USMLE-STEP-3 Online Practice Questions and Answers

Correct Answer: C Section: (none)

Explanation:

This patient's presentation is consistent with Graves' disease. Infiltrative ophthalmopathy is a common finding in this condition. Approximately 2040% of patients with Graves' disease possess clinically evident eye disease. Complaints include photophobia, diplopia, reduced visual acuity, and easy tearing; and, signs of corneal or conjunctival irritation are oftentimes present. Periorbital edema, chemosis, lid retraction with restricted ocular movement, proptosis, and upward gaze impairment may also be found. Optic nerve compression may also arise, leading to decreased visual acuity, visual field defects, impaired color vision, and papilledema. Macroglossia, hyperkeratosis, cerebellar ataxia, and pericardial effusion are all findings in hypothyroidism. (Ceci Textbook of Medicine, pp. 13961400) Free T3 levels are elevated in all patients with Graves' disease. Most patients also have elevated free T4 levels, but occasionally this level will remain within the normal reference range in a state known as T3 toxicosis. This generally occurs during the initial phases of Graves' disease or at the onset of a relapse. TSH levels are suppressed by the elevated thyroid hormone levels.

Correct Answer: A Section: (none)

Explanation:

Although gastric lymphomas are less common than adenocarcinomas, they are much more treatable with a more favorable prognosis. Gastric lymphomas, especially well-differentiated mucosa-associated lymphoid tissue (MALT), are associated with Helicobacter pylori infection, and antibiotic therapy to eradicate H. pylori has been associated with regression of 75% of such tumors. Higher-grade gastric lymphomas may require chemotherapy with a standard regimen, such as CHOP, and consideration for surgical resection with curative intent.

Correct Answer: D Section: (none)

Explanation:

Pyloric stenosis usually presents in the first 48 weeks of life. Parents usually report nonbilious emesis after feeding, which progresses to a projectile nature. Untreated, this will become a complete obstruction. On examination, an "olive sign" or mass in the right upper quadrant is often found. Ultrasound is the best radiologic test. These infants may present with dehydration and metabolic abnormalities from the emesis. The most common abnormality is hypokalemic, hypochloremic metabolic alkalosis. While surgical correction is urgent, it is not emergent. These infants should be resuscitated with IV fluids and their metabolic derangements corrected before an operation. The surgical treatment is a pyloromyotomy, which involves splitting the hypertrophic muscles of the pylorus while keeping the mucosa intact. This can be performed either open or laparoscopically. Patients are usually allowedto feed within hours of their operation.

Correct Answer: C Section: (none)

Explanation:

The Glasgow Coma Scale is used to quantify a neurologic examination in patients with a head injury. It is based on three elements: eye opening, motor response, and verbal response. The total score ranges from 3 (worst) to 15 (best) with a score of 8 or lower indicating a coma. The scale is shown below. This patient has a score of 2E. + 4(M) + 2(V) = 8. This patient has evidence of a severe head injury. The initial step should be to protect his airway and prevent hypoxia, which could adversely affect his head injury. Thus, the initial step should be endotracheal intubation. Neurosurgical expertise, imaging to define the injury, and screens to rule out drugs or alcohol as contributions are all important, but should be performed after airway, breathing, and circulation are addressed. Mannitol is indicated in patients with evidence of herniation, such as those with pupillary dilatation.

Correct Answer: E Section: (none)

Explanation:

Vital capacity is an important measure of respiratory function. It is defined as the maximum volume of air a person can expel following a maximum inspiratory effort. When vital capacity is normal, significant restrictive pulmonary disease is not present. Acutely decreased vital capacity indicates decreased ventilatory reserve.

Correct Answer: A Section: (none)

Explanation:

Barrett's esophagus is related to GERD. It is found proximal to the LES and is thought to be a result of constant acidic exposure. It is a condition where the normal esophageal squamous cell epithelium is replaced by columnar epithelium, similar to intestinal metaplasia. A single biopsy is all that is needed to confirm the diagnosis. In fact, many biopsies should be taken during endoscopy if the diagnosis is suspected in an effort to find dypslasia. The risk of malignant degeneration is the most important risk associated with Barrett's esophagus.

Correct Answer: E Section: (none)

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.

Correct Answer: B Section: (none)

Explanation:

The fetal monitoring strip in these questions shows the presence of early decelerations. Early decelerations are characterized by a gradual decrease in the fetal heart rate and gradual return to the baseline in association with a contraction. The onset and recovery of the heart rate are coincident with the onset and recovery of the contraction. These are thought to be due to vagal stimulation due to fetal head compression. They are not associated with fetal hypoxia or acidosis and no intervention, other than continued careful labor monitoring, is indicated. Variable decelerations are caused by umbilical cord compression. They are characterized by the abrupt decrease in heart rate. The onset of the deceleration frequently varies in successive contractions, and they generally last less than 2 minutes. Late decelerations are gradual decreases in heart rate that begin at or after the peak of the contraction and return to baseline after the contraction has ended. It is often the first fetal heart rate abnormality seen in uteroplacentalinduced hypoxia. Any process that causes maternal hypotension, excessive uterine activity, or placental dysfunction can induce late decelerations. Fetal tachycardia is defined as a baseline fetal heart rate of >160 bpm and is considered severe if the rate is >180 bpm. The most common cause of this is maternal fever, but it can also be due to fetal compromise, arrhythmias, or certain medications. Hyperstimulation is a nonreassuring heart rate pattern caused by the presence of frequent uterine contractions. This occurs most commonly in labors that are being augmented with oxytocin. The initial management includes reduction in the dose, or discontinuation, of the oxytocin:

Correct Answer: D Section: (none)

Explanation:

This patient clearly presents with a paranoid stance, although he is not overtly psychotic. Individuals with antisocial personality disorder are usually more dishonest, aggressive, and exploitative in their attitudes. Narcissistic patients may become easily offended by interactions when not feeling as though they are being treated as "special," but they do not display as much overt mistrust. Patients with schizoid and schizotypal personality disorders appear indifferent or odd, usually with a detached attitude. Patients with paranoid personality disorder display a pervasive suspiciousness toward others, continuously feeling slighted and bearing grudges, not unusually in the form of litigiousness

Correct Answer: C Section: (none)

Explanation:

Many psychotropic medications, including most of the antidepressants, cause a variety of sexual dysfunction symptoms. Both painful intercourse and retrograde ejaculation are not seen with antidepressant therapy. These are usually caused by other classes of medications, medical conditions, or surgical procedures. Premature ejaculation is not caused by antidepressants and, in fact, may actually be helped by antidepressants, especially SSRIs. Priapism is an uncommon side effect seen in patients treated with trazodone and even more rarely with the other antidepressants. Decreased libido is a frequent sexual side effect seen in individuals taking antidepressants, especially SSRIs. Other sexual problems caused by these medications include decreased erection and delayed ejaculation.

Almost all of the antidepressants, including the tricyclic antidepressants such as desipramine and the monoamine oxidase inhibitors such as phenelzine, can cause sexual dysfunction. Fluoxetine is a SSRI that commonly causes sexual dysfunction. Venlafaxine is a serotonin and norepinephrine reuptake inhibitor that has also been shown to cause similar problems with sexual performance. Mirtazapine, a novel antidepressant which blocks serotonin and noradrenergic receptors, causes little to no sexual dysfunction. Bupropion has likely dopaminergic properties, and it not only causes little sexual dysfunction, but it also is used to help treat antidepressantinduced sexual dysfunction in some patients.

Correct Answer: A Section: (none)

Explanation:

The quit rates for abrupt cessation and education/advice are quite low when used alone. The rates increase significantly with behavioral interventions or the use of medications such as nicotine replacement. The highest quit rates are likely seen with the combination of medications plus behavioral therapy such as group therapy. (Synopsis, p. 446) The reinforcing aspects of nicotine addiction are thought to involve the dopaminergic system in the central nervous system. This may be one reason why bupropion, which likely increases dopamine activity, is very effective in helping patients to quit smoking. The other antidepressants listed have not demonstrated efficacy for nicotine dependence.

Correct Answer: E Section: (none)

Explanation: Explanations: The Seventh Report of the Joint National Committee on the Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7) was released in May, 2003. It provides evidence-based guidelines for the detection, evaluation, and treatment of hypertension, the most common primary diagnosis in the United States. One of the key guidelines presented in this report is the classification of blood pressure for adults. The classification is based on the average of two or more properly measured, seated, blood pressure readings on each of two or more office visits. The proper measurement of blood pressure is critical. Blood pressure should be measured using a properly calibrated instrument in a patient who has been seated quietly in a chair for at least 5 minutes, with his feet on the floor and arm supported at heart level. The blood pressure cuff should encircle at least 80% of the arm. The systolic blood pressure is the point at which the first of two or more sounds is heard and the diastolic blood pressure is the point before the sounds disappear. In question 10, where an incidentally noted elevated blood pressure reading is found, it is then necessary to perform blood pressure measurements following the JNC 7 guidelines--two or more readings after the patient has been seated quietly in a chair for 5 or more minutes. Institution of antihypertensive medications would be inappropriate based on one blood pressure reading in this range, as the patient has not been diagnosed as hypertensive as of yet. Aspirin therapy is recommended for most persons over the age of 50 for the primary prevention of CHD events and would be recommended for others at high risk of heart disease.

In persons with hypertension, it is recommended to start aspirin after their blood pressure is controlled because the risk of hemorrhagic stroke is increased in uncontrolled hypertension. Risk stratification with an exercise stress test at this point is not supported by evidence showing a reduction of morbidity or mortality and is likely to have many false positive results. Discontinuation of his nasal steroid is unnecessary as it is unlikely to be affecting his blood pressure adversely and should provide good symptomatic relief of his seasonal allergy symptoms. The blood pressure classifications from the JNC 7 report are as follows:

This classification regimen represents a change from previous JNC guidelines with the designation of a prehypertension classification and the combination of the previous stage 2 and stage 3 into a single stage 2 category. By this categorization, the patient in this question has stage 2 hypertension. Recommended evaluation of patients with hypertension includes an ECG, measurement of blood glucose, hematocrit, serum potassium, creatinine and calcium, urinalysis, and a fasting lipid profile. Other testing is not indicated unless suggested by the presence of symptoms or if blood pressure control cannot be achieved. The management of hypertension involves the institution of lifestyle recommendations and, frequently, the use of antihypertensive medications. Lifestyle modifications can lower blood pressure, enhance the effectiveness of medications, and reduce cardiovascular risks. A low salt diet by itself may lower systolic blood pressure by 28 mmHg and is not likely to bring this patient to a goal blood pressure if that is the only modification made. Other lifestyle modifications, including the DASH (dietary approaches to stop hypertension) eating plan and increasing physical

Correct Answer: D Section: (none)

Explanation: Explanations: Bacterial endocarditis is a rare, but life-threatening, disease. It occurs primarily in persons with underlying structural heart defects who develop bacteremia with organisms that are likely to cause endocarditis. Most cases of endocarditis are not a complication of invasive medical or dental procedures. Because of the risks associated with the disease, efforts should be made to prevent bacterial endocarditis when appropriate. The American Heart Association has published updated, evidence-based recommendations on the prevention of bacterial endocarditis. These guidelines are available at the American Heart Association web site (www.americanheart.org). These guidelines outline conditions for which endocarditis prophylaxis is appropriate, procedures for which endocarditis prophylaxis is necessary, and antibiotic regimens that are recommended.

Cardiac conditions are stratified into high-risk, moderate-risk, and negligible risk. Negligible risk conditions are those in which, although endocarditis may develop, the risk is no greater than in the general population. This patient has a history of rheumatic fever, which can potentially result in high-risk valvular damage. However, his echocardiogram did not reveal any such condition. Mitral valve prolapse without a regurgitant jet (which is not a complication of rheumatic fever) is considered a negligible risk condition, so the proposed dental work can proceed without delay. Of the conditions listed in question 30, only bicuspid aortic valve would require antibiotic prophylaxis, as it is a moderate-risk congenital cardiac malformation. All of the other conditions listed are considered to be of negligible risk. Procedures which require antibiotic prophylaxis are those which produce a significant bacteremia with organisms commonly causing endocarditis. For dental procedures, those that tend to cause significant bleeding from hard or soft tissues would necessitate prophylaxis. Of the procedures listed, only dental extraction is likely to do this. During the course of other procedures, if unexpected significant bleeding occurs, antibiotics within 2 hours following the procedure would be recommended

Correct Answer: A Section: (none)

Explanation: Explanations: There is an increased risk of influenzarelated complications in pregnant women who contract influenza, therefore the influenza vaccine is recommended for all pregnant women who will be beyond the first trimester during influenza season. The live, attenuated influenza vaccine is contraindicated during pregnancy but the inactivated influenza vaccine is recommended. The hepatitis B vaccine contains only noninfectious hepatitis B surface antigen particles and poses no real or theoretical risk of fetal infection, whereas the disease hepatitis B may cause severe illness for the pregnant woman and chronic disease for the newborn. For these reasons, neither pregnancy nor lactation is a contraindication to vaccination with hepatitis B vaccine. All pregnant women should routinely be tested for immunity to the rubella virus and should be immunized postpartum if they have no measurable immunity. The rubella vaccine, like other livevirus vaccines, is contraindicated during pregnancy due to the theoretical risk of causing fetal infection. In reality, studies of women who were pregnant or soon became pregnant after receiving rubella vaccination showed that the risk is extremely small. Aregistry of 226 usceptible women who received the rubella vaccine between 3 months before and 3 months after conception showed no evidence of congenital rubella syndrome. Women who inadvertently receive this vaccine should be counseled about the theoretical risk involved, however this would not be considered a reason to terminate a pregnancy. Finally, Td toxoid is routinely indicated for pregnant women.

Correct Answer: E Section: (none)

Explanation:

Adenocarcinoma of the colon is the most common type of malignancy arising in the large intestine. Iron deficiency and microcytic anemia may be the presenting symptoms due to the bleeding from the tumor's ulceration. Alternatively, the tumor may be suspected by detention of occult fecal blood test, bowel obstruction, or through the development of hepatic enlargement secondary to metastasis. The gross appearance of this tumor is usually polypoid and ulcerated. Many ulcerating tumors involve the full circumference of the bowel and appear radiologically as an "apple core" lesion. The microscopic appearance is that of gland-forming malignant cells and usually mucin production is present. The prognosis is related to the stage of the disease. Ulcerative colitis is an inflammatory disease of uncertain etiology that has a relapsing course. Patients with ulcerative colitis have a higher than normal incidence of developing colon carcinoma, approximately 10%. Carcinoid tumors originate in the neuroendocrine cells throughout the intestinal tract. The appendix is most frequently involved, followed by the terminal ileum. On histologic examination, carcinoids are composed of uniform, round cells forming small nests or cords without encapsulation. Special stains performed show neurosecretory granules in the cytoplasm, which are positive for chromogranin, neuron-specific enolase, and other staining.