation of the bleeding is crucial. It can be both diagnostic and therapeutic. Endoscopic techniques for controlling hemorrhage can include sclerotherapy, banding, or balloon tamponade. If these methods are ineffective, or the patient has numerous recurrences, portal shunts can be considered. TIPS have increased in popularity as a method for portal decompression. This can be performed in the acute setting. Surgical shunts are also an option, but are primarily reserved for stable patients with recurrent bleeding episodes and not performed in an acutely unstable patient. Mesocaval shunts connect the SMV to the IVC in a variety of manners. Splenorenal shunts are actually the most common type of shunt. Nonselective shunts that completely divert portal blood flow from the liver can actually increase hepatic encephalopathy. Most surgeons prefer selective shunts, which preserve a component of hepatic blood flow and thus function. Synthetic graft material can be safely used to create the shunts.

  Postoperative mortality is directly related to the patient's preprocedure medical condition and degree of hepatic failure.

• Question 442:

  A 22-year-old female (G3P0020) presents to your office for an initial obstetric visit in her third pregnancy. She reports a sure LMP date approximately 6 weeks ago, with a history of regular cycles. Her two previous pregnancies ended in spontaneous abortions. She denies any significant medical or surgical history. She denies use of alcohol, tobacco, or illicit drugs, though she does report a history of IV drug use as a teenager. She is a full-time student. She reports that twins run in her family, but she does not have any family history of diabetes, hypertension, or congenital anomalies. On review of her prenatal labs that have already been drawn, you find that her human immunodeficiency virus (HIV) antibody test (enzyme-linked immunosorbent assay [ELISA]) is positive. Her test results are otherwise normal. Which of the following indicates how you counsel the patient?

  A. This result is a false positive due to pregnancy, and she does not need any further testing.
  B. She is infected with HIV and will need to begin treatment right away.
  C. She will require an additional, confirmatory test to determine whether or not she has HIV.
  D. She may have HIV, but she should wait until after she delivers her baby to have further testing.
  E. Because it has been years since she participated in high-risk behaviors, she is unlikely to have HIV.
  C. She will require an additional, confirmatory test to determine whether or not she has HIV.

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  Explanation

  Screening for HIV should be offered to all pregnant women as part of routine prenatal care. Screening for HIV infection is done using an enzyme immunoassay (EIA). If the screening test is positive, it may be repeated. Once the screening test is determined to be positive, a Western blot assay or immunofluorescent antibody assay (IFA) is done as a confirmatory test. If the confirmatory test is positive, the patient is then considered to be infected with HIV. Pregnant patients should be treated for HIV by the same standards as any other adult with HIV, though some consideration is given to selection of antiretroviral medications that are safest in pregnancy. Appropriate HIV-related care should not be deferred because of pregnancy. For patients with significant HIV disease, the combination of elective scheduled cesarean and antiretroviral therapy has been shown to be more effective than antiretrovirals alone at reducing perinatal transmission of HIV. In the absence of any therapy, the risk of vertical transmission is estimated at 25%. With zidovudine therapy, the risk is decreased to approximately 58%. When zidovudine is given in combination with elective cesarean for appropriate patients, the risk is decreased to approximately 2%. In a recent meta-analysis, perinatal transmission occurred in only 1% of treated women with RNA viral loads less than 1000 copies/ mL. Given the low risk of transmission in this group, it is unclear whether cesarean delivery would provide additional benefit. After reviewing this data, the American College of Obstetricians and Gynecologists Committee on Obstetric Practice has issued a Committee Opinion concerning route of delivery, recommending consideration of scheduled cesarean delivery for HIV-1-infected pregnant women with HIV- 1 RNA levels >1000 copies/mL near the time of delivery.

• Question 443:

  You see a 3-week-old infant in your office for an acute visit. She was born via spontaneous vaginal delivery following a term, uncomplicated prenatal course. The parents are concerned because they have seen some streaks of blood in her diaper over the past few days. The infant's stools have been soft and not difficult to pass. The parents relate that she is eating 2 oz every 2 hours of a cow's milk based formula.

  What is the most likely cause of the blood in her stool?

  A. Meckel diverticulum
  B. group B streptococcal colitis
  C. cow's milk protein intolerance
  D. pseudomembranous colitis
  E. lactose intolerance
  C. cow's milk protein intolerance

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  Explanation

  Most infant formulas are cow's milk based. The most common form of carbohydrate in these infant formulas is lactose. Soy formulas use corn syrup and/or sucrose as their source of carbohydrate. Casein is a form of protein. Human milk fortifier is a supplement added to breast milk for the premature infant and is a combination of protein and carbohydrate. GBS colitis is an uncommon disease in infants. Cow's milk protein intolerance is a common cause of blood-streaked stool in an infant on cow's milk based formulas. Lactose intolerance is very uncommon in an infant and usually causes chronic, nonbloody diarrhea. Pseudomembranous colitis would be a consideration in a child with diarrhea who recently had been on antibiotics

• Question 444:

  A 60-year-old woman presents to your office to discuss her ongoing treatment with HRT that she takes for menopausal symptoms. She was started on estrogen and progesterone replacement at the age of 51 and has been on them since that time. She has read several articles in newspapers and on the Internet stating that hormone therapy is dangerous. You briefly review the results of the Women's Health Initiative study, a randomized-controlled trial comparing health outcomes in women taking combined estrogen-progestin therapy (HRT) versus a placebo. The results are as follows:

  

  The authors provided composite data on total cardiovascular disease, cancer, fracture, and mortality risks, which are summarized in the chart.

  

  Based on the data presented, which of the following statements is true?

  A. There is an increase in total cancer risk for women on HRT.
  B. There is an increase in cardiovascular disease risk for women on HRT.
  C. There is an increase in combined fracture risk for women on HRT.
  D. There is a reduction in total mortality for women on HRT.
  E. There is an overall detriment to the quality of life of women on HRT.
  B. There is an increase in cardiovascular disease risk for women on HRT.

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  Explanation

  The hazard ratio statistic as presented is a comparison of the rate of development of an outcome in the treatment group divided by the rate of development of the same outcome in the control group. It is a "hazard" ratio because all of the outcomes measured are adverse. Ahazard ratio of 1.00 means that there is no difference in the rate of development of the outcome between the two groups. Further, if the 95% CI crosses 1.00 then there is no statistically significant difference between the two groups. From the data presented, the hazard ratio for the development of endometrial cancer is 0.83, suggesting that there may be a reduction in the risk of endometrial cancer for women on HRT. However, the 95% CI crosses 1, therefore we cannot consider this result to be statistically significant. For the other outcomes listed, the 95% CIs do not cross 1.00, thus representing statistically significant increases in the risk of CHD, pulmonary embolism, and stroke and a statistically significant reduction in the risk of hip fracture. The data reveal statistically significant rates of combined cardiovascular disease and fracture risk between the two groups. The risk of cardiovascular disease is increased but the combined fracture risk is reduced in women on HRT. The combined cancer risk and total mortality do not reach the level of statistical significance. There are no data presented on quality of life in the chart, so we cannot state that option E is true.

• Question 445:

  As an intern on a medical consultation service, you are providing a cardiology consultation for a patient who developed a myocardial infarction while undergoing an elective cholecystectomy. Although not described in the medical record, the cardiology consultant attending stated the patient experienced the myocardial infarction because of prolonged general anesthesia. The surgical attending did not make the initial incision until the patient had been sedated for more than 1 hour. As you review the medical record, you realize the patient is the father of your college roommate. When you walk in the room, the family is very happy to see you and asks, "What happened? What went wrong?" Which of the following is a commonly used mechanism for reducing medical errors in hospitals?

  A. confidential peer review
  B. national hospital accreditation
  C. departmental grand rounds
  D. longer work shifts for employees to promote continuity of patient care
  E. random drug testing
  A. confidential peer review

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  Explanation

  Disclosure of unanticipated outcomes is one of the most challenging communications that can occur in the physician-patient relationship. Determining which events require disclosure and the appropriate mechanism to provide this information is part of the professional behavior inherent in our roles as physicians. Concepts for effective disclosure include:

  Many institutions have already developed policies and mechanisms to provide this communication. The attending physician is the most appropriate person to lead this process. Your knowledge of the clinical circumstances is hearsay. It is not appropriate for you to provide unsubstantiated information to the patient or to the friend. Appropriate documentation in the medical record provides the facts surrounding the primary event. It is inappropriate to document opinions, accusations, or arguments. Medical errors are responsible for more than 98,000 excessive patient deaths per year. In order for medical errors to be reduced, there need to be mechanisms for accountability which occur within a supportive environment. Peer review, morbidity and mortality rounds, shorter work weeks, and root cause analysis are all mechanisms to prevent future errors from fatigue, impaired system processes, and inadequate knowledge. Frequently when medical errors occur, the families want to know what is being done to prevent this from happening again. Although the peer review process is confidential and not subject to subpoena, it provides an effective mechanism to honestly evaluate our colleagues and enforce necessary discipline to improve patient safety. Random drug testing is not a systemic solution.

• Question 446:

  Parents bring their 12-year-old son to your clinic for evaluation. The child states that he gets teased a lot in school because of his short stature. His weight and height are below the 10th percentile for his age. His parents are of average height. Following your physical examination, you determine that he has tanner stage 1 development and his bone age is that of a 9-year-old male. His examination is otherwise normal.

  What is the most likely diagnosis?

  Which of the following is a true statement regarding the assessment of a child with short stature?

  A. An advanced bone age indicates that the child's final height will be greater than his peers.
  B. A slower growth velocity means the child will have more time to "catch up."
  C. A spot GH level is a good test in screening for GH deficiency.
  D. Somatomedin-C (ILGF-1) will be low in a child with GH deficiency.
  E. The most common cause of short stature in children is chronic renal disease.
  D. Somatomedin-C (ILGF-1) will be low in a child with GH deficiency.

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  Explanation

  Short stature in an adolescent is a common reason for visiting the pediatrician or endocrinologist. Most short stature in adolescence is constitutional growth delay. These children will have normal growth velocity and delayed bone age. Growth is normal for the first 412 months, then decelerates to below the fifth percentile. These children will catch up to their peers in a slightly delayed fashion. Frequently, other family members have a history of short stature in childhood, delayed puberty, and eventual normal stature as adults. In contrast, children with familial short stature have a normal bone age and regular onset of puberty. These children will maintain their short stature as adults. Somatomedin-C (ILGF-1) is commonly used as a surrogate measure for the end-organ effect of the pulsatile GH release. In children with GH deficiency, the end-organ effect will be a low somatomedin- C level. An advanced bone age (advanced bone maturation) usually results in shorter final height. Chronic renal failure is a cause of growth delay, but not a common one

• Question 447:

  A 45-year-old male comes to your office for his first annual checkup in the last 10 years. On first impression, he appears overweight but is otherwise healthy and has no specific complaints. He has a brother with diabetes and a sister with high blood pressure. Both of his parents are deceased and his father died of a stroke at age 73. He is a long-standing heavy smoker and only drinks alcohol on special occasions. On physical examination, his blood pressure is 166/90 in the left arm and 164/88 in the right arm. The rest of the examination is unremarkable. He is concerned about his health and does not want to end up on medication, like his siblings. Regarding your initial recommendations, which of the following would be most appropriate?

  A. You should take no action and ask him to return to the clinic in 1 year for a repeat blood pressure check.
  B. You should immediately start him on an oral antihypertensive medication and ask him to return to the clinic in 1 week.
  C. You should advise him to stop smoking, start a strict diet and exercise routine with the goal of losing weight, and return to the clinic in 6 months.
  D. You should consider starting a workup for potential causes of secondary hypertension.
  E. You should screen him for diabetes and evaluate him for other cardiovascular risk factors before proceeding any further.
  E. You should screen him for diabetes and evaluate him for other cardiovascular risk factors before proceeding any further.

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  Explanation

  Although this is the first time that your patient has been noted to have an elevated blood pressure reading, given his family history and obesity, it is important to consider the coexistence of other cardiovascular risk factors. His evaluation should include, among other things, screening for DM and dyslipidemia along with an ECG. It is reasonable to ask the patient to submit himself to a strict diet (low in fat and salt) and to increase his exercise and activity, since these lifestyle modifications will likely result in weight loss, decreased blood pressure, and improve his risk profile for cardiovascular disease. Nonetheless, it is rarely enough to normalize blood pressure in all but the earliest stages of hypertension. Provided that no other comorbidities exist, the patient should return to clinic in no more than 2 months for a repeat blood pressure check. There is no need to consider secondary causes of hypertension, given his age and presentation.

  You should not start antihypertensive medications until further evaluation is completed, and a second elevated reading confirms your diagnosis of hypertension. In the initial evaluation of hypertension (as per the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure [JNC-7], 2003), it is important to evaluate the patient for end-organ damage. This should include the heart, kidneys, eyes, and nervous system. It is recommended to obtain a urinalysis to assess for proteinuria, glucosuria, or hematuria; to obtain an ECG to evaluate the heart for potential hypertrophy or early signs of cardiovascular disease; to obtain a fasting lipid profile, particularly after the age of 35, to assess the cardiovascular risk profile; and to check the patient's renal function to assess for damage or dysfunction. Thyroid function tests are only indicated in the workup of secondary causes of hypertension. According to the JNC-7, this patient's blood pressure falls into the stage 2 hypertension classification in which either systolic blood pressure (SBP) is at least 160 mmHg or diastolic blood pressure (DBP) is at least 100 mmHg.

  Stage 1 hypertension is characterized by a SBP of 140159 mmHg and a DBP of 9099 mmHg. Prehypertension is characterized by a SBP of 120139 mmHg and a DBP of 8089 mmHg. Normal blood pressure is characterized by a SBP of less than 120 mmHg and a DBP of less than 80 mmHg. In classifying a patient's blood pressure and determining appropriate therapy, the higher of the two categories corresponding to the SBP and DBP is the one that is used. Per JNC-7 guidelines, treatment of stage 2 hypertension should involve the consideration of a two-drug regimen initially. The goal blood pressure in patients with diabetes is a SBP less than 130 mmHg and a DBP less than 80 mmHg. An ACE inhibitor should be used as the drug class has been shown to slow the progression of diabetic nephropathy and reduce albuminuria. Thiazide diuretics, betablockers, and calcium channel blockers are appropriate choices to consider in this patient in addition to an ACE inhibitor.

• Question 448:

  You are called to see a newborn in the nursery because the nurse is concerned that the baby may have Down syndrome.

  Which of the following signs is associated with Down syndrome?

  A. caf?au lait spots
  B. high arched palate
  C. ambiguous genitalia
  D. hypotonia
  E. club feet
  D. hypotonia

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  Explanation

  The most common finding in a newborn with Down syndrome is hypotonia. Other common findings include single palmar crease, flat facial profile, macroglossia, and wide space between the first and second toes. Hypotonia in the newborn period should prompt close evaluation and follow-up. Caf?au lait spots are associated with neurofibromatosis. High arched palates are associated with fragile X syndrome.

  Ambiguous genitalia are commonly seen in CAH.

  Children with Down syndrome are at an increased risk for hypothyroidism. It may be hard to detect without routine laboratory screening as they will commonly have mental retardation and developmental delay as part of their syndrome. Hypothyroidism may not be present in the immediate newborn period and requires, at a minimum, annual testing throughout the child's life. The other findings listed are not specifically associated with Down syndrome. Lens dislocation is commonly found with Marfan syndrome or homocysteinuria.

  Children with Down syndrome have an increased prevalence of duodenal atresia. Pyloric stenosis is uncommon to see in the newborn period. It tends to present with nonbilious vomiting usually after 24 weeks of age. Hirschsprung disease (aganglionosis coli) presents with constipation and failure to pass stool. Infants with Hirschsprung disease commonly will not pass stool in the first days of life. Biliary atresia is a progressive cause of jaundice in an infant. It is the most common cause of a cholestatic jaundice in the newborn period. Emesis is not typically associated with biliary atresia. Milk protein allergy is a common cause of bloody stools in the first few months of life, but does not have bilious emesis associated with it.

• Question 449:

  A22-year-old nulliparous woman who desires future fertility is found to have a pap smear consistent with high-grade squamous intraepithelial lesion (HGSIL). Initial management should be which of the following?

  A. routine pap smear in 1 year
  B. random cervical biopsies
  C. colposcopy
  D. endometrial biopsy
  E. human papilloma virus (HPV) testing
  C. colposcopy

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  Explanation

  Current American Society for Colposcopy and Cervical Pathology (ASCCP) guidelines for treating a pap smear consistent with HGSIL is to perform colposcopy with directed biopsies if a lesion is seen. Routine pap smear in 1 year is an unacceptable option for this patient given her increased risk for developing cervical cancer. Random biopsies have a high false negative rate if there is no visible lesion to biopsy, thus, are not helpful. The pap smear is a screening test of the cervix, not the endometrium. There is no reason to suspect that this patient has endometrial pathology, therefore, an endometrial biopsy is not warranted. HPV testing is not recommended for high-grade pap smears. All high-grade pap smears require further investigation with colposcopy regardless of HPV status. If colposcopy is unsatisfactory, meaning no lesion is identified, the full transformation zone is not visualized or the full extent of the lesion is not identified, then a diagnostic excisional procedure is warranted. A loop excisional electrocautery procedure (LEEP) would be appropriate. However, note that if your suspicion for cancer is high, the cauterized edges from a LEEP procedure can complicate the pathologic assessment of positive margins. A cold knife cervical conization can be performed in the operating room as an outpatient surgery and provides the best surgical specimen for pathologic evaluation. In this case, a TVUS, endometrial dilation, and curettage, and ECC are all inappropriate options since they do not accurately evaluate the cervix, which is the primary site of concern. This patient has, by definition, microinvasive cervical cancer. Approximately 1015% of patients in the United States with stage I cervical cancer will have a microinvasive cancer. Microinvasive cancer is defined as stage IA with invasion limited to a depth of 5 mm with lateral extent not to exceed 7 mm. Stage IA is further subdivided into stage IA1 with stromal invasion less than 3 mm and IA2 with invasion 35 mm in depth. Young patients with microinvasive squamous cell carcinoma of the cervix who desire future fertility can be treated with conization alone, provided that certain strict criteria are met. The cone specimen should be properly excised and then evaluated by an experienced pathologist. The tumor must meet the criteria for stage IA1 disease with invasion less than 3 mm and a lateral extent less than 7 mm. The cone margins must be negative, and there should be no lymphvascular space invasion.

• Question 450:

  The background of major congenital anomalies in a general obstetric population is closest to which of the following numbers?

  A. 0.1% (1 in 1000)
  B. 0.5% (5 in 1000)
  C. 1% (10 in 1000)
  D. 3% (30 in 1000)
  E. 7% (70 in 1000)
  D. 3% (30 in 1000)

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  Explanation

  A major congenital anomaly is defined as one that is not compatible with survival or one that requires major corrective surgery to restore normal function. The risk of such anomalies in a general obstetric population is usually reported to be between 2 and 3%. If minor congenital anomalies are included, 7 10% of pregnancies will be affected.