USMLE USMLE Certifications USMLE-STEP-2 Questions & Answers

• Question 11:

  A 28-year-old woman with 28-day menstrual cycle is attempting to conceive and is considering the use of a home ovulation predictor kit to time intercourse at ovulation. She asks you what day of her menstrual cycle her luteinizing hormone (LH) peak is most likely to occur. What should you tell her?

  A. day 12

  B. day 14

  C. day 18

  D. day 20

  E. day 27

  Correct Answer: B

  The LH surge classically triggers ovulation 14 days before the onset of the subsequent menstrual period. Subtract 14 days from the typical cycle length to estimate the cycle day of the LH surge and ovulation. It is pertinent to remind this woman that her probability of conceiving in each cycle is no higher than 1520%, even with intercourse timed to the preovulatory LH surge.

• Question 12:

  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

  Correct Answer: B

  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.

• Question 13:

  A31-year-old pregnant woman 67 weeks from her last menses comes to the emergency department of your hospital complaining of lower abdominal pain for 3 hours. The pain is diffused in the lower abdomen but worse on the right side. Her serum human chorionic gonadotropin (hCG) concentration is 9600 mIU/ mL.

  Which of the following is the strongest evidence that she has a tubal ectopic pregnancy?

  A. absence of an extrauterine sac on ultrasonography

  B. absence of blood on culdocentesis

  C. absence of a mass on bimanual examination

  D. absence of an intrauterine sac on ultrasonography

  E. her hCG concentration

  Correct Answer: D

  At serum hCG concentrations above the discriminatory zone (usually about 4000 mIU/mL), transvaginal sonography should reveal an intrauterine pregnancy. The absence of such a finding suggests either an extrauterine pregnancy or a spontaneous abortion. Higher levels of hCG are necessary before an extrauterine gestational sac may be seen by sonography. At each week of gestation, hCG concentrations normally vary by a large amount. For this reason, a single measurement is not helpful, although serial measurements to determine whether the hCG fails to double in 48 hours is helpful to suggest a failing pregnancy (ectopic or intrauterine). Nonclotting blood obtained from the cul-de-sac by a culdocentesis may be the result of a ruptured ectopic pregnancy or a ruptured ovarian cyst. An adnexal mass is palpated in only 50% of women with an ectopic pregnancy.

• Question 14:

  A 27-year-old woman with amenorrhea of 6 months' duration relates a 4-month growth of thick, black hair on her face, chest, and abdomen. She takes no medications with androgenic effects. Her family history is negative for hirsutism. The hirsutism is confirmed by your examination. Her pelvic examination is normal other than a mild male pubic hair pattern. Your evaluation of this hirsute, amenorrheic woman is normal except for a significantly increased serum DHEAS concentration. Additional history discloses that her menses have always been somewhat irregular since menarche at age 10 years. She has a 23-year-old sister with irregular menstrual intervals and hirsutism to a lesser degree. This patient has a blood pressure of 96/64 mmHg. Which of the following is the most likely diagnosis?

  A. polycystic ovary syndrome

  B. 21-hydroxylase deficiency

  C. 11-hydroxylase deficiency

  D. 17-hydroxylase deficiency

  E. Sertoli-Leydig cell tumor

  Correct Answer: B

  A history of irregular menses from menarche suggests a functional disorder, such as polycystic ovary syndrome or attenuated adrenal hyperplasia attributable to an inherited enzyme deficiency. The absence of a unilateral ovarian mass on pelvic examination, the positive family history, and the early menarche favor a diagnosis of attenuated adrenal hyperplasia over that of a virilizing ovarian tumor. Women with 17hydroxylase deficiency or 11-hydroxylase deficiency are hypertensive. Women with 17- hydroxylase deficiency are also sexually infantile, not hirsute, because they are unable to produce androgens or estrogens in normal amounts. Women with 21-hydroxylase deficiency may have salt wasting and hypotension if the enzyme deficiency is sufficiently severe.

• Question 15:

  A 27-year-old woman with amenorrhea of 6 months' duration relates a 4-month growth of thick, black hair on her face, chest, and abdomen. She takes no medications with androgenic effects. Her family history is negative for hirsutism. The hirsutism is confirmed by your examination. Her pelvic examination is normal other than a mild male pubic hair pattern.

  Which of the following is the most appropriate next step in her evaluation?

  A. serum prolactin concentration

  B. 24-hour urine for 17-ketosteroid excretion

  C. serum dehydroepiandrosterone sulfate (DHEAS) concentration

  D. CT scan of the pituitary sella

  E. pelvic ultrasound

  Correct Answer: C

  Hirsutism occurs when a woman is exposed to increased amounts of biologically active androgens, or when hair follicles are extrasensitive to normal amounts of androgens. Women with regular menstrual intervals usually have familial hirsutism, and it usually begins at or soon after puberty. Hirsutism associated with menstrual disturbances usually means exposure to increased amounts of androgens, either endogenous secretion from the ovaries or adrenal glands or ingestion of a drug with androgenic effects. The amenorrhea suggests increased androgen exposure, while the negative drug history suggests an endogenous source. Testosterone may arise from the ovaries, the adrenal glands, and from extraglandular formation. A serum testosterone concentration is not helpful to distinguish which source of androgen is responsible for hirsutism. Furthermore, the serum testosterone level is often misleadingly low, because increased production rates of testosterone stimulate an increase in the rate of removal (the metabolic clearance rate) of testosterone from the circulation. The degree of hirsutism is the best gauge of the amount of excessive androgen production. Most virilizing ovarian tumors are palpable in young women, and a pelvic ultrasound is useful only when the bimanual examination is inadequate. Elevated prolactin levels may cause amenorrhea but do not cause hirsutism. There is no use for measurement of urinary androgen (17-ketosteroid or 17-ketogenic steroid) excretion in modern gynecology. The best next step is to measure a serum DHEAS concentration, because it is elevated in adrenal disorders and normal or only slightly elevated in ovarian causes of hirsutism.

• Question 16:

  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

  Correct Answer: D

  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 17:

  Labor and vaginal delivery occur successfully in a 29-year-old woman after administration of oxytocin (Pitocin) for 9 hours. Spontaneous onset of labor at term is the result of which of the following?

  A. cortisol production in the amniotic cavity

  B. prostaglandin release from the fetal membranes

  C. prolactin produced in the decidua

  D. fetal pituitary secretion of oxytocin from the neurohypophysis

  E. events that are currently uncertain

  Correct Answer: E

  Although many mechanisms involving the fetal pituitary axis, placental membranes, decidual secretions, and fetal-placental interaction have been investigated, no mechanism has been established for the initiation of labor in humans. Cortisol mechanisms probably initiate labor in sheep, and sheep generally are the experimental animals used to study human parturition. It has, however, been shown that this mechanism does not incite labor in humans. Women who are pregnant with an anencephalic fetus often do not begin labor until after 42 weeks, but they do begin spontaneous labor even in the absence of a fetal pituitary gland. The most current thinking is that a fetal-placental-uterine interaction initiates labor. It is uncertain exactly how the pieces fit in this puzzle. (There is a comprehensive and complex review of the physiologic and iochemical processes of human parturition in Cunningham et al.)

• Question 18:

  A 17-year-old G1P1001 is now 5 weeks postpartum after a routine vaginal delivery. She calls your office to report a 3-week history of difficulty sleeping and "feeling blue." On further questioning, she reports difficulty concentrating, very poor appetite, occasional wishes that she had never become pregnant, and feelings of guilt about those wishes. She has not left her home in more than a week because she "just can't find the energy to go anywhere." This patient's symptoms are most consistent with:

  A. postpartum blues

  B. normal adolescent adjustment to motherhood

  C. postpartum depression

  D. hypothyroidism

  E. postpartum psychosis

  Correct Answer: C

  Postpartum mood disorders are much more common than previously believed. Postpartum blues (also called maternity blues or baby blues) occurs in most women within the first 2 weeks of delivery and is characterized by irritability, mood lability, and anxiety. This condition is enerally resolved within 2 weeks. Hypothyroidism can mimic postpartum depression or contribute to it, but this diagnosis is based on laboratory studies and is not as common as postpartum depression itself. Psychosis is a very serious condition that occurs in up to 0.2% of deliveries and is marked by confusion, bizarre behavior, disordered thoughts, delusions, and hallucinations. There is a high risk of suicide or harm to others and immediate psychiatric care is required. Postpartum mood disorders are more common in adolescents but cannot be blamed on "typical teenage adjustment." This patient's case fits most closely the definition of postpartum epression, using the same DSM-IV Diagnostic and Statistical Manual of Mental Disorders, 4th Edition) criteria as major depression. Five lakh postpartum women in the United States have postpartum depression annually. Treatment should include antidepressant therapy (generally using SSRIs) and psychotherapy as indicated.

• Question 19:

  A35-year-old man has a history of alternating episodes of major depression and severe mania, several of which have required hospitalization. According to the clinical vignette, select the pharmacotherapeutic agent which is most likely to be helpful to the patient.

  A. buspirone

  B. sertraline

  C. risperidone

  D. lithium carbonate

  E. acamprosate

  F. dextroamphetamine

  Correct Answer: D

  Lithium carbonate is an effective treatment for manic and depressive episodes due to bipolar I disorder, as well as for the prophylaxis of manic and depressive episodes in patients with bipolar I disorder. It can impede the release of thyroid hormone from the thyroid, and it can reduce the ability of the kidneys to concentrate urine; its use requires regular blood levels to ensure the avoidance of toxic blood levels that could cause tremor, dysarthria, ataxia, or death. Acamprosate (Campral) is gabanergic and decreases the craving for alcohol in patients with alcohol dependence. Sertraline (Zoloft) is a SSRI which is effective in the treatment of major depressive disorder, as well as in the treatment of panic disorder, obsessive-compulsive disorder, and PTSD. Risperidone is an atypical antipsychotic that is effective in the treatment of psychotic conditions, including schizophrenia, and is associated with fewer serious longterm side effects, such as tardive dyskinesia, than traditional neuroleptics. Risperidone is a potent blocker of both 5-HT2 serotonin receptors and D2 dopamine receptors. Buspirone, a nonaddictive azapirone, acts as an agonist or partial agonist of 5-HT1 serotonin receptors, and is effective in the treatment of generalized anxiety disorder. Dextroamphetamine is a stimulant and is an effective treatment for ADHD.

• Question 20:

  Monoamine oxidase (MAO) inhibitory effect. Match the antidepressants below with the effect described.

  A. amitriptyline

  B. nefazodone

  C. citalopram

  D. phenelzine

  E. duloxetine

  Correct Answer: D

  The drugs listed in this question are examples of the various classes of antidepressants. These classes include the tricyclics, the SSRIs, the MAOIs, the triazolopyridines, and the serotonin-norepinephrine reuptake inhibitors. Understanding the site of action, neurotransmitter( s) involved, and side effects characteristic of these classes is helpful in selecting an antidepressant for a particular patient. SSRIs that are comparable in their antidepressant effects to the older tricyclics but significantly safer when taken in larger doses, as in suicidal overdose, are frequently used as the first choice in the treatment of depression. An example here is citalopram. Drugs that both inhibit serotonin reuptake and block 5-HT2 receptors are characteristic of the triazolopyridines. The overall effect of these actions is believed to decrease both depression and anxiety in patients. There are two drugs in this class: trazodone and nefazodone. Strong sedation caused by histaminergic and anticholinergic activity is seen in the older antidepressants--the tricyclics. These also have both serotonin and norepinephrine effects that are important in decreasing depression. Amitriptyline is the drug example listed here.

  Drugs demonstrating little sedation and significant serotonin, norepinephrine, and dopamine effects are more characteristic of the serotoninnorepinephrine reuptake inhibitors. They are effective in managing depression because there is no antihistaminergic activity and little sedation is seen. Duloxetine and Venlafaxine are examples. MAOIs increase the concentrations of serotonin, norepinephrine, and dopamine by inhibiting their degradation. The MAOIs, although effective as antidepressants, are used relatively infrequently because of the potential development of a hypertensive crisis induced by consuming tyramine- containing foods while on the MAOI. An example here is phenelzine.