USMLE USMLE-STEP-2 Online Practice Questions and Exam Preparation

USMLE USMLE-STEP-2 Online Questions & Answers

• Question 531:

  During diagnostic evaluation, a 14-year-old girl with menorrhagia, frequent nosebleeds, and irondeficiency anemia is found to have a low platelet count with a normal coagulation profile. Bone marrow biopsy reveals abundant megakaryocytes. On abdominal examination, no organomegaly is noted. Which of the following is the most appropriate initial therapy for this patient?

  A. splenectomy
  B. platelet transfusion when peripheral platelet count drops below 50,000/mL
  C. systemic steroids
  D. chemotherapy
  E. expectant, with intervention only if the patient develops significant clinicalbleeding
  C. systemic steroids

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  Explanation

  This patient has idiopathic thrombocytopenic purpura (ITP), a disease characterized by a low platelet count, normal coagulation profile, increased megakaryocytes, and a normal-sized spleen. Patients with ITP will often demonstrate excessive bleeding in response to a minor injury. Circulating antiplatelet antibodies coat normal platelets, which are then sequestered by the spleen, with resultant platelet destruction. The majority of patients respond to initial therapy with systemic steroids. Splenectomy is indicated in patients who become steroid dependent with significant side effects or in patients requiring increasing doses of steroids to maintain a satisfactory platelet count. The entire spleen must be excised, including any accessory spleens found at surgery. Residual splenic parenchyma would result in persistent platelet sequestration. Splenectomy is not indicated in the initial management of ITP. Platelet transfusion is rarely required. Spontaneous bleeding is unusual unless the platelet counts drop below 20,000/L. When this occurs, if the patient is not responsive to steroids, platelet transfusion and urgent splenectomy is indicated. Antineoplastic chemotherapy is not used in the management of ITP. Expectant management is associated with significant risk, as the most life- threatening complication of ITP is spontaneous intracerebral hemorrhage. Bone marrow transplant is not indicated. ITP is a disease of peripheral platelet destruction, with normal or increased platelet production.

• Question 532:

  Identify the most likely diagnosis with the case descriptions below. A 23-year-old violinist reports to his neurologist that he thinks he has had a stroke. He is unable to feel anything with his left fingers and is barely able to hold down the violin strings with this same hand because of "paralysis." The numbness he describes reaches to his wrist only, and he "even feels a band" around the wrist delineating the sensitive from the insensitive areas.

  A. body dysmorphic disorder
  B. conversion disorder
  C. factitious disorder
  D. hypochondriasis
  E. malingering
  F. pain disorder
  G. panic disorder
  H. somatization disorder
  B. conversion disorder

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  Explanation

  Complaints involving both psychological and medical conditions are difficult to diagnose and treat. At times, medically identifiable causes are present, but the psychological factors contributing to the discomfort complicate the diagnosis and treatment and lead to frustration in both physician and patient. At other times, no identifiable cause for pain or other physical symptoms can be found; nevertheless, the patient still has the symptoms. Questions arise:

  Is the patient lying? Is there some deep psychological problem? Could there be a medical disorder in the early stages of development that gives rise to physical symptoms but no clear physical signs to make the diagnosis? One group of psychiatric disorders addresses some of these issues--the somatoform disorders. Somatization disorder is an axis I psychiatric disorder where a patient complains of multiple somatic complaints involving multiple organ systems, but which cannot be explained by physical and/ or laboratory findings. Conversion disorder is another axis I disorder where there is a disturbance of bodily function that does not conform to anatomic or neurologic concepts, and it is due to psychological factors. Body dysmorphic disorder is a pervasive subjective feeling/belief that some aspect of the patient's appearance is ugly or deformed.

  Hypochondriasis is a persistent belief in the presence of one or two serious physical diseases despite medical assurance that one does not have the disease/illness. Pain disorder (somatoform pain disorder) is a disorder with the presence of severe, distressing and persistent pain which cannot be explained adequately by evidence of a physiologic process or physical disorder. Panic disorder is a kind of anxiety disorder. Discrete periods of extreme sympathetic nervous system symptoms occur, including tachycardia, sweating, shortness of breath, and others, during which time a person experiences extreme fear. Malingering is the deliberate manufacture of false or exaggerated symptoms for financial gain or to avoid an unpleasant situation such as jail time or military duty. In a factitious disorder, there is the deliberate production of signs and symptoms of illness in order to assume the sick role.

• Question 533:

  A woman at 31 weeks' gestation complains of feeling dizzy and lightheaded when she lies on her back. She is Rh negative but denies vaginal bleeding, abdominal trauma, or abdominal pain. The diagnosis is probably the supine hypotensive syndrome.

  In which of the following circumstances is the administration of anti-D immune globulin not necessary?

  A. threatened abortion and first-trimester bleeding
  B. genetic amniocentesis at 16 weeks' gestation
  C. at 28 weeks
  D. at 40 weeks with the onset of labor
  E. after delivery of an Rh-positive fetus
  D. at 40 weeks with the onset of labor

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  Explanation

  Anti-D immune globulin should be given at the time of any vaginal bleeding, trauma, or invasive procedure (e.g., amniocentesis) during pregnancy. Although maternal isoimmunization usually occurs as a result of fetomaternal transfusion at the time of delivery, a small percentage of women become isoimmunized during pregnancy. Anti-D immune globulin is routinely given to unsensitized Rh- negative women at 28 weeks' gestation to reduce this risk. Anti-D immune globulin must also be administered within 72 hours after the birth of an Rh-positive infant. Administration at 40 weeks' gestation before the onset of labor is unnecessary if the infant is Rh negative and may be ineffective if the infant is Rh positive and there is a significant fetomaternal transfusion.

• Question 534:

  A pregnant woman has been taking phenytoin (Dilantin) for a seizure disorder. She is concerned that the drug will cause fetal abnormalities. Which of the following defects is the most common anomaly associated with phenytoin?

  A. atrial septal defect
  B. ventricular septal defect
  C. cleft lip/palate
  D. spina bifida
  E. hydrocephalus
  C. cleft lip/palate

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  Explanation

  As many as 30% of fetuses exposed to phenytoin had minor craniofacial and digital anomalies. Cleft lip/ palate, hypertelorism, broad nasal bridge, and epicanthal folds are the craniofacial anomalies observed. Hypoplasia of the distal phalanges and nails are the digital anomalies. In addition, these infants may have growth and cognitive deficiencies. Trimethadione, another anticonvulsant, causes similar anomalies. Spina bifida occurs in 12% of infants whose mothers took valproic acid during pregnancy.

• Question 535:

  At 24 weeks' gestation, where are most fetal red blood cells produced?

  A. the yolk sac
  B. spleen
  C. bone marrow
  D. liver
  E. lymph nodes
  D. liver

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  Explanation

  The first site of hematopoiesis in the fetus is the yolk sac. Between 12 and 24 weeks' gestation, the fetal liver makes the largest contribution. After 28 weeks, the fetal bone marrow is the most important site.

• Question 536:

  Select the organism associated with the Nursery epidemics of watery diarrhea

  A. aureus
  B. beta-hemolytic Streptococcus
  C. perfringens
  D. Mycoplasma pneumoniae
  E. Haemophilus pertussis
  F. Helicobacter pylori
  G. Escherichia coli
  H. Rickettsia prowazekii
  I. Giardia lamblia
  G. Escherichia coli

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  Explanation

  Giardiasis may cause cramping and a chronic diarrheal syndrome, with malabsorption and weight loss. Its distribution is worldwide, particularly where hygienic standards are not high. It also occurs sporadically in high-risk individuals. Streptococcal pyoderma, including erysipelas and impetigo, has been demonstrated to precede acute glomerulonephritis. Even when appropriate antibiotics are given in adequate dosage and duration for these conditions, renal damage may still result. Prevention thus consists of wound care, including cleaning wounds well and removal of crust. Mycoplasma infections are particularly common in families with younger children. They are frequently imported to the family by school-aged children, leading to a low-grade fever and persisting tracheobronchitis in the parents, or more acutely, an atypical pneumonia. G. lamblia is found in up to 20% of homosexual males, and may cause chronic diarrhea, although in these patients it tends to be asymptomatic. E. coli was first reported as a cause of watery diarrhea in nurseries in the 1940s. Although nursery epidemics with enteropathogenic serotypes had decreased in recent years in the United States, the increase of infant- child day care centers has resulted in their relatively frequent occurrence. Furunculosis is most frequently caused by coagulase-positive staphylococcal infections. The public health significance of this largely relates to the hazards of skin infections in food handlers and subsequent staphylococcal toxin in the food, leading to staphylococcal intoxication food-borne disease. H. pylori has been associated with gastric ulcers, but not with duodenal ulcers. Otitis media, whether acute or with effusion, commonly results from viral infection, such as by RSV. Various other organisms may be responsible including Streptococcu pneumoniae, H. influenzae, and others. C. perfringens, with rare exceptions, is transmitted in a meat dish prepared in bulk. Under propitious circumstances for the organism, especially on cooling of the food, bacterial multiplication can be very rapid. Symptoms begin to occur in the affected population in about 12 hours. Epidemic typhus is a rickettsial illness. Man is the host and long-term reservoir. The vectors are body lice (P. humanus corporis). The rickettsia are not present in human excretions and cannot be transmitted by person-to-person contact.

• Question 537:

  A 23-year-old married woman consults you because she and her husband have never consummated their marriage because she has severe pain with attempts at vaginal penetration. Her pelvic examination is normal except for involuntary tightening of her vaginal muscles when you attempt to insert a speculum. Which of the following conditions would best be treated with the use of vaginal dilators?

  A. primary dysmenorrhea
  B. vaginismus
  C. deep-thrust dyspareunia
  D. anorgasmia
  E. vulvar vestibulitis
  B. vaginismus

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  Explanation

  Vaginismus is the painful, involuntary spasm of the musculature of the pelvis and lower third of the vagina. It may respond to properly administered dilator therapy, although there is a lack of conclusive evidence. Deepthrust dyspareunia is often the result of pelvic pathology, such as fibroids, endometriosis, ovarian cysts, pelvic adhesions, and others. Anorgasmia is usually a psychological disorder best dealt with by a psychologist or psychiatrist expert in sexual counseling and therapy. Sexual or physical abuse should be considered and the woman questioned about this possibility. Vulvar vestibulitis is an inflammatory condition of uncertain (perhaps multiple) etiology and is usually treated with topical glucocorticoids. Failure of medical therapy may require surgical excision of the affected area.

• Question 538:

  Several groups of organic compounds are associated with serious toxic effects when used in the production of resins, plasticizers, and solvents

  A. nitrosamines
  B. epoxy compounds
  C. PCBs
  D. formaldehydes
  E. organophosphorus compounds
  B. epoxy compounds

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  Explanation

  Epoxy compounds are used in the production of resins. They cause irritation of the skin and mucosa and have caused acute pulmonary edema

• Question 539:

  An 18-month-old girl is brought to the physician's office for evaluation of left neck mass. Examination reveals a 2-cm soft, nontender, fluctuant mass in the left lateral neck. This is located at the anterior border of the sternomastoid, midway between the mastoid and clavicle. For the above patient with a neck mass, select the most likely diagnosis.

  A. thyroid carcinoma
  B. cystic hygroma
  C. acute suppurative lymphadenitis
  D. thyroglossal duct cyst
  E. lipoma
  F. carotid artery aneurysm
  G. mixed parotid tumor (pleomorphic adenoma)
  H. laryngeal carcinoma
  I. parathyroid adenoma
  J. branchial cleft cystK. tuberculosis
  J. branchial cleft cystK. tuberculosis

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  Explanation

  The location of this mass and its cystic nature are typical for a second branchial cleft remnant. Surgical excision is recommended, including the associated tract, which traverses between the carotid bifurcation and ends at the tonsillar fossa.

• Question 540:

  A 22-year-old primiparous woman is in premature labor at 30 weeks' gestation. Despite administration of tocolytic agents, it seems she will deliver soon. Pulmonary maturity might be enhanced by the administration of which of the following drugs?

  A. magnesium sulfate
  B. betamethasone
  C. hydroxyprogesterone
  D. chloroprocaine
  E. digitalis
  B. betamethasone

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  Explanation

  The only agents currently recognized to enhance production of fetal pulmonary surfactant are glucocorticoids. There is good evidence that pulmonary immaturity is reduced by 50% when corticosteroids are given to mothers at a gestational age less than 31 weeks. Also, there is evidence that neonatal death is decreased by about 50% with corticosteroid therapy, and other major infant morbidity is reduced as well (intraventricular hemorrhage, necrotizing nterocolitis). To achieve these benefits, delivery must be delayed 48 hours. Of the agents listed, magnesium sulfate can prevent eclamptic seizures and may inhibit uterine contractions. The other agents have no role in the treatment of fetal lung immaturity.