USMLE USMLE Certifications USMLE-STEP-3 Questions & Answers

• Question 371:

  A 24-year-old G1 presents to you for initiation of obstetric care. She informs you that she is on a medication that was prescribed for acne. The drug is listed as category X in your pharmacy book.

  The pregnancy risk factor category X for a drug indicates which of the following?

  A. Controlled human studies demonstrate no risk to a fetus.

  B. This drug should never be used by a pregnant female under any circumstances.

  C. Evidence of human teratogenic risk exists but in some cases the known risks may be outweighed in some serious situations, such as life-threatening disease.

  D. Animal reproduction studies have not demonstrated fetal risk but there are no controlled human studies to assess the risk.

  E. Animal reproduction studies have demonstrated risk to a fetus and no controlled human studies are available.

  Correct Answer: B Section: (none)

  Explanation:

  The pregnancy risk factor category assists the physician and patient to understand the safety of the use of a medication during pregnancy. The summary of the categories is as follows: category A--controlled human studies demonstrate no risk to a fetus. Category B--animal-reproduction studies have not demonstrated fetal risk but there are no controlled human studies to assess the risk. Category C--animalreproduction studies have demonstrated risk to a fetus and no controlled human studies are available. Category D--evidence of human teratogenic risk exists but in some cases the known risks may be outweighed in serious situations, such as lifethreatening disease. Class X--this drug should never be used by a pregnant female under any circumstances. The principle of autonomy states that the patient has the right and capability to control the course of her medical care and to participate in the decision-making process.

• Question 372:

  Implantation of the embryo into the endometrium occurs how many days after ovulation?

  A. 1

  B. 2

  C. 4

  D. 6

  E. 10

  Correct Answer: D Section: (none)

  Explanation:

  Following ovulation, fertilization of the egg by the sperm occurs in the Fallopian tube. The embryo then divides and grows as it migrates down the Fallopian tube and into the uterine cavity. As early as 6 days postovulation the embryo implants in the uterine endometrium. Trophoblast invasion then occurs allowing the embryo to burrow into the endometrium. A uteroplacental circulation is established by 1112 days after ovulation allowing -hCG to be detectable in maternal serum or urine.

• Question 373:

  A woman complains of amenorrhea for several months following a dilation and curettage. Which of the following is the most likely reason?

  A. occult perforation of uterus during the procedure

  B. intrauterine scarring

  C. infection of the endometrium (endometritis)

  D. iron-deficiency anemia from blood loss during the procedure

  E. premature menopause

  Correct Answer: B Section: (none)

  Explanation:

  Asherman syndrome describes intrauterine synechiae (scarring) of the uterine cavity following a surgery of infection of the uterine endometrium. Asherman syndrome is seen following uterine surgery (such as a uterine curettage or myomectomy), septic abortion, or other endometrial cavity infection. The damaged endometrium scars together lead to impairment of the endometrial function. This may result in amenorrhea, dysmenorrhea, infertility, or miscarriage. If the scarring causes obstruction of outflow of menstrual tissue, then hematometra and dysmenorrhea can occur. Severe scarring leads to complete obliteration of the uterine cavity

• Question 374:

  An amenorrheic 17-year-old female is diagnosed with Kallmann syndrome. Blood testing of this patient would indicate which of the following results?

  A. FSH, LH, normal estradiol

  B. high FSH, high LH, low estradiol

  C. normal FSH, normal LH, normal estradiol

  D. low FSH, low LH, normal estradiol

  E. low FSH, low LH, low estradiol

  Correct Answer: E Section: (none)

  Explanation:

  Kallmann syndrome is a genetic problem due to failure of migration of olfactory and GnRH secreting neurons to make their appropriate connections in the brain. Classically, this leads to anosmia (inability to smell), delayed puberty, and amenorrhea. The GnRH is not secreted, and pituitary FSH and LH release does not occur. In the absence of stimulation the ovaries do not produce significant estrogen. This is an example of hypogonadotropic hypogonadism, also termed hypothalamic amenorrhea.

• Question 375:

  A15-year-old female presents to the emergency room (ER) with acute onset right lower quadrant pain and nausea. She recently became sexually active and is "in the middle" of her menstrual cycle. Physical examination is notable for generalized guarding, rebound, and 8/10 pain in both lower quadrants. A pelvic examination shows no vaginal discharge, a normal appearing cervix, and general pelvic tenderness, but the examination is limited by the patient's guarding. Her complete blood count is notable for a borderline elevated white blood cell (WBC) count, and a urinary -hCG is negative. Pelvic ultrasound shows a 2-cm simple appearing cyst on the right ovary and a mild amount of fluid in the cul-de-sac. Acomputed tomographic (CT) scan cannot definitively visualize the appendix, confirms the presence of a 2-cm cystic structure in the right ovary, and otherwise notes normal anatomy.

  Which of the following is the most appropriate next step?

  A. diagnostic laparoscopy

  B. pelvic MRI

  C. intravenous antibiotics

  D. admission for serial physical examinations and pain control

  E. discharge home on oral antibiotics

  Correct Answer: A Section: (none)

  Explanation:

  Acute pelvic pain is a difficult diagnostic dilemma. An acute abdomen can result from appendicitis, ovarian torsion, ruptured ovarian cyst, ectopic pregnancy, PID, diverticular abscess, and other causes. Misdiagnosis of PID is common and the most likely diagnosis confused with PID is appendicitis. In the setting where the etiology of the acute abdomen is not certain, a laparoscopy is indicated both for diagnostic and, in many cases, therapeutic purposes. A pelvic MRI or serial examinations would further delay the diagnosis. In the case of ovarian torsion or appendicitis, rapid diagnosis and treatment is critical to optimize outcomes.

• Question 376:

  A 17-year-old female presents with primary amenorrhea. On physical examination, she has normal secondary sexual characteristics, scant pubic and axillary hair, and a blind ending vaginal pouch. Apelvic MRI indicates inguinal gonads and no uterus. Her karyotype is 46,XY.

  Which of the following is the most likely etiology of primary amenorrhea in this patient?

  A. Müllerian agenesis (Mayer-Rokitansky-Küster-Hauser syndrome)

  B. Klinefelter syndrome

  C. androgen insensitivity

  D. Turner mosaic

  E. Kallmann syndrome

  Correct Answer: C Section: (none)

  Explanation:

  Androgen insensitivity is an inherited disease resulting from the lack of functional androgen receptors. Gonadal function is that of normal testicles; however, there is no end-organ effect due to the lack of any functional receptors. Because the gonads produce Müllerian inhibiting substance (MIS), the Müllerian structures regress. Primary amenorrhea is therefore a common cause for presentation to a physician. Normal female secondary sexual characteristics and external genitalia result due to the absence of any effect of endogenous androgens and the production of small, but adequate, amounts of estrogen, mostly from peripheral conversion of androstenedione.

• Question 377:

  A39-year-old obese female presents with irregular menstrual periods, mild acne and hirsutism, and acanthosis nigricans on the nuchal fold, axilla, and intertriginous areas (inner upper thighs). You suspect PCOS. Which of the following laboratory tests would be most important to perform to rule out a likely confounding diagnosis?

  A. 2-hour oral glucose tolerance test

  B. testosterone

  C. prolactin

  D. dehydroepiandrosterone sulfate (DHEAS)

  E. LH and FSH

  Correct Answer: A Section: (none)

  Explanation:

  PCOS is the most common endocrine disorder of reproductive age women. Common symptoms include oligo-or amenorrhea, acne, hirsutism, infertility, and weight gain. Common tests used to support the diagnosis of PCOS include LH to FSH ratio, testosterone, DHEAS, and pelvic ultrasound. Acanthosis nigricans is a raised, velvety, tan skin lesion commonly seen on the back of the neck, in the axilla, and the intertriginous areas. Acanthosis nigricans is associated with hyperinsulinemia and is a sign that the patient is at significant risk for prediabetes and frank diabetes. Up to 30% of patients with suspected PCOS have prediabetes, and 8% are frank type II diabetics. PCOS is a diagnosis of exclusion and requires ruling out other possible confounding diagnoses. Given the obesity and acanthosis nigricans in this patient, a 75-g, 2hour oral glucose tolerance test would be recommended. Other common confounding diagnoses in patients with PCOS include late-onset congenital adrenal hyperplasia (screened with a serum 17hydroxyprogesterone), Cushing syndrome (screened with a 24 hour urinary free cortisol, or overnight dexamethasone suppression test), and thyroid disease.

• Question 378:

  A 5-year-old girl presents for evaluation of breast development, history of multiple bone fractures, and vaginal bleeding. Physical examination is notable for "café au lait" spots on her skin, tanner stage 2 breasts, and she appears tall for her age. What is the most likely cause of precocious puberty in this child?

  A. acromegaly

  B. McCune-Albright syndrome

  C. ovarian cyst

  D. ingestion of her mother's oral contraceptives

  E. hyperparathyroidism

  Correct Answer: B Section: (none)

  Explanation:

  The McCune-Albright syndrome is due to a G-protein mutation in the alpha-subunit that causes constitutive stimulatory activity of the tissues. Affected tissues are autonomously active. McCune-Albright syndrome classically consists of a triad of café au lait skin spots, cystic bone lesions (polyostotic fibrous dysplasia), and autonomous endocrine hyperfunction resulting in sexual precocity. Adominant ovarian cyst develops independent of stimulation by gonadotropins and it secretes estradiol, resulting in sexual precocity and skeletal maturity. Therefore, the finding of elevated estradiol levels and suppressed or undetectable gonadotropins is diagnostic. Affected individuals also may have hyperthyroidism, hypercortisolism, pituitary gigantism, or acromegaly.

• Question 379:

  A 61-year-old female is diagnosed with osteoporosis by a screening dual-energy x-ray absorptiometry (DEXA) scan.

  Which of these is a risk factor for postmenopausal osteoporosis?

  A. black race

  B. lack of exercise

  C. obesity

  D. multiparity

  E. late menopause

  Correct Answer: B Section: (none)

  Explanation:

  Risk factors for postmenopausal osteoporosis include cigarette smoking, thinness, early menopause (natural or surgical), nulliparity, northern European heritage, some medications (e.g., glucocorticoids), high alcohol or caffeine intake, low dietary calcium consumption, and a family history of osteoporosis. Dietary calcium and vitamin D supplementation and exercise (preferably weight bearing) are the classic lifestyle changes recommended to prevent or treat osteoporosis. (

• Question 380:

  In order to prevent unintended pregnancy following an episode of unprotected intercourse, by when is it recommended that "emergency" oral contraception should be initiated?

  A. 12 hours

  B. 24 hours

  C. 48 hours

  D. 72 hours

  E. 1 week

  Correct Answer: D Section: (none)

  Explanation:

  The U.S. Food and Drug Administration (FDA) has approved the use of oral contraceptives as an effective method of postcoital contraception, often termed emergency contraception. The most common regimens involve two to four oral contraceptive tablets, depending on the dosage of the brand used, repeated 12 hours later. Progestin-only regimens are also highly effective. Initiating treatment greater than 72 hours after the event of unprotected intercourse is associated with a lower success rate.