USMLE-STEP-2 Online Practice Questions and Answers

Correct Answer: D

S. pneumoniae is the most common cause of adult meningitis in people over 30 and accounts for about 15% of cases. H. influenzae is the most common cause in children over 1 month old. Group B Streptococcus is an important cause of neonatal meningitis, but is very rare in adults. Staphylococcus, E. coli, and Klebsiella may be seen with penetrating head wounds or postneurosurgical procedures.

Correct Answer: B

The main mechanism by which hemostasis is achieved following delivery is contraction of the myometrium to compress the uterine vessels that had been supplying the placenta. Lack of effective myometrial contraction (i.e., uterine atony) is the major cause of postpartum hemorrhage. If the uterus is found to be firmly contracted, then other factors, such as cervical or vaginal lacerations or a coagulopathy, must be sought.

Correct Answer: B

The advantages of a fine-needle aspiration of a breast mass are that it can distinguish between a cystic and solid lesion, and it reduces the number of open breast biopsies when it is positive for cancer. However, a negative needle biopsy is nondiagnostic (and nonreassuring), and an open biopsy is still necessary. A fineneedle biopsy does not differentiate between noninvasive and invasive cancer, nor does it delineate the extent of in situ disease. Most breast surgeons will not perform definitive surgery (e.g., mastectomy or lumpectomy with lymph node dissection) without histologic confirmation of cancer: core-needle biopsy, surgical biopsy, or frozen section at the time of lumpectomy or mastectomy

Correct Answer: D

Infiltrating (invasive) ductal carcinoma accounts for 6580% of all breast carcinomas. Infiltrating lobular carcinoma accounts for 1014%, and the others 5% or less

Correct Answer: D

Children frequently insert foreign bodies into the nose. Initial symptoms are local obstruction, sneezing, and pain. Subsequently, there is swelling and infection leading to a purulent, malodorous, and often bloody discharge. The infection clears after removal of the foreign body. Nasal polyps cause obstruction of the nasal passages, hyponasal speech, and mouth breathing; gray, grape-like masses can be visualized on nasal examination. An upper respiratory infection is usually suggested by a careful history. Initial symptoms include a scratchy throat, followed by development of thin nasal discharge and sneezing. Myalgia, low- grade fever, headache, malaise, and decreased appetite may be present. By the 2nd or 3rd day, the discharge becomes thicker and more purulent. Cough is common. Symptoms usually resolve by 710 days. Adolescents with sinusitis may have classic symptoms of headache and sinus tenderness. In children, cough and nasal discharge are common; the cough is worse when supine. If upper respiratory infection symptoms persist without improvement for >10 days, sinusitis should be considered. A more acute form may occur, with a shorter duration and more severe symptoms such as fever >39°C, purulent nasal discharge, headache, and eye swelling. Children with allergic rhinitis present with sneezing, clear watery, rhinorrhea, and itching of the nose, palate, pharynx, and eyes. Itching, redness, and tearing of the eyes may be present. This occurs in response to exposure to an allergen such as pollen, mold spores, and animal or mite antigens

Correct Answer: C

In patients 1118 years of age with a clean, minor wound, Tdap vaccine is required if the patient has had <3 tetanus vaccinations or if the immunization status is unknown. In contaminated wounds (dirt, feces, soil, and saliva), puncture wound, avulsions, and wounds resulting from missiles, crushing, burns and frostbite, TIG and Tdap should be given in the 1118 years age group. Waiting for immunization records is not appropriate in an emergency situation.

Correct Answer: C

Infectious mononucleosis may affect children of all ages. The rapid slide (Monospot) test response is positive in approximately 90% of infected persons; however, younger children with mononucleosis may have a negative result. Moreover, many younger children have poor antibody response to the heterophil titer test. The specific serodiagnostic test for EBV, the agent responsible for most cases of infectious mononucleosis, confirms the diagnosis. A repeat throat culture, even if positive for betahemolytic Streptococcus, may be of only partial value, because both infectious mononucleosis and streptococcal pharyngitis may be present simultaneously. Bone marrow examinations potentially are painful and contribute little to the correct diagnosis.

Correct Answer: D

Typical neuroleptic antipsychotic medications frequently cause unpleasant side effects, which occur at various times during treatment. The extrapyramidal side effect most likely to occur in the first few days of treatment is an acute dystonia, such as a muscle spasm in the neck. A pill-rolling tremor of the hands and masked facies are signs of Parkinsonian EPS, which tend to have their onset several weeks after treatment is begun; whereas severe restlessness of the arms and legs is caused by an unpleasant sensation called "akathisia," which also tends to have its onset several weeks after treatment is begun. Involuntary lip smacking is a sign of tardive dyskinesia, a sometimes irreversible motor syndrome that tends to occur after months or years of treatment with typical antipsychotics. Anticholinergic medications such as benztropine are effective in treating dystonias and pill-rolling tremors. Propranolol is effective in treating akathisia. Haldoperidol would worsen EPS. Dantrolene uncouples muscle contractions and is used occasionally in severe NMS. L-Dopa would decrease the Parkinsonian EPS, but would worsen the psychosis and therefore is not used. Fluoxetine is an SSRI.

Correct Answer: A

The gradual onset of left lower quadrant pain over a number of days with left lower quadrant abdominal tenderness and CT scan showing sigmoid colon inflammatory changes is most consistent with diverticulitis. Acontained perforation, either due to the diverticulitis or colon cancer, should be noted on the CT scan. There is no history of antecedent antibiotic therapy to suggest the diagnosis of pseudomembranous colitis. Though WBCs were present in the urinalysis, a diagnosis of pyelonephritis cannot be made on this basis alone, because pericolonic inflammation may be responsible for the WBCs. CT scanning is very accurate in diagnosing diverticulitis, so there is no need for any additional test. Barium enema and colonoscopy should not be performed in patients with suspected acute diverticulitis. The increased intraluminal pressure from either of these examinations may lead to free rupture of a contained abscess or phlegmon, leading to emergency surgery. However, either examination, or both, should be performed after complete resolution of diverticulitis (e.g., in 6 weeks' time) to evaluate for extent of disease, complications, and carcinoma. IVP and angiography are not indicated for diverticulitis. The appropriate management in this patient with his first episode of diverticulitis is medical management with IV antibiotics for gram- negative and anaerobic bacteria. Colon resection, either immediate or elective, should not be undertaken unless the patient's condition deteriorates or recurs. Bowel preparation cannot be performed safely in patients with acute diverticulitis. Anticoagulation has no role in therapy. Metronidazole or vancomycin therapy would be appropriate for pseudomembranous colitis, but not for diverticulitis

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.