USMLE USMLE Certifications USMLE-STEP-2 Questions & Answers

• Question 461:

  A specific pattern of abnormalities has been identified among infants born to mothers who consume moderate-to-large amounts of alcohol during their pregnancies. Which of the following abnormalities is characteristic of these infants?

  A. cataracts

  B. developmental dysplasia of the hip

  C. gonadal dysgenesis

  D. neural tube defects

  E. mental retardation

  Correct Answer: E

  The characteristics of fetal alcohol syndrome include: A. persistent deficient growth affecting weight, height, and head circumference and beginning in utero; B. such facial abnormalities as micrognathia, short palpebral fissures, and a thin upper lip; (C) cardiac abnormalities, commonly septal defects; (D) minor limb abnormalities with some restriction of mobility and some alteration in palmar crease patterns; and (E) mental deficiency ranging from mild to severe. There is a decided relationship between the extent of abnormalities and the degree of mental retardation. Affected infants may present with hypoglycemia and alcohol withdrawal symptoms which may last for 4872 hours. Immediate management of these infants consists of correction of the hypoglycemia. Ongoing monitoring of the child's development is essential. Prevention by restriction of alcohol consumption during pregnancy is advised.

• Question 462:

  A10-year-old boy presents with a 3- to 4-day history of left ear pain. He is afebrile; he has had no symptoms of cold or cough. He has been swimming daily. On physical examination, there is pain on moving the pinna and the tragus. There is erythema and swelling of the ear canal; the tympanic membrane is obscured by thick white discharge. Which of the following is the most likely diagnosis?

  A. otitis externa

  B. furunculosis

  C. otitis media with effusion

  D. mastoiditis

  E. foreign body in the ear

  Correct Answer: A

  Otitis externa is an infection of the external ear canal. Predisposing factors include excessive wetness (swimming), dryness (lack of protective cerumen), trauma (foreign body), and other skin pathology (eczema). It is characterized by pain, accentuated by moving the pinna and especially the tragus; edema and inflammation of the canal; and discharge. Furuncles usually cause a localized swelling or papule in the hairbearing part of the canal. If the tympanic membrane is not visualized, otitis media is hard to differentiate from otitis externa. Otitis media does not cause pain with movement of the pinna. In severe otitis externa, the periauricular edema may push the pinna forward; this may be confused with mastoiditis. In mastoiditis, however, the postauricular fold is usually obliterated. There is often a history of otitis media and hearing loss and tenderness over the mastoid antrum.

• Question 463:

  A7-month-old baby presents with a history of constipation for 1 month. He has one hard stool every week. He has been well otherwise. His physical examination is normal. Which of the following is the most likely cause of his problem?

  A. hypothyroidism

  B. lead poisoning

  C. functional constipation

  D. Hirschsprung disease

  E. hypocalcemia

  Correct Answer: C

  Hypocalcemia is not a cause of constipation. On the contrary, it increases irritability of nerve cells and may result in diarrhea. Hypothyroidism, lead poisoning, and Hirschsprung disease all may be associated with constipation. Congenital hypothyroidism and Hirschsprung disease (a congenital disorder characterized by regional absence of ganglion cells from the myenteric plexus of the colon) present at birth. Lead poisoning is more common after the child becomes mobile. Functional constipation is the most common cause of constipation at this age. It is usually due to dietary factors.

• Question 464:

  A 4-day-old infant presents with yellow discoloration of the skin and sclera. The baby was born at term by a normal vaginal delivery. Pregnancy was uncomplicated; there were no risk factors for sepsis and no history of maternal alcohol or drug use. The baby is breast-fed and has been nursing every 2 hours, about 10 minutes at each breast. The bilirubin level is 15 mg/dL (all unconjugated), the hematocrit is 45%, and the Coombs test is negative. Which of the following is the most likely diagnosis?

  A. congenital biliary atresia

  B. isoimmune hemolytic disease

  C. Crigler-Najjar syndrome

  D. breast milk jaundice

  E. breast-feeding jaundice

  Correct Answer: E

  The most common causes of neonatal cholestasis are extrahepatic biliary atresia and idiopathic neonatal hepatitis. Infants usually develop icterus by 26 weeks of age. They have conjugated hyperbilirubinemia, dark urine, and acholic stools. At time of presentation, there is usually hepatomegaly, as well as pruritis, splenomegaly, and ascites. The use of RhoGAM (anti-D gamma globulin) has reduced the incidence of Rh sensitization and resulting jaundice. ABO incompatibility can also cause a milder form of isoimmune hemolytic disease and jaundice. It is more common in infants with blood types Aand B born to mothers with blood type O. Anemia is usually present; direct Coombs test is weakly positive; and indirect Coombs test is positive. Crigler-Najjar syndrome is autosomal recessive; there is usually marked hyperbilirubinemia (240 mg/dL) in an otherwise asymptomatic infant. The high levels result in kernicterus. Physiologic jaundice is the most common cause of unconjugated hyperbilirubinemia; it is characterized by peak bilirubin level of <13 mg/dL on day of life 35, decrease to normal within 2 weeks. In breast-fed infants, this is often exaggerated, with levels >13 mg/dL. This occurs in 1025% of breastfed infants, as opposed to 47% of formulafed infants. It is known as "breast-feeding" jaundice. "Breast-milk" jaundice, develops after the first week of life, peaking between the 2nd and 3rd week to 1020 mg/dL. The cause of this has not been established.

• Question 465:

  Varicella vaccination is a live virus vaccine. It is generally not recommended in immunocompromised patients. Which of the following is an exception to this rule?

  A. children on high doses of corticosteroids

  B. leukemia in inducton therapy

  C. lymphoma

  D. congenital T-cell abnormalities

  E. leukemia in remission for >1 year and a normal lymphocyte count

  Correct Answer: E

  Varicella vaccine should not be routinely given to children with T-lymphocyte deficiency, including lymphoma, leukemia, neoplasms affecting the bone marrow or lymphatic systems, and congenital T- cell abnormalities. One exception is children with ALL, in continuous remission for at least 1 year, with a lymphocyte count >700/L and a platelet count >100 . 103/L. Another exception is HIV- infected children in CDC class 1. These children are at increased risk of morbidity from varicella and herpes zoster; therefore, the benefits outweigh the risks in these limited circumstances. Children receiving high doses of steroids should not receive the vaccine. This is defined as >2 mg/kg/day of prednisone or its equivalent, or 20 mg/ day, if their weight is >10 kg, for 14 days or more. The vaccine may be given a month after discontinuation of the therapy.

• Question 466:

  A1-year-old patient is in the office for a health maintenance visit and is ready for immunizations. The child has a mild upper respiratory infection and a low-grade fever. The mother does not want the child to receive vaccine because she has been told that the vaccine could make the illness worse. You tell her the only true contraindication to vaccination is which of the following?

  A. if the child has a skin rash

  B. if there is an immunosuppressed adult in the household

  C. if the child has hypersensitivity to a vaccine component

  D. if a pregnant woman is in the household

  E. if the mother is breast-feeding

  Correct Answer: C

  Mild illness is not a contraindication to vaccination, nor is breast-feeding. Such live vaccines as MMR and varicella are not recommended for pregnant women, but may be safely given to their children. They are also not recommended in many immunocompromised children; however, it is recommended that household contacts receive the vaccinations to decrease the patient's chances of exposure. It is not necessary to restart a vaccine series if there has been a long gap between immunizations.

• Question 467:

  Children with sickle cell anemia are at increased risk of developing overwhelming infection with certain microorganisms. Which of the following is the most reasonable step to prevent such infection?

  A. periodic injections of gamma globulin

  B. injection of VZIG after exposure to varicella

  C. withholding live virus vaccines

  D. prophylactic administration of oral penicillin daily

  E. early use of amoxicillin at home for episodes of fever

  Correct Answer: D

  Children with sickle cell disease develop functional asplenia, presumably from repeated splenic infarction. This results in vulnerability to bacteremia and overwhelming infection, especially with encapsulated bacteria. The organism most commonly involved is S. pneumoniae. Daily prophylactic oral penicillin is indicated for young children. Because of the risk of bacteremia, these patients need careful medical evaluation when they develop fever. There are no data to support the use of gamma globulin in these children. They are not at higher risk for complications from live virus vaccines or from varicella.

• Question 468:

  A16-year-old male is brought to the emergency department with a crush injury due to a farm accident. His immunization status is unknown. The wound is heavily contaminated with soil, and you are concerned about tetanus.

  Which of the following is the most appropriate management step?

  A. administer a Tdap vaccination

  B. administer a Td vaccine only

  C. administer Tdap and tetanus immune globulin (TIG)

  D. administer TIG only

  E. await immunization records

  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.

• Question 469:

  A4-month-old baby is in for a well-child check and routine immunizations. The baby had a fever of 39°C the day he received his 2-month immunizations. The parents have read about the vaccine on the Internet and express their concerns. Which of the following is an absolute contraindication to giving the diphtheria and tetanus toxoids and acellular pertussis (DTaP)?

  A. history of fever >38°C after previous vaccination

  B. history of local reaction after previous vaccination (redness, soreness, swelling)

  C. family history of seizures

  D. encephalopathy within 7 days of administration of previous dose of vaccine

  E. current antibiotic therapy

  Correct Answer: D

  Absolute contraindications to use of DTP/DTaP include history of anaphylactic reaction to the vaccine or history of encephalopathy. The following are precautions. These circumstances should be carefully reviewed, and if vaccine benefits outweigh the risks, the vaccine should be given. Precautions include any of the following after a prior dose of DTP/DTaP: temperature of 40.5°C within 48 hours; collapse or sh ocklike state (hypotonichyporesponsive episode) within 48 hours; seizures within 3 days; persistent inconsolable crying lasting 3 hours within 48 hours. Moderate or severe illness with or without a fever may be considered a precaution; however, a mild illness, such as an upper respiratory infection, is not a contraindication. Low-grade fevers and local reactions are common and are not contraindications; nor are antibiotic therapy or a family history of seizures.

• Question 470:

  A newborn infant requires repeated resuscitation in the delivery room because of failure to breathe and cyanosis. During spells of crying, which appear to alleviate the cyanosis, his breath and heart sounds are normal, as is direct laryngoscopy. Vigorous respiratory movements appear ineffectual. Immediate management of this infant consists of which of the following?

  A. obtaining a chest x-ray

  B. obtaining an electrocardiogram (ECG)

  C. arterial blood gas determinations

  D. inserting an oropharyngeal airway

  E. administration of naloxone

  Correct Answer: D

  The presence of a congenital membranous or bony septum between the nose and pharynx is called choanal atresia. Most newborns are obligatory nose breathers and breathe effectively only through their noses. Therefore, if choanal obstruction is unilateral, breathing difficulty may not occur until the first respiratory infection. On the other hand, those newborns with bilateral atresia who are also obligatory nose breathers will make vigorous attempts to inspire with sucking in of their lips, or may promptly become apneic and cyanotic, requiring resuscitation. Those who are able to mouth breathe may have difficulty when feeding or manifest persistent mouth breathing and cyanosis that is relieved by crying. Treatment consists of surgical correction.