USMLE-STEP-3 Online Practice Questions and Answers

Correct Answer: B Section: (none)

Explanation: The patient's history and examination are worrisome for pancreatic disease, and he has strong signs of pancreatic insufficiency. His long history of alcohol use suggests the possibility of chronic pancreatitis or pancreatic cancer. Fecal fat studies would only confirm or quantify his steatorrhea. ACT scan would image the pancreas for changes consistent with chronic pancreatitis (duct dilation, calcifications, pseudocysts) and could look for a neoplasm of the pancreas as well. ERCP is not indicated as a first-line test in patients with abdominal pain given its risk of causing acute pancreatitis. Upper endoscopy would be helpful to rule out peptic ulcer disease and other gastric complaints, but would not provide more global information about the abdomen. The patient has greasy stools and weight loss, findings seen in patients with steatorrhea due to chronic pancreatitis.

Patients with steatorrhea malabsorb fat-soluble vitamins (vitamins A, D, E, and K). "Night blindness" (poor night vision) due to vitamin Adeficiency is common among patients with advanced chronic pancreatitis and likely led to this patient's motor vehicle accident. The patient has DM as a consequence of pancreatic endocrine insufficiency, another feature of chronic pancreatitis. Diabetes develops when greater than 8090% of the gland has been destroyed. Patients with chronic pancreatitis have a coexisting loss of glucagon from islet cells and, thus, often become brittle diabetics, with hypoglycemia seen after insulin administration. Vitamin K and B12 deficiency, which the patient may have, do not cause hypoglycemia. The patient was previously noted to eat well, so inadequate oral intake is unlikely. Diabetic education should decrease the rate of chronic insulin overdosage.

The patient has pancreatic exocrine insufficiency and thus cannot produce enough pancreatic enzymes to digest his food. Pancreatic enzyme replacement therapy in tablet form is a mainstay of therapy for chronic pancreatitis. It can rapidly reverse this problem by providing exogenously produced pancreatic enzymes to break down fats, carbohydrates, and proteins for absorption in the small bowel. The patient would not benefit from additional oral feedings without enzyme supplementation and would only worsen his steatorrhea by doing so. He can take food orally, so feeding via gastrostomy, TPN, or PPN are not indicated. The patient's worsening pain and weight loss despite therapy is worrisome for the development of pancreatic cancer. CA-19-9 is frequently (but not universally) elevated in pancreatic cancers, although it can be elevated in cholangiocarcinoma as well. PSA is associated with prostate cancer. CEA is associated with colon cancer. CA-125 is associated with ovarian cancer. AFP is associated with hepatocellular carcinoma.

Correct Answer: D Section: (none)

Explanation:

Iron-deficiency anemia (IDA) is characterized by a low MCV, low ferritin, and a high erythrocyte protoporphyrin in serum. Microcytosis and hypochromia are the hallmark in the peripheral smear. Elevated erythrocyte protoporphyrin in serum can also be seen in anemia of chronic disease and chronic lead poisoning. The USPSTF recommends screening pregnant women for IDA, but found insufficient evidence to recommend for or against routine screening in other asymptomatic persons. However, the guidelines did recommend routine iron supplementation in asymptomatic infants 612 months of age who are at high risk of IDA. Infants are considered to be at high risk if they are living in poverty; are Black, Native American, or Alaskan Native; are immigrants from a developing country; are preterm or low birth weight; or if their primary dietary intake is unfortified cow's milk. The most common cause of cobalamin deficiency is pernicious anemia. Rarely, hypersecretion of gastric acid (i.e., Zollinger-Ellison syndrome) results in cobalamin deficiency. The peripheral smears in folate and cobalamin deficiency are indistinguishable, showing macrocytosis and hypersegmented neutrophils. Both methylmalonic acid and homocysteine levels become elevated with cobalamin deficiency. Folate deficiency is caused by decreased intake, increased utilization, or impaired absorption. Because body stores of folate are low, persons who have an inadequate consumption will become anemic in several months. The recommended amount of dietary folate is 400 g/day. Anemia is not a diagnosis in itself; it is an objective sign of the presence of a disease. It is always secondary to an underlying condition. In most cases, a thorough history and physical examination can help elicit the pathogenesis of the anemia and direct appropriate treatment.

Correct Answer: C Section: (none)

Explanation:

This patient's presentation is most consistent with pulmonary edema from decompensated CHF. The BNP test has been found to be both sensitive and specific for the diagnosis of CHF. It can be a very useful test to order when a patient is dyspneic to help to determine if CHF is the cause. Troponin, CK-MB, and LDH are markers of damage to cardiac muscle and can be diagnostic in a MI. While MI can be a cause of CHF, and most patients presenting with CHF will have cardiac enzymes drawn as part of their evaluation, cardiac enzymes are neither sensitive nor specific for CHF. Similarly, a CXR can determine the presence of pulmonary edema but not its cause.

Acute pulmonary edema secondary to CHF will require management with diuresis for acute symptomatic relief. ACE inhibitors and beta-blockers do decrease mortality and morbidity in CHF; however their use in acute decompensated heart failure is suspected as they may induce hypotension and further cardiogenic shock. Digoxin is used for symptomatic relief either when other modalities fail or when rate control from atrial fibrillation is an issue. In patients with CHF and atrial fibrillation, beta-blockers have shown better effect and reduced morbidity than digoxin. Nevertheless, in the acute setting of decompensated heart failure with pulmonary edema, diuresis is the optimal initial treatment, not digoxin. In chronic heart failure, digoxin is reserved for patients with systolic failure that are symptomatic despite adequate ACE inhibitor and beta-blocker use. Furosemide is effective in treating the acute pulmonary edema associated with CHF by virtue of its potent diuretic action, which rapidly eliminates excess body fluid volume.

Correct Answer: E Section: (none)

Explanation:

This patient has achalasia. This disorder is defined by a nonrelaxing lower esophageal sphincter (LES) and decreased peristalsis of the esophageal body. The "bird's beak" deformity is a classic sign with a dilated esophagus which tapers to a small area at the LES. Esophagomyotomy is the treatment of choice for longstanding disease. Serial botox injections and dilations can be used early in the disease process, however their long-term results are inferior to myotomy. Proton pump inhibitors can be used for gastroesophageal reflux disease (GERD). A Nissen fundoplication is also a treatment for GERD. Calcium channel blockers are sometimes used to treat other esophageal motility disorders.

Correct Answer: C Section: (none)

Explanation:

The distal small bowel (ileum) is the site of absorption of fat-soluble vitamins (vitamins A, D, E, and K) as well as vitamin B12. Vitamin B12 binds with intrinsic factor, a glycoprotein secreted from parietal cells of the gastric fundus and body. Specific receptors in the terminal ileum take up the B12 intrinsic factor complex. Vitamin B12 deficiency leads to megaloblastic anemia. The patient will require monthly vitamin B12 injections

Correct Answer: E Section: (none)

Explanation:

The constellation of cryptorchidism, posterior urethral valves, and abnormal abdominal musculature is called Eagle-Barrett syndrome. Another name is prune belly syndrome. The greatest morbidity comes from the poor amniotic fluid production, due to bladder outlet obstruction, with a resulting pulmonary hypoplasia. Cushing's triad are hypertension, bradycardia, and widened pulse pressure. This is seen as terminal findings associated with increased intracranial pressure. VATER association has multiple anomalies, none of which are the three mentioned. VATER is a mnemonic which stands for Vertebral anomalies, Anal atresia (imperforate), Tracheo-Esophageal fistula, and Renal anomalies (the R also indicated Radial anomalies). It is sometimes referred to as VACTERL association in which the C indicates Cardiac anomalies with the L indicating Limb anomalies. Potter's syndrome is bilateral renal agenesis. This condition is fatal, due to marked pulmonary hypoplasia. The Jones criteria are used in the diagnosis of ARF.

Correct Answer: B Section: (none)

Explanation: This case is a common presentation for viral croup, with the symptoms of a seal-barking cough, stridor, tachypnea, and fever in the winter. Pneumonia must also be considered with tachypnea, cough, and fever, but it is less likely to cause stridor and may not have the seal-bark type of cough. Sinusitis may cause cough and fever, but would be more likely to have a purulent nasal discharge and less likely to have the typical croupy cough. Bronchiolitis due to RSV is a common cause of wintertime cough and fever. It is less likely to have stridor and more likely to have wheezing. Children with epiglottitis are typically found in the "tripod position" and may be drooling. It is, fortunately, becoming rare with the widespread use of the H. influenzae vaccine. Parainfluenza types 1 and 2 account for 6070% of all viral croup. HIB was a common cause of epiglottitis, but is now rare because of widespread vaccinations. Influenza B and RSV can cause croup, but not as commonly as parainfluenza types 1 and 2. S. pneumoniae would be the most common bacterial cause of pneumonia or sinusitis. (American Academy of Pediatrics, 2003, pp. 454455) The steeple sign is subglottic narrowing of the trachea seen on an AP view of the trachea or a CXR. The trachea is seen to narrow, almost to a point, like the steeple of a church. Swollen adenoids are difficult to identify in lateral neck x-rays. The presence of swollen adenoids is unrelated to the airway narrowing seen in croup. The thumb sign is a swollen epiglottis seen with epiglottitis. Alobar pulmonary infiltrate may be seen with a typical bacterial pneumonia.

Correct Answer: C Section: (none)

Explanation:

Leukocoria, a white pupillary reflex, can be caused by several conditions. The most serious, and potentially life threatening, is retinoblastoma. Retinoblastoma is a malignant neoplasm of the retina that may appear as a white mass extending into the vitreous, a mass lesion underlying a retinal detachment or as a diffusely spreading lesion. Retinoblastomas may be unilateral, bilateral, or multifocal. The diagnosis is usually made between 1 and 2 years of age. Other causes of leukocoria may include retinopathy of prematurity, congenital cataracts, toxocarisis (a nematode infection), or Coats disease (a retinal vascular abnormality). The treatment of retinoblastoma may involve surgery, chemotherapy, or other modalities such as cryotherapy and photocoagulation.

Correct Answer: E Section: (none)

Explanation: VAIN is frequently found in women who have a history of cervical dysplasia. Although the etiology of VAIN has not been thoroughly elucidated, like cervical intraepithelial neoplasia (CIN), it is thought that HPV is the carcinogenic agent. Thus, when vaginal cytology is abnormal, the evaluation is very similar to that of an abnormal pap smear. It is important to assess the histologic severity and the extent of the lesion. To do this, the next step in management is a thorough colposcopic evaluation of the entire vaginal canal, especially because many patients will have multifocal disease.

During colposcopy the application of acetic acid (4%) is useful. The speculum should be fully inserted to visualize the upper vagina and then slowly removed while rotating the speculum, being careful to view the entire vaginal mucosal surface. Most vaginal lesions are not grossly visible. However, a raised white epithelium may occasionally be seen. If a lesion is visible, then directed biopsy of the lesion is indicated to confirm the diagnosis. The image provided shows HGSIL. In the presence of high-grade vaginal cytology, repeat cytology in 6 months, and observation are not viable management options given the concern for carcinoma in situ or for invasive carcinoma of the vagina. Random vaginal biopsies are also not likely to be helpful since they will most likely miss the involved area and lead to a false negative result. Intravaginal estrogen cream is reserved for postmenopausal women with vaginal atrophy and low-grade VAIN without evidence of invasion. Estrogen is not a treatment for VAIN 3, or high-grade VAIN.

Correct Answer: D Section: (none)

Explanation: This patient meets criteria for the diagnosis of osteoporosis, with a T score falling below -2.5 standard SD. AT score indicates the number of standard deviations below or above the average peak bone mass in young, healthy adults of the same gender. Bisphosphonate therapy has been shown to reduce vertebral and hip fracture risk in up to 50% of women with documented osteoporosis. GnRH therapy and discontinuation of her vitamin D therapy would worsen, not improve, this patient's bone density. Although testosterone may arrest further bone loss, the side effects of the medication are too great compared to any potential benefit.

For women who have osteoporosis the serum calcium level is generally normal. In premenopausal osteoporosis, or more severe cases of bone loss/fractures, the presence of metabolic bone disease should be considered. In hyperparathyroidism the serum calcium is elevated. With renal failure, as with osteomalacia, serum calcium is low. The serum calcium level is normal, and the alkaline phosphatase level is elevated in patients with Paget disease. The use of tobacco, a family history of mother or maternal grandmother with hip fractures, postmenopausal state without estrogen replacement, vision problems, and a body mass index of less than 23 are all increased risks for fractures. Abody mass index of greater than 23 does not represent an increased risk for fracture.

Correct Answer: D Section: (none)

Explanation:

This woman likely suffers from major depressive disorder. Treatment with a SSRI is considered to be first-line therapy. Although the neurovegetative symptoms of depression (e.g., insomnia, change in appetite, anergia, poor concentration) can sometimes improve after several days of initiating pharmacotherapy, the feelings of depression and hopelessness may take up to 46 weeks to significantly improve. As long as she is tolerating the SSRI, the urge to quickly increase the dose should be avoided so as to minimize side effects. Upon initiation of a SSRI, education and reassurance should be provided to the patient regarding the expected time until remission. Although there are characteristic side effects, most patients tolerate treatment with SSRIs. Many of these side effects, such as headaches, gastrointestinal disturbances, and vivid dreams, transpire at the start of treatment and may resolve over days to weeks. Sexual dysfunction, such as impotence or inhibited orgasm, not uncommonly occurs after several weeks to months of treatment with SSRIs and can continue with ongoing treatment.

Correct Answer: B Section: (none)

Explanation: Explanations: Pregestational diabetes is associated with numerous risks to both the mother and the fetus. Stillbirths are more common in pregnancies to diabetic women and stillbirths without an identifiable cause, called "unexplained" stillbirths, are a well-described phenomenon. Similarly, preterm births are more common in diabetics than nondiabetics. While congenital malformations are more common in pregnancies to diabetic women, fetal chromosomal abnormalities are not more common. Children of women with diabetes have an approximately 13% incidence of developing type 1 diabetes. While earlier obstetrical teaching suggested that maternal diabetes delayed fetal lung maturation, more recent studies do not support this. Gestational age is likely the most significant factor in the development of respiratory distress. While there are significant maternal risks from the interaction of diabetes and pregnancy, with the possible exception of diabetic retinopathy, the long-term course of diabetes does not appear to be affected by pregnancy.

Pregnancy neither exacerbates nor modifies diabetic nephropathy and the development of diabetic peripheral neuropathy during pregnancy is uncommon. While preeclampsia is a significant risk and the perinatal mortality rate is 20 times higher in preeclamptic diabetic women compared to normotensive women, the occurrence of preeclampsia does not appear to be related to diabetic control. Diabetic ketoacidosis is a serious complication with an approximately 20% rate of fetal loss. However, it is estimated to occur in 1% of pregnancies of diabetic women. Infections occur in approximately 80% of pregnancies in insulin-dependent diabetics, with candida vaginitis, urinary tract infections, and respiratory infections being common. Preconception counseling in diabetic women who desire to become pregnant is a critical issue that often is best served by a team that includes the obstetrician, primary care physician, endocrinologist, and diabetic educators. When possible, attempts should be made to attain optimal diabetic control. Women with good diabetic control have been shown in observational studies to have a lower rate of having infants with congenital anomalies than women with poorer diabetic control. Optimal diabetic control has been defined as glycated hemoglobin levels within or near the upper limit of the normal range. This can be obtained with multiple daily insulin injections or, in selected patients, a continuous infusion via an insulin pump. All women--diabetic or not should be counseled to take folic acid prior to conception in order to lower the rate of neural tube defects. ACE inhibitors are contraindicated during pregnancy and should, whenever possible, be discontinued prior to conception.

Correct Answer: E Section: (none)

Explanation:

Screening for prostate cancer with the PSA test is a controversial area. Some advocate routine screening of most men over the age of 50 while others recommend selective screening or no routine screening at all. The USPSTF gives prostate cancer screening an "I" recommendation, stating that there is insufficient evidence to recommend for or against this intervention. Prostate cancer is the second most common cause of cancer death in men (behind lung cancer). PSA screening does not help to prevent prostate cancer but it does increase the likelihood of detection of prostate cancer. However, many prostate cancers are slow growing and many with prostate cancer die of other causes. PSA screening has not been shown to reduce all cause mortality. While the mortality from prostate cancer has been decreasing over the years, the reason for this is not yet clear. PSA screening may play a role in this but improvements in the treatment of prostate cancer may also be responsible. The PSA also has significant rates of false positive and false negative readings. Benign conditions such as prostatic hyperplasia or prostatitis can elevate PSA readings and prostate cancer can exist in men with normal PSA readings. Another factor that can interfere with PSA readings is the presence of medications. Finasteride and dutasteride, which are widely used in the treatment of benign prostatic hyperplasia, can lower PSA readings, even in the presence of prostate cancer. If PSA screening is chosen by the patient and his physician, selection of appropriate patients for screening is important. The presence of symptoms related to the prostate may influence one's decision to perform a PSA test. However, many prostate cancers are asymptomatic, so the absence of symptoms may not be a reason to withhold testing. Most authorities would not recommend the routine screening of men with significant comorbidities that would result in them having a life expectancy of fewer than 10 years. One of the reasons for the controversy surrounding PSA screening is the risk of harm of testing. Elevated PSA levels frequently result in further--sometimes invasive--testing and may result in the detection of cancers that may or may not have become clinically significant.

Correct Answer: A Section: (none)

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. In question 69, 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.

Correct Answer: A Section: (none)

Explanation:

The Reed-Sternberg cell can be classified as the classic type, the mononuclear variant, the lymphocytic histiocytic variant, lacunar and pleomorphic variant. The classic Reed-Sternberg cell is a binucleated cell that contains an ovoid-shaped nucleus with regular contours and prominent eosinophilic nucleoli. Cytoplasm is abundant and eosinophilic. On cytogenetic studies, the Reed-Sternberg cells are either aneuploid or frequently hypertetraploid. The classic Reed-Sternberg cell is thought to be an end-stage cell that does not divide. The mononuclear variants of the Reed-Sternberg cells (so-called Hodgkin cells) could be identified in any type of Hodgkin disease, but they are not diagnostic of Hodgkin's.