Repro USMLE step 1 9-1 (4)

Question 1

This patient presents with urethritis and a purulent discharge, symptoms that are characteristic of infection with Neisseria gonorrhoeae in a man. A Gram stain showing gram-negative diplococci within neutrophils (pictured above) is sufficient for a diagnosis of gonorrhea in male patients. The same is not true for the presence of gram-negative organism in a female sample because non-pathogenic (commensal) Neisseria comprise part of the normal vaginal flora and would be present absent a gonococcal infection.
N. gonorrhoeae have specialized?

Answer 1

antigenically variable pili that mediate its attachment to mucosal surfaces

Question 2

Clomiphene citrate is a selective estrogen receptor modulator (SERM) that works as an antiestrogen at the level of the hypothalamus, reducing the?

Answer 2

feedback inhibition effect of estrogen. This leads to increased secretion of gonadotropin-releasing hormone (GnRH) from the hypothalamus, which ultimately leads to increased secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the pituitary. LH increases testosterone production in the Leydig cells, which in some men results in increased fertility. Clomiphene for male hypogonadism is an off-label use, but it has been proven to be a more desirable treatment than testosterone replacement therapy. Clomiphene is more commonly used for female infertility, particularly in the treatment of anovulation associated with polycystic ovarian syndrome.

Question 3

Gonadotropin-releasing hormone inhibition would result in decreased secretion of FSH and LH from the pituitary, resulting in decreased testosterone production in the Leydig cells.
Inhibin stimulation would act as negative feedback at the anterior pituitary for FSH secretion, thereby decreasing spermatogenesis. This would not benefit fertility in this patient.
Luteinizing hormone stimulation would act on?

Answer 3

the Leydig cells of the testes to stimulate testosterone synthesis, which is key to improvement in fertility. However, it is not the most direct effect of clomiphene citrate.
Testosterone stimulation can enhance fertility in some men and is the end product of clomiphene citrate; however, it is not the most direct effect of this medication.

Question 4

Clomiphene citrate is a SERM that acts as an antiestrogen, which leads to?

Answer 4

increased secretion of GnRH and ultimately to increased testosterone. This effect explains why clomiphene citrate may be used to improve male fertility.

Question 5

This woman’s presentation with amenorrhea, lower abdominal pain, and vaginal spotting is classic for?

Answer 5

ectopic pregnancy. Ectopic pregnancy exists when implantation occurs anywhere other than the normal, intrauterine endometrial sites. Salpingitis (pelvic inflammatory disease) may cause tubal scarring and adhesions, which commonly result in chronic pelvic pain, infertility, and increased risk for ectopic pregnancy.

Question 6

At this point, this patient has a ß-hCG level of 2100 mIU/mL, which is above the discriminatory threshold of 1500–2000 mIU/mL. At levels at or above this threshold, an intrauterine gestational sac is usually observable by transvaginal sonography. Because no intrauterine pregnancy is seen in this case, the likelihood of ectopic pregnancy is very high; the fact that no adnexal mass is noted, however, does not rule out the diagnosis.

With normal intrauterine pregnancies, ß-hCG levels usually double every 1.5–2 days until 6–7 weeks’ gestation. In this patient, the ß-hCG level increased from 1700 to 2100 mIU/mL over a period of 3 days, which indicates a nonviable pregnancy.

Aside from salpingitis (pelvic inflammatory disease), other risk factors for ectopic pregnancy include?

Answer 6

salpingostomy, endometriosis, prior tubal surgery, and altered tubal motility.

Question 7

Noncompliance with oral contraceptive is a risk factor for pregnancy in general. Extremes of age (<15 years or >45 years) are risk factors for?

Answer 7

the formation of a complete hydatidiform mole. History of miscarriage and multiparity do not increase the risk of ectopic pregnancy.

Question 8

Ectopic pregnancy presents with sharp lower abdominal pain, amenorrhea, vaginal spotting, and lack of an observable intrauterine gestational sac by the time β-hCG has reached 2000 mIU/mL. Major risk factors include?

Answer 8

salpingitis (pelvic inflammatory disease), prior tubal surgery, endometriosis, and altered tubal motility.

Question 9

This patient presents with hirsutism, weight gain, irregular menstrual cycles, and infertility. These symptoms suggest a diagnosis of polycystic ovarian syndrome (PCOS). PCOS results from hormone derangements (luteinizing hormone hypersecretion is the hallmark of PCOS), which manifest as obesity, hirsutism, oligomenorrhea, and acanthosis nigricans (velvety hyperpigmentation, often around the neck and axillae).
PCOS is often associated with insulin resistance, which leads to?

Answer 9

hyperinsulinemia. PCOS can also cause hyperglycemia and hyperlipidemia. Oral contraceptive pills are often prescribed to reduce the levels of circulating androgens that cause the hirsutism and to help regulate the menstrual cycle. Clomiphene is prescribed for women who desire pregnancy.

Question 10

Hypermagnesemia can be seen in patients with renal failure. Renal failure presents with decreased urine output, edema, fatigue, shortness of breath, and confusion, which are not symptoms seen in this patient. Hyperuricemia is associated with gout. Patients with gout typically have a history of extremely painful monoarticular arthritis, hyperuricemia, and subcortical bone cysts (tophi), which this patient does not have. Hypothyroidism presents with?

Answer 10

weight gain and menstrual irregularities, but the patient does not have any other symptoms of this condition, such as brittle hair and cold intolerance. Similarly, hypercortisolism, seen in patients with Cushing syndrome, can cause weight gain and menstrual irregularities, but this patient lacks many of the other symptoms, such as moon facies, fat pads, and abdominal striae.

Question 11

PCOS often presents with obesity, hirsutism, oligomenorrhea, and acanthosis nigricans. Many patients with PCOS have insulin resistance leading to?

Answer 11

hyperinsulinemia. Treatment of insulin resistance in these patients can be a useful adjuvant to standard management, which includes weight loss and use of oral contraceptives.

Question 12

Bacterial vaginosis is generally associated with a vaginal pH range of 5.0–6.0, moderately elevated from normal values. Addition of potassium hydroxide (KOH) to the vaginal discharge would generate a strong fishy or amine odor, thereby confirming the diagnosis of ?

Answer 12

bacterial vaginosis; this is called the whiff test. Bacterial vaginosis would present with gray or white thin and malodorous discharge, in contrast to this patient’s odorless thick, white discharge.

Question 13

The patient is a young boy who presents with delayed developmental milestones, short stature, hypotonia (poor suckling as an infant), obesity, small hands and feet, and hypogonadism. These signs and symptoms are most suggestive of Prader-Willi syndrome. The images below illustrate some of the typical facial features (eg, narrow forehead, downward corners of the mouth) associated with this syndrome.
Prader-Willi syndrome has been localized to the 15q12 band. Some genes in the 15q12 region are maternally imprinted (turned off via histone and DNA modifications), whereas some genes in the same region are paternally imprinted. Imprinted genes are epigenetically silenced. In an individual with Prader-Willi syndrome, the genes that would normally only be active on the chromosome inherited from the father (because they are maternally imprinted) have been deleted in ?

Answer 13

the paternal chromosome; thus an individual with Prader-Willi syndrome has no functional copies of these genes.

Question 14

The other answer choices would not be associated with this patient’s symptoms and features. Deletion of q12 on the maternally derived chromosome 15 causes Angelman syndrome, which presents with severe intellectual and developmental disability, ataxia, inappropriate laughter or smiling, and seizures. Maternal alcohol use during pregnancy leads to?

Answer 14

distinctive craniofacial abnormalities and intellectual disability. Maternal use of phenytoin during pregnancy leads to fetal hydantoin syndrome, which is associated with growth deficiencies, facial deformities, and hypoplastic nails of the fingers and toes. Trinucleotide CGG repeats lead to fragile X syndrome, characterized by intellectual disability, attention deficit/hyperactivity disorder, prominent ears, hyperextensibility of joints, and macroorchidism.

Question 15

Prader-Willi syndrome (deletion of q12 on paternally derived chromosome 15) is a genetic disease that manifests with?

Answer 15

hypotonia at birth and later with intellectual disability, short stature, and obesity.

Question 16

This patient has a vaginal pH of 4.0 and thick white vaginal discharge daily that she describes as being less than a teaspoon in volume. Both her pH level and the amount and quality of her discharge are ?

Answer 16

normal. The normal vaginal pH range is between 4.0–4.5. Moreover, women normally have 1–4 mL of clear to white to yellowish, mostly odorless vaginal discharge (“physiologic leukorrhea”) daily. Not all discharge is patholog

Question 17

Bacterial vaginosis would present with a malodorous grey discharge. Trichomoniasis is characterized by a purulent and foul-smelling discharge, and vulvovaginal candidiasis (or yeast infection) with a thicker discharge and pruritis. Gonococcal cervicitis would present with?

Answer 17

a greater amount of more purulent discharge, possibly in the absence of other symptoms.

Women normally have 1–4 mL of clear to white to yellowish, mostly odorless vaginal discharge (“physiologic leukorrhea”) daily.

Question 18

This patient’s presentation—consisting of a fever, lower abdominal pain, nausea, vomiting, yellow-green vaginal discharge, and most importantly, cervical motion tenderness—is most consistent with pelvic inflammatory disease (PID). Of the bacteria that cause PID, Neisseria gonorrhoeae is most likely to cause high fever and purulent discharge, and the presence of these bacteria is confirmed by the Gram stain provided, which shows gram-negative diplococci. N. gonorrhoeae have?

Answer 18

type IV pili, which are used for attachment to host cells and are the primary virulence factor of these bacteria.

Question 19

Complications of PID include tubo-ovarian abscess, scarring of the fallopian tubes, ectopic pregnancy, infertility, and chronic pain.

The other answer choices do not describe findings consistent with an N. gonorrhoeae infection. Chlamydia trachomatis can cause PID, but the Gram stain would reveal?

Answer 19

pleomorphic and gram-variable organisms. The microscopic finding of a flagellated protozoan would be consistent with Trichomonas vaginalis. A dimorphic opportunist describes Candida albicans, the organism responsible for vulvovaginitis.

Question 20

Pelvic inflammatory disease (PID) is commonly caused by?

Answer 20

Neisseria gonorrhoeae or Chlamydia trachomatis. Adherent pili are the primary virulence factor of N. gonorrhoeae, and gram-negative diplococci in vaginal discharge point to gonococcal PID.

Question 21

This patient, who has been experiencing vaginal itching for the past week, is found to have greenish vaginal discharge and a friable cervix, a presentation that suggests a diagnosis of trichomoniasis, a sexually transmitted infection (STI). Three million Trichomonas infections are diagnosed annually in the United States. Although both women and men may be infected, men have no symptoms. All sexual partners of the infected patient must be treated with metronidazole. Trichomonas vaginalis is typically seen as ?

Answer 21

flagellated trophozoites on a wet mount. Polymerase chain reaction (PCR) may also be used to identify the organism. Because the frequency of mixed STIs is relatively high, the finding of motile protozoa means further workup is needed.