USMLE-STEP-2 Online Practice Questions and Answers

Correct Answer: D

The typical migraine attack consists of a visual aura with flashes, scintillating scotomata (field loss), or fortification spectra followed by a throbbing unilateral temporal headache. There may be associated vestibular, GI, or neurologic symptoms. Attacks are often precipitated by stress, fatigue, or foods that contain tyramine (e.g., cheese, yogurt, nuts) or phenylethylamine (wine, chocolate). Symptoms peak within an hour of onset and persist for hours to days. A positive family history is found in as many as 50% of cases. Tension headaches are more often bilateral and described as band like or vise like and are not usually associated with visual auras. TIAs more typically present as transient monocular blindness without aura or headache. Temporal arteritis may present as painless loss of vision without aura, but is usually in older people. Cluster headaches are much more common in men. Sumatriptan and the other triptans work by inhibiting the release of vasoactive peptides, promoting vasoconstriction, and blocking brainstem pain pathways. Sumatriptan comes in oral, injectable, and nasal spray form. Ergotamine tartrate, antiemetics, and analgesics may also be used in the acute treatment of migraine headache. Prophylactic medications such as beta-blockers, tricyclic antidepressants, calcium channel blockers, and anticonvulsants are ineffective for acute attacks. Avoidance of known precipitants and control of stress are also important in prevention.

Correct Answer: D

Meningococcemia is a fulminant systemic rapidly progressing infection that results in shock and is followed by death in 20% of afflicted children. The presence of meningitis has been shown to increase the survival rate to approximately 95%. Sensorineural deafness is the most common residual following bacterial meningitis. Penicillin, ampicillin, or a third-generation cephalosporin would be an appropriate antibiotic to choose for treatment. Vancomycin's spectrum of activity is limited to gram-positive organisms.

Correct Answer: A

Public health sanitation measures in emergency conditions should reduce fecal contamination of food and water supplies. Communicable disease such as typhoid fever, cholera, bacillary and amoebic dysentery, hepatitis, polio, schistosomiasis, various helminthes infestations, and viral gastroenteritis can be transmitted through contact with human feces. Avoiding putting fecal material in the mouth is key to avoiding infection.

Correct Answer: D

Carbon disulfide causes sensorimotor peripheral neuropathy. Central nervous system (CNS) effects and optic neuritis are also common. Long-term exposure may increase cardiovascular risk. Lower sperm counts and more abnormal spermatozoa are observed than in unexposed subjects.

Correct Answer: C

The incubation period for diphtheria is 17 days. The incubation period for chicken pox is 1021 days, average 14. Infectious mononucleosis, caused by the Epstein-Barr virus, has an estimated incubation period of 3050 days. The incubation period following infection by the mumps virus is usually 1618 days but, like chicken pox, may vary from 14 to 25 days. Pertussis has a shorter incubation period, usually 710 days, with a variation of 421 days. The usual period from contamination with tetanus spores to clinical symptoms is generally 68 days. For rubella, the incubation period is from 14 to 21 days, but usually ranges from 16 to 18 days.

Correct Answer: E

The design of a cohort study requires a follow-up of a group of subjects who are susceptible but free of the disease of interest at the beginning of the study period.

Correct Answer: A

Medicaid and Medicare began under federal legislation in 1966. Medicaid is a state-run program funded with federal and state tax dollars. It was established to provide medical services to the poor, with special consideration to pregnant women and small children. Although eligibility varies greatly from state to state, persons who receive SSI welfare payments are categorically eligible. Medicare is a federal program, completely financed and run by the federal government. Its purpose is to provide medical care to citizens over 65. Blue Cross/Blue Shield is a private insurance that must be purchased; the Robert Wood Johnson Foundation is a large foundation that provides grants; and the WIC program is a food supplement program for needy mothers and children.

Correct Answer: E

It is true that mammography for detection of breast cancer in older women is technically easier and probably more sensitive than in younger women. However, the burden of cost and mortality resulting from screening women less than 40 was the real reason that screening them was not recommended. For first mammograms of women aged 4049, cancers were diagnosed at half the rate of women aged 50 59 years old, yet twice as many follow-up diagnostic tests were performed. Simply put, the cost in terms of dollars, mortality from testing, and mortality from radiation exposure for women under 40 were not considered to be worth the benefit.

Correct Answer: A

Donepezil is a cholinesterase inhibitor used for the treatment of mild-to-moderate impairment in Alzheimer's disease. Fluoxetine is an SSRI antidepressant. Aspirin would decrease clotting. Amitriptyline is a tricyclic antidepressant and with its anticholinergic properties, it would worsen cognition. Ginkgo is an herbal medicine.

Correct Answer: J

Persons with personality disorders are rigidly bound to the use of patterns of defense and various traits that distinguish the disorders. All have problems with interpersonal relationships

Correct Answer: B

Persons with personality disorders are rigidly bound to the use of patterns of defense and various traits that distinguish the disorders. All have problems with interpersonal relationships

Correct Answer: D

Acute appendicitis initially presents with periumbilical pain secondary to obstruction of the appendiceal lumen. This is mediated through visceral pain fibers, and because the appendix is from the embryologic midgut, the pain is referred to the umbilicus. With obstruction of a hollow viscus, there may be associated nausea. As the inflammatory process progresses to involve the visceral and parietal peritoneal surfaces, the pain becomes localized directly over the appendix in the right lower quadrant. Fever and leukocytosis are nonspecific signs of an inflammatory process. Gastroenteritis may be associated with nausea, anorexia, and lowgrade fever. Periumbilical pain is colicky and secondary to increased peristalsis. Localized pain and signs of peritoneal irritation are uncommon. Aruptured right ovarian cyst may mimic appendicitis. Patients may exhibit right lower abdominal peritoneal irritation. However, the onset of pain is usually sudden, and the pain is initially felt in the right lower quadrant.

These patients do not have anorexia or other gastrointestinal symptoms. The clinical picture of regional enteritis (Crohn's disease) is one of a chronic illness, often associated with weight loss, intermittent cramps, and diarrhea. Fever, tenderness, and a palpable right lower quadrant inflammatory mass may result from complications of ileal involvement. Sigmoid diverticulitis is more common in older patients, often with a prodromal history of irregular bowel habits. There may be left lower quadrant pain and tenderness, with a palpable left-sided inflammatory mass. A cecal volvulus presents with sudden onset of colicky abdominal pain and signs and symptoms of a bowel obstruction, including bilious emesis and abdominal distention. Alcohol-related acute pancreatitis presents with pain referred to the epigastrium, with radiation to the back mediated through the celiac ganglia. The patient may develop abdominal distention secondary to the associated paralytic ileus. Hyperamylasemia and an elevated serum lipase, in this clinical setting, are suggestive of pancreatitis. Perforated peptic ulcer and acute cholecystitis may also present with epigastric pain, and elevations of both serum lipase and amylase. Pain from a perforated ulcer, however, is sudden in onset and may be associated with shoulder-tip pain from diaphragmatic irritation. About 75% of patients with perforated duodenal ulcers have pneumoperitoneum on chest and abdominal radiographs. Acute cholecystitis will usually commence after a large meal and initially presents as colicky epigastric pain, progressing to pain localized in the right upper abdomen when transmural inflammation of the gallbladder wall produces peritoneal irritation. Acute mesenteric occlusion presents with sudden onset of severe but poorly localized periumbilical abdominal pain, associated with acidosis. There may be elevation of serum amylase and lipase. A ruptured abdominal aortic aneurysm will present with sudden onset of midabdominal pain, back pain, and hemodynamic instability.

Correct Answer: B

The diagnosis of sigmoid volvulus is based on the history, examination, and radiographs. Acute onset of abdominal pain, distention, and obstipation is suggestive of volvulus. Barium enema is diagnostic of sigmoid volvulus showing the characteristic tapering to a "bird's beak" pointing to the site of obstruction. Cecal volvulus would show complete filling of the left colon. Stricture as a result of ischemic colitis would show a long, narrowed segment of colon. Diverticulitis would be suggested by a different clinical presentation including fever, sepsis, and pain localized to the left lower quadrant. Obstruction from colon cancer would show an irregular narrowing of the colon segment rather than a smooth tapering. In patients who have no signs of bowel wall ischemia (e.g., rebound tenderness, sepsis, and so forth), nonoperative reduction should be attempted and would be expected to be successful in 7080% of patients. The most widely used method of reduction is proctoscopy and rectal tube placement under direct vision. Blind passage of a rectal tube may lead to perforation and is contraindicated. Operation is indicated if nonoperative reduction is unsuccessful, with operative reduction preferred, followed by delayed resection and primary anastomosis rather than sigmoid resection. Operative reduction by detorsion alone is unacceptable because of the high recurrence rate and is, therefore, combined with sigmoidopexy or sigmoidostomy. Proximal colostomy alone is contraindicated, because strangulation of the sigmoid or recurrent volvulus is not prevented.

Correct Answer: D

Amulticolored brown or black pigmented lesion with irregular borders should raise the concern of melanoma. Squamous cell carcinoma usually presents as an erythematous papular nodule. The most common type of basal carcinoma presents as an ulcerative, well-circumscribed nodule, although occasionally it may be pigmented and confused with melanoma. Merkel cell carcinoma appears as red to purple papular nodules. Keratoacanthoma is a well-circumscribed keratotic lesion that may regress without treatment. The most appropriate next step is to perform an excisional biopsy with narrow margins to confirm the diagnosis and determine depth of invasion. Shave biopsy would yield a pathologic diagnosis, but would not allow appropriate staging and is never recommended. The margin of resection and determination of lymph node management would depend on the depth of invasion of the melanoma measured in millimeters. Therefore, wide excision is not recommended until the depth of invasion of the lesion is determined by excisional biopsy with narrow margins. Mohs' surgery should be considered for nonmelanoma tumors but is not recommended for melanoma.

Correct Answer: E

Perforated duodenal ulcer usually presents as a sudden onset of acute abdominal pain. Examination usually reveals severe abdominal tenderness with rigidity of the abdominal musculature (i.e., an acute abdomen). With a prior history of abdominal pain relieved by antacids, a chronic ulcer that has now perforated is strongly suggested. Perforated colon cancer occurs in an older age group, as well as gastric ulcer. Following plain radiographs that show pneumoperitoneum, no additional diagnostic tests are required and serve only to delay treatment. The treatment is laparotomy and either patch closure of the perforation or definitive operation, the latter being preferred, depending on operative findings. However, the patient must receive fluid resuscitation before laparotomy to avoid hypotension and its consequences. Although nonoperative management for contained perforations has been suggested by some authors, an acute abdomen is an indication for operative management.